Rewrite, fix a bug with multiple long filenames, simplify structure, remove cruft...
authorGlenn L McGrath <bug1@ihug.co.nz>
Fri, 15 Dec 2000 06:50:09 +0000 (06:50 -0000)
committerGlenn L McGrath <bug1@ihug.co.nz>
Fri, 15 Dec 2000 06:50:09 +0000 (06:50 -0000)
ar.c
archival/ar.c

diff --git a/ar.c b/ar.c
index 88cdd4f9fe18c41a1f379a319d78fd747439dac1..bd54bb6b869b5806cb2ab710d8cfc1ab70a9f49c 100644 (file)
--- a/ar.c
+++ b/ar.c
@@ -3,7 +3,7 @@
  * Mini ar implementation for busybox 
  *
  * Copyright (C) 2000 by Glenn McGrath
- * Written by Glenn McGrath <bug1@netconnect.com.au> 1 June 2000
+ * Written by Glenn McGrath <bug1@optushome.com.au> 1 June 2000
  *             
  * Based in part on BusyBox tar, Debian dpkg-deb and GNU ar.
  *
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  *
- * Last modified 20 September 2000
  */
-#include <stdio.h>
-#include <string.h>
 #include <fcntl.h>
-#include <errno.h>
-#include <ctype.h>
-#include <time.h>
-#include <utime.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <malloc.h>
 #include "busybox.h"
 
-#define BLOCK_SIZE 60
-#define PRESERVE_DATE 1        /* preserve original dates */
-#define VERBOSE       2        /* be verbose */
-#define DISPLAY       4        /* display contents */
-#define EXT_TO_FILE   8        /* extract contents of archive */
-#define EXT_TO_STDOUT 16       /* extract to stdout */
-#define RECURSIVE     32        
+typedef struct ar_headers_s {
+       char *name;
+       size_t size;
+       uid_t uid;
+       gid_t gid;
+       mode_t mode;
+       time_t mtime;
+       off_t offset;
+       struct ar_headers_s *next;
+} ar_headers_t;
 
