src/fold.c

   1 /* fold -- wrap each input line to fit in specified width.
   2    Copyright (C) 1991, 1995-2006, 2008-2012 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     emit_try_help ();
  64   else
  65     {
  66       printf (_("\
  67 Usage: %s [OPTION]... [FILE]...\n\
  68 "),
  69               program_name);
  70       fputs (_("\
  71 Wrap input lines in each FILE (standard input by default), writing to\n\
  72 standard output.\n\
  73 \n\
  74 "), stdout);
  75       fputs (_("\
  76 Mandatory arguments to long options are mandatory for short options too.\n\
  77 "), stdout);
  78       fputs (_("\
  79   -b, --bytes         count bytes rather than columns\n\
  80   -s, --spaces        break at spaces\n\
  81   -w, --width=WIDTH   use WIDTH columns instead of 80\n\
  82 "), stdout);
  83       fputs (HELP_OPTION_DESCRIPTION, stdout);
  84       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  85       emit_ancillary_info ();
  86     }
  87   exit (status);
  88 }
  89
  90 /* Assuming the current column is COLUMN, return the column that
  91    printing C will move the cursor to.
  92    The first column is 0. */
  93
  94 static size_t
  95 adjust_column (size_t column, char c)
  96 {
  97   if (!count_bytes)
  98     {
  99       if (c == '\b')
 100         {
 101           if (column > 0)
 102             column--;
 103         }
 104       else if (c == '\r')
 105         column = 0;
 106       else if (c == '\t')
 107         column += TAB_WIDTH - column % TAB_WIDTH;
 108       else /* if (isprint (c)) */
 109         column++;
 110     }
 111   else
 112     column++;
 113   return column;
 114 }
 115
 116 /* Fold file FILENAME, or standard input if FILENAME is "-",
 117    to stdout, with maximum line length WIDTH.
 118    Return true if successful.  */
 119
 120 static bool
 121 fold_file (char const *filename, size_t width)
 122 {
 123   FILE *istream;
 124   int c;
 125   size_t column = 0;            /* Screen column where next char will go. */
 126   size_t offset_out = 0;        /* Index in `line_out' for next char. */
 127   static char *line_out = NULL;
 128   static size_t allocated_out = 0;
 129   int saved_errno;
 130
 131   if (STREQ (filename, "-"))
 132     {
 133       istream = stdin;
 134       have_read_stdin = true;
 135     }
 136   else
 137     istream = fopen (filename, "r");
 138
 139   if (istream == NULL)
 140     {
 141       error (0, errno, "%s", filename);
 142       return false;
 143     }
 144
 145   fadvise (istream, FADVISE_SEQUENTIAL);
 146
 147   while ((c = getc (istream)) != EOF)
 148     {
 149       if (offset_out + 1 >= allocated_out)
 150         line_out = X2REALLOC (line_out, &allocated_out);
 151
 152       if (c == '\n')
 153         {
 154           line_out[offset_out++] = c;
 155           fwrite (line_out, sizeof (char), offset_out, stdout);
 156           column = offset_out = 0;
 157           continue;
 158         }
 159
 160     rescan:
 161       column = adjust_column (column, c);
 162
 163       if (column > width)
 164         {
 165           /* This character would make the line too long.
 166              Print the line plus a newline, and make this character
 167              start the next line. */
 168           if (break_spaces)
 169             {
 170               bool found_blank = false;
 171               size_t logical_end = offset_out;
 172
 173               /* Look for the last blank. */
 174               while (logical_end)
 175                 {
 176                   --logical_end;
 177                   if (isblank (to_uchar (line_out[logical_end])))
 178                     {
 179                       found_blank = true;
 180                       break;
 181                     }
 182                 }
 183
 184               if (found_blank)
 185                 {
 186                   size_t i;
 187
 188                   /* Found a blank.  Don't output the part after it. */
 189                   logical_end++;
 190                   fwrite (line_out, sizeof (char), (size_t) logical_end,
 191                           stdout);
 192                   putchar ('\n');
 193                   /* Move the remainder to the beginning of the next line.
