Removed trailing \n from error_msg{,_and_die} messages.

[oweals/busybox.git] / gzip.c

/* vi: set sw=4 ts=4: */
/*
 * Gzip implementation for busybox
 *
 * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
 *
 * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
 *              "this is a stripped down version of gzip I put into busybox, it does
 *              only standard in to standard out with -9 compression.  It also requires
 *              the zcat module for some important functions."
 *
 * Adjusted further by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>
 * to support files as well as stdin/stdout, and to generally behave itself wrt
 * command line handling.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#include "busybox.h"
#define BB_DECLARE_EXTERN
#define bb_need_memory_exhausted
#include "messages.c"

/* These defines are very important for BusyBox.  Without these,
 * huge chunks of ram are pre-allocated making the BusyBox bss 
 * size Freaking Huge(tm), which is a bad thing.*/
#define SMALL_MEM
#define DYN_ALLOC

/* I don't like nested includes, but the string and io functions are used
 * too often
 */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define memzero(s, n)     memset ((void *)(s), 0, (n))

#ifndef RETSIGTYPE
#  define RETSIGTYPE void
#endif

#define local static

typedef unsigned char uch;
typedef unsigned short ush;
typedef unsigned long ulg;

/* Return codes from gzip */
#define OK      0
#define ERROR   1
#define WARNING 2

/* Compression methods (see algorithm.doc) */
#define STORED      0
#define COMPRESSED  1
#define PACKED      2
#define LZHED       3
/* methods 4 to 7 reserved */
#define DEFLATED    8
#define MAX_METHODS 9
extern int method;                              /* compression method */

/* To save memory for 16 bit systems, some arrays are overlaid between
 * the various modules:
 * deflate:  prev+head   window      d_buf  l_buf  outbuf
 * unlzw:    tab_prefix  tab_suffix  stack  inbuf  outbuf
 * inflate:              window             inbuf
 * unpack:               window             inbuf  prefix_len
 * unlzh:    left+right  window      c_table inbuf c_len
 * For compression, input is done in window[]. For decompression, output
 * is done in window except for unlzw.
 */

#ifndef INBUFSIZ
#  ifdef SMALL_MEM
#    define INBUFSIZ  0x2000    /* input buffer size */
#  else
#    define INBUFSIZ  0x8000    /* input buffer size */
#  endif
#endif
#define INBUF_EXTRA  64                 /* required by unlzw() */

#ifndef OUTBUFSIZ
#  ifdef SMALL_MEM
#    define OUTBUFSIZ   8192    /* output buffer size */
#  else
#    define OUTBUFSIZ  16384    /* output buffer size */
#  endif
#endif
#define OUTBUF_EXTRA 2048               /* required by unlzw() */

#ifndef DIST_BUFSIZE
#  ifdef SMALL_MEM
#    define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
#  else
#    define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
#  endif
#endif

#ifdef DYN_ALLOC
#  define EXTERN(type, array)  extern type * array
#  define DECLARE(type, array, size)  type * array
#  define ALLOC(type, array, size) { \
      array = (type*)calloc((size_t)(((size)+1L)/2), 2*sizeof(type)); \
      if (array == NULL) error_msg(memory_exhausted); \
   }
#  define FREE(array) {if (array != NULL) free(array), array=NULL;}
#else
#  define EXTERN(type, array)  extern type array[]
#  define DECLARE(type, array, size)  type array[size]
#  define ALLOC(type, array, size)
#  define FREE(array)
#endif

EXTERN(uch, inbuf);                             /* input buffer */
EXTERN(uch, outbuf);                    /* output buffer */
EXTERN(ush, d_buf);                             /* buffer for distances, see trees.c */
EXTERN(uch, window);                    /* Sliding window and suffix table (unlzw) */
#define tab_suffix window
#ifndef MAXSEG_64K
#  define tab_prefix prev               /* hash link (see deflate.c) */
#  define head (prev+WSIZE)             /* hash head (see deflate.c) */
EXTERN(ush, tab_prefix);                /* prefix code (see unlzw.c) */
#else
#  define tab_prefix0 prev
#  define head tab_prefix1
EXTERN(ush, tab_prefix0);               /* prefix for even codes */
EXTERN(ush, tab_prefix1);               /* prefix for odd  codes */
#endif

extern unsigned insize;                 /* valid bytes in inbuf */
extern unsigned inptr;                  /* index of next byte to be processed in inbuf */
extern unsigned outcnt;                 /* bytes in output buffer */

extern long bytes_in;                   /* number of input bytes */
extern long bytes_out;                  /* number of output bytes */
extern long header_bytes;               /* number of bytes in gzip header */

#define isize bytes_in
/* for compatibility with old zip sources (to be cleaned) */

extern int ifd;                                 /* input file descriptor */
extern int ofd;                                 /* output file descriptor */
extern char ifname[];                   /* input file name or "stdin" */
extern char ofname[];                   /* output file name or "stdout" */
extern char *progname;                  /* program name */

extern long time_stamp;                 /* original time stamp (modification time) */
extern long ifile_size;                 /* input file size, -1 for devices (debug only) */

typedef int file_t;                             /* Do not use stdio */

#define NO_FILE  (-1)                   /* in memory compression */


#define PACK_MAGIC     "\037\036"       /* Magic header for packed files */
#define GZIP_MAGIC     "\037\213"       /* Magic header for gzip files, 1F 8B */
#define OLD_GZIP_MAGIC "\037\236"       /* Magic header for gzip 0.5 = freeze 1.x */
#define LZH_MAGIC      "\037\240"       /* Magic header for SCO LZH Compress files */
#define PKZIP_MAGIC    "\120\113\003\004"       /* Magic header for pkzip files */

/* gzip flag byte */
#define ASCII_FLAG   0x01               /* bit 0 set: file probably ascii text */
#define CONTINUATION 0x02               /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04               /* bit 2 set: extra field present */
#define ORIG_NAME    0x08               /* bit 3 set: original file name present */
#define COMMENT      0x10               /* bit 4 set: file comment present */
#define ENCRYPTED    0x20               /* bit 5 set: file is encrypted */
#define RESERVED     0xC0               /* bit 6,7:   reserved */

/* internal file attribute */
#define UNKNOWN 0xffff
#define BINARY  0
#define ASCII   1

#ifndef WSIZE
#  define WSIZE 0x8000                  /* window size--must be a power of two, and */
#endif                                                  /*  at least 32K for zip's deflate method */

#define MIN_MATCH  3
#define MAX_MATCH  258
/* The minimum and maximum match lengths */

#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.
 */

#define MAX_DIST  (WSIZE-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
 * distances are limited to MAX_DIST instead of WSIZE.
 */

extern int decrypt;                             /* flag to turn on decryption */
extern int exit_code;                   /* program exit code */
extern int verbose;                             /* be verbose (-v) */
extern int quiet;                               /* be quiet (-q) */
extern int test;                                /* check .z file integrity */
extern int save_orig_name;              /* set if original name must be saved */

#define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(0))
#define try_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(1))

/* put_byte is used for the compressed output, put_ubyte for the
 * uncompressed output. However unlzw() uses window for its
 * suffix table instead of its output buffer, so it does not use put_ubyte
 * (to be cleaned up).
 */
#define put_byte(c) {outbuf[outcnt++]=(uch)(c); if (outcnt==OUTBUFSIZ)\
   flush_outbuf();}
#define put_ubyte(c) {window[outcnt++]=(uch)(c); if (outcnt==WSIZE)\
   flush_window();}

/* Output a 16 bit value, lsb first */
#define put_short(w) \
{ if (outcnt < OUTBUFSIZ-2) { \
    outbuf[outcnt++] = (uch) ((w) & 0xff); \
    outbuf[outcnt++] = (uch) ((ush)(w) >> 8); \
  } else { \
    put_byte((uch)((w) & 0xff)); \
    put_byte((uch)((ush)(w) >> 8)); \
  } \
}

/* Output a 32 bit value to the bit stream, lsb first */
#define put_long(n) { \
    put_short((n) & 0xffff); \
    put_short(((ulg)(n)) >> 16); \
}

#define seekable()    0                 /* force sequential output */
#define translate_eol 0                 /* no option -a yet */

#define tolow(c)  (isupper(c) ? (c)-'A'+'a' : (c))      /* force to lower case */

/* Macros for getting two-byte and four-byte header values */
#define SH(p) ((ush)(uch)((p)[0]) | ((ush)(uch)((p)[1]) << 8))
#define LG(p) ((ulg)(SH(p)) | ((ulg)(SH((p)+2)) << 16))

/* Diagnostic functions */
#ifdef DEBUG
#  define Assert(cond,msg) {if(!(cond)) error_msg(msg);}
#  define Trace(x) fprintf x
#  define Tracev(x) {if (verbose) fprintf x ;}
#  define Tracevv(x) {if (verbose>1) fprintf x ;}
#  define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
#  define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
#else
#  define Assert(cond,msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c,x)
#  define Tracecv(c,x)
#endif

#define WARN(msg) {if (!quiet) fprintf msg ; \
                   if (exit_code == OK) exit_code = WARNING;}


        /* in zip.c: */
extern int zip (int in, int out);
extern int file_read (char *buf, unsigned size);

        /* in unzip.c */
extern int unzip (int in, int out);
extern int check_zipfile (int in);

        /* in unpack.c */
extern int unpack (int in, int out);

        /* in unlzh.c */
extern int unlzh (int in, int out);

        /* in gzip.c */
RETSIGTYPE abort_gzip (void);

                /* in deflate.c */
void lm_init (ush * flags);
ulg deflate (void);

                /* in trees.c */
void ct_init (ush * attr, int *method);
int ct_tally (int dist, int lc);
ulg flush_block (char *buf, ulg stored_len, int eof);

                /* in bits.c */
void bi_init (file_t zipfile);
void send_bits (int value, int length);
unsigned bi_reverse (unsigned value, int length);
void bi_windup (void);
void copy_block (char *buf, unsigned len, int header);
extern int (*read_buf) (char *buf, unsigned size);

        /* in util.c: */
extern int copy (int in, int out);
extern ulg updcrc (uch * s, unsigned n);
extern void clear_bufs (void);
extern int fill_inbuf (int eof_ok);
extern void flush_outbuf (void);
extern void flush_window (void);
extern void write_buf (int fd, void * buf, unsigned cnt);
extern char *strlwr (char *s);
extern char *add_envopt (int *argcp, char ***argvp, char *env);
extern void read_error_msg (void);
extern void write_error_msg (void);
extern void display_ratio (long num, long den, FILE * file);

        /* in inflate.c */
extern int inflate (void);

/* lzw.h -- define the lzw functions.
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#if !defined(OF) && defined(lint)
#  include "gzip.h"
#endif

#ifndef BITS
#  define BITS 16
#endif
#define INIT_BITS 9                             /* Initial number of bits per code */

#define BIT_MASK    0x1f                /* Mask for 'number of compression bits' */
/* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
 * It's a pity that old uncompress does not check bit 0x20. That makes
 * extension of the format actually undesirable because old compress
 * would just crash on the new format instead of giving a meaningful
 * error message. It does check the number of bits, but it's more
 * helpful to say "unsupported format, get a new version" than
 * "can only handle 16 bits".
 */

#define BLOCK_MODE  0x80
/* Block compression: if table is full and compression rate is dropping,
 * clear the dictionary.
 */

#define LZW_RESERVED 0x60               /* reserved bits */

#define CLEAR  256                              /* flush the dictionary */
#define FIRST  (CLEAR+1)                /* first free entry */

extern int maxbits;                             /* max bits per code for LZW */
extern int block_mode;                  /* block compress mode -C compatible with 2.0 */

/* revision.h -- define the version number
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#define VERSION "1.2.4"
#define PATCHLEVEL 0
#define REVDATE "18 Aug 93"

/* This version does not support compression into old compress format: */
#ifdef LZW
#  undef LZW
#endif

/* tailor.h -- target dependent definitions
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/* The target dependent definitions should be defined here only.
 * The target dependent functions should be defined in tailor.c.
 */


#if defined(__MSDOS__) && !defined(MSDOS)
#  define MSDOS
#endif

#if defined(__OS2__) && !defined(OS2)
#  define OS2
#endif

#if defined(OS2) && defined(MSDOS)      /* MS C under OS/2 */
#  undef MSDOS
#endif

