coreutils/fold.c

   1 /* vi: set sw=4 ts=4: */
   2 /* fold -- wrap each input line to fit in specified width.
   3
   4    Written by David MacKenzie, djm@gnu.ai.mit.edu.
   5    Copyright (C) 91, 1995-2002 Free Software Foundation, Inc.
   6
   7    Modified for busybox based on coreutils v 5.0
   8    Copyright (C) 2003 Glenn McGrath
   9
  10    Licensed under GPLv2 or later, see file LICENSE in this source tree.
  11 */
  12 //config:config FOLD
  13 //config:       bool "fold"
  14 //config:       default y
  15 //config:       help
  16 //config:         Wrap text to fit a specific width.
  17
  18 //applet:IF_FOLD(APPLET_NOEXEC(fold, fold, BB_DIR_USR_BIN, BB_SUID_DROP, fold))
  19
  20 //kbuild:lib-$(CONFIG_FOLD) += fold.o
  21
  22 //usage:#define fold_trivial_usage
  23 //usage:       "[-bs] [-w WIDTH] [FILE]..."
  24 //usage:#define fold_full_usage "\n\n"
  25 //usage:       "Wrap input lines in each FILE (or stdin), writing to stdout\n"
  26 //usage:     "\n        -b      Count bytes rather than columns"
  27 //usage:     "\n        -s      Break at spaces"
  28 //usage:     "\n        -w      Use WIDTH columns instead of 80"
  29
  30 #include "libbb.h"
  31 #include "unicode.h"
  32
  33 /* This is a NOEXEC applet. Be very careful! */
  34
  35 /* Must match getopt32 call */
  36 #define FLAG_COUNT_BYTES        1
  37 #define FLAG_BREAK_SPACES       2
  38 #define FLAG_WIDTH              4
  39
  40 /* Assuming the current column is COLUMN, return the column that
  41    printing C will move the cursor to.
  42    The first column is 0. */
  43 static int adjust_column(unsigned column, char c)
  44 {
  45         if (option_mask32 & FLAG_COUNT_BYTES)
  46                 return ++column;
  47
  48         if (c == '\t')
  49                 return column + 8 - column % 8;
  50
  51         if (c == '\b') {
  52                 if ((int)--column < 0)
  53                         column = 0;
  54         }
  55         else if (c == '\r')
  56                 column = 0;
  57         else { /* just a printable char */
  58                 if (unicode_status != UNICODE_ON /* every byte is a new char */
  59                  || (c & 0xc0) != 0x80 /* it isn't a 2nd+ byte of a Unicode char */
  60                 ) {
  61                         column++;
  62                 }
  63         }
  64         return column;
  65 }
  66
  67 /* Note that this function can write NULs, unlike fputs etc. */
  68 static void write2stdout(const void *buf, unsigned size)
  69 {
  70         fwrite(buf, 1, size, stdout);
  71 }
  72
  73 int fold_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  74 int fold_main(int argc UNUSED_PARAM, char **argv)
  75 {
  76         char *line_out = NULL;
  77         const char *w_opt = "80";
  78         unsigned width;
  79         smallint exitcode = EXIT_SUCCESS;
  80
  81         init_unicode();
  82
  83         if (ENABLE_INCLUDE_SUSv2) {
  84                 /* Turn any numeric options into -w options.  */
  85                 int i;
  86                 for (i = 1; argv[i]; i++) {
  87                         const char *a = argv[i];
  88                         if (*a == '-') {
  89                                 a++;
  90                                 if (*a == '-' && !a[1]) /* "--" */
  91                                         break;
  92                                 if (isdigit(*a))
  93                                         argv[i] = xasprintf("-w%s", a);
  94                         }
  95                 }
  96         }
  97
  98         getopt32(argv, "bsw:", &w_opt);
  99         width = xatou_range(w_opt, 1, 10000);
 100
 101         argv += optind;
 102         if (!*argv)
 103                 *--argv = (char*)"-";
 104
 105         do {
 106                 FILE *istream = fopen_or_warn_stdin(*argv);
 107                 int c;
 108                 unsigned column = 0;     /* Screen column where next char will go */
 109                 unsigned offset_out = 0; /* Index in 'line_out' for next char */
 110
 111                 if (istream == NULL) {
 112                         exitcode = EXIT_FAILURE;
 113                         continue;
 114                 }
 115
 116                 while ((c = getc(istream)) != EOF) {
 117                         /* We grow line_out in chunks of 0x1000 bytes */
 118                         if ((offset_out & 0xfff) == 0) {
 119                                 line_out = xrealloc(line_out, offset_out + 0x1000);
 120                         }
 121  rescan:
 122                         line_out[offset_out] = c;
 123                         if (c == '\n') {
 124                                 write2stdout(line_out, offset_out + 1);
 125                                 column = offset_out = 0;
 126                                 continue;
 127                         }
 128                         column = adjust_column(column, c);
 129                         if (column <= width || offset_out == 0) {
 130                                 /* offset_out == 0 case happens
 131                                  * with small width (say, 1) and tabs.
 132                                  * The very first tab already goes to column 8,
 133                                  * but we must not wrap it */
 134                                 offset_out++;
 135                                 continue;
 136                         }
 137
 138                         /* This character would make the line too long.
 139                          * Print the line plus a newline, and make this character
 140                          * start the next line */
 141                         if (option_mask32 & FLAG_BREAK_SPACES) {
 142                                 unsigned i;
 143                                 unsigned logical_end;
 144
 145                                 /* Look for the last blank. */
 146                                 for (logical_end = offset_out - 1; (int)logical_end >= 0; logical_end--) {
 147                                         if (!isblank(line_out[logical_end]))
 148                                                 continue;
 149
 150                                         /* Found a space or tab.
 151                                          * Output up to and including it, and start a new line */
 152                                         logical_end++;
 153                                         /*line_out[logical_end] = '\n'; - NO! this nukes one buffered character */
 154                                         write2stdout(line_out, logical_end);
 155                                         putchar('\n');
 156                                         /* Move the remainder to the beginning of the next line.
 157                                          * The areas being copied here might overlap. */
 158                                         memmove(line_out, line_out + logical_end, offset_out - logical_end);
 159                                         offset_out -= logical_end;
 160                                         for (column = i = 0; i < offset_out; i++) {
 161                                                 column = adjust_column(column, line_out[i]);
 162                                         }
 163                                         goto rescan;
 164                                 }
 165                                 /* No blank found, wrap will split the overlong word */
 166                         }
 167                         /* Output what we accumulated up to now, and start a new line */
 168                         line_out[offset_out] = '\n';
 169                         write2stdout(line_out, offset_out + 1);
 170                         column = offset_out = 0;
 171                         goto rescan;
 172                 } /* while (not EOF) */
 173
 174                 if (offset_out) {
 175                         write2stdout(line_out, offset_out);
 176                 }
 177
 178                 if (fclose_if_not_stdin(istream)) {
 179                         bb_simple_perror_msg(*argv);
 180                         exitcode = EXIT_FAILURE;
 181                 }
 182         } while (*++argv);
 183
 184         fflush_stdout_and_exit(exitcode);
 185 }