src/unexpand.c

   1 /* unexpand - convert blanks to tabs
   2    Copyright (C) 89, 91, 1995-2006 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 Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 /* By default, convert only maximal strings of initial blanks and tabs
  19    into tabs.
  20    Preserves backspace characters in the output; they decrement the
  21    column count for tab calculations.
  22    The default action is equivalent to -8.
  23
  24    Options:
  25    --tabs=tab1[,tab2[,...]]
  26    -t tab1[,tab2[,...]]
  27    -tab1[,tab2[,...]]   If only one tab stop is given, set the tabs tab1
  28                         columns apart instead of the default 8.  Otherwise,
  29                         set the tabs at columns tab1, tab2, etc. (numbered from
  30                         0); preserve any blanks beyond the tab stops given.
  31    --all
  32    -a                   Use tabs wherever they would replace 2 or more blanks,
  33                         not just at the beginnings of lines.
  34
  35    David MacKenzie <djm@gnu.ai.mit.edu> */
  36
  37 #include <config.h>
  38
  39 #include <stdio.h>
  40 #include <getopt.h>
  41 #include <sys/types.h>
  42 #include "system.h"
  43 #include "error.h"
  44 #include "quote.h"
  45 #include "xstrndup.h"
  46
  47 /* The official name of this program (e.g., no `g' prefix).  */
  48 #define PROGRAM_NAME "unexpand"
  49
  50 #define AUTHORS "David MacKenzie"
  51
  52 /* The number of bytes added at a time to the amount of memory
  53    allocated for the output line.  */
  54 #define OUTPUT_BLOCK 256
  55
  56 /* The name this program was run with.  */
  57 char *program_name;
  58
  59 /* If true, convert blanks even after nonblank characters have been
  60    read on the line.  */
  61 static bool convert_entire_line;
  62
  63 /* If nonzero, the size of all tab stops.  If zero, use `tab_list' instead.  */
  64 static size_t tab_size;
  65
  66 /* The maximum distance between tab stops.  */
  67 static size_t max_column_width;
  68
  69 /* Array of the explicit column numbers of the tab stops;
  70    after `tab_list' is exhausted, the rest of the line is printed
  71    unchanged.  The first column is column 0.  */
  72 static uintmax_t *tab_list;
  73
  74 /* The number of allocated entries in `tab_list'.  */
  75 static size_t n_tabs_allocated;
  76
  77 /* The index of the first invalid element of `tab_list',
  78    where the next element can be added.  */
  79 static size_t first_free_tab;
  80
  81 /* Null-terminated array of input filenames.  */
  82 static char **file_list;
  83
  84 /* Default for `file_list' if no files are given on the command line.  */
  85 static char *stdin_argv[] =
  86 {
  87   "-", NULL
  88 };
  89
  90 /* True if we have ever read standard input.  */
  91 static bool have_read_stdin;
  92
  93 /* The desired exit status.  */
  94 static int exit_status;
  95
  96 /* For long options that have no equivalent short option, use a
  97    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  98 enum
  99 {
 100   CONVERT_FIRST_ONLY_OPTION = CHAR_MAX + 1
 101 };
 102
 103 static struct option const longopts[] =
 104 {
 105   {"tabs", required_argument, NULL, 't'},
 106   {"all", no_argument, NULL, 'a'},
 107   {"first-only", no_argument, NULL, CONVERT_FIRST_ONLY_OPTION},
 108   {GETOPT_HELP_OPTION_DECL},
 109   {GETOPT_VERSION_OPTION_DECL},
 110   {NULL, 0, NULL, 0}
 111 };
 112
 113 void
 114 usage (int status)
 115 {
 116   if (status != EXIT_SUCCESS)
 117     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 118              program_name);
 119   else
 120     {
 121       printf (_("\
 122 Usage: %s [OPTION]... [FILE]...\n\
 123 "),
 124               program_name);
 125       fputs (_("\
 126 Convert blanks in each FILE to tabs, writing to standard output.\n\