#ifdef MSDOS
#  ifdef __GNUC__
         /* DJGPP version 1.09+ on MS-DOS.
          * The DJGPP 1.09 stat() function must be upgraded before gzip will
          * fully work.
          * No need for DIRENT, since <unistd.h> defines POSIX_SOURCE which
          * implies DIRENT.
          */
#    define near
#  else
#    define MAXSEG_64K
#    ifdef __TURBOC__
#      define NO_OFF_T
#      ifdef __BORLANDC__
#        define DIRENT
#      else
#        define NO_UTIME
#      endif
#    else                                               /* MSC */
#      define HAVE_SYS_UTIME_H
#      define NO_UTIME_H
#    endif
#  endif
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  128
#  define NO_MULTIPLE_DOTS
#  define MAX_EXT_CHARS 3
#  define Z_SUFFIX "z"
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  define NO_SIZE_CHECK
#  define casemap(c) tolow(c)   /* Force file names to lower case */
#  include <io.h>
#  define OS_CODE  0x00
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  if !defined(NO_ASM) && !defined(ASMV)
#    define ASMV
#  endif
#else
#  define near
#endif

#ifdef OS2
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  260
#  ifdef OS2FAT
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define casemap(c) tolow(c)
#  endif
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  include <io.h>
#  define OS_CODE  0x06
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  ifdef _MSC_VER
#    define HAVE_SYS_UTIME_H
#    define NO_UTIME_H
#    define MAXSEG_64K
#    undef near
#    define near _near
#  endif
#  ifdef __EMX__
#    define HAVE_SYS_UTIME_H
#    define NO_UTIME_H
#    define DIRENT
#    define EXPAND(argc,argv) \
       {_response(&argc, &argv); _wildcard(&argc, &argv);}
#  endif
#  ifdef __BORLANDC__
#    define DIRENT
#  endif
#  ifdef __ZTC__
#    define NO_DIR
#    define NO_UTIME_H
#    include <dos.h>
#    define EXPAND(argc,argv) \
       {response_expand(&argc, &argv);}
#  endif
#endif

#ifdef WIN32                                    /* Windows NT */
#  define HAVE_SYS_UTIME_H
#  define NO_UTIME_H
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  260
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  include <io.h>
#  include <malloc.h>
#  ifdef NTFAT
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define casemap(c) tolow(c) /* Force file names to lower case */
#  endif
#  define OS_CODE  0x0b
#endif

#ifdef MSDOS
#  ifdef __TURBOC__
#    include <alloc.h>
#    define DYN_ALLOC
         /* Turbo C 2.0 does not accept static allocations of large arrays */
void *fcalloc(unsigned items, unsigned size);
void fcfree(void *ptr);
#  else                                                 /* MSC */
#    include <malloc.h>
#    define fcalloc(nitems,itemsize) halloc((long)(nitems),(itemsize))
#    define fcfree(ptr) hfree(ptr)
#  endif
#else
#  ifdef MAXSEG_64K
#    define fcalloc(items,size) calloc((items),(size))
#  else
#    define fcalloc(items,size) malloc((size_t)(items)*(size_t)(size))
#  endif
#  define fcfree(ptr) free(ptr)
#endif

#if defined(VAXC) || defined(VMS)
#  define PATH_SEP ']'
#  define PATH_SEP2 ':'
#  define SUFFIX_SEP ';'
#  define NO_MULTIPLE_DOTS
#  define Z_SUFFIX "-gz"
#  define RECORD_IO 1
#  define casemap(c) tolow(c)
#  define OS_CODE  0x02
#  define OPTIONS_VAR "GZIP_OPT"
#  define STDC_HEADERS
#  define NO_UTIME
#  define EXPAND(argc,argv) vms_expand_args(&argc,&argv);
#  include <file.h>
#  define unlink delete
#  ifdef VAXC
#    define NO_FCNTL_H
#    include <unixio.h>
#  endif
#endif

#ifdef AMIGA
#  define PATH_SEP2 ':'
#  define STDC_HEADERS
#  define OS_CODE  0x01
#  define ASMV
#  ifdef __GNUC__
#    define DIRENT
#    define HAVE_UNISTD_H
#  else                                                 /* SASC */
#    define NO_STDIN_FSTAT
#    define SYSDIR
#    define NO_SYMLINK
#    define NO_CHOWN
#    define NO_FCNTL_H
#    include <fcntl.h>                  /* for read() and write() */
#    define direct dirent
extern void _expand_args(int *argc, char ***argv);

#    define EXPAND(argc,argv) _expand_args(&argc,&argv);
#    undef  O_BINARY                    /* disable useless --ascii option */
#  endif
#endif

#if defined(ATARI) || defined(atarist)
#  ifndef STDC_HEADERS
#    define STDC_HEADERS
#    define HAVE_UNISTD_H
#    define DIRENT
#  endif
#  define ASMV
#  define OS_CODE  0x05
#  ifdef TOSFS
#    define PATH_SEP2 '\\'
#    define PATH_SEP3 ':'
#    define MAX_PATH_LEN  128
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define NO_CHOWN
#    define casemap(c) tolow(c) /* Force file names to lower case */
#    define NO_SYMLINK
#  endif
#endif

#ifdef MACOS
#  define PATH_SEP ':'
#  define DYN_ALLOC
#  define PROTO
#  define NO_STDIN_FSTAT
#  define NO_CHOWN
#  define NO_UTIME
#  define chmod(file, mode) (0)
#  define OPEN(name, flags, mode) open(name, flags)
#  define OS_CODE  0x07
#  ifdef MPW
#    define isatty(fd) ((fd) <= 2)
#  endif
#endif

#ifdef __50SERIES                               /* Prime/PRIMOS */
#  define PATH_SEP '>'
#  define STDC_HEADERS
#  define NO_MEMORY_H
#  define NO_UTIME_H
#  define NO_UTIME
#  define NO_CHOWN
#  define NO_STDIN_FSTAT
#  define NO_SIZE_CHECK
#  define NO_SYMLINK
#  define RECORD_IO  1
#  define casemap(c)  tolow(c)  /* Force file names to lower case */
#  define put_char(c) put_byte((c) & 0x7F)
#  define get_char(c) ascii2pascii(get_byte())
#  define OS_CODE  0x0F                 /* temporary, subject to change */
#  ifdef SIGTERM
#    undef SIGTERM                              /* We don't want a signal handler for SIGTERM */
#  endif
#endif

#if defined(pyr) && !defined(NOMEMCPY)  /* Pyramid */
#  define NOMEMCPY                              /* problem with overlapping copies */
#endif

#ifdef TOPS20
#  define OS_CODE  0x0a
#endif

#ifndef unix
#  define NO_ST_INO                             /* don't rely on inode numbers */
#endif


        /* Common defaults */

#ifndef OS_CODE
#  define OS_CODE  0x03                 /* assume Unix */
#endif

#ifndef PATH_SEP
#  define PATH_SEP '/'
#endif

#ifndef casemap
#  define casemap(c) (c)
#endif

#ifndef OPTIONS_VAR
#  define OPTIONS_VAR "GZIP"
#endif

#ifndef Z_SUFFIX
#  define Z_SUFFIX ".gz"
#endif

#ifdef MAX_EXT_CHARS
#  define MAX_SUFFIX  MAX_EXT_CHARS
#else
#  define MAX_SUFFIX  30
#endif

#ifndef MAKE_LEGAL_NAME
#  ifdef NO_MULTIPLE_DOTS
#    define MAKE_LEGAL_NAME(name)   make_simple_name(name)
#  else
#    define MAKE_LEGAL_NAME(name)
#  endif
#endif

#ifndef MIN_PART
#  define MIN_PART 3
   /* keep at least MIN_PART chars between dots in a file name. */
#endif

#ifndef EXPAND
#  define EXPAND(argc,argv)
#endif

#ifndef RECORD_IO
#  define RECORD_IO 0
#endif

#ifndef SET_BINARY_MODE
#  define SET_BINARY_MODE(fd)
#endif

#ifndef OPEN
#  define OPEN(name, flags, mode) open(name, flags, mode)
#endif

#ifndef get_char
#  define get_char() get_byte()
#endif

#ifndef put_char
#  define put_char(c) put_byte(c)
#endif
/* bits.c -- output variable-length bit strings
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */


/*
 *  PURPOSE
 *
 *      Output variable-length bit strings. Compression can be done
 *      to a file or to memory. (The latter is not supported in this version.)
 *
 *  DISCUSSION
 *
 *      The PKZIP "deflate" file format interprets compressed file data
 *      as a sequence of bits.  Multi-bit strings in the file may cross
 *      byte boundaries without restriction.
 *
 *      The first bit of each byte is the low-order bit.
 *
 *      The routines in this file allow a variable-length bit value to
 *      be output right-to-left (useful for literal values). For
 *      left-to-right output (useful for code strings from the tree routines),
 *      the bits must have been reversed first with bi_reverse().
 *
 *      For in-memory compression, the compressed bit stream goes directly
 *      into the requested output buffer. The input data is read in blocks
 *      by the mem_read() function. The buffer is limited to 64K on 16 bit
 *      machines.
 *
 *  INTERFACE
 *
 *      void bi_init (FILE *zipfile)
 *          Initialize the bit string routines.
 *
 *      void send_bits (int value, int length)
 *          Write out a bit string, taking the source bits right to
 *          left.
 *
 *      int bi_reverse (int value, int length)
 *          Reverse the bits of a bit string, taking the source bits left to
 *          right and emitting them right to left.
 *
 *      void bi_windup (void)
 *          Write out any remaining bits in an incomplete byte.
 *
 *      void copy_block(char *buf, unsigned len, int header)
 *          Copy a stored block to the zip file, storing first the length and
 *          its one's complement if requested.
 *
 */

#ifdef DEBUG
#  include <stdio.h>
#endif

/* ===========================================================================
 * Local data used by the "bit string" routines.
 */

local file_t zfile;                             /* output gzip file */

local unsigned short bi_buf;

/* Output buffer. bits are inserted starting at the bottom (least significant
 * bits).
 */

#define Buf_size (8 * 2*sizeof(char))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
 * more than 16 bits on some systems.)
 */

local int bi_valid;

/* Number of valid bits in bi_buf.  All bits above the last valid bit
 * are always zero.
 */

int (*read_buf) (char *buf, unsigned size);

/* Current input function. Set to mem_read for in-memory compression */

#ifdef DEBUG
ulg bits_sent;                                  /* bit length of the compressed data */
#endif

/* ===========================================================================
 * Initialize the bit string routines.
 */
void bi_init(zipfile)
file_t zipfile;                                 /* output zip file, NO_FILE for in-memory compression */
{
        zfile = zipfile;
        bi_buf = 0;
        bi_valid = 0;
#ifdef DEBUG
        bits_sent = 0L;
#endif

        /* Set the defaults for file compression. They are set by memcompress
         * for in-memory compression.
         */
        if (zfile != NO_FILE) {
                read_buf = file_read;
        }
}

/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
void send_bits(value, length)
int value;                                              /* value to send */
int length;                                             /* number of bits */
{
#ifdef DEBUG
        Tracev((stderr, " l %2d v %4x ", length, value));
        Assert(length > 0 && length <= 15, "invalid length");
        bits_sent += (ulg) length;
#endif
        /* If not enough room in bi_buf, use (valid) bits from bi_buf and
         * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
         * unused bits in value.
         */
        if (bi_valid > (int) Buf_size - length) {
                bi_buf |= (value << bi_valid);
                put_short(bi_buf);
                bi_buf = (ush) value >> (Buf_size - bi_valid);
                bi_valid += length - Buf_size;
        } else {
                bi_buf |= value << bi_valid;
                bi_valid += length;
        }
}

/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
unsigned bi_reverse(code, len)
unsigned code;                                  /* the value to invert */
int len;                                                /* its bit length */
{
        register unsigned res = 0;

        do {
                res |= code & 1;
                code >>= 1, res <<= 1;
        } while (--len > 0);
        return res >> 1;
}