 194                      The areas being copied here might overlap. */
 195                   memmove (line_out, line_out + logical_end,
 196                            offset_out - logical_end);
 197                   offset_out -= logical_end;
 198                   for (column = i = 0; i < offset_out; i++)
 199                     column = adjust_column (column, line_out[i]);
 200                   goto rescan;
 201                 }
 202             }
 203
 204           if (offset_out == 0)
 205             {
 206               line_out[offset_out++] = c;
 207               continue;
 208             }
 209
 210           line_out[offset_out++] = '\n';
 211           fwrite (line_out, sizeof (char), (size_t) offset_out, stdout);
 212           column = offset_out = 0;
 213           goto rescan;
 214         }
 215
 216       line_out[offset_out++] = c;
 217     }
 218
 219   saved_errno = errno;
 220
 221   if (offset_out)
 222     fwrite (line_out, sizeof (char), (size_t) offset_out, stdout);
 223
 224   if (ferror (istream))
 225     {
 226       error (0, saved_errno, "%s", filename);
 227       if (!STREQ (filename, "-"))
 228         fclose (istream);
 229       return false;
 230     }
 231   if (!STREQ (filename, "-") && fclose (istream) == EOF)
 232     {
 233       error (0, errno, "%s", filename);
 234       return false;
 235     }
 236
 237   return true;
 238 }
 239
 240 int
 241 main (int argc, char **argv)
 242 {
 243   size_t width = 80;
 244   int i;
 245   int optc;
 246   bool ok;
 247
 248   initialize_main (&argc, &argv);
 249   set_program_name (argv[0]);
 250   setlocale (LC_ALL, "");
 251   bindtextdomain (PACKAGE, LOCALEDIR);
 252   textdomain (PACKAGE);
 253
 254   atexit (close_stdout);
 255
 256   break_spaces = count_bytes = have_read_stdin = false;
 257
 258   while ((optc = getopt_long (argc, argv, shortopts, longopts, NULL)) != -1)
 259     {
 260       char optargbuf[2];
 261
 262       switch (optc)
 263         {
 264         case 'b':               /* Count bytes rather than columns. */
 265           count_bytes = true;
 266           break;
 267
 268         case 's':               /* Break at word boundaries. */
 269           break_spaces = true;
 270           break;
 271
 272         case '0': case '1': case '2': case '3': case '4':
 273         case '5': case '6': case '7': case '8': case '9':
 274           if (optarg)
 275             optarg--;
 276           else
 277             {
 278               optargbuf[0] = optc;
 279               optargbuf[1] = '\0';
 280               optarg = optargbuf;
 281             }
 282           /* Fall through.  */
 283         case 'w':               /* Line width. */
 284           {
 285             unsigned long int tmp_ulong;
 286             if (! (xstrtoul (optarg, NULL, 10, &tmp_ulong, "") == LONGINT_OK
 287                    && 0 < tmp_ulong && tmp_ulong < SIZE_MAX - TAB_WIDTH))
 288               error (EXIT_FAILURE, 0,
 289                      _("invalid number of columns: %s"), quote (optarg));
 290             width = tmp_ulong;
 291           }
 292           break;
 293
 294         case_GETOPT_HELP_CHAR;
 295
 296         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 297
 298         default:
 299           usage (EXIT_FAILURE);
 300         }
 301     }
 302
 303   if (argc == optind)
 304     ok = fold_file ("-", width);
 305   else
 306     {
 307       ok = true;
 308       for (i = optind; i < argc; i++)
 309         ok &= fold_file (argv[i], width);
 310     }
 311
 312   if (have_read_stdin && fclose (stdin) == EOF)
 313     error (EXIT_FAILURE, errno, "-");
 314
 315   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 316 }