-#define MAX_NAME_LENGTH 100
-
-//#define BB_DECLARE_EXTERN
-//#define bb_need_io_error
-//#include "messages.c"
-
-//#define BB_AR_EXPERIMENTAL_UNTAR
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-typedef struct rawTarHeader {
-        char name[100];               /*   0-99 */
-        char mode[8];                 /* 100-107 */
-        char uid[8];                  /* 108-115 */
-        char gid[8];                  /* 116-123 */
-        char size[12];                /* 124-135 */
-        char mtime[12];               /* 136-147 */
-        char chksum[8];               /* 148-155 */
-        char typeflag;                /* 156-156 */
-        char linkname[100];           /* 157-256 */
-        char magic[6];                /* 257-262 */
-        char version[2];              /* 263-264 */
-        char uname[32];               /* 265-296 */
-        char gname[32];               /* 297-328 */
-        char devmajor[8];             /* 329-336 */
-        char devminor[8];             /* 337-344 */
-        char prefix[155];             /* 345-499 */
-        char padding[12];             /* 500-512 */
-} rawTarHeader_t;
-#endif
-
-typedef struct rawArHeader {    /* Byte Offset */
-        char name[16];          /*  0-15 */
-        char date[12];          /* 16-27 */
-        char uid[6], gid[6];    /* 28-39 */
-        char mode[8];           /* 40-47 */
-        char size[10];          /* 48-57 */
-        char fmag[2];           /* 58-59 */
-} rawArHeader_t;
-
-typedef struct headerL {
-       char name[MAX_NAME_LENGTH];
-        size_t size;
-        uid_t uid;
-        gid_t gid;
-        mode_t mode;
-        time_t mtime;
-        off_t offset;
-       struct headerL *next;
-} headerL_t;
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
 /*
- * identify Tar header (magic field) and reset srcFd to entry position
+ * return the headerL_t struct for the filename descriptor
  */
-static int checkTarMagic(int srcFd)
-{
-        off_t headerStart;
-        char magic[6];
-
-        headerStart = lseek(srcFd, 0, SEEK_CUR);
-        lseek(srcFd, (off_t) 257, SEEK_CUR);
-        full_read(srcFd, magic, 6);
-        lseek(srcFd, headerStart, SEEK_SET);
-        if (strncmp(magic, "ustar", 5)!=0)
-                return(FALSE);
-        return(TRUE);
-}
-
-
-static int readTarHeader(int srcFd, headerL_t *current)
+static ar_headers_t get_headers(int srcFd)
 {
-       rawTarHeader_t rawTarHeader;
-        unsigned char *temp = (unsigned char *) &rawTarHeader;
-        long sum = 0;
-        int i;
-       off_t initialOffset;
-
-        initialOffset = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, (char *) &rawTarHeader, 512) != 512) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-        for (i =  0; i < 148 ; i++)
-        sum += temp[i];
-        sum += ' ' * 8;
-        for (i =  156; i < 512 ; i++)
-                sum += temp[i];
-        if (sum!= strtol(rawTarHeader.chksum, NULL, 8))
-               return(FALSE);
-       sscanf(rawTarHeader.name, "%s", current->name);
-        current->size = strtol(rawTarHeader.size, NULL, 8);
-        current->uid = strtol(rawTarHeader.uid, NULL, 8);
-        current->gid = strtol(rawTarHeader.gid, NULL, 8);
-        current->mode = strtol(rawTarHeader.mode, NULL, 8);
-        current->mtime = strtol(rawTarHeader.mtime, NULL, 8);
-        current->offset = lseek(srcFd, 0 , SEEK_CUR);
-
-        current->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-        current = current->next;
-       return(TRUE);
-}
-#endif
-
-/*
- * identify Ar header (magic) and reset srcFd to entry position
- */
-static int checkArMagic(int srcFd)
-{
-        off_t headerStart;
-        char arMagic[8];
-
-        headerStart = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, arMagic, 8) != 8) {
-                error_msg("fatal error\n");
-                return (FALSE);
-        }
-        lseek(srcFd, headerStart, SEEK_SET);
-
-        if (strncmp(arMagic,"!<arch>",7) != 0)
-                return(FALSE);
-        return(TRUE);
-}
-
-/*
- * get, check and correct the converted header
- */ 
-static int readArEntry(int srcFd, headerL_t *entry)
-{
-       size_t nameLength;
-        rawArHeader_t rawArHeader;
-        off_t   initialOffset;
-
-        initialOffset = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, (char *) &rawArHeader, 60) != 60) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-        if ((rawArHeader.fmag[0]!='`') || (rawArHeader.fmag[1]!='\n')) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-
-        strncpy(entry->name, rawArHeader.name, 16);
-        nameLength=strcspn(entry->name, " \\");
-        entry->name[nameLength]='\0';
-        parse_mode(rawArHeader.mode, &entry->mode);
-        entry->mtime = atoi(rawArHeader.date);
-        entry->uid = atoi(rawArHeader.uid);
-        entry->gid = atoi(rawArHeader.gid);
-        entry->size = (size_t) atoi(rawArHeader.size);
-        entry->offset = initialOffset + (off_t) 60;
-
-       nameLength = strcspn(entry->name, "/");
+       typedef struct raw_ar_header_s {        /* Byte Offset */
+               char name[16];  /*  0-15 */
+               char date[12];  /* 16-27 */
+               char uid[6];    
+               char gid[6];    /* 28-39 */
+               char mode[8];   /* 40-47 */
+               char size[10];  /* 48-57 */
+               char fmag[2];   /* 58-59 */
+       } raw_ar_header_t;
+       raw_ar_header_t raw_ar_header;
+
+       ar_headers_t *head, *entry;
+       char ar_magic[8];
+       char *long_name=NULL;
        
-       /* handle GNU style short filenames, strip trailing '/' */
-       if (nameLength > 0)
-               entry->name[nameLength]='\0';
+       head = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+       entry = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
        
-       /* handle GNU style long filenames */ 
-       if (nameLength == 0) {
-               /* escape from recursive call */
-               if (entry->name[1]=='0') 
-                       return(TRUE);
-
-               /* the data section contains the real filename */
-               if (entry->name[1]=='/') {
-                       char tempName[MAX_NAME_LENGTH];
-
-                       if (entry->size > MAX_NAME_LENGTH)
-                               entry->size = MAX_NAME_LENGTH;
-                       full_read(srcFd, tempName, entry->size);
-                       tempName[entry->size-3]='\0';
-                       
-                       /* read the second header for this entry */
-                       /* be carefull, this is recursive */
-                       if (readArEntry(srcFd, entry)==FALSE)
-                               return(FALSE);
+       /* check ar magic */
+       if (full_read(srcFd, ar_magic, 8) != 8)
+               error_msg_and_die("cannot read magic\n");
+       if (strncmp(ar_magic,"!<arch>",7) != 0)
+               error_msg_and_die("invalid magic\n");
+
+       while (full_read(srcFd, (char *) &raw_ar_header, 60)==60) {
+               /* check the end of header markers are valid */
+               if ((raw_ar_header.fmag[0]!='`') || (raw_ar_header.fmag[1]!='\n')) {
+                       char newline[1];
+                       if (raw_ar_header.fmag[1]!='`') {
+                               break;
+                       }
+                       /* some version of ar, have an extra '\n' after each entry */
+                       read(srcFd, newline, 1);
+                       if (newline[0]!='\n') {
+                               break;
+                       }
+                       /* fix up the header, we started reading 1 byte too early due to a '\n' */
+                       memmove((char *) &raw_ar_header, (char *)&raw_ar_header+1, 59);
+                       /* dont worry about adding the last '\n', we dont need it now */
+               }
                