/* ===========================================================================
 * Write out any remaining bits in an incomplete byte.
 */
void bi_windup()
{
        if (bi_valid > 8) {
                put_short(bi_buf);
        } else if (bi_valid > 0) {
                put_byte(bi_buf);
        }
        bi_buf = 0;
        bi_valid = 0;
#ifdef DEBUG
        bits_sent = (bits_sent + 7) & ~7;
#endif
}

/* ===========================================================================
 * Copy a stored block to the zip file, storing first the length and its
 * one's complement if requested.
 */
void copy_block(buf, len, header)
char *buf;                                              /* the input data */
unsigned len;                                   /* its length */
int header;                                             /* true if block header must be written */
{
        bi_windup();                            /* align on byte boundary */

        if (header) {
                put_short((ush) len);
                put_short((ush) ~ len);
#ifdef DEBUG
                bits_sent += 2 * 16;
#endif
        }
#ifdef DEBUG
        bits_sent += (ulg) len << 3;
#endif
        while (len--) {
#ifdef CRYPT
                int t;

                if (key)
                        zencode(*buf, t);
#endif
                put_byte(*buf++);
        }
}

/* deflate.c -- compress data using the deflation algorithm
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/*
 *  PURPOSE
 *
 *      Identify new text as repetitions of old text within a fixed-
 *      length sliding window trailing behind the new text.
 *
 *  DISCUSSION
 *
 *      The "deflation" process depends on being able to identify portions
 *      of the input text which are identical to earlier input (within a
 *      sliding window trailing behind the input currently being processed).
 *
 *      The most straightforward technique turns out to be the fastest for
 *      most input files: try all possible matches and select the longest.
 *      The key feature of this algorithm is that insertions into the string
 *      dictionary are very simple and thus fast, and deletions are avoided
 *      completely. Insertions are performed at each input character, whereas
 *      string matches are performed only when the previous match ends. So it
 *      is preferable to spend more time in matches to allow very fast string
 *      insertions and avoid deletions. The matching algorithm for small
 *      strings is inspired from that of Rabin & Karp. A brute force approach
 *      is used to find longer strings when a small match has been found.
 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
 *      (by Leonid Broukhis).
 *         A previous version of this file used a more sophisticated algorithm
 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
 *      time, but has a larger average cost, uses more memory and is patented.
 *      However the F&G algorithm may be faster for some highly redundant
 *      files if the parameter max_chain_length (described below) is too large.
 *
 *  ACKNOWLEDGEMENTS
 *
 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
 *      I found it in 'freeze' written by Leonid Broukhis.
 *      Thanks to many info-zippers for bug reports and testing.
 *
 *  REFERENCES
 *
 *      APPNOTE.TXT documentation file in PKZIP 1.93a distribution.
 *
 *      A description of the Rabin and Karp algorithm is given in the book
 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
 *
 *      Fiala,E.R., and Greene,D.H.
 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
 *
 *  INTERFACE
 *
 *      void lm_init (int pack_level, ush *flags)
 *          Initialize the "longest match" routines for a new file
 *
 *      ulg deflate (void)
 *          Processes a new input file and return its compressed length. Sets
 *          the compressed length, crc, deflate flags and internal file
 *          attributes.
 */

#include <stdio.h>

/* ===========================================================================
 * Configuration parameters
 */

/* Compile with MEDIUM_MEM to reduce the memory requirements or
 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
 * entire input file can be held in memory (not possible on 16 bit systems).
 * Warning: defining these symbols affects HASH_BITS (see below) and thus
 * affects the compression ratio. The compressed output
 * is still correct, and might even be smaller in some cases.
 */

#ifdef SMALL_MEM
#   define HASH_BITS  13                /* Number of bits used to hash strings */
#endif
#ifdef MEDIUM_MEM
#   define HASH_BITS  14
#endif
#ifndef HASH_BITS
#   define HASH_BITS  15
   /* For portability to 16 bit machines, do not use values above 15. */
#endif

/* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
 * window with tab_suffix. Check that we can do this:
 */
#if (WSIZE<<1) > (1<<BITS)
error:cannot overlay window with tab_suffix and prev with tab_prefix0
#endif
#if HASH_BITS > BITS-1
error:cannot overlay head with tab_prefix1
#endif
#define HASH_SIZE (unsigned)(1<<HASH_BITS)
#define HASH_MASK (HASH_SIZE-1)
#define WMASK     (WSIZE-1)
/* HASH_SIZE and WSIZE must be powers of two */
#define NIL 0
/* Tail of hash chains */
#define FAST 4
#define SLOW 2
/* speed options for the general purpose bit flag */
#ifndef TOO_FAR
#  define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
/* ===========================================================================
 * Local data used by the "longest match" routines.
 */
typedef ush Pos;
typedef unsigned IPos;

/* A Pos is an index in the character window. We use short instead of int to
 * save space in the various tables. IPos is used only for parameter passing.
 */

/* DECLARE(uch, window, 2L*WSIZE); */
/* Sliding window. Input bytes are read into the second half of the window,
 * and move to the first half later to keep a dictionary of at least WSIZE
 * bytes. With this organization, matches are limited to a distance of
 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
 * performed with a length multiple of the block size. Also, it limits
 * the window size to 64K, which is quite useful on MSDOS.
 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
 * be less efficient).
 */

/* DECLARE(Pos, prev, WSIZE); */
/* Link to older string with same hash index. To limit the size of this
 * array to 64K, this link is maintained only for the last 32K strings.
 * An index in this array is thus a window index modulo 32K.
 */

/* DECLARE(Pos, head, 1<<HASH_BITS); */
/* Heads of the hash chains or NIL. */

ulg window_size = (ulg) 2 * WSIZE;

/* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
 * input file length plus MIN_LOOKAHEAD.
 */

long block_start;

/* window position at the beginning of the current output block. Gets
 * negative when the window is moved backwards.
 */

local unsigned ins_h;                   /* hash index of string to be inserted */

#define H_SHIFT  ((HASH_BITS+MIN_MATCH-1)/MIN_MATCH)
/* Number of bits by which ins_h and del_h must be shifted at each
 * input step. It must be such that after MIN_MATCH steps, the oldest
 * byte no longer takes part in the hash key, that is:
 *   H_SHIFT * MIN_MATCH >= HASH_BITS
 */

unsigned int near prev_length;

/* Length of the best match at previous step. Matches not greater than this
 * are discarded. This is used in the lazy match evaluation.
 */

unsigned near strstart;                 /* start of string to insert */
unsigned near match_start;              /* start of matching string */
local int eofile;                               /* flag set at end of input file */
local unsigned lookahead;               /* number of valid bytes ahead in window */

unsigned near max_chain_length;

/* To speed up deflation, hash chains are never searched beyond this length.
 * A higher limit improves compression ratio but degrades the speed.
 */

local unsigned int max_lazy_match;

/* Attempt to find a better match only when the current match is strictly
 * smaller than this value. This mechanism is used only for compression
 * levels >= 4.
 */
#define max_insert_length  max_lazy_match
/* Insert new strings in the hash table only if the match length
 * is not greater than this length. This saves time but degrades compression.
 * max_insert_length is used only for compression levels <= 3.
 */

unsigned near good_match;

/* Use a faster search when the previous match is longer than this */


/* Values for max_lazy_match, good_match and max_chain_length, depending on
 * the desired pack level (0..9). The values given below have been tuned to
 * exclude worst case performance for pathological files. Better values may be
 * found for specific files.
 */

typedef struct config {
        ush good_length;                        /* reduce lazy search above this match length */
        ush max_lazy;                           /* do not perform lazy search above this match length */
        ush nice_length;                        /* quit search above this match length */
        ush max_chain;
} config;

#ifdef  FULL_SEARCH
# define nice_match MAX_MATCH
#else
int near nice_match;                    /* Stop searching when current match exceeds this */
#endif

local config configuration_table =
                                                                /* 9 */ { 32, 258, 258, 4096 };
                                                                /* maximum compression */

/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 * meaning.
 */

#define EQUAL 0
/* result of memcmp for equal strings */

/* ===========================================================================
 *  Prototypes for local functions.
 */
local void fill_window (void);

int longest_match (IPos cur_match);

#ifdef ASMV
void match_init (void);         /* asm code initialization */
#endif

#ifdef DEBUG
local void check_match (IPos start, IPos match, int length);
#endif

/* ===========================================================================
 * Update a hash value with the given input byte
 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
 *    input characters, so that a running hash key can be computed from the
 *    previous key instead of complete recalculation each time.
 */
#define UPDATE_HASH(h,c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)

/* ===========================================================================
 * Insert string s in the dictionary and set match_head to the previous head
 * of the hash chain (the most recent string with same hash key). Return
 * the previous length of the hash chain.
 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
 *    input characters and the first MIN_MATCH bytes of s are valid
 *    (except for the last MIN_MATCH-1 bytes of the input file).
 */
#define INSERT_STRING(s, match_head) \
   (UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]), \
    prev[(s) & WMASK] = match_head = head[ins_h], \
    head[ins_h] = (s))

/* ===========================================================================
 * Initialize the "longest match" routines for a new file
 */
void lm_init(flags)
ush *flags;                                             /* general purpose bit flag */
{
        register unsigned j;

        /* Initialize the hash table. */
#if defined(MAXSEG_64K) && HASH_BITS == 15
        for (j = 0; j < HASH_SIZE; j++)
                head[j] = NIL;
#else
        memzero((char *) head, HASH_SIZE * sizeof(*head));
#endif
        /* prev will be initialized on the fly */

        /* Set the default configuration parameters:
         */
        max_lazy_match = configuration_table.max_lazy;
        good_match = configuration_table.good_length;
#ifndef FULL_SEARCH
        nice_match = configuration_table.nice_length;
#endif
        max_chain_length = configuration_table.max_chain;
        *flags |= SLOW;
        /* ??? reduce max_chain_length for binary files */

        strstart = 0;
        block_start = 0L;
#ifdef ASMV
        match_init();                           /* initialize the asm code */
#endif

        lookahead = read_buf((char *) window,
                                                 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);

        if (lookahead == 0 || lookahead == (unsigned) EOF) {
                eofile = 1, lookahead = 0;
                return;
        }
        eofile = 0;
        /* Make sure that we always have enough lookahead. This is important
         * if input comes from a device such as a tty.
         */
        while (lookahead < MIN_LOOKAHEAD && !eofile)
                fill_window();

        ins_h = 0;
        for (j = 0; j < MIN_MATCH - 1; j++)
                UPDATE_HASH(ins_h, window[j]);
        /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
         * not important since only literal bytes will be emitted.
         */
}

/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 */
#ifndef ASMV
/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
 * match.s. The code is functionally equivalent, so you can use the C version
 * if desired.
 */
int longest_match(cur_match)
IPos cur_match;                                 /* current match */
{
        unsigned chain_length = max_chain_length;       /* max hash chain length */
        register uch *scan = window + strstart; /* current string */
        register uch *match;            /* matched string */
        register int len;                       /* length of current match */
        int best_len = prev_length;     /* best match length so far */
        IPos limit =

                strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : NIL;
        /* Stop when cur_match becomes <= limit. To simplify the code,
         * we prevent matches with the string of window index 0.
         */

/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
 * It is easy to get rid of this optimization if necessary.
 */
#if HASH_BITS < 8 || MAX_MATCH != 258
  error:Code too clever
#endif
#ifdef UNALIGNED_OK
                /* Compare two bytes at a time. Note: this is not always beneficial.
                 * Try with and without -DUNALIGNED_OK to check.
                 */
        register uch *strend = window + strstart + MAX_MATCH - 1;
        register ush scan_start = *(ush *) scan;
        register ush scan_end = *(ush *) (scan + best_len - 1);
#else
        register uch *strend = window + strstart + MAX_MATCH;
        register uch scan_end1 = scan[best_len - 1];
        register uch scan_end = scan[best_len];
#endif

        /* Do not waste too much time if we already have a good match: */
        if (prev_length >= good_match) {
                chain_length >>= 2;
        }
        Assert(strstart <= window_size - MIN_LOOKAHEAD,
                   "insufficient lookahead");

        do {
                Assert(cur_match < strstart, "no future");
                match = window + cur_match;

