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