-                       if ((entry->name[0]='/') && (entry->name[1]='0'))
-                               strcpy(entry->name, tempName);
+               entry->size = (size_t) atoi(raw_ar_header.size);
+               /* long filenames have '/' as the first character */
+               if (raw_ar_header.name[0] == '/') {
+                       if (raw_ar_header.name[1] == '/') {
+                               /* multiple long filenames are stored as data in one entry */
+                               long_name = (char *) xrealloc(long_name, entry->size);
+                               full_read(srcFd, long_name, entry->size);
+                               continue;
+                       }
                        else {
-                               error_msg("Invalid long filename\n");
-                               return(FALSE);
+                               /* The number after the '/' indicates the offset in the ar data section
+                                       (saved in variable long_name) that conatains the real filename */
+                               const int long_name_offset = (int) atoi((char *) &raw_ar_header.name[1]);
+                               entry->name = xmalloc(strlen(&long_name[long_name_offset]));
+                               strcpy(entry->name, &long_name[long_name_offset]);
                        }
                }
-       }
-       return(TRUE);   
-}
-
-/*
- * return the headerL_t struct for the specified filename
- */
-static headerL_t *getHeaders(int srcFd, headerL_t *head, int funct)
-{
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-        int tar=FALSE;
-#endif
-       int ar=FALSE;
-       headerL_t *list;
-       off_t initialOffset;
-
-       list = (headerL_t *) xmalloc(sizeof(headerL_t));
-       initialOffset=lseek(srcFd, 0, SEEK_CUR);
-       if (checkArMagic(srcFd)==TRUE) 
-               ar=TRUE;
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-       if (checkTarMagic(srcFd)==TRUE)
-               tar=TRUE;
-
-        if (tar==TRUE) {
-                while(readTarHeader(srcFd, list)==TRUE) {
-                       off_t tarOffset;
-                        list->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                        *list->next = *head;
-                        *head = *list;
-
-                        /* recursive check for sub-archives */
-                        if ((funct & RECURSIVE) == RECURSIVE)
-                                head = getHeaders(srcFd, head, funct);
-                        tarOffset = (off_t) head->size/512;
-                        if ( head->size % 512 > 0)
-                                tarOffset++;
-                        tarOffset=tarOffset*512;
-                        lseek(srcFd, head->offset + tarOffset, SEEK_SET);
-                }
-        }
-#endif
-
-        if (ar==TRUE) {
-               lseek(srcFd, 8, SEEK_CUR); 
-               while(1) {
-                       if (readArEntry(srcFd, list) == FALSE) {
-                               lseek(srcFd, ++initialOffset, SEEK_CUR); 
-                               if (readArEntry(srcFd, list) == FALSE)
-                                       return(head);
-                       }
-                       list->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                       *list->next = *head;
-                       *head = *list;
-                       /* recursive check for sub-archives */
-                       if (funct & RECURSIVE)  
-                               head = getHeaders(srcFd, head, funct);
-                       lseek(srcFd, head->offset + head->size, SEEK_SET);
+               else {
+                       /* short filenames */
+                       entry->name = xmalloc(16);
+                       strncpy(entry->name, raw_ar_header.name, 16);
                }
+               entry->name[strcspn(entry->name, " /")]='\0';
+
+               /* convert the rest of the now valid char header to its typed struct */ 
+               parse_mode(raw_ar_header.mode, &entry->mode);
+               entry->mtime = atoi(raw_ar_header.date);
+               entry->uid = atoi(raw_ar_header.uid);
+               entry->gid = atoi(raw_ar_header.gid);
+               entry->offset = lseek(srcFd, 0, SEEK_CUR);
+
+               /* add this entries header to our combined list */
+               entry->next = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+               *entry->next = *head;
+               *head = *entry;
+               lseek(srcFd, (off_t) entry->size, SEEK_CUR);
        }
-        return(head);
-}
-
-/*
- * find an entry in the linked list matching the filename
- */
-static headerL_t *findEntry(headerL_t *head, const char *filename)
-{
-       while(head->next != NULL) {
-               if (strcmp(filename, head->name)==0) 
-                       return(head);
-               head=head->next;
-       }
-       return(NULL);
+       return(*head);
 }
 
 extern int ar_main(int argc, char **argv)
 {
-        int funct = 0, opt=0;
+       const int preserve_date = 1;    /* preserve original dates */
+       const int verbose = 2;          /* be verbose */
+       const int display = 4;          /* display contents */
+       const int extract_to_file = 8;  /* extract contents of archive */
+       const int extract_to_stdout = 16;       /* extract to stdout */
+
+       int funct = 0, opt=0;
        int srcFd=0, dstFd=0;
-       headerL_t *header, *entry, *extractList;
 