                /* Skip to next match if the match length cannot increase
                 * or if the match length is less than 2:
                 */
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
                /* This code assumes sizeof(unsigned short) == 2. Do not use
                 * UNALIGNED_OK if your compiler uses a different size.
                 */
                if (*(ush *) (match + best_len - 1) != scan_end ||
                        *(ush *) match != scan_start)
                        continue;

                /* It is not necessary to compare scan[2] and match[2] since they are
                 * always equal when the other bytes match, given that the hash keys
                 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
                 * strstart+3, +5, ... up to strstart+257. We check for insufficient
                 * lookahead only every 4th comparison; the 128th check will be made
                 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
                 * necessary to put more guard bytes at the end of the window, or
                 * to check more often for insufficient lookahead.
                 */
                scan++, match++;
                do {
                } while (*(ush *) (scan += 2) == *(ush *) (match += 2) &&
                                 *(ush *) (scan += 2) == *(ush *) (match += 2) &&
                                 *(ush *) (scan += 2) == *(ush *) (match += 2) &&
                                 *(ush *) (scan += 2) == *(ush *) (match += 2) &&
                                 scan < strend);
                /* The funny "do {}" generates better code on most compilers */

                /* Here, scan <= window+strstart+257 */
                Assert(scan <= window + (unsigned) (window_size - 1), "wild scan");
                if (*scan == *match)
                        scan++;

                len = (MAX_MATCH - 1) - (int) (strend - scan);
                scan = strend - (MAX_MATCH - 1);

#else                                                   /* UNALIGNED_OK */

                if (match[best_len] != scan_end ||
                        match[best_len - 1] != scan_end1 ||
                        *match != *scan || *++match != scan[1])
                        continue;

                /* The check at best_len-1 can be removed because it will be made
                 * again later. (This heuristic is not always a win.)
                 * It is not necessary to compare scan[2] and match[2] since they
                 * are always equal when the other bytes match, given that
                 * the hash keys are equal and that HASH_BITS >= 8.
                 */
                scan += 2, match++;

                /* We check for insufficient lookahead only every 8th comparison;
                 * the 256th check will be made at strstart+258.
                 */
                do {
                } while (*++scan == *++match && *++scan == *++match &&
                                 *++scan == *++match && *++scan == *++match &&
                                 *++scan == *++match && *++scan == *++match &&
                                 *++scan == *++match && *++scan == *++match &&
                                 scan < strend);

                len = MAX_MATCH - (int) (strend - scan);
                scan = strend - MAX_MATCH;

#endif                                                  /* UNALIGNED_OK */

                if (len > best_len) {
                        match_start = cur_match;
                        best_len = len;
                        if (len >= nice_match)
                                break;
#ifdef UNALIGNED_OK
                        scan_end = *(ush *) (scan + best_len - 1);
#else
                        scan_end1 = scan[best_len - 1];
                        scan_end = scan[best_len];
#endif
                }
        } while ((cur_match = prev[cur_match & WMASK]) > limit
                         && --chain_length != 0);

        return best_len;
}
#endif                                                  /* ASMV */

#ifdef DEBUG
/* ===========================================================================
 * Check that the match at match_start is indeed a match.
 */
local void check_match(start, match, length)
IPos start, match;
int length;
{
        /* check that the match is indeed a match */
        if (memcmp((char *) window + match,
                           (char *) window + start, length) != EQUAL) {
                fprintf(stderr,
                                " start %d, match %d, length %d\n", start, match, length);
                error_msg("invalid match");
        }
        if (verbose > 1) {
                fprintf(stderr, "\\[%d,%d]", start - match, length);
                do {
                        putc(window[start++], stderr);
                } while (--length != 0);
        }
}
#else
#  define check_match(start, match, length)
#endif

/* ===========================================================================
 * Fill the window when the lookahead becomes insufficient.
 * Updates strstart and lookahead, and sets eofile if end of input file.
 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
 * OUT assertions: at least one byte has been read, or eofile is set;
 *    file reads are performed for at least two bytes (required for the
 *    translate_eol option).
 */
local void fill_window()
{
        register unsigned n, m;
        unsigned more =

                (unsigned) (window_size - (ulg) lookahead - (ulg) strstart);
        /* Amount of free space at the end of the window. */

        /* If the window is almost full and there is insufficient lookahead,
         * move the upper half to the lower one to make room in the upper half.
         */
        if (more == (unsigned) EOF) {
                /* Very unlikely, but possible on 16 bit machine if strstart == 0
                 * and lookahead == 1 (input done one byte at time)
                 */
                more--;
        } else if (strstart >= WSIZE + MAX_DIST) {
                /* By the IN assertion, the window is not empty so we can't confuse
                 * more == 0 with more == 64K on a 16 bit machine.
                 */
                Assert(window_size == (ulg) 2 * WSIZE, "no sliding with BIG_MEM");

                memcpy((char *) window, (char *) window + WSIZE, (unsigned) WSIZE);
                match_start -= WSIZE;
                strstart -= WSIZE;              /* we now have strstart >= MAX_DIST: */

                block_start -= (long) WSIZE;

                for (n = 0; n < HASH_SIZE; n++) {
                        m = head[n];
                        head[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
                }
                for (n = 0; n < WSIZE; n++) {
                        m = prev[n];
                        prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
                        /* If n is not on any hash chain, prev[n] is garbage but
                         * its value will never be used.
                         */
                }
                more += WSIZE;
        }
        /* At this point, more >= 2 */
        if (!eofile) {
                n = read_buf((char *) window + strstart + lookahead, more);
                if (n == 0 || n == (unsigned) EOF) {
                        eofile = 1;
                } else {
                        lookahead += n;
                }
        }
}

/* ===========================================================================
 * Flush the current block, with given end-of-file flag.
 * IN assertion: strstart is set to the end of the current match.
 */
#define FLUSH_BLOCK(eof) \
   flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
                (char*)NULL, (long)strstart - block_start, (eof))

/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
ulg deflate()
{
        IPos hash_head;                         /* head of hash chain */
        IPos prev_match;                        /* previous match */
        int flush;                                      /* set if current block must be flushed */
        int match_available = 0;        /* set if previous match exists */
        register unsigned match_length = MIN_MATCH - 1; /* length of best match */

#ifdef DEBUG
        extern long isize;                      /* byte length of input file, for debug only */
#endif

        /* Process the input block. */
        while (lookahead != 0) {
                /* Insert the string window[strstart .. strstart+2] in the
                 * dictionary, and set hash_head to the head of the hash chain:
                 */
                INSERT_STRING(strstart, hash_head);

                /* Find the longest match, discarding those <= prev_length.
                 */
                prev_length = match_length, prev_match = match_start;
                match_length = MIN_MATCH - 1;

                if (hash_head != NIL && prev_length < max_lazy_match &&
                        strstart - hash_head <= MAX_DIST) {
                        /* To simplify the code, we prevent matches with the string
                         * of window index 0 (in particular we have to avoid a match
                         * of the string with itself at the start of the input file).
                         */
                        match_length = longest_match(hash_head);
                        /* longest_match() sets match_start */
                        if (match_length > lookahead)
                                match_length = lookahead;

                        /* Ignore a length 3 match if it is too distant: */
                        if (match_length == MIN_MATCH
                                && strstart - match_start > TOO_FAR) {
                                /* If prev_match is also MIN_MATCH, match_start is garbage
                                 * but we will ignore the current match anyway.
                                 */
                                match_length--;
                        }
                }
                /* If there was a match at the previous step and the current
                 * match is not better, output the previous match:
                 */
                if (prev_length >= MIN_MATCH && match_length <= prev_length) {

                        check_match(strstart - 1, prev_match, prev_length);

                        flush =
                                ct_tally(strstart - 1 - prev_match,
                                                 prev_length - MIN_MATCH);

                        /* Insert in hash table all strings up to the end of the match.
                         * strstart-1 and strstart are already inserted.
                         */
                        lookahead -= prev_length - 1;
                        prev_length -= 2;
                        do {
                                strstart++;
                                INSERT_STRING(strstart, hash_head);
                                /* strstart never exceeds WSIZE-MAX_MATCH, so there are
                                 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
                                 * these bytes are garbage, but it does not matter since the
                                 * next lookahead bytes will always be emitted as literals.
                                 */
                        } while (--prev_length != 0);
                        match_available = 0;
                        match_length = MIN_MATCH - 1;
                        strstart++;
                        if (flush)
                                FLUSH_BLOCK(0), block_start = strstart;

                } else if (match_available) {
                        /* If there was no match at the previous position, output a
                         * single literal. If there was a match but the current match
                         * is longer, truncate the previous match to a single literal.
                         */
                        Tracevv((stderr, "%c", window[strstart - 1]));
                        if (ct_tally(0, window[strstart - 1])) {
                                FLUSH_BLOCK(0), block_start = strstart;
                        }
                        strstart++;
                        lookahead--;
                } else {
                        /* There is no previous match to compare with, wait for
                         * the next step to decide.
                         */
                        match_available = 1;
                        strstart++;
                        lookahead--;
                }
                Assert(strstart <= isize && lookahead <= isize, "a bit too far");

                /* Make sure that we always have enough lookahead, except
                 * at the end of the input file. We need MAX_MATCH bytes
                 * for the next match, plus MIN_MATCH bytes to insert the
                 * string following the next match.
                 */
                while (lookahead < MIN_LOOKAHEAD && !eofile)
                        fill_window();
        }
        if (match_available)
                ct_tally(0, window[strstart - 1]);

        return FLUSH_BLOCK(1);          /* eof */
}

/* gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * The unzip code was written and put in the public domain by Mark Adler.
 * Portions of the lzw code are derived from the public domain 'compress'
 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
 * Ken Turkowski, Dave Mack and Peter Jannesen.
 *
 * See the license_msg below and the file COPYING for the software license.
 * See the file algorithm.doc for the compression algorithms and file formats.
 */

/* Compress files with zip algorithm and 'compress' interface.
 * See usage() and help() functions below for all options.
 * Outputs:
 *        file.gz:   compressed file with same mode, owner, and utimes
 *     or stdout with -c option or if stdin used as input.
 * If the output file name had to be truncated, the original name is kept
 * in the compressed file.
 * On MSDOS, file.tmp -> file.tmz. On VMS, file.tmp -> file.tmp-gz.
 *
 * Using gz on MSDOS would create too many file name conflicts. For
 * example, foo.txt -> foo.tgz (.tgz must be reserved as shorthand for
 * tar.gz). Similarly, foo.dir and foo.doc would both be mapped to foo.dgz.
 * I also considered 12345678.txt -> 12345txt.gz but this truncates the name
 * too heavily. There is no ideal solution given the MSDOS 8+3 limitation. 
 *
 * For the meaning of all compilation flags, see comments in Makefile.in.
 */

#include <ctype.h>
#include <sys/types.h>
#include <signal.h>
#include <errno.h>

                /* configuration */

#ifdef NO_TIME_H
#  include <sys/time.h>
#else
#  include <time.h>
#endif

#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif

#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
#  include <stdlib.h>
#else
extern int errno;
#endif

#if defined(DIRENT)
#  include <dirent.h>
typedef struct dirent dir_type;

#  define NLENGTH(dirent) ((int)strlen((dirent)->d_name))
#  define DIR_OPT "DIRENT"
#else
#  define NLENGTH(dirent) ((dirent)->d_namlen)
#  ifdef SYSDIR
#    include <sys/dir.h>
typedef struct direct dir_type;

#    define DIR_OPT "SYSDIR"
#  else
#    ifdef SYSNDIR
#      include <sys/ndir.h>
typedef struct direct dir_type;

#      define DIR_OPT "SYSNDIR"
#    else
#      ifdef NDIR
#        include <ndir.h>
typedef struct direct dir_type;

#        define DIR_OPT "NDIR"
#      else
#        define NO_DIR
#        define DIR_OPT "NO_DIR"
#      endif
#    endif
#  endif
#endif

#ifndef NO_UTIME
#  ifndef NO_UTIME_H
#    include <utime.h>
#    define TIME_OPT "UTIME"
#  else
#    ifdef HAVE_SYS_UTIME_H
#      include <sys/utime.h>
#      define TIME_OPT "SYS_UTIME"
#    else
struct utimbuf {
        time_t actime;
        time_t modtime;
};

