coreutils/fold.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * fold -- wrap each input line to fit in specified width.
   4  *
   5  * Written by David MacKenzie, djm@gnu.ai.mit.edu.
   6  * Copyright (C) 91, 1995-2002 Free Software Foundation, Inc.
   7  *
   8  * Modified for busybox based on coreutils v 5.0
   9  * Copyright (C) 2003 Glenn McGrath
  10  *
  11  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  12  */
  13 //config:config FOLD
  14 //config:       bool "fold (4.8 kb)"
  15 //config:       default y
  16 //config:       help
  17 //config:       Wrap text to fit a specific width.
  18
  19 //applet:IF_FOLD(APPLET_NOEXEC(fold, fold, BB_DIR_USR_BIN, BB_SUID_DROP, fold))
  20
  21 //kbuild:lib-$(CONFIG_FOLD) += fold.o
  22
  23 //usage:#define fold_trivial_usage
  24 //usage:       "[-bs] [-w WIDTH] [FILE]..."
  25 //usage:#define fold_full_usage "\n\n"
  26 //usage:       "Wrap input lines in FILEs (or stdin), writing to stdout\n"
  27 //usage:     "\n        -b      Count bytes rather than columns"
  28 //usage:     "\n        -s      Break at spaces"
  29 //usage:     "\n        -w      Use WIDTH columns instead of 80"
  30
  31 #include "libbb.h"
  32 #include "unicode.h"
  33
  34 /* This is a NOEXEC applet. Be very careful! */
  35
  36 /* Must match getopt32 call */
  37 #define FLAG_COUNT_BYTES        1
  38 #define FLAG_BREAK_SPACES       2
  39 #define FLAG_WIDTH              4
  40
  41 /* Assuming the current column is COLUMN, return the column that
  42    printing C will move the cursor to.
  43    The first column is 0. */
  44 static int adjust_column(unsigned column, char c)
  45 {
  46         if (option_mask32 & FLAG_COUNT_BYTES)
  47                 return ++column;
  48
  49         if (c == '\t')
  50                 return column + 8 - column % 8;
  51
  52         if (c == '\b') {
  53                 if ((int)--column < 0)
  54                         column = 0;
  55         }
  56         else if (c == '\r')
  57                 column = 0;
  58         else { /* just a printable char */
  59                 if (unicode_status != UNICODE_ON /* every byte is a new char */
  60                  || (c & 0xc0) != 0x80 /* it isn't a 2nd+ byte of a Unicode char */
  61                 ) {
  62                         column++;
  63                 }
  64         }
  65         return column;
  66 }
  67
  68 /* Note that this function can write NULs, unlike fputs etc. */
  69 static void write2stdout(const void *buf, unsigned size)
  70 {
  71         fwrite(buf, 1, size, stdout);
  72 }
  73
  74 int fold_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  75 int fold_main(int argc UNUSED_PARAM, char **argv)
  76 {
  77         char *line_out = NULL;
  78         const char *w_opt = "80";
  79         unsigned width;
  80         exitcode_t exitcode = EXIT_SUCCESS;
  81
  82         init_unicode();
  83
  84         if (ENABLE_INCLUDE_SUSv2) {
  85                 /* Turn any numeric options into -w options.  */
  86                 int i;
  87                 for (i = 1; argv[i]; i++) {
  88                         const char *a = argv[i];
  89                         if (*a == '-') {
  90                                 a++;
  91                                 if (*a == '-' && !a[1]) /* "--" */
  92                                         break;
  93                                 if (isdigit(*a))
  94                                         argv[i] = xasprintf("-w%s", a);
  95                         }
  96                 }
  97         }
  98
  99         getopt32(argv, "bsw:", &w_opt);
 100         width = xatou_range(w_opt, 1, 10000);
 101
 102         argv += optind;
 103         if (!*argv)
 104                 *--argv = (char*)"-";
 105
 106         do {
 107                 FILE *istream = fopen_or_warn_stdin(*argv);
 108                 int c;
 109                 unsigned column = 0;     /* Screen column where next char will go */
 110                 unsigned offset_out = 0; /* Index in 'line_out' for next char */
 111
 112                 if (istream == NULL) {
 113                         exitcode = EXIT_FAILURE;
 114                         continue;
 115                 }
 116
 117                 while ((c = getc(istream)) != EOF) {
 118                         /* We grow line_out in chunks of 0x1000 bytes */
 119                         if ((offset_out & 0xfff) == 0) {
 120                                 line_out = xrealloc(line_out, offset_out + 0x1000);
 121                         }
 122  rescan:
 123                         line_out[offset_out] = c;
 124                         if (c == '\n') {
 125                                 write2stdout(line_out, offset_out + 1);
 126                                 column = offset_out = 0;
 127                                 continue;
 128                         }
 129                         column = adjust_column(column, c);
 130                         if (column <= width || offset_out == 0) {
 131                                 /* offset_out == 0 case happens
 132                                  * with small width (say, 1) and tabs.
 133                                  * The very first tab already goes to column 8,
 134                                  * but we must not wrap it */
 135                                 offset_out++;
 136                                 continue;
 137                         }
 138
 139                         /* This character would make the line too long.
 140                          * Print the line plus a newline, and make this character
 141                          * start the next line */
 142                         if (option_mask32 & FLAG_BREAK_SPACES) {
 143                                 unsigned i;
 144                                 unsigned logical_end;
 145
 146                                 /* Look for the last blank. */
 147                                 for (logical_end = offset_out - 1; (int)logical_end >= 0; logical_end--) {
 148                                         if (!isblank(line_out[logical_end]))
 149                                                 continue;
 150
 151                                         /* Found a space or tab.
 152                                          * Output up to and including it, and start a new line */
 153                                         logical_end++;
 154                                         /*line_out[logical_end] = '\n'; - NO! this nukes one buffered character */
 155                                         write2stdout(line_out, logical_end);
 156                                         putchar('\n');
 157                                         /* Move the remainder to the beginning of the next line.
 158                                          * The areas being copied here might overlap. */
 159                                         memmove(line_out, line_out + logical_end, offset_out - logical_end);
 160                                         offset_out -= logical_end;
 161                                         for (column = i = 0; i < offset_out; i++) {
 162                                                 column = adjust_column(column, line_out[i]);
 163                                         }
 164                                         goto rescan;
 165                                 }
 166                                 /* No blank found, wrap will split the overlong word */
 167                         }
 168                         /* Output what we accumulated up to now, and start a new line */
 169                         line_out[offset_out] = '\n';
 170                         write2stdout(line_out, offset_out + 1);
 171                         column = offset_out = 0;
 172                         goto rescan;
 173                 } /* while (not EOF) */
 174
 175                 if (offset_out) {
 176                         write2stdout(line_out, offset_out);
 177                 }
 178
 179                 if (fclose_if_not_stdin(istream)) {
 180                         bb_simple_perror_msg(*argv);
 181                         exitcode = EXIT_FAILURE;
 182                 }
 183         } while (*++argv);
 184
 185         fflush_stdout_and_exit(exitcode);
 186 }