 127 With no FILE, or when FILE is -, read standard input.\n\
 128 \n\
 129 "), stdout);
 130       fputs (_("\
 131 Mandatory arguments to long options are mandatory for short options too.\n\
 132 "), stdout);
 133       fputs (_("\
 134   -a, --all        convert all blanks, instead of just initial blanks\n\
 135       --first-only  convert only leading sequences of blanks (overrides -a)\n\
 136   -t, --tabs=N     have tabs N characters apart instead of 8 (enables -a)\n\
 137   -t, --tabs=LIST  use comma separated LIST of tab positions (enables -a)\n\
 138 "), stdout);
 139       fputs (HELP_OPTION_DESCRIPTION, stdout);
 140       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 141       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 142     }
 143   exit (status);
 144 }
 145
 146 /* Add tab stop TABVAL to the end of `tab_list'.  */
 147
 148 static void
 149 add_tab_stop (uintmax_t tabval)
 150 {
 151   uintmax_t prev_column = first_free_tab ? tab_list[first_free_tab - 1] : 0;
 152   uintmax_t column_width = prev_column <= tabval ? tabval - prev_column : 0;
 153
 154   if (first_free_tab == n_tabs_allocated)
 155     tab_list = X2NREALLOC (tab_list, &n_tabs_allocated);
 156   tab_list[first_free_tab++] = tabval;
 157
 158   if (max_column_width < column_width)
 159     {
 160       if (SIZE_MAX < column_width)
 161         error (EXIT_FAILURE, 0, _("tabs are too far apart"));
 162       max_column_width = column_width;
 163     }
 164 }
 165
 166 /* Add the comma or blank separated list of tab stops STOPS
 167    to the list of tab stops.  */
 168
 169 static void
 170 parse_tab_stops (char const *stops)
 171 {
 172   bool have_tabval = false;
 173   uintmax_t tabval IF_LINT (= 0);
 174   char const *num_start IF_LINT (= NULL);
 175   bool ok = true;
 176
 177   for (; *stops; stops++)
 178     {
 179       if (*stops == ',' || isblank (to_uchar (*stops)))
 180         {
 181           if (have_tabval)
 182             add_tab_stop (tabval);
 183           have_tabval = false;
 184         }
 185       else if (ISDIGIT (*stops))
 186         {
 187           if (!have_tabval)
 188             {
 189               tabval = 0;
 190               have_tabval = true;
 191               num_start = stops;
 192             }
 193
 194           /* Detect overflow.  */
 195           if (!DECIMAL_DIGIT_ACCUMULATE (tabval, *stops - '0', uintmax_t))
 196             {
 197               size_t len = strspn (num_start, "0123456789");
 198               char *bad_num = xstrndup (num_start, len);
 199               error (0, 0, _("tab stop is too large %s"), quote (bad_num));
 200               free (bad_num);
 201               ok = false;
 202               stops = num_start + len - 1;
 203             }
 204         }
 205       else
 206         {
 207           error (0, 0, _("tab size contains invalid character(s): %s"),
 208                  quote (stops));
 209           ok = false;
 210           break;
 211         }
 212     }
 213
 214   if (!ok)
 215     exit (EXIT_FAILURE);
 216
 217   if (have_tabval)
 218     add_tab_stop (tabval);
 219 }
 220
 221 /* Check that the list of tab stops TABS, with ENTRIES entries,
 222    contains only nonzero, ascending values.  */
 223
 224 static void
 225 validate_tab_stops (uintmax_t const *tabs, size_t entries)
 226 {
 227   uintmax_t prev_tab = 0;
 228   size_t i;
 229
 230   for (i = 0; i < entries; i++)
 231     {
 232       if (tabs[i] == 0)
 233         error (EXIT_FAILURE, 0, _("tab size cannot be 0"));
 234       if (tabs[i] <= prev_tab)
 235         error (EXIT_FAILURE, 0, _("tab sizes must be ascending"));
 236       prev_tab = tabs[i];
 237     }
 238 }
 239
 240 /* Close the old stream pointer FP if it is non-NULL,
 241    and return a new one opened to read the next input file.