#      define TIME_OPT ""
#    endif
#  endif
#else
#  define TIME_OPT "NO_UTIME"
#endif

#if !defined(S_ISDIR) && defined(S_IFDIR)
#  define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif
#if !defined(S_ISREG) && defined(S_IFREG)
#  define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif

typedef RETSIGTYPE(*sig_type) (int);

#ifndef O_BINARY
#  define  O_BINARY  0                  /* creation mode for open() */
#endif

#ifndef O_CREAT
   /* Pure BSD system? */
#  include <sys/file.h>
#  ifndef O_CREAT
#    define O_CREAT FCREAT
#  endif
#  ifndef O_EXCL
#    define O_EXCL FEXCL
#  endif
#endif

#ifndef S_IRUSR
#  define S_IRUSR 0400
#endif
#ifndef S_IWUSR
#  define S_IWUSR 0200
#endif
#define RW_USER (S_IRUSR | S_IWUSR)     /* creation mode for open() */

#ifndef MAX_PATH_LEN
#  define MAX_PATH_LEN   1024   /* max pathname length */
#endif

#ifndef SEEK_END
#  define SEEK_END 2
#endif

#ifdef NO_OFF_T
typedef long off_t;
off_t lseek (int fd, off_t offset, int whence);
#endif

/* Separator for file name parts (see shorten_name()) */
#ifdef NO_MULTIPLE_DOTS
#  define PART_SEP "-"
#else
#  define PART_SEP "."
#endif

                /* global buffers */

DECLARE(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
DECLARE(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
DECLARE(ush, d_buf, DIST_BUFSIZE);
DECLARE(uch, window, 2L * WSIZE);
#ifndef MAXSEG_64K
DECLARE(ush, tab_prefix, 1L << BITS);
#else
DECLARE(ush, tab_prefix0, 1L << (BITS - 1));
DECLARE(ush, tab_prefix1, 1L << (BITS - 1));
#endif

                /* local variables */

static int foreground;                                  /* set if program run in foreground */
static int method = DEFLATED;   /* compression method */
static int exit_code = OK;              /* program exit code */
static int part_nb;                                     /* number of parts in .gz file */
static long time_stamp;                         /* original time stamp (modification time) */
static long ifile_size;                         /* input file size, -1 for devices (debug only) */
static char z_suffix[MAX_SUFFIX + 1];   /* default suffix (can be set with --suffix) */
static int z_len;                                               /* strlen(z_suffix) */

static long bytes_in;                                   /* number of input bytes */
static long bytes_out;                                  /* number of output bytes */
static char ifname[MAX_PATH_LEN];               /* input file name */
static char ofname[MAX_PATH_LEN];               /* output file name */
static int ifd;                                         /* input file descriptor */
static int ofd;                                         /* output file descriptor */
static unsigned insize;                         /* valid bytes in inbuf */
static unsigned outcnt;                         /* bytes in output buffer */

/* local functions */

#define strequ(s1, s2) (strcmp((s1),(s2)) == 0)

/* ======================================================================== */
// int main (argc, argv)
//    int argc;
//    char **argv;
int gzip_main(int argc, char **argv)
{
        int result;
        int inFileNum;
        int outFileNum;
        struct stat statBuf;
        char *delFileName;
        int tostdout = 0;
        int fromstdin = 0;
        int force = 0;

        /* Parse any options */
        while (--argc > 0 && **(++argv) == '-') {
                if (*((*argv) + 1) == '\0') {
                        tostdout = 1;
                }
                while (*(++(*argv))) {
                        switch (**argv) {
                        case 'c':
                                tostdout = 1;
                                break;
                        case 'f':
                                force = 1;
                                break;
                        /* Ignore 1-9 (compression level) options */
                        case '1': case '2': case '3': case '4': case '5':
                        case '6': case '7': case '8': case '9':
                                break;
                        case 'd':
                                exit(gunzip_main(argc, argv));
                        default:
                                usage(gzip_usage);
                        }
                }
        }
        if (argc <= 0 ) {
                fromstdin = 1;
                tostdout = 1;
        }

        if (isatty(fileno(stdin)) && fromstdin==1 && force==0)
                error_msg_and_die( "data not read from terminal. Use -f to force it.");
        if (isatty(fileno(stdout)) && tostdout==1 && force==0)
                error_msg_and_die( "data not written to terminal. Use -f to force it.");

        foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
        if (foreground) {
                (void) signal(SIGINT, (sig_type) abort_gzip);
        }
#ifdef SIGTERM
        if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
                (void) signal(SIGTERM, (sig_type) abort_gzip);
        }
#endif
#ifdef SIGHUP
        if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
                (void) signal(SIGHUP, (sig_type) abort_gzip);
        }
#endif

        strncpy(z_suffix, Z_SUFFIX, sizeof(z_suffix) - 1);
        z_len = strlen(z_suffix);

        /* Allocate all global buffers (for DYN_ALLOC option) */
        ALLOC(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
        ALLOC(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
        ALLOC(ush, d_buf, DIST_BUFSIZE);
        ALLOC(uch, window, 2L * WSIZE);
#ifndef MAXSEG_64K
        ALLOC(ush, tab_prefix, 1L << BITS);
#else
        ALLOC(ush, tab_prefix0, 1L << (BITS - 1));
        ALLOC(ush, tab_prefix1, 1L << (BITS - 1));
#endif

        if (fromstdin == 1) {
                strcpy(ofname, "stdin");

                inFileNum = fileno(stdin);
                time_stamp = 0;                 /* time unknown by default */
                ifile_size = -1L;               /* convention for unknown size */
        } else {
                /* Open up the input file */
                if (argc <= 0)
                        usage(gzip_usage);
                strncpy(ifname, *argv, MAX_PATH_LEN);

                /* Open input file */
                inFileNum = open(ifname, O_RDONLY);
                if (inFileNum < 0)
                        perror_msg_and_die("%s", ifname);
                /* Get the time stamp on the input file. */
                if (stat(ifname, &statBuf) < 0)
                        perror_msg_and_die("%s", ifname);
                time_stamp = statBuf.st_ctime;
                ifile_size = statBuf.st_size;
        }


        if (tostdout == 1) {
                /* And get to work */
                strcpy(ofname, "stdout");
                outFileNum = fileno(stdout);
                SET_BINARY_MODE(fileno(stdout));

                clear_bufs();                   /* clear input and output buffers */
                part_nb = 0;

                /* Actually do the compression/decompression. */
                zip(inFileNum, outFileNum);

        } else {

                /* And get to work */
                strncpy(ofname, ifname, MAX_PATH_LEN - 4);
                strcat(ofname, ".gz");


                /* Open output fille */
#if (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 1)
                outFileNum = open(ofname, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW);
#else
                outFileNum = open(ofname, O_RDWR | O_CREAT | O_EXCL);
#endif
                if (outFileNum < 0)
                        perror_msg_and_die("%s", ofname);
                SET_BINARY_MODE(outFileNum);
                /* Set permissions on the file */
                fchmod(outFileNum, statBuf.st_mode);

                clear_bufs();                   /* clear input and output buffers */
                part_nb = 0;

                /* Actually do the compression/decompression. */
                result = zip(inFileNum, outFileNum);
                close(outFileNum);
                close(inFileNum);
                /* Delete the original file */
                if (result == OK)
                        delFileName = ifname;
                else
                        delFileName = ofname;

                if (unlink(delFileName) < 0)
                        perror_msg_and_die("%s", delFileName);
        }

        return(exit_code);
}

/* trees.c -- output deflated data using Huffman coding
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/*
 *  PURPOSE
 *
 *      Encode various sets of source values using variable-length
 *      binary code trees.
 *
 *  DISCUSSION
 *
 *      The PKZIP "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in the ZIP file in a compressed form
 *      which is itself a Huffman encoding of the lengths of
 *      all the code strings (in ascending order by source values).
 *      The actual code strings are reconstructed from the lengths in
 *      the UNZIP process, as described in the "application note"
 *      (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
 *
 *  REFERENCES
 *
 *      Lynch, Thomas J.
 *          Data Compression:  Techniques and Applications, pp. 53-55.
 *          Lifetime Learning Publications, 1985.  ISBN 0-534-03418-7.
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 *
 *  INTERFACE
 *
 *      void ct_init (ush *attr, int *methodp)
 *          Allocate the match buffer, initialize the various tables and save
 *          the location of the internal file attribute (ascii/binary) and
 *          method (DEFLATE/STORE)
 *
 *      void ct_tally (int dist, int lc);
 *          Save the match info and tally the frequency counts.
 *
 *      long flush_block (char *buf, ulg stored_len, int eof)
 *          Determine the best encoding for the current block: dynamic trees,
 *          static trees or store, and output the encoded block to the zip
 *          file. Returns the total compressed length for the file so far.
 *
 */

#include <ctype.h>

/* ===========================================================================
 * Constants
 */

#define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

#define LITERALS  256
/* number of literal bytes 0..255 */

#define END_BLOCK 256
/* end of block literal code */

#define L_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */

#define D_CODES   30
/* number of distance codes */

#define BL_CODES  19
/* number of codes used to transfer the bit lengths */


local int near extra_lbits[LENGTH_CODES]        /* extra bits for each length code */
        = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
                4, 4, 5, 5, 5, 5, 0 };

local int near extra_dbits[D_CODES]     /* extra bits for each distance code */
        = { 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
                10, 10, 11, 11, 12, 12, 13, 13 };

local int near extra_blbits[BL_CODES]   /* extra bits for each bit length code */
= { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };

#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES    2
/* The three kinds of block type */

#ifndef LIT_BUFSIZE
#  ifdef SMALL_MEM
#    define LIT_BUFSIZE  0x2000
#  else
#  ifdef MEDIUM_MEM
#    define LIT_BUFSIZE  0x4000
#  else
#    define LIT_BUFSIZE  0x8000
#  endif
#  endif
#endif
#ifndef DIST_BUFSIZE
#  define DIST_BUFSIZE  LIT_BUFSIZE
#endif
/* Sizes of match buffers for literals/lengths and distances.  There are
 * 4 reasons for limiting LIT_BUFSIZE to 64K:
 *   - frequencies can be kept in 16 bit counters
 *   - if compression is not successful for the first block, all input data is
 *     still in the window so we can still emit a stored block even when input
 *     comes from standard input.  (This can also be done for all blocks if
 *     LIT_BUFSIZE is not greater than 32K.)
 *   - if compression is not successful for a file smaller than 64K, we can
 *     even emit a stored file instead of a stored block (saving 5 bytes).
 *   - creating new Huffman trees less frequently may not provide fast
 *     adaptation to changes in the input data statistics. (Take for
 *     example a binary file with poorly compressible code followed by
 *     a highly compressible string table.) Smaller buffer sizes give
 *     fast adaptation but have of course the overhead of transmitting trees
 *     more frequently.
 *   - I can't count above 4
 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
 * memory at the expense of compression). Some optimizations would be possible
 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
 */
#if LIT_BUFSIZE > INBUFSIZ
error cannot overlay l_buf and inbuf
#endif
#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */
#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) *//* ===========================================================================
 * Local data
 *//* Data structure describing a single value and its code string. */ typedef struct ct_data {
        union {
                ush freq;                               /* frequency count */
                ush code;                               /* bit string */
        } fc;
        union {
                ush dad;                                /* father node in Huffman tree */
                ush len;                                /* length of bit string */
        } dl;
} ct_data;

#define Freq fc.freq
#define Code fc.code
#define Dad  dl.dad
#define Len  dl.len

#define HEAP_SIZE (2*L_CODES+1)
/* maximum heap size */

local ct_data near dyn_ltree[HEAP_SIZE];        /* literal and length tree */
local ct_data near dyn_dtree[2 * D_CODES + 1];  /* distance tree */

local ct_data near static_ltree[L_CODES + 2];

/* The static literal tree. Since the bit lengths are imposed, there is no
 * need for the L_CODES extra codes used during heap construction. However
 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
 * below).
 */

local ct_data near static_dtree[D_CODES];

