src/fold.c

   1 /* fold -- wrap each input line to fit in specified width.
   2    Copyright (C) 1991, 1995-2006, 2008-2010 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by David MacKenzie, djm@gnu.ai.mit.edu. */
  18
  19 #include <config.h>
  20
  21 #include <stdio.h>
  22 #include <getopt.h>
  23 #include <sys/types.h>
  24
  25 #include "system.h"
  26 #include "error.h"
  27 #include "fadvise.h"
  28 #include "quote.h"
  29 #include "xstrtol.h"
  30
  31 #define TAB_WIDTH 8
  32
  33 /* The official name of this program (e.g., no `g' prefix).  */
  34 #define PROGRAM_NAME "fold"
  35
  36 #define AUTHORS proper_name ("David MacKenzie")
  37
  38 /* If nonzero, try to break on whitespace. */
  39 static bool break_spaces;
  40
  41 /* If nonzero, count bytes, not column positions. */
  42 static bool count_bytes;
  43
  44 /* If nonzero, at least one of the files we read was standard input. */
  45 static bool have_read_stdin;
  46
  47 static char const shortopts[] = "bsw:0::1::2::3::4::5::6::7::8::9::";
  48
  49 static struct option const longopts[] =
  50 {
  51   {"bytes", no_argument, NULL, 'b'},
  52   {"spaces", no_argument, NULL, 's'},
  53   {"width", required_argument, NULL, 'w'},
  54   {GETOPT_HELP_OPTION_DECL},
  55   {GETOPT_VERSION_OPTION_DECL},
  56   {NULL, 0, NULL, 0}
  57 };
  58
  59 void
  60 usage (int status)
  61 {
  62   if (status != EXIT_SUCCESS)
  63     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  64              program_name);
  65   else
  66     {
  67       printf (_("\
  68 Usage: %s [OPTION]... [FILE]...\n\
  69 "),
  70               program_name);
  71       fputs (_("\
  72 Wrap input lines in each FILE (standard input by default), writing to\n\
  73 standard output.\n\
  74 \n\
  75 "), stdout);
  76       fputs (_("\
  77 Mandatory arguments to long options are mandatory for short options too.\n\
  78 "), stdout);
  79       fputs (_("\
  80   -b, --bytes         count bytes rather than columns\n\
  81   -s, --spaces        break at spaces\n\
  82   -w, --width=WIDTH   use WIDTH columns instead of 80\n\
  83 "), stdout);
  84       fputs (HELP_OPTION_DESCRIPTION, stdout);
  85       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  86       emit_ancillary_info ();
  87     }
  88   exit (status);
  89 }
  90
  91 /* Assuming the current column is COLUMN, return the column that
  92    printing C will move the cursor to.
  93    The first column is 0. */
  94
  95 static size_t
  96 adjust_column (size_t column, char c)
  97 {
  98   if (!count_bytes)
  99     {
 100       if (c == '\b')
 101         {
 102           if (column > 0)
 103             column--;
 104         }
 105       else if (c == '\r')
 106         column = 0;
 107       else if (c == '\t')
 108         column += TAB_WIDTH - column % TAB_WIDTH;
 109       else /* if (isprint (c)) */
 110         column++;
 111     }
 112   else
 113     column++;
 114   return column;
 115 }
 116
 117 /* Fold file FILENAME, or standard input if FILENAME is "-",
 118    to stdout, with maximum line length WIDTH.
 119    Return true if successful.  */
 120
 121 static bool
 122 fold_file (char const *filename, size_t width)
 123 {
 124   FILE *istream;
 125   int c;
 126   size_t column = 0;            /* Screen column where next char will go. */
 127   size_t offset_out = 0;        /* Index in `line_out' for next char. */
 128   static char *line_out = NULL;
 129   static size_t allocated_out = 0;
 130   int saved_errno;
 131
 132   if (STREQ (filename, "-"))
 133     {
 134       istream = stdin;
 135       have_read_stdin = true;
 136     }
 137   else
 138     istream = fopen (filename, "r");
 139
 140   if (istream == NULL)
 141     {
 142       error (0, errno, "%s", filename);
 143       return false;
 144     }
 145
 146   fadvise (istream, FADVISE_SEQUENTIAL);
 147
 148   while ((c = getc (istream)) != EOF)
 149     {
 150       if (offset_out + 1 >= allocated_out)
 151         line_out = X2REALLOC (line_out, &allocated_out);
 152
 153       if (c == '\n')
 154         {
 155           line_out[offset_out++] = c;
 156           fwrite (line_out, sizeof (char), offset_out, stdout);
 157           column = offset_out = 0;
 158           continue;
 159         }
 160
 161     rescan:
 162       column = adjust_column (column, c);
 163
 164       if (column > width)
 165         {
 166           /* This character would make the line too long.