-       while ((opt = getopt(argc, argv, "ovtpxR")) != -1) {
+       ar_headers_t head, *extract_list=NULL;
+
+       extract_list = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+
+       while ((opt = getopt(argc, argv, "ovtpx")) != -1) {
                switch (opt) {
                case 'o':
-                       funct |= PRESERVE_DATE;
+                       funct |= preserve_date;
                        break;
                case 'v':
-                       funct |= VERBOSE;
+                       funct |= verbose;
                        break;
                case 't':
-                       funct |= DISPLAY;
-                       break;
-               case 'x':
-                       funct |= EXT_TO_FILE;
+                       funct |= display;
                        break;
                case 'p':
-                       funct |= EXT_TO_STDOUT;
+                       funct |= extract_to_stdout;
                        break;
-               case 'R':
-                       funct |= RECURSIVE;
+               case 'x':
+                       funct |= extract_to_file;
                        break;
                default:
                        usage(ar_usage);
@@ -345,47 +166,54 @@ extern int ar_main(int argc, char **argv)
        if ( (srcFd = open(argv[optind], O_RDONLY)) < 0)
                error_msg_and_die("Cannot read %s\n", argv[optind]);
 
-       optind++;       
-       entry = (headerL_t *) xmalloc(sizeof(headerL_t));
-       header = (headerL_t *) xmalloc(sizeof(headerL_t));
-       extractList = (headerL_t *) xmalloc(sizeof(headerL_t)); 
+       optind++;       
+       head = get_headers(srcFd);
 
-       header = getHeaders(srcFd, header, funct);
        /* find files to extract or display */
-       if (optind<argc) {
-               /* only handle specified files */
-               while(optind < argc) { 
-                       if ( (entry = findEntry(header, argv[optind])) != NULL) {
-                               entry->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                               *entry->next = *extractList;
-                               *extractList = *entry;
+       /* search through argv and build extract list */
+       for (;optind<argc; optind++) {
+               ar_headers_t *ar_entry;
+               ar_entry = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+               ar_entry = &head;
+               while (ar_entry->next != NULL) {
+                       if (strcmp(argv[optind], ar_entry->name) == 0) {
+                               ar_headers_t *tmp;
+                               tmp = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+                               *tmp = *extract_list;
+                               *extract_list = *ar_entry;
+                               extract_list->next = tmp;
+                               break;                                  
                        }
-                       optind++;
-               }       
+                       ar_entry=ar_entry->next;
+               }
+       }
+
+       /* if individual files not found extract all files */   
+       if (extract_list->next==NULL) {
+               extract_list = &head;
        }
-       else  
-               extractList = header;
        
-        while(extractList->next != NULL) {     
-               if (funct & EXT_TO_FILE) {
-                       if (is_directory(extractList->name, TRUE, NULL)==FALSE)
-                               create_path(extractList->name, 0666);
-                       dstFd = open(extractList->name, O_WRONLY | O_CREAT, extractList->mode);
-                       lseek(srcFd, extractList->offset, SEEK_SET);
-                       copy_file_chunk(srcFd, dstFd, (size_t) extractList->size);
+       /* find files to extract or display */  
+       while (extract_list->next != NULL) {
+               if (funct & extract_to_file) {
+                       dstFd = open(extract_list->name, O_WRONLY | O_CREAT, extract_list->mode);                               
+               }
+               else if (funct & extract_to_stdout) {
+                       dstFd = fileno(stdout);
+               }
+               if ((funct & extract_to_file) || (funct & extract_to_stdout)) {
+                       lseek(srcFd, extract_list->offset, SEEK_SET);
+                       copy_file_chunk(srcFd, dstFd, (size_t) extract_list->size);                     
                }
-               if (funct & EXT_TO_STDOUT) {    
-                       lseek(srcFd, extractList->offset, SEEK_SET);
-                        copy_file_chunk(srcFd, fileno(stdout), (size_t) extractList->size);
+               if (funct & verbose) {
+                       printf("%s %d/%d %8d %s ", mode_string(extract_list->mode), 
+                               extract_list->uid, extract_list->gid,
+                               extract_list->size, time_string(extract_list->mtime));
                }
-               if ( (funct & DISPLAY) || (funct & VERBOSE)) {
-                       if (funct & VERBOSE)
-                               printf("%s %d/%d %8d %s ", mode_string(extractList->mode), 
-                                       extractList->uid, extractList->gid,
-                                       extractList->size, time_string(extractList->mtime));
-                       printf("%s\n", extractList->name);
+               if ((funct & display) || (funct & verbose)){
+                       printf("%s\n", extract_list->name);
                }
-               extractList=extractList->next;
+               extract_list=extract_list->next;
        }
        return EXIT_SUCCESS;
 }
index 88cdd4f9fe18c41a1f379a319d78fd747439dac1..bd54bb6b869b5806cb2ab710d8cfc1ab70a9f49c 100644 (file)
@@ -3,7 +3,7 @@
  * Mini ar implementation for busybox 
  *
  * Copyright (C) 2000 by Glenn McGrath
- * Written by Glenn McGrath <bug1@netconnect.com.au> 1 June 2000
+ * Written by Glenn McGrath <bug1@optushome.com.au> 1 June 2000
  *             
  * Based in part on BusyBox tar, Debian dpkg-deb and GNU ar.
  *
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  *
- * Last modified 20 September 2000
  */
-#include <stdio.h>
-#include <string.h>
 #include <fcntl.h>
-#include <errno.h>
-#include <ctype.h>
-#include <time.h>
-#include <utime.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <malloc.h>
 #include "busybox.h"
 