/* The static distance tree. (Actually a trivial tree since all codes use
 * 5 bits.)
 */

local ct_data near bl_tree[2 * BL_CODES + 1];

/* Huffman tree for the bit lengths */

typedef struct tree_desc {
        ct_data near *dyn_tree;         /* the dynamic tree */
        ct_data near *static_tree;      /* corresponding static tree or NULL */
        int near *extra_bits;           /* extra bits for each code or NULL */
        int extra_base;                         /* base index for extra_bits */
        int elems;                                      /* max number of elements in the tree */
        int max_length;                         /* max bit length for the codes */
        int max_code;                           /* largest code with non zero frequency */
} tree_desc;

local tree_desc near l_desc =
        { dyn_ltree, static_ltree, extra_lbits, LITERALS + 1, L_CODES,
                MAX_BITS, 0 };

local tree_desc near d_desc =
        { dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0 };

local tree_desc near bl_desc =
        { bl_tree, (ct_data near *) 0, extra_blbits, 0, BL_CODES, MAX_BL_BITS,
                0 };


local ush near bl_count[MAX_BITS + 1];

/* number of codes at each bit length for an optimal tree */

local uch near bl_order[BL_CODES]
= { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */

local int near heap[2 * L_CODES + 1];   /* heap used to build the Huffman trees */
local int heap_len;                             /* number of elements in the heap */
local int heap_max;                             /* element of largest frequency */

/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
 * The same heap array is used to build all trees.
 */

local uch near depth[2 * L_CODES + 1];

/* Depth of each subtree used as tie breaker for trees of equal frequency */

local uch length_code[MAX_MATCH - MIN_MATCH + 1];

/* length code for each normalized match length (0 == MIN_MATCH) */

local uch dist_code[512];

/* distance codes. The first 256 values correspond to the distances
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
 * the 15 bit distances.
 */

local int near base_length[LENGTH_CODES];

/* First normalized length for each code (0 = MIN_MATCH) */

local int near base_dist[D_CODES];

/* First normalized distance for each code (0 = distance of 1) */

#define l_buf inbuf
/* DECLARE(uch, l_buf, LIT_BUFSIZE);  buffer for literals or lengths */

/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */

local uch near flag_buf[(LIT_BUFSIZE / 8)];

/* flag_buf is a bit array distinguishing literals from lengths in
 * l_buf, thus indicating the presence or absence of a distance.
 */

local unsigned last_lit;                /* running index in l_buf */
local unsigned last_dist;               /* running index in d_buf */
local unsigned last_flags;              /* running index in flag_buf */
local uch flags;                                /* current flags not yet saved in flag_buf */
local uch flag_bit;                             /* current bit used in flags */

/* bits are filled in flags starting at bit 0 (least significant).
 * Note: these flags are overkill in the current code since we don't
 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
 */

local ulg opt_len;                              /* bit length of current block with optimal trees */
local ulg static_len;                   /* bit length of current block with static trees */

local ulg compressed_len;               /* total bit length of compressed file */

local ulg input_len;                    /* total byte length of input file */

/* input_len is for debugging only since we can get it by other means. */

ush *file_type;                                 /* pointer to UNKNOWN, BINARY or ASCII */
int *file_method;                               /* pointer to DEFLATE or STORE */

#ifdef DEBUG
extern ulg bits_sent;                   /* bit length of the compressed data */
extern long isize;                              /* byte length of input file */
#endif

extern long block_start;                /* window offset of current block */
extern unsigned near strstart;  /* window offset of current string */

/* ===========================================================================
 * Local (static) routines in this file.
 */

local void init_block (void);
local void pqdownheap (ct_data near * tree, int k);
local void gen_bitlen (tree_desc near * desc);
local void gen_codes (ct_data near * tree, int max_code);
local void build_tree (tree_desc near * desc);
local void scan_tree (ct_data near * tree, int max_code);
local void send_tree (ct_data near * tree, int max_code);
local int build_bl_tree (void);
local void send_all_trees (int lcodes, int dcodes, int blcodes);
local void compress_block (ct_data near * ltree, ct_data near * dtree);
local void set_file_type (void);


#ifndef DEBUG
#  define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
   /* Send a code of the given tree. c and tree must not have side effects */

#else                                                   /* DEBUG */
#  define send_code(c, tree) \
     { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
       send_bits(tree[c].Code, tree[c].Len); }
#endif

#define d_code(dist) \
   ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
/* Mapping from a distance to a distance code. dist is the distance - 1 and
 * must not have side effects. dist_code[256] and dist_code[257] are never
 * used.
 */

/* the arguments must not have side effects */

/* ===========================================================================
 * Allocate the match buffer, initialize the various tables and save the
 * location of the internal file attribute (ascii/binary) and method
 * (DEFLATE/STORE).
 */
void ct_init(attr, methodp)
ush *attr;                                              /* pointer to internal file attribute */
int *methodp;                                   /* pointer to compression method */
{
        int n;                                          /* iterates over tree elements */
        int bits;                                       /* bit counter */
        int length;                                     /* length value */
        int code;                                       /* code value */
        int dist;                                       /* distance index */

        file_type = attr;
        file_method = methodp;
        compressed_len = input_len = 0L;

        if (static_dtree[0].Len != 0)
                return;                                 /* ct_init already called */

        /* Initialize the mapping length (0..255) -> length code (0..28) */
        length = 0;
        for (code = 0; code < LENGTH_CODES - 1; code++) {
                base_length[code] = length;
                for (n = 0; n < (1 << extra_lbits[code]); n++) {
                        length_code[length++] = (uch) code;
                }
        }
        Assert(length == 256, "ct_init: length != 256");
        /* Note that the length 255 (match length 258) can be represented
         * in two different ways: code 284 + 5 bits or code 285, so we
         * overwrite length_code[255] to use the best encoding:
         */
        length_code[length - 1] = (uch) code;

        /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
        dist = 0;
        for (code = 0; code < 16; code++) {
                base_dist[code] = dist;
                for (n = 0; n < (1 << extra_dbits[code]); n++) {
                        dist_code[dist++] = (uch) code;
                }
        }
        Assert(dist == 256, "ct_init: dist != 256");
        dist >>= 7;                                     /* from now on, all distances are divided by 128 */
        for (; code < D_CODES; code++) {
                base_dist[code] = dist << 7;
                for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
                        dist_code[256 + dist++] = (uch) code;
                }
        }
        Assert(dist == 256, "ct_init: 256+dist != 512");

        /* Construct the codes of the static literal tree */
        for (bits = 0; bits <= MAX_BITS; bits++)
                bl_count[bits] = 0;
        n = 0;
        while (n <= 143)
                static_ltree[n++].Len = 8, bl_count[8]++;
        while (n <= 255)
                static_ltree[n++].Len = 9, bl_count[9]++;
        while (n <= 279)
                static_ltree[n++].Len = 7, bl_count[7]++;
        while (n <= 287)
                static_ltree[n++].Len = 8, bl_count[8]++;
        /* Codes 286 and 287 do not exist, but we must include them in the
         * tree construction to get a canonical Huffman tree (longest code
         * all ones)
         */
        gen_codes((ct_data near *) static_ltree, L_CODES + 1);

        /* The static distance tree is trivial: */
        for (n = 0; n < D_CODES; n++) {
                static_dtree[n].Len = 5;
                static_dtree[n].Code = bi_reverse(n, 5);
        }

        /* Initialize the first block of the first file: */
        init_block();
}

/* ===========================================================================
 * Initialize a new block.
 */
local void init_block()
{
        int n;                                          /* iterates over tree elements */

        /* Initialize the trees. */
        for (n = 0; n < L_CODES; n++)
                dyn_ltree[n].Freq = 0;
        for (n = 0; n < D_CODES; n++)
                dyn_dtree[n].Freq = 0;
        for (n = 0; n < BL_CODES; n++)
                bl_tree[n].Freq = 0;

        dyn_ltree[END_BLOCK].Freq = 1;
        opt_len = static_len = 0L;
        last_lit = last_dist = last_flags = 0;
        flags = 0;
        flag_bit = 1;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */


/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(tree, top) \
{\
    top = heap[SMALLEST]; \
    heap[SMALLEST] = heap[heap_len--]; \
    pqdownheap(tree, SMALLEST); \
}

/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
local void pqdownheap(tree, k)
ct_data near *tree;                             /* the tree to restore */
int k;                                                  /* node to move down */
{
        int v = heap[k];
        int j = k << 1;                         /* left son of k */

        while (j <= heap_len) {
                /* Set j to the smallest of the two sons: */
                if (j < heap_len && smaller(tree, heap[j + 1], heap[j]))
                        j++;

                /* Exit if v is smaller than both sons */
                if (smaller(tree, v, heap[j]))
                        break;

                /* Exchange v with the smallest son */
                heap[k] = heap[j];
                k = j;

                /* And continue down the tree, setting j to the left son of k */
                j <<= 1;
        }
        heap[k] = v;
}

/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
local void gen_bitlen(desc)
tree_desc near *desc;                   /* the tree descriptor */
{
        ct_data near *tree = desc->dyn_tree;
        int near *extra = desc->extra_bits;
        int base = desc->extra_base;
        int max_code = desc->max_code;
        int max_length = desc->max_length;
        ct_data near *stree = desc->static_tree;
        int h;                                          /* heap index */
        int n, m;                                       /* iterate over the tree elements */
        int bits;                                       /* bit length */
        int xbits;                                      /* extra bits */
        ush f;                                          /* frequency */
        int overflow = 0;                       /* number of elements with bit length too large */

        for (bits = 0; bits <= MAX_BITS; bits++)
                bl_count[bits] = 0;

        /* In a first pass, compute the optimal bit lengths (which may
         * overflow in the case of the bit length tree).
         */
        tree[heap[heap_max]].Len = 0;   /* root of the heap */

        for (h = heap_max + 1; h < HEAP_SIZE; h++) {
                n = heap[h];
                bits = tree[tree[n].Dad].Len + 1;
                if (bits > max_length)
                        bits = max_length, overflow++;
                tree[n].Len = (ush) bits;
                /* We overwrite tree[n].Dad which is no longer needed */

                if (n > max_code)
                        continue;                       /* not a leaf node */

                bl_count[bits]++;
                xbits = 0;
                if (n >= base)
                        xbits = extra[n - base];
                f = tree[n].Freq;
                opt_len += (ulg) f *(bits + xbits);

                if (stree)
                        static_len += (ulg) f *(stree[n].Len + xbits);
        }
        if (overflow == 0)
                return;

        Trace((stderr, "\nbit length overflow\n"));
        /* This happens for example on obj2 and pic of the Calgary corpus */

        /* Find the first bit length which could increase: */
        do {
                bits = max_length - 1;
                while (bl_count[bits] == 0)
                        bits--;
                bl_count[bits]--;               /* move one leaf down the tree */
                bl_count[bits + 1] += 2;        /* move one overflow item as its brother */
                bl_count[max_length]--;
                /* The brother of the overflow item also moves one step up,
                 * but this does not affect bl_count[max_length]
                 */
                overflow -= 2;
        } while (overflow > 0);

        /* Now recompute all bit lengths, scanning in increasing frequency.
         * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
         * lengths instead of fixing only the wrong ones. This idea is taken
         * from 'ar' written by Haruhiko Okumura.)
         */
        for (bits = max_length; bits != 0; bits--) {
                n = bl_count[bits];
                while (n != 0) {
                        m = heap[--h];
                        if (m > max_code)
                                continue;
                        if (tree[m].Len != (unsigned) bits) {
                                Trace(
                                          (stderr, "code %d bits %d->%d\n", m, tree[m].Len,
                                           bits));
                                opt_len +=
                                        ((long) bits -
                                         (long) tree[m].Len) * (long) tree[m].Freq;
                                tree[m].Len = (ush) bits;
                        }
                        n--;
                }
        }
}

/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
local void gen_codes(tree, max_code)
ct_data near *tree;                             /* the tree to decorate */
int max_code;                                   /* largest code with non zero frequency */
{
        ush next_code[MAX_BITS + 1];    /* next code value for each bit length */
        ush code = 0;                           /* running code value */
        int bits;                                       /* bit index */
        int n;                                          /* code index */