 167              Print the line plus a newline, and make this character
 168              start the next line. */
 169           if (break_spaces)
 170             {
 171               bool found_blank = false;
 172               size_t logical_end = offset_out;
 173
 174               /* Look for the last blank. */
 175               while (logical_end)
 176                 {
 177                   --logical_end;
 178                   if (isblank (to_uchar (line_out[logical_end])))
 179                     {
 180                       found_blank = true;
 181                       break;
 182                     }
 183                 }
 184
 185               if (found_blank)
 186                 {
 187                   size_t i;
 188
 189                   /* Found a blank.  Don't output the part after it. */
 190                   logical_end++;
 191                   fwrite (line_out, sizeof (char), (size_t) logical_end,
 192                           stdout);
 193                   putchar ('\n');
 194                   /* Move the remainder to the beginning of the next line.
 195                      The areas being copied here might overlap. */
 196                   memmove (line_out, line_out + logical_end,
 197                            offset_out - logical_end);
 198                   offset_out -= logical_end;
 199                   for (column = i = 0; i < offset_out; i++)
 200                     column = adjust_column (column, line_out[i]);
 201                   goto rescan;
 202                 }
 203             }
 204
 205           if (offset_out == 0)
 206             {
 207               line_out[offset_out++] = c;
 208               continue;
 209             }
 210
 211           line_out[offset_out++] = '\n';
 212           fwrite (line_out, sizeof (char), (size_t) offset_out, stdout);
 213           column = offset_out = 0;
 214           goto rescan;
 215         }
 216
 217       line_out[offset_out++] = c;
 218     }
 219
 220   saved_errno = errno;
 221
 222   if (offset_out)
 223     fwrite (line_out, sizeof (char), (size_t) offset_out, stdout);
 224
 225   if (ferror (istream))
 226     {
 227       error (0, saved_errno, "%s", filename);
 228       if (!STREQ (filename, "-"))
 229         fclose (istream);
 230       return false;
 231     }
 232   if (!STREQ (filename, "-") && fclose (istream) == EOF)
 233     {
 234       error (0, errno, "%s", filename);
 235       return false;
 236     }
 237
 238   return true;
 239 }
 240
 241 int
 242 main (int argc, char **argv)
 243 {
 244   size_t width = 80;
 245   int i;
 246   int optc;
 247   bool ok;
 248
 249   initialize_main (&argc, &argv);
 250   set_program_name (argv[0]);
 251   setlocale (LC_ALL, "");
 252   bindtextdomain (PACKAGE, LOCALEDIR);
 253   textdomain (PACKAGE);
 254
 255   atexit (close_stdout);
 256
 257   break_spaces = count_bytes = have_read_stdin = false;
 258
 259   while ((optc = getopt_long (argc, argv, shortopts, longopts, NULL)) != -1)
 260     {
 261       char optargbuf[2];
 262
 263       switch (optc)
 264         {
 265         case 'b':               /* Count bytes rather than columns. */
 266           count_bytes = true;
 267           break;
 268
 269         case 's':               /* Break at word boundaries. */
 270           break_spaces = true;
 271           break;
 272
 273         case '0': case '1': case '2': case '3': case '4':
 274         case '5': case '6': case '7': case '8': case '9':
 275           if (optarg)
 276             optarg--;
 277           else
 278             {
 279               optargbuf[0] = optc;
 280               optargbuf[1] = '\0';
 281               optarg = optargbuf;
 282             }
 283           /* Fall through.  */
 284         case 'w':               /* Line width. */
 285           {
 286             unsigned long int tmp_ulong;
 287             if (! (xstrtoul (optarg, NULL, 10, &tmp_ulong, "") == LONGINT_OK
 288                    && 0 < tmp_ulong && tmp_ulong < SIZE_MAX - TAB_WIDTH))
 289               error (EXIT_FAILURE, 0,
 290                      _("invalid number of columns: %s"), quote (optarg));
 291             width = tmp_ulong;
 292           }
 293           break;
 294
 295         case_GETOPT_HELP_CHAR;
 296
 297         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 298
 299         default:
 300           usage (EXIT_FAILURE);
 301         }
 302     }
 303
 304   if (argc == optind)
 305     ok = fold_file ("-", width);
 306   else
 307     {
 308       ok = true;
 309       for (i = optind; i < argc; i++)
 310         ok &= fold_file (argv[i], width);
 311     }
 312
 313   if (have_read_stdin && fclose (stdin) == EOF)
 314     error (EXIT_FAILURE, errno, "-");
 315
 316   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 317 }