-#define BLOCK_SIZE 60
-#define PRESERVE_DATE 1        /* preserve original dates */
-#define VERBOSE       2        /* be verbose */
-#define DISPLAY       4        /* display contents */
-#define EXT_TO_FILE   8        /* extract contents of archive */
-#define EXT_TO_STDOUT 16       /* extract to stdout */
-#define RECURSIVE     32        
+typedef struct ar_headers_s {
+       char *name;
+       size_t size;
+       uid_t uid;
+       gid_t gid;
+       mode_t mode;
+       time_t mtime;
+       off_t offset;
+       struct ar_headers_s *next;
+} ar_headers_t;
 
-#define MAX_NAME_LENGTH 100
-
-//#define BB_DECLARE_EXTERN
-//#define bb_need_io_error
-//#include "messages.c"
-
-//#define BB_AR_EXPERIMENTAL_UNTAR
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-typedef struct rawTarHeader {
-        char name[100];               /*   0-99 */
-        char mode[8];                 /* 100-107 */
-        char uid[8];                  /* 108-115 */
-        char gid[8];                  /* 116-123 */
-        char size[12];                /* 124-135 */
-        char mtime[12];               /* 136-147 */
-        char chksum[8];               /* 148-155 */
-        char typeflag;                /* 156-156 */
-        char linkname[100];           /* 157-256 */
-        char magic[6];                /* 257-262 */
-        char version[2];              /* 263-264 */
-        char uname[32];               /* 265-296 */
-        char gname[32];               /* 297-328 */
-        char devmajor[8];             /* 329-336 */
-        char devminor[8];             /* 337-344 */
-        char prefix[155];             /* 345-499 */
-        char padding[12];             /* 500-512 */
-} rawTarHeader_t;
-#endif
-
-typedef struct rawArHeader {    /* Byte Offset */
-        char name[16];          /*  0-15 */
-        char date[12];          /* 16-27 */
-        char uid[6], gid[6];    /* 28-39 */
-        char mode[8];           /* 40-47 */
-        char size[10];          /* 48-57 */
-        char fmag[2];           /* 58-59 */
-} rawArHeader_t;
-
-typedef struct headerL {
-       char name[MAX_NAME_LENGTH];
-        size_t size;
-        uid_t uid;
-        gid_t gid;
-        mode_t mode;
-        time_t mtime;
-        off_t offset;
-       struct headerL *next;
-} headerL_t;
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
 /*
- * identify Tar header (magic field) and reset srcFd to entry position
+ * return the headerL_t struct for the filename descriptor
  */
-static int checkTarMagic(int srcFd)
-{
-        off_t headerStart;
-        char magic[6];
-
-        headerStart = lseek(srcFd, 0, SEEK_CUR);
-        lseek(srcFd, (off_t) 257, SEEK_CUR);
-        full_read(srcFd, magic, 6);
-        lseek(srcFd, headerStart, SEEK_SET);
-        if (strncmp(magic, "ustar", 5)!=0)
-                return(FALSE);
-        return(TRUE);
-}
-
-
-static int readTarHeader(int srcFd, headerL_t *current)
+static ar_headers_t get_headers(int srcFd)
 {
-       rawTarHeader_t rawTarHeader;
-        unsigned char *temp = (unsigned char *) &rawTarHeader;
-        long sum = 0;
-        int i;
-       off_t initialOffset;
-
-        initialOffset = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, (char *) &rawTarHeader, 512) != 512) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-        for (i =  0; i < 148 ; i++)
-        sum += temp[i];
-        sum += ' ' * 8;
-        for (i =  156; i < 512 ; i++)
-                sum += temp[i];
-        if (sum!= strtol(rawTarHeader.chksum, NULL, 8))
-               return(FALSE);
-       sscanf(rawTarHeader.name, "%s", current->name);
-        current->size = strtol(rawTarHeader.size, NULL, 8);
-        current->uid = strtol(rawTarHeader.uid, NULL, 8);
-        current->gid = strtol(rawTarHeader.gid, NULL, 8);
-        current->mode = strtol(rawTarHeader.mode, NULL, 8);
-        current->mtime = strtol(rawTarHeader.mtime, NULL, 8);
-        current->offset = lseek(srcFd, 0 , SEEK_CUR);
-
-        current->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-        current = current->next;
-       return(TRUE);
-}
-#endif
-
-/*
- * identify Ar header (magic) and reset srcFd to entry position
- */
-static int checkArMagic(int srcFd)
-{
-        off_t headerStart;
-        char arMagic[8];
-
-        headerStart = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, arMagic, 8) != 8) {
-                error_msg("fatal error\n");
-                return (FALSE);
-        }
-        lseek(srcFd, headerStart, SEEK_SET);
-
-        if (strncmp(arMagic,"!<arch>",7) != 0)
-                return(FALSE);
-        return(TRUE);
-}
-
-/*
- * get, check and correct the converted header
- */ 
-static int readArEntry(int srcFd, headerL_t *entry)
-{
-       size_t nameLength;
-        rawArHeader_t rawArHeader;
-        off_t   initialOffset;
-
-        initialOffset = lseek(srcFd, 0, SEEK_CUR);
-        if (full_read(srcFd, (char *) &rawArHeader, 60) != 60) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-        if ((rawArHeader.fmag[0]!='`') || (rawArHeader.fmag[1]!='\n')) {
-                lseek(srcFd, initialOffset, SEEK_SET);
-                return(FALSE);
-        }
-
-        strncpy(entry->name, rawArHeader.name, 16);
-        nameLength=strcspn(entry->name, " \\");
-        entry->name[nameLength]='\0';
-        parse_mode(rawArHeader.mode, &entry->mode);
-        entry->mtime = atoi(rawArHeader.date);
-        entry->uid = atoi(rawArHeader.uid);
-        entry->gid = atoi(rawArHeader.gid);
-        entry->size = (size_t) atoi(rawArHeader.size);
-        entry->offset = initialOffset + (off_t) 60;
-
-       nameLength = strcspn(entry->name, "/");
+       typedef struct raw_ar_header_s {        /* Byte Offset */
+               char name[16];  /*  0-15 */
+               char date[12];  /* 16-27 */
+               char uid[6];    
+               char gid[6];    /* 28-39 */
+               char mode[8];   /* 40-47 */
+               char size[10];  /* 48-57 */
+               char fmag[2];   /* 58-59 */
+       } raw_ar_header_t;
+       raw_ar_header_t raw_ar_header;
+
+       ar_headers_t *head, *entry;
+       char ar_magic[8];
+       char *long_name=NULL;
        