        /* The distribution counts are first used to generate the code values
         * without bit reversal.
         */
        for (bits = 1; bits <= MAX_BITS; bits++) {
                next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
        }
        /* Check that the bit counts in bl_count are consistent. The last code
         * must be all ones.
         */
        Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
                   "inconsistent bit counts");
        Tracev((stderr, "\ngen_codes: max_code %d ", max_code));

        for (n = 0; n <= max_code; n++) {
                int len = tree[n].Len;

                if (len == 0)
                        continue;
                /* Now reverse the bits */
                tree[n].Code = bi_reverse(next_code[len]++, len);

                Tracec(tree != static_ltree,
                           (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
                                (isgraph(n) ? n : ' '), len, tree[n].Code,
                                next_code[len] - 1));
        }
}

/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
local void build_tree(desc)
tree_desc near *desc;                   /* the tree descriptor */
{
        ct_data near *tree = desc->dyn_tree;
        ct_data near *stree = desc->static_tree;
        int elems = desc->elems;
        int n, m;                                       /* iterate over heap elements */
        int max_code = -1;                      /* largest code with non zero frequency */
        int node = elems;                       /* next internal node of the tree */

        /* Construct the initial heap, with least frequent element in
         * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
         * heap[0] is not used.
         */
        heap_len = 0, heap_max = HEAP_SIZE;

        for (n = 0; n < elems; n++) {
                if (tree[n].Freq != 0) {
                        heap[++heap_len] = max_code = n;
                        depth[n] = 0;
                } else {
                        tree[n].Len = 0;
                }
        }

        /* The pkzip format requires that at least one distance code exists,
         * and that at least one bit should be sent even if there is only one
         * possible code. So to avoid special checks later on we force at least
         * two codes of non zero frequency.
         */
        while (heap_len < 2) {
                int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);

                tree[new].Freq = 1;
                depth[new] = 0;
                opt_len--;
                if (stree)
                        static_len -= stree[new].Len;
                /* new is 0 or 1 so it does not have extra bits */
        }
        desc->max_code = max_code;

        /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
         * establish sub-heaps of increasing lengths:
         */
        for (n = heap_len / 2; n >= 1; n--)
                pqdownheap(tree, n);

        /* Construct the Huffman tree by repeatedly combining the least two
         * frequent nodes.
         */
        do {
                pqremove(tree, n);              /* n = node of least frequency */
                m = heap[SMALLEST];             /* m = node of next least frequency */

                heap[--heap_max] = n;   /* keep the nodes sorted by frequency */
                heap[--heap_max] = m;

                /* Create a new node father of n and m */
                tree[node].Freq = tree[n].Freq + tree[m].Freq;
                depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
                tree[n].Dad = tree[m].Dad = (ush) node;
#ifdef DUMP_BL_TREE
                if (tree == bl_tree) {
                        fprintf(stderr, "\nnode %d(%d), sons %d(%d) %d(%d)",
                                        node, tree[node].Freq, n, tree[n].Freq, m,
                                        tree[m].Freq);
                }
#endif
                /* and insert the new node in the heap */
                heap[SMALLEST] = node++;
                pqdownheap(tree, SMALLEST);

        } while (heap_len >= 2);

        heap[--heap_max] = heap[SMALLEST];

        /* At this point, the fields freq and dad are set. We can now
         * generate the bit lengths.
         */
        gen_bitlen((tree_desc near *) desc);

        /* The field len is now set, we can generate the bit codes */
        gen_codes((ct_data near *) tree, max_code);
}

/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree. Updates opt_len to take into account the repeat
 * counts. (The contribution of the bit length codes will be added later
 * during the construction of bl_tree.)
 */
local void scan_tree(tree, max_code)
ct_data near *tree;                             /* the tree to be scanned */
int max_code;                                   /* and its largest code of non zero frequency */
{
        int n;                                          /* iterates over all tree elements */
        int prevlen = -1;                       /* last emitted length */
        int curlen;                                     /* length of current code */
        int nextlen = tree[0].Len;      /* length of next code */
        int count = 0;                          /* repeat count of the current code */
        int max_count = 7;                      /* max repeat count */
        int min_count = 4;                      /* min repeat count */

        if (nextlen == 0)
                max_count = 138, min_count = 3;
        tree[max_code + 1].Len = (ush) 0xffff;  /* guard */

        for (n = 0; n <= max_code; n++) {
                curlen = nextlen;
                nextlen = tree[n + 1].Len;
                if (++count < max_count && curlen == nextlen) {
                        continue;
                } else if (count < min_count) {
                        bl_tree[curlen].Freq += count;
                } else if (curlen != 0) {
                        if (curlen != prevlen)
                                bl_tree[curlen].Freq++;
                        bl_tree[REP_3_6].Freq++;
                } else if (count <= 10) {
                        bl_tree[REPZ_3_10].Freq++;
                } else {
                        bl_tree[REPZ_11_138].Freq++;
                }
                count = 0;
                prevlen = curlen;
                if (nextlen == 0) {
                        max_count = 138, min_count = 3;
                } else if (curlen == nextlen) {
                        max_count = 6, min_count = 3;
                } else {
                        max_count = 7, min_count = 4;
                }
        }
}

/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
local void send_tree(tree, max_code)
ct_data near *tree;                             /* the tree to be scanned */
int max_code;                                   /* and its largest code of non zero frequency */
{
        int n;                                          /* iterates over all tree elements */
        int prevlen = -1;                       /* last emitted length */
        int curlen;                                     /* length of current code */
        int nextlen = tree[0].Len;      /* length of next code */
        int count = 0;                          /* repeat count of the current code */
        int max_count = 7;                      /* max repeat count */
        int min_count = 4;                      /* min repeat count */

/* tree[max_code+1].Len = -1; *//* guard already set */
        if (nextlen == 0)
                max_count = 138, min_count = 3;

        for (n = 0; n <= max_code; n++) {
                curlen = nextlen;
                nextlen = tree[n + 1].Len;
                if (++count < max_count && curlen == nextlen) {
                        continue;
                } else if (count < min_count) {
                        do {
                                send_code(curlen, bl_tree);
                        } while (--count != 0);

                } else if (curlen != 0) {
                        if (curlen != prevlen) {
                                send_code(curlen, bl_tree);
                                count--;
                        }
                        Assert(count >= 3 && count <= 6, " 3_6?");
                        send_code(REP_3_6, bl_tree);
                        send_bits(count - 3, 2);

                } else if (count <= 10) {
                        send_code(REPZ_3_10, bl_tree);
                        send_bits(count - 3, 3);

                } else {
                        send_code(REPZ_11_138, bl_tree);
                        send_bits(count - 11, 7);
                }
                count = 0;
                prevlen = curlen;
                if (nextlen == 0) {
                        max_count = 138, min_count = 3;
                } else if (curlen == nextlen) {
                        max_count = 6, min_count = 3;
                } else {
                        max_count = 7, min_count = 4;
                }
        }
}

/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
local int build_bl_tree()
{
        int max_blindex;                        /* index of last bit length code of non zero freq */

        /* Determine the bit length frequencies for literal and distance trees */
        scan_tree((ct_data near *) dyn_ltree, l_desc.max_code);
        scan_tree((ct_data near *) dyn_dtree, d_desc.max_code);

        /* Build the bit length tree: */
        build_tree((tree_desc near *) (&bl_desc));
        /* opt_len now includes the length of the tree representations, except
         * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
         */

        /* Determine the number of bit length codes to send. The pkzip format
         * requires that at least 4 bit length codes be sent. (appnote.txt says
         * 3 but the actual value used is 4.)
         */
        for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
                if (bl_tree[bl_order[max_blindex]].Len != 0)
                        break;
        }
        /* Update opt_len to include the bit length tree and counts */
        opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
        Tracev(
                   (stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len,
                        static_len));

        return max_blindex;
}

/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
local void send_all_trees(lcodes, dcodes, blcodes)
int lcodes, dcodes, blcodes;    /* number of codes for each tree */
{
        int rank;                                       /* index in bl_order */

        Assert(lcodes >= 257 && dcodes >= 1
                   && blcodes >= 4, "not enough codes");
        Assert(lcodes <= L_CODES && dcodes <= D_CODES
                   && blcodes <= BL_CODES, "too many codes");
        Tracev((stderr, "\nbl counts: "));
        send_bits(lcodes - 257, 5);     /* not +255 as stated in appnote.txt */
        send_bits(dcodes - 1, 5);
        send_bits(blcodes - 4, 4);      /* not -3 as stated in appnote.txt */
        for (rank = 0; rank < blcodes; rank++) {
                Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
                send_bits(bl_tree[bl_order[rank]].Len, 3);
        }
        Tracev((stderr, "\nbl tree: sent %ld", bits_sent));

        send_tree((ct_data near *) dyn_ltree, lcodes - 1);      /* send the literal tree */
        Tracev((stderr, "\nlit tree: sent %ld", bits_sent));

        send_tree((ct_data near *) dyn_dtree, dcodes - 1);      /* send the distance tree */
        Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
}

/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and output the encoded block to the zip file. This function
 * returns the total compressed length for the file so far.
 */
ulg flush_block(buf, stored_len, eof)
char *buf;                                              /* input block, or NULL if too old */
ulg stored_len;                                 /* length of input block */
int eof;                                                /* true if this is the last block for a file */
{
        ulg opt_lenb, static_lenb;      /* opt_len and static_len in bytes */
        int max_blindex;                        /* index of last bit length code of non zero freq */

        flag_buf[last_flags] = flags;   /* Save the flags for the last 8 items */

        /* Check if the file is ascii or binary */
        if (*file_type == (ush) UNKNOWN)
                set_file_type();

        /* Construct the literal and distance trees */
        build_tree((tree_desc near *) (&l_desc));
        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));

        build_tree((tree_desc near *) (&d_desc));
        Tracev(
                   (stderr, "\ndist data: dyn %ld, stat %ld", opt_len,
                        static_len));
        /* At this point, opt_len and static_len are the total bit lengths of
         * the compressed block data, excluding the tree representations.
         */

        /* Build the bit length tree for the above two trees, and get the index
         * in bl_order of the last bit length code to send.
         */
        max_blindex = build_bl_tree();

        /* Determine the best encoding. Compute first the block length in bytes */
        opt_lenb = (opt_len + 3 + 7) >> 3;
        static_lenb = (static_len + 3 + 7) >> 3;
        input_len += stored_len;        /* for debugging only */

        Trace(
                  (stderr,
                   "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
                   opt_lenb, opt_len, static_lenb, static_len, stored_len,
                   last_lit, last_dist));

        if (static_lenb <= opt_lenb)
                opt_lenb = static_lenb;

        /* If compression failed and this is the first and last block,
         * and if the zip file can be seeked (to rewrite the local header),
         * the whole file is transformed into a stored file:
         */
#ifdef FORCE_METHOD
#else
        if (stored_len <= opt_lenb && eof && compressed_len == 0L
                && seekable()) {
#endif
                /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
                if (buf == (char *) 0)
                        error_msg("block vanished");

                copy_block(buf, (unsigned) stored_len, 0);      /* without header */
                compressed_len = stored_len << 3;
                *file_method = STORED;