 242    Open a filename of `-' as the standard input.
 243    Return NULL if there are no more input files.  */
 244
 245 static FILE *
 246 next_file (FILE *fp)
 247 {
 248   static char *prev_file;
 249   char *file;
 250
 251   if (fp)
 252     {
 253       if (ferror (fp))
 254         {
 255           error (0, errno, "%s", prev_file);
 256           exit_status = EXIT_FAILURE;
 257         }
 258       if (STREQ (prev_file, "-"))
 259         clearerr (fp);          /* Also clear EOF.  */
 260       else if (fclose (fp) != 0)
 261         {
 262           error (0, errno, "%s", prev_file);
 263           exit_status = EXIT_FAILURE;
 264         }
 265     }
 266
 267   while ((file = *file_list++) != NULL)
 268     {
 269       if (STREQ (file, "-"))
 270         {
 271           have_read_stdin = true;
 272           prev_file = file;
 273           return stdin;
 274         }
 275       fp = fopen (file, "r");
 276       if (fp)
 277         {
 278           prev_file = file;
 279           return fp;
 280         }
 281       error (0, errno, "%s", file);
 282       exit_status = EXIT_FAILURE;
 283     }
 284   return NULL;
 285 }
 286
 287 /* Change blanks to tabs, writing to stdout.
 288    Read each file in `file_list', in order.  */
 289
 290 static void
 291 unexpand (void)
 292 {
 293   /* Input stream.  */
 294   FILE *fp = next_file (NULL);
 295
 296   /* The array of pending blanks.  In non-POSIX locales, blanks can
 297      include characters other than spaces, so the blanks must be
 298      stored, not merely counted.  */
 299   char *pending_blank;
 300
 301   if (!fp)
 302     return;
 303
 304   /* The worst case is a non-blank character, then one blank, then a
 305      tab stop, then MAX_COLUMN_WIDTH - 1 blanks, then a non-blank; so
 306      allocate MAX_COLUMN_WIDTH bytes to store the blanks.  */
 307   pending_blank = xmalloc (max_column_width);
 308
 309   for (;;)
 310     {
 311       /* Input character, or EOF.  */
 312       int c;
 313
 314       /* If true, perform translations.  */
 315       bool convert = true;
 316
 317
 318       /* The following variables have valid values only when CONVERT
 319          is true:  */
 320
 321       /* Column of next input character.  */
 322       uintmax_t column = 0;
 323
 324       /* Column the next input tab stop is on.  */
 325       uintmax_t next_tab_column = 0;
 326
 327       /* Index in TAB_LIST of next tab stop to examine.  */
 328       size_t tab_index = 0;
 329
 330       /* If true, the first pending blank came just before a tab stop.  */
 331       bool one_blank_before_tab_stop = false;
 332
 333       /* If true, the previous input character was a blank.  This is
 334          initially true, since initial strings of blanks are treated
 335          as if the line was preceded by a blank.  */
 336       bool prev_blank = true;
 337
 338       /* Number of pending columns of blanks.  */
 339       size_t pending = 0;
 340
 341
 342       /* Convert a line of text.  */
 343
 344       do
 345         {
 346           while ((c = getc (fp)) < 0 && (fp = next_file (fp)))
 347             continue;
 348
 349           if (convert)
 350             {
 351               bool blank = !! isblank (c);
 352
 353               if (blank)
 354                 {
 355                   if (next_tab_column <= column)
 356                     {
 357                       if (tab_size)
 358                         next_tab_column =
 359                           column + (tab_size - column % tab_size);
 360                       else
 361                         for (;;)
 362                           if (tab_index == first_free_tab)
 363                             {
 364                               convert = false;
 365                               break;
 366                             }
 367                           else
 368                             {
 369                               uintmax_t tab = tab_list[tab_index++];
 370                               if (column < tab)
 371                                 {
 372                                   next_tab_column = tab;
 373                                   break;
 374                                 }
 375                             }
 376                     }
 377
 378                   if (convert)
 379                     {
 380                       if (next_tab_column < column)
 381                         error (EXIT_FAILURE, 0, _("input line is too long"));
 382
 383                       if (c == '\t')
 384                         {
 385                           column = next_tab_column;
 386
 387                           /* Discard pending blanks, unless it was a single
 388                              blank just before the previous tab stop.  */
 389                           if (! (pending == 1 && one_blank_before_tab_stop))
 390                             {
 391                               pending = 0;