-       /* handle GNU style short filenames, strip trailing '/' */
-       if (nameLength > 0)
-               entry->name[nameLength]='\0';
+       head = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+       entry = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
        
-       /* handle GNU style long filenames */ 
-       if (nameLength == 0) {
-               /* escape from recursive call */
-               if (entry->name[1]=='0') 
-                       return(TRUE);
-
-               /* the data section contains the real filename */
-               if (entry->name[1]=='/') {
-                       char tempName[MAX_NAME_LENGTH];
-
-                       if (entry->size > MAX_NAME_LENGTH)
-                               entry->size = MAX_NAME_LENGTH;
-                       full_read(srcFd, tempName, entry->size);
-                       tempName[entry->size-3]='\0';
-                       
-                       /* read the second header for this entry */
-                       /* be carefull, this is recursive */
-                       if (readArEntry(srcFd, entry)==FALSE)
-                               return(FALSE);
+       /* check ar magic */
+       if (full_read(srcFd, ar_magic, 8) != 8)
+               error_msg_and_die("cannot read magic\n");
+       if (strncmp(ar_magic,"!<arch>",7) != 0)
+               error_msg_and_die("invalid magic\n");
+
+       while (full_read(srcFd, (char *) &raw_ar_header, 60)==60) {
+               /* check the end of header markers are valid */
+               if ((raw_ar_header.fmag[0]!='`') || (raw_ar_header.fmag[1]!='\n')) {
+                       char newline[1];
+                       if (raw_ar_header.fmag[1]!='`') {
+                               break;
+                       }
+                       /* some version of ar, have an extra '\n' after each entry */
+                       read(srcFd, newline, 1);
+                       if (newline[0]!='\n') {
+                               break;
+                       }
+                       /* fix up the header, we started reading 1 byte too early due to a '\n' */
+                       memmove((char *) &raw_ar_header, (char *)&raw_ar_header+1, 59);
+                       /* dont worry about adding the last '\n', we dont need it now */
+               }
                