#ifdef FORCE_METHOD
#else
        } else if (stored_len + 4 <= opt_lenb && buf != (char *) 0) {
                /* 4: two words for the lengths */
#endif
                /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
                 * Otherwise we can't have processed more than WSIZE input bytes since
                 * the last block flush, because compression would have been
                 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
                 * transform a block into a stored block.
                 */
                send_bits((STORED_BLOCK << 1) + eof, 3);        /* send block type */
                compressed_len = (compressed_len + 3 + 7) & ~7L;
                compressed_len += (stored_len + 4) << 3;

                copy_block(buf, (unsigned) stored_len, 1);      /* with header */

#ifdef FORCE_METHOD
#else
        } else if (static_lenb == opt_lenb) {
#endif
                send_bits((STATIC_TREES << 1) + eof, 3);
                compress_block((ct_data near *) static_ltree,
                                           (ct_data near *) static_dtree);
                compressed_len += 3 + static_len;
        } else {
                send_bits((DYN_TREES << 1) + eof, 3);
                send_all_trees(l_desc.max_code + 1, d_desc.max_code + 1,
                                           max_blindex + 1);
                compress_block((ct_data near *) dyn_ltree,
                                           (ct_data near *) dyn_dtree);
                compressed_len += 3 + opt_len;
        }
        Assert(compressed_len == bits_sent, "bad compressed size");
        init_block();

        if (eof) {
                Assert(input_len == isize, "bad input size");
                bi_windup();
                compressed_len += 7;    /* align on byte boundary */
        }
        Tracev((stderr, "\ncomprlen %lu(%lu) ", compressed_len >> 3,
                        compressed_len - 7 * eof));

        return compressed_len >> 3;
}

/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
int ct_tally(dist, lc)
int dist;                                               /* distance of matched string */
int lc;                                                 /* match length-MIN_MATCH or unmatched char (if dist==0) */
{
        l_buf[last_lit++] = (uch) lc;
        if (dist == 0) {
                /* lc is the unmatched char */
                dyn_ltree[lc].Freq++;
        } else {
                /* Here, lc is the match length - MIN_MATCH */
                dist--;                                 /* dist = match distance - 1 */
                Assert((ush) dist < (ush) MAX_DIST &&
                           (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH) &&
                           (ush) d_code(dist) < (ush) D_CODES, "ct_tally: bad match");

                dyn_ltree[length_code[lc] + LITERALS + 1].Freq++;
                dyn_dtree[d_code(dist)].Freq++;

                d_buf[last_dist++] = (ush) dist;
                flags |= flag_bit;
        }
        flag_bit <<= 1;

        /* Output the flags if they fill a byte: */
        if ((last_lit & 7) == 0) {
                flag_buf[last_flags++] = flags;
                flags = 0, flag_bit = 1;
        }
        /* Try to guess if it is profitable to stop the current block here */
        if ((last_lit & 0xfff) == 0) {
                /* Compute an upper bound for the compressed length */
                ulg out_length = (ulg) last_lit * 8L;
                ulg in_length = (ulg) strstart - block_start;
                int dcode;

                for (dcode = 0; dcode < D_CODES; dcode++) {
                        out_length +=
                                (ulg) dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
                }
                out_length >>= 3;
                Trace(
                          (stderr,
                           "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
                           last_lit, last_dist, in_length, out_length,
                           100L - out_length * 100L / in_length));
                if (last_dist < last_lit / 2 && out_length < in_length / 2)
                        return 1;
        }
        return (last_lit == LIT_BUFSIZE - 1 || last_dist == DIST_BUFSIZE);
        /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
         * on 16 bit machines and because stored blocks are restricted to
         * 64K-1 bytes.
         */
}

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
local void compress_block(ltree, dtree)
ct_data near *ltree;                    /* literal tree */
ct_data near *dtree;                    /* distance tree */
{
        unsigned dist;                          /* distance of matched string */
        int lc;                                         /* match length or unmatched char (if dist == 0) */
        unsigned lx = 0;                        /* running index in l_buf */
        unsigned dx = 0;                        /* running index in d_buf */
        unsigned fx = 0;                        /* running index in flag_buf */
        uch flag = 0;                           /* current flags */
        unsigned code;                          /* the code to send */
        int extra;                                      /* number of extra bits to send */

        if (last_lit != 0)
                do {
                        if ((lx & 7) == 0)
                                flag = flag_buf[fx++];
                        lc = l_buf[lx++];
                        if ((flag & 1) == 0) {
                                send_code(lc, ltree);   /* send a literal byte */
                                Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
                        } else {
                                /* Here, lc is the match length - MIN_MATCH */
                                code = length_code[lc];
                                send_code(code + LITERALS + 1, ltree);  /* send the length code */
                                extra = extra_lbits[code];
                                if (extra != 0) {
                                        lc -= base_length[code];
                                        send_bits(lc, extra);   /* send the extra length bits */
                                }
                                dist = d_buf[dx++];
                                /* Here, dist is the match distance - 1 */
                                code = d_code(dist);
                                Assert(code < D_CODES, "bad d_code");

                                send_code(code, dtree); /* send the distance code */
                                extra = extra_dbits[code];
                                if (extra != 0) {
                                        dist -= base_dist[code];
                                        send_bits(dist, extra); /* send the extra distance bits */
                                }
                        }                                       /* literal or match pair ? */
                        flag >>= 1;
                } while (lx < last_lit);

        send_code(END_BLOCK, ltree);
}

/* ===========================================================================
 * Set the file type to ASCII or BINARY, using a crude approximation:
 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
 * IN assertion: the fields freq of dyn_ltree are set and the total of all
 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
 */
local void set_file_type()
{
        int n = 0;
        unsigned ascii_freq = 0;
        unsigned bin_freq = 0;

        while (n < 7)
                bin_freq += dyn_ltree[n++].Freq;
        while (n < 128)
                ascii_freq += dyn_ltree[n++].Freq;
        while (n < LITERALS)
                bin_freq += dyn_ltree[n++].Freq;
        *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII;
        if (*file_type == BINARY && translate_eol) {
                error_msg("-l used on binary file");
        }
}

/* util.c -- utility functions for gzip support
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#include <ctype.h>
#include <errno.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif
#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
#  include <stdlib.h>
#else
extern int errno;
#endif

/* ===========================================================================
 * Copy input to output unchanged: zcat == cat with --force.
 * IN assertion: insize bytes have already been read in inbuf.
 */
int copy(in, out)
int in, out;                                    /* input and output file descriptors */
{
        errno = 0;
        while (insize != 0 && (int) insize != EOF) {
                write_buf(out, (char *) inbuf, insize);
                bytes_out += insize;
                insize = read(in, (char *) inbuf, INBUFSIZ);
        }
        if ((int) insize == EOF && errno != 0) {
                read_error_msg();
        }
        bytes_in = bytes_out;
        return OK;
}

/* ========================================================================
 * Put string s in lower case, return s.
 */
char *strlwr(s)
char *s;
{
        char *t;

        for (t = s; *t; t++)
                *t = tolow(*t);
        return s;
}

#if defined(NO_STRING_H) && !defined(STDC_HEADERS)

/* Provide missing strspn and strcspn functions. */

int strspn (const char *s, const char *accept);
int strcspn (const char *s, const char *reject);

/* ========================================================================
 * Return the length of the maximum initial segment
 * of s which contains only characters in accept.
 */
int strspn(s, accept)
const char *s;
const char *accept;
{
        register const char *p;
        register const char *a;
        register int count = 0;

        for (p = s; *p != '\0'; ++p) {
                for (a = accept; *a != '\0'; ++a) {
                        if (*p == *a)
                                break;
                }
                if (*a == '\0')
                        return count;
                ++count;
        }
        return count;
}

/* ========================================================================
 * Return the length of the maximum inital segment of s
 * which contains no characters from reject.
 */
int strcspn(s, reject)
const char *s;
const char *reject;
{
        register int count = 0;

        while (*s != '\0') {
                if (strchr(reject, *s++) != NULL)
                        return count;
                ++count;
        }
        return count;
}

#endif                                                  /* NO_STRING_H */

/* ========================================================================
 * Add an environment variable (if any) before argv, and update argc.
 * Return the expanded environment variable to be freed later, or NULL 
 * if no options were added to argv.
 */
#define SEPARATOR       " \t"           /* separators in env variable */

char *add_envopt(argcp, argvp, env)
int *argcp;                                             /* pointer to argc */
char ***argvp;                                  /* pointer to argv */
char *env;                                              /* name of environment variable */
{
        char *p;                                        /* running pointer through env variable */
        char **oargv;                           /* runs through old argv array */
        char **nargv;                           /* runs through new argv array */
        int oargc = *argcp;                     /* old argc */
        int nargc = 0;                          /* number of arguments in env variable */

        env = (char *) getenv(env);
        if (env == NULL)
                return NULL;

        p = (char *) xmalloc(strlen(env) + 1);
        env = strcpy(p, env);           /* keep env variable intact */

        for (p = env; *p; nargc++) {    /* move through env */
                p += strspn(p, SEPARATOR);      /* skip leading separators */
                if (*p == '\0')
                        break;

                p += strcspn(p, SEPARATOR);     /* find end of word */
                if (*p)
                        *p++ = '\0';            /* mark it */
        }
        if (nargc == 0) {
                free(env);
                return NULL;
        }
        *argcp += nargc;
        /* Allocate the new argv array, with an extra element just in case
         * the original arg list did not end with a NULL.
         */
        nargv = (char **) calloc(*argcp + 1, sizeof(char *));

        if (nargv == NULL)
                error_msg(memory_exhausted);
        oargv = *argvp;
        *argvp = nargv;

        /* Copy the program name first */
        if (oargc-- < 0)
                error_msg("argc<=0");
        *(nargv++) = *(oargv++);

        /* Then copy the environment args */
        for (p = env; nargc > 0; nargc--) {
                p += strspn(p, SEPARATOR);      /* skip separators */
                *(nargv++) = p;                 /* store start */
                while (*p++);                   /* skip over word */
        }

        /* Finally copy the old args and add a NULL (usual convention) */
        while (oargc--)
                *(nargv++) = *(oargv++);
        *nargv = NULL;
        return env;
}

/* ========================================================================
 * Display compression ratio on the given stream on 6 characters.
 */
void display_ratio(num, den, file)
long num;
long den;
FILE *file;
{
        long ratio;                                     /* 1000 times the compression ratio */

        if (den == 0) {
                ratio = 0;                              /* no compression */
        } else if (den < 2147483L) {    /* (2**31 -1)/1000 */
                ratio = 1000L * num / den;
        } else {
                ratio = num / (den / 1000L);
        }
        if (ratio < 0) {
                putc('-', file);
                ratio = -ratio;
        } else {
                putc(' ', file);
        }
        fprintf(file, "%2ld.%1ld%%", ratio / 10L, ratio % 10L);
}


/* zip.c -- compress files to the gzip or pkzip format
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#include <ctype.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif
#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

local ulg crc;                                  /* crc on uncompressed file data */
long header_bytes;                              /* number of bytes in gzip header */

/* ===========================================================================
 * Deflate in to out.
 * IN assertions: the input and output buffers are cleared.
 *   The variables time_stamp and save_orig_name are initialized.
 */
int zip(in, out)
int in, out;                                    /* input and output file descriptors */
{
        uch flags = 0;                          /* general purpose bit flags */
        ush attr = 0;                           /* ascii/binary flag */
        ush deflate_flags = 0;          /* pkzip -es, -en or -ex equivalent */

        ifd = in;
        ofd = out;
        outcnt = 0;

        /* Write the header to the gzip file. See algorithm.doc for the format */


        method = DEFLATED;
        put_byte(GZIP_MAGIC[0]);        /* magic header */
        put_byte(GZIP_MAGIC[1]);
        put_byte(DEFLATED);                     /* compression method */

        put_byte(flags);                        /* general flags */
        put_long(time_stamp);

        /* Write deflated file to zip file */
        crc = updcrc(0, 0);

        bi_init(out);
        ct_init(&attr, &method);
        lm_init(&deflate_flags);

        put_byte((uch) deflate_flags);  /* extra flags */
        put_byte(OS_CODE);                      /* OS identifier */

        header_bytes = (long) outcnt;

        (void) deflate();

        /* Write the crc and uncompressed size */
        put_long(crc);
        put_long(isize);
        header_bytes += 2 * sizeof(long);

        flush_outbuf();
        return OK;
}


/* ===========================================================================
 * Read a new buffer from the current input file, perform end-of-line
 * translation, and update the crc and input file size.
 * IN assertion: size >= 2 (for end-of-line translation)
 */
int file_read(buf, size)
char *buf;
unsigned size;
{
        unsigned len;

        Assert(insize == 0, "inbuf not empty");

        len = read(ifd, buf, size);
        if (len == (unsigned) (-1) || len == 0)
                return (int) len;

        crc = updcrc((uch *) buf, len);
        isize += (ulg) len;
        return (int) len;
}

/* ===========================================================================
 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
 * (used for the compressed data only)
 */
void flush_outbuf()
{
        if (outcnt == 0)
                return;

        write_buf(ofd, (char *) outbuf, outcnt);
        bytes_out += (ulg) outcnt;
        outcnt = 0;
}