 392                               one_blank_before_tab_stop = false;
 393                             }
 394                         }
 395                       else
 396                         {
 397                           column++;
 398
 399                           if (! (prev_blank && column == next_tab_column))
 400                             {
 401                               /* It is not yet known whether the pending blanks
 402                                  will be replaced by tabs.  */
 403                               if (column == next_tab_column)
 404                                 one_blank_before_tab_stop = true;
 405                               pending_blank[pending++] = c;
 406                               prev_blank = true;
 407                               continue;
 408                             }
 409
 410                           /* Replace the pending blanks by a tab or two.  */
 411                           pending_blank[0] = c = '\t';
 412                           pending = one_blank_before_tab_stop;
 413                         }
 414                     }
 415                 }
 416               else if (c == '\b')
 417                 {
 418                   /* Go back one column, and force recalculation of the
 419                      next tab stop.  */
 420                   column -= !!column;
 421                   next_tab_column = column;
 422                   tab_index -= !!tab_index;
 423                 }
 424               else
 425                 {
 426                   column++;
 427                   if (!column)
 428                     error (EXIT_FAILURE, 0, _("input line is too long"));
 429                 }
 430
 431               if (pending)
 432                 {
 433                   if (fwrite (pending_blank, 1, pending, stdout) != pending)
 434                     error (EXIT_FAILURE, errno, _("write error"));
 435                   pending = 0;
 436                   one_blank_before_tab_stop = false;
 437                 }
 438
 439               prev_blank = blank;
 440               convert &= convert_entire_line | blank;
 441             }
 442
 443           if (c < 0)
 444             {
 445               free (pending_blank);
 446               return;
 447             }
 448
 449           if (putchar (c) < 0)
 450             error (EXIT_FAILURE, errno, _("write error"));
 451         }
 452       while (c != '\n');
 453     }
 454 }
 455
 456 int
 457 main (int argc, char **argv)
 458 {
 459   bool have_tabval = false;
 460   uintmax_t tabval IF_LINT (= 0);
 461   int c;
 462
 463   /* If true, cancel the effect of any -a (explicit or implicit in -t),
 464      so that only leading blanks will be considered.  */
 465   bool convert_first_only = false;
 466
 467   initialize_main (&argc, &argv);
 468   program_name = argv[0];
 469   setlocale (LC_ALL, "");
 470   bindtextdomain (PACKAGE, LOCALEDIR);
 471   textdomain (PACKAGE);
 472
 473   atexit (close_stdout);
 474
 475   have_read_stdin = false;
 476   exit_status = EXIT_SUCCESS;
 477   convert_entire_line = false;
 478   tab_list = NULL;
 479   first_free_tab = 0;
 480
 481   while ((c = getopt_long (argc, argv, ",0123456789at:", longopts, NULL))
 482          != -1)
 483     {
 484       switch (c)
 485         {
 486         case '?':
 487           usage (EXIT_FAILURE);
 488         case 'a':
 489           convert_entire_line = true;
 490           break;
 491         case 't':
 492           convert_entire_line = true;
 493           parse_tab_stops (optarg);
 494           break;
 495         case CONVERT_FIRST_ONLY_OPTION:
 496           convert_first_only = true;
 497           break;
 498         case ',':
 499           if (have_tabval)
 500             add_tab_stop (tabval);
 501           have_tabval = false;
 502           break;
 503         case_GETOPT_HELP_CHAR;
 504         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 505         default:
 506           if (!have_tabval)
 507             {
 508               tabval = 0;
 509               have_tabval = true;
 510             }
 511           if (!DECIMAL_DIGIT_ACCUMULATE (tabval, c - '0', uintmax_t))
 512             error (EXIT_FAILURE, 0, _("tab stop value is too large"));
 513           break;
 514         }
 515     }
 516
 517   if (convert_first_only)
 518     convert_entire_line = false;
 519
 520   if (have_tabval)
 521     add_tab_stop (tabval);
 522
 523   validate_tab_stops (tab_list, first_free_tab);
 524
 525   if (first_free_tab == 0)
 526     tab_size = max_column_width = 8;
 527   else if (first_free_tab == 1)
 528     tab_size = tab_list[0];
 529   else
 530     tab_size = 0;
 531
 532   file_list = (optind < argc ? &argv[optind] : stdin_argv);
 533
 534   unexpand ();
 535
 536   if (have_read_stdin && fclose (stdin) != 0)
 537     error (EXIT_FAILURE, errno, "-");
 538
 539   exit (exit_status);
 540 }