-                       if ((entry->name[0]='/') && (entry->name[1]='0'))
-                               strcpy(entry->name, tempName);
+               entry->size = (size_t) atoi(raw_ar_header.size);
+               /* long filenames have '/' as the first character */
+               if (raw_ar_header.name[0] == '/') {
+                       if (raw_ar_header.name[1] == '/') {
+                               /* multiple long filenames are stored as data in one entry */
+                               long_name = (char *) xrealloc(long_name, entry->size);
+                               full_read(srcFd, long_name, entry->size);
+                               continue;
+                       }
                        else {
-                               error_msg("Invalid long filename\n");
-                               return(FALSE);
+                               /* The number after the '/' indicates the offset in the ar data section
+                                       (saved in variable long_name) that conatains the real filename */
+                               const int long_name_offset = (int) atoi((char *) &raw_ar_header.name[1]);
+                               entry->name = xmalloc(strlen(&long_name[long_name_offset]));
+                               strcpy(entry->name, &long_name[long_name_offset]);
                        }
                }
-       }
-       return(TRUE);   
-}
-
-/*
- * return the headerL_t struct for the specified filename
- */
-static headerL_t *getHeaders(int srcFd, headerL_t *head, int funct)
-{
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-        int tar=FALSE;
-#endif
-       int ar=FALSE;
-       headerL_t *list;
-       off_t initialOffset;
-
-       list = (headerL_t *) xmalloc(sizeof(headerL_t));
-       initialOffset=lseek(srcFd, 0, SEEK_CUR);
-       if (checkArMagic(srcFd)==TRUE) 
-               ar=TRUE;
-
-#if defined BB_AR_EXPERIMENTAL_UNTAR
-       if (checkTarMagic(srcFd)==TRUE)
-               tar=TRUE;
-
-        if (tar==TRUE) {
-                while(readTarHeader(srcFd, list)==TRUE) {
-                       off_t tarOffset;
-                        list->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                        *list->next = *head;
-                        *head = *list;
-
-                        /* recursive check for sub-archives */
-                        if ((funct & RECURSIVE) == RECURSIVE)
-                                head = getHeaders(srcFd, head, funct);
-                        tarOffset = (off_t) head->size/512;
-                        if ( head->size % 512 > 0)
-                                tarOffset++;
-                        tarOffset=tarOffset*512;
-                        lseek(srcFd, head->offset + tarOffset, SEEK_SET);
-                }
-        }
-#endif
-
-        if (ar==TRUE) {
-               lseek(srcFd, 8, SEEK_CUR); 
-               while(1) {
-                       if (readArEntry(srcFd, list) == FALSE) {
-                               lseek(srcFd, ++initialOffset, SEEK_CUR); 
-                               if (readArEntry(srcFd, list) == FALSE)
-                                       return(head);
-                       }
-                       list->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                       *list->next = *head;
-                       *head = *list;
-                       /* recursive check for sub-archives */
-                       if (funct & RECURSIVE)  
-                               head = getHeaders(srcFd, head, funct);
-                       lseek(srcFd, head->offset + head->size, SEEK_SET);
+               else {
+                       /* short filenames */
+                       entry->name = xmalloc(16);
+                       strncpy(entry->name, raw_ar_header.name, 16);
                }
+               entry->name[strcspn(entry->name, " /")]='\0';
+
+               /* convert the rest of the now valid char header to its typed struct */ 
+               parse_mode(raw_ar_header.mode, &entry->mode);
+               entry->mtime = atoi(raw_ar_header.date);
+               entry->uid = atoi(raw_ar_header.uid);
+               entry->gid = atoi(raw_ar_header.gid);
+               entry->offset = lseek(srcFd, 0, SEEK_CUR);
+
+               /* add this entries header to our combined list */
+               entry->next = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+               *entry->next = *head;
+               *head = *entry;
+               lseek(srcFd, (off_t) entry->size, SEEK_CUR);
        }
-        return(head);
-}
-
-/*
- * find an entry in the linked list matching the filename
- */
-static headerL_t *findEntry(headerL_t *head, const char *filename)
-{
-       while(head->next != NULL) {
-               if (strcmp(filename, head->name)==0) 
-                       return(head);
-               head=head->next;
-       }
-       return(NULL);
+       return(*head);
 }
 
 extern int ar_main(int argc, char **argv)
 {
-        int funct = 0, opt=0;
+       const int preserve_date = 1;    /* preserve original dates */
+       const int verbose = 2;          /* be verbose */
+       const int display = 4;          /* display contents */
+       const int extract_to_file = 8;  /* extract contents of archive */
+       const int extract_to_stdout = 16;       /* extract to stdout */
+
+       int funct = 0, opt=0;
        int srcFd=0, dstFd=0;
-       headerL_t *header, *entry, *extractList;
 
