src/fold.c

   1 /* fold -- wrap each input line to fit in specified width.
   2    Copyright (C) 1991, 1995 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 2, or (at your option)
   7    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, write to the Free Software
  16    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by David MacKenzie, djm@gnu.ai.mit.edu. */
  19
  20 #include <config.h>
  21
  22 /* Get isblank from GNU libc.  */
  23 #define _GNU_SOURCE
  24
  25 #include <stdio.h>
  26 #include <getopt.h>
  27 #include <sys/types.h>
  28 #include "system.h"
  29 #include "version.h"
  30 #include "error.h"
  31
  32 char *xrealloc ();
  33 char *xmalloc ();
  34
  35 /* The name this program was run with. */
  36 char *program_name;
  37
  38 /* If nonzero, try to break on whitespace. */
  39 static int break_spaces;
  40
  41 /* If nonzero, count bytes, not column positions. */
  42 static int count_bytes;
  43
  44 /* If nonzero, at least one of the files we read was standard input. */
  45 static int have_read_stdin;
  46
  47 /* If nonzero, display usage information and exit.  */
  48 static int show_help;
  49
  50 /* If nonzero, print the version on standard output then exit.  */
  51 static int show_version;
  52
  53 static struct option const longopts[] =
  54 {
  55   {"bytes", no_argument, NULL, 'b'},
  56   {"spaces", no_argument, NULL, 's'},
  57   {"width", required_argument, NULL, 'w'},
  58   {"help", no_argument, &show_help, 1},
  59   {"version", no_argument, &show_version, 1},
  60   {NULL, 0, NULL, 0}
  61 };
  62
  63 static void
  64 usage (int status)
  65 {
  66   if (status != 0)
  67     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  68              program_name);
  69   else
  70     {
  71       printf (_("\
  72 Usage: %s [OPTION]... [FILE]...\n\
  73 "),
  74               program_name);
  75       printf (_("\
  76 Wrap input lines in each FILE (standard input by default), writing to\n\
  77 standard output.\n\
  78 \n\
  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 "));
  83     }
  84   exit (status);
  85 }
  86
  87 /* Assuming the current column is COLUMN, return the column that
  88    printing C will move the cursor to.
  89    The first column is 0. */
  90
  91 static int
  92 adjust_column (int column, char c)
  93 {
  94   if (!count_bytes)
  95     {
  96       if (c == '\b')
  97         {
  98           if (column > 0)
  99             column--;
 100         }
 101       else if (c == '\r')
 102         column = 0;
 103       else if (c == '\t')
 104         column = column + 8 - column % 8;
 105       else /* if (isprint (c)) */
 106         column++;
 107     }
 108   else
 109     column++;
 110   return column;
 111 }
 112
 113 /* Fold file FILENAME, or standard input if FILENAME is "-",
 114    to stdout, with maximum line length WIDTH.
 115    Return 0 if successful, 1 if an error occurs. */
 116
 117 static int
 118 fold_file (char *filename, int width)
 119 {
 120   FILE *istream;
 121   register int c;
 122   int column = 0;               /* Screen column where next char will go. */
 123   size_t offset_out = 0;        /* Index in `line_out' for next char. */
 124   static char *line_out = NULL;
 125   static size_t allocated_out = 0;
 126
 127   if (!strcmp (filename, "-"))
 128     {
 129       istream = stdin;
 130       have_read_stdin = 1;
 131     }
 132   else
 133     istream = fopen (filename, "r");
 134
 135   if (istream == NULL)
 136     {
 137       error (0, errno, "%s", filename);
 138       return 1;
 139     }
 140
 141   while ((c = getc (istream)) != EOF)
 142     {
 143       if (offset_out + 1 >= allocated_out)
 144         {
 145           allocated_out += 1024;
 146           line_out = xrealloc (line_out, allocated_out);
 147         }
 148
 149       if (c == '\n')
 150         {
 151           line_out[offset_out++] = c;
 152           fwrite (line_out, sizeof (char), offset_out, stdout);
 153           column = offset_out = 0;
 154           continue;
 155         }
 156
 157     rescan:
 158       column = adjust_column (column, c);
 159
 160       if (column > width)
 161         {
 162           /* This character would make the line too long.