-       while ((opt = getopt(argc, argv, "ovtpxR")) != -1) {
+       ar_headers_t head, *extract_list=NULL;
+
+       extract_list = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+
+       while ((opt = getopt(argc, argv, "ovtpx")) != -1) {
                switch (opt) {
                case 'o':
-                       funct |= PRESERVE_DATE;
+                       funct |= preserve_date;
                        break;
                case 'v':
-                       funct |= VERBOSE;
+                       funct |= verbose;
                        break;
                case 't':
-                       funct |= DISPLAY;
-                       break;
-               case 'x':
-                       funct |= EXT_TO_FILE;
+                       funct |= display;
                        break;
                case 'p':
-                       funct |= EXT_TO_STDOUT;
+                       funct |= extract_to_stdout;
                        break;
-               case 'R':
-                       funct |= RECURSIVE;
+               case 'x':
+                       funct |= extract_to_file;
                        break;
                default:
                        usage(ar_usage);
@@ -345,47 +166,54 @@ extern int ar_main(int argc, char **argv)
        if ( (srcFd = open(argv[optind], O_RDONLY)) < 0)
                error_msg_and_die("Cannot read %s\n", argv[optind]);
 
-       optind++;       
-       entry = (headerL_t *) xmalloc(sizeof(headerL_t));
-       header = (headerL_t *) xmalloc(sizeof(headerL_t));
-       extractList = (headerL_t *) xmalloc(sizeof(headerL_t)); 
+       optind++;       
+       head = get_headers(srcFd);
 
-       header = getHeaders(srcFd, header, funct);
        /* find files to extract or display */
-       if (optind<argc) {
-               /* only handle specified files */
-               while(optind < argc) { 
-                       if ( (entry = findEntry(header, argv[optind])) != NULL) {
-                               entry->next = (headerL_t *) xmalloc(sizeof(headerL_t));
-                               *entry->next = *extractList;
-                               *extractList = *entry;
+       /* search through argv and build extract list */
+       for (;optind<argc; optind++) {
+               ar_headers_t *ar_entry;
+               ar_entry = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+               ar_entry = &head;
+               while (ar_entry->next != NULL) {
+                       if (strcmp(argv[optind], ar_entry->name) == 0) {
+                               ar_headers_t *tmp;
+                               tmp = (ar_headers_t *) xmalloc(sizeof(ar_headers_t));
+                               *tmp = *extract_list;
+                               *extract_list = *ar_entry;
+                               extract_list->next = tmp;
+                               break;                                  
                        }
-                       optind++;
-               }       
+                       ar_entry=ar_entry->next;
+               }
+       }
+
+       /* if individual files not found extract all files */   
+       if (extract_list->next==NULL) {
+               extract_list = &head;
        }
-       else  
-               extractList = header;
        
-        while(extractList->next != NULL) {     
-               if (funct & EXT_TO_FILE) {
-                       if (is_directory(extractList->name, TRUE, NULL)==FALSE)
-                               create_path(extractList->name, 0666);
-                       dstFd = open(extractList->name, O_WRONLY | O_CREAT, extractList->mode);
-                       lseek(srcFd, extractList->offset, SEEK_SET);
-                       copy_file_chunk(srcFd, dstFd, (size_t) extractList->size);
+       /* find files to extract or display */  
+       while (extract_list->next != NULL) {
+               if (funct & extract_to_file) {
+                       dstFd = open(extract_list->name, O_WRONLY | O_CREAT, extract_list->mode);                               
+               }
+               else if (funct & extract_to_stdout) {
+                       dstFd = fileno(stdout);
+               }
+               if ((funct & extract_to_file) || (funct & extract_to_stdout)) {
+                       lseek(srcFd, extract_list->offset, SEEK_SET);
+                       copy_file_chunk(srcFd, dstFd, (size_t) extract_list->size);                     
                }
-               if (funct & EXT_TO_STDOUT) {    
-                       lseek(srcFd, extractList->offset, SEEK_SET);
-                        copy_file_chunk(srcFd, fileno(stdout), (size_t) extractList->size);
+               if (funct & verbose) {
+                       printf("%s %d/%d %8d %s ", mode_string(extract_list->mode), 
+                               extract_list->uid, extract_list->gid,
+                               extract_list->size, time_string(extract_list->mtime));
                }
-               if ( (funct & DISPLAY) || (funct & VERBOSE)) {
-                       if (funct & VERBOSE)
-                               printf("%s %d/%d %8d %s ", mode_string(extractList->mode), 
-                                       extractList->uid, extractList->gid,
-                                       extractList->size, time_string(extractList->mtime));
-                       printf("%s\n", extractList->name);
+               if ((funct & display) || (funct & verbose)){
+                       printf("%s\n", extract_list->name);
                }
-               extractList=extractList->next;
+               extract_list=extract_list->next;
        }
        return EXIT_SUCCESS;
 }