 163              Print the line plus a newline, and make this character
 164              start the next line. */
 165           if (break_spaces)
 166             {
 167               /* Look for the last blank. */
 168               int logical_end;
 169
 170               for (logical_end = offset_out - 1; logical_end >= 0;
 171                    logical_end--)
 172                 if (ISBLANK (line_out[logical_end]))
 173                   break;
 174               if (logical_end >= 0)
 175                 {
 176                   int i;
 177
 178                   /* Found a blank.  Don't output the part after it. */
 179                   logical_end++;
 180                   fwrite (line_out, sizeof (char), logical_end, stdout);
 181                   putchar ('\n');
 182                   /* Move the remainder to the beginning of the next line.
 183                      The areas being copied here might overlap. */
 184                   memmove (line_out, line_out + logical_end,
 185                            offset_out - logical_end);
 186                   offset_out -= logical_end;
 187                   for (column = i = 0; i < offset_out; i++)
 188                     column = adjust_column (column, line_out[i]);
 189                   goto rescan;
 190                 }
 191             }
 192           else
 193             {
 194               if (offset_out == 0)
 195                 {
 196                   line_out[offset_out++] = c;
 197                   continue;
 198                 }
 199             }
 200           line_out[offset_out++] = '\n';
 201           fwrite (line_out, sizeof (char), offset_out, stdout);
 202           column = offset_out = 0;
 203           goto rescan;
 204         }
 205
 206       line_out[offset_out++] = c;
 207     }
 208
 209   if (offset_out)
 210     fwrite (line_out, sizeof (char), offset_out, stdout);
 211
 212   if (ferror (istream))
 213     {
 214       error (0, errno, "%s", filename);
 215       if (strcmp (filename, "-"))
 216         fclose (istream);
 217       return 1;
 218     }
 219   if (strcmp (filename, "-") && fclose (istream) == EOF)
 220     {
 221       error (0, errno, "%s", filename);
 222       return 1;
 223     }
 224
 225   if (ferror (stdout))
 226     {
 227       error (0, errno, _("write error"));
 228       return 1;
 229     }
 230
 231   return 0;
 232 }
 233
 234 void
 235 main (int argc, char **argv)
 236 {
 237   int width = 80;
 238   int i;
 239   int optc;
 240   int errs = 0;
 241
 242   program_name = argv[0];
 243   break_spaces = count_bytes = have_read_stdin = 0;
 244
 245   /* Turn any numeric options into -w options.  */
 246   for (i = 1; i < argc; i++)
 247     {
 248       if (argv[i][0] == '-' && ISDIGIT (argv[i][1]))
 249         {
 250           char *s;
 251
 252           s = xmalloc (strlen (argv[i]) + 2);
 253           s[0] = '-';
 254           s[1] = 'w';
 255           strcpy (s + 2, argv[i] + 1);
 256           argv[i] = s;
 257         }
 258     }
 259
 260   while ((optc = getopt_long (argc, argv, "bsw:", longopts, (int *) 0))
 261          != EOF)
 262     {
 263       switch (optc)
 264         {
 265         case 0:
 266           break;
 267
 268         case 'b':               /* Count bytes rather than columns. */
 269           count_bytes = 1;
 270           break;
 271
 272         case 's':               /* Break at word boundaries. */
 273           break_spaces = 1;
 274           break;
 275
 276         case 'w':               /* Line width. */
 277           width = atoi (optarg);
 278           if (width < 1)
 279             error (1, 0, _("%s: invalid line width"), optarg);
 280           break;
 281
 282         default:
 283           usage (1);
 284         }
 285     }
 286
 287   if (show_version)
 288     {
 289       printf ("fold - %s\n", version_string);
 290       exit (0);
 291     }
 292
 293   if (show_help)
 294     usage (0);
 295
 296   if (argc == optind)
 297     errs |= fold_file ("-", width);
 298   else
 299     for (i = optind; i < argc; i++)
 300       errs |= fold_file (argv[i], width);
 301
 302   if (have_read_stdin && fclose (stdin) == EOF)
 303     error (1, errno, "-");
 304   if (fclose (stdout) == EOF)
 305     error (1, errno, _("write error"));
 306
 307   exit (errs);
 308 }