colorize.c

   1 /*
   2  * colorize - Read text from standard input stream or file and print
   3  *            it colorized through use of ANSI escape sequences
   4  *
   5  * Copyright (c) 2011-2013 Steven Schubiger
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation, either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 #define _POSIX_SOURCE
  23 #include <assert.h>
  24 #include <ctype.h>
  25 #include <errno.h>
  26 #include <getopt.h>
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <sys/time.h>
  32 #include <sys/types.h>
  33 #include <sys/stat.h>
  34 #include <time.h>
  35 #include <unistd.h>
  36
  37 #define DEBUG 0
  38
  39 #define str(arg) #arg
  40 #define to_str(arg) str(arg)
  41
  42 #define streq(s1, s2) (strcmp (s1, s2) == 0)
  43
  44 #define xmalloc(size)       malloc_wrap(size,       __FILE__, __LINE__)
  45 #define xrealloc(ptr, size) realloc_wrap(ptr, size, __FILE__, __LINE__)
  46 #define xstrdup(str)        strdup_wrap(str,        __FILE__, __LINE__)
  47
  48 #if !defined BUF_SIZE || BUF_SIZE <= 0
  49 # undef BUF_SIZE
  50 # define BUF_SIZE 4096 + 1
  51 #endif
  52
  53 #define LF 0x01
  54 #define CR 0x02
  55
  56 #define SKIP_LINE_ENDINGS(flags) (((flags) & CR) && ((flags) & LF) ? 2 : 1)
  57
  58 #define STACK_VAR(ptr) do {                                   \
  59     stack_var (&vars_list, &stacked_vars, stacked_vars, ptr); \
  60 } while (false);
  61
  62 #define RELEASE_VAR(ptr) do {                             \
  63     release_var (vars_list, stacked_vars, (void **)&ptr); \
  64 } while (false);
  65
  66 #if DEBUG
  67 # define MEM_ALLOC_FAIL(file, line) do {                                                    \
  68     fprintf (stderr, "Memory allocation failure in source file %s, line %d\n", file, line); \
  69     exit (2);                                                                               \
  70 } while (false);
  71 #else
  72 # define MEM_ALLOC_FAIL(file, line) do {                               \
  73     fprintf (stderr, "%s: memory allocation failure\n", program_name); \
  74     exit (2);                                                          \
  75 } while (false);
  76 #endif
  77
  78 #define ABORT_TRACE()                                                              \
  79     fprintf (stderr, "Aborting in source file %s, line %d\n", __FILE__, __LINE__); \
  80     abort ();                                                                      \
  81
  82 #define CHECK_COLORS_RANDOM(color1, color2)        \
  83      streq (color_names[color1]->name, "random")   \
  84  && (streq (color_names[color2]->name, "none")     \
  85   || streq (color_names[color2]->name, "default")) \
  86
  87 #define VERSION "0.48"
  88
  89 typedef unsigned short bool;
  90
  91 enum { false, true };
  92
  93 struct color_name {
  94     char *name;
  95     char *orig;
  96 };
  97
  98 static struct color_name *color_names[3] = { NULL, NULL, NULL };
  99
 100 struct color {
 101     const char *name;
 102     const char *code;
 103 };
 104
 105 static const struct color fg_colors[] = {
 106     { "none",     NULL },
 107     { "black",   "30m" },
 108     { "red",     "31m" },
 109     { "green",   "32m" },
 110     { "yellow",  "33m" },
 111     { "blue",    "34m" },
 112     { "cyan",    "35m" },
 113     { "magenta", "36m" },
 114     { "white",   "37m" },
 115     { "default", "39m" },
 116 };
 117 static const struct color bg_colors[] = {
 118     { "none",     NULL },
 119     { "black",   "40m" },
 120     { "red",     "41m" },
 121     { "green",   "42m" },
 122     { "yellow",  "43m" },
 123     { "blue",    "44m" },
 124     { "cyan",    "45m" },
 125     { "magenta", "46m" },
 126     { "white",   "47m" },
 127     { "default", "49m" },
 128 };
 129
 130 enum fmts {
 131     FMT_GENERIC,
 132     FMT_COLOR,
 133     FMT_RANDOM,
 134     FMT_ERROR,
 135     FMT_FILE
 136 };
 137 static const char *formats[] = {
 138     "%s",                    /* generic */
 139     "%s color '%s' %s",      /* color   */
 140     "%s color '%s' %s '%s'", /* random  */
 141     "less than %d bytes %s", /* error   */
 142     "%s: %s",                /* file    */
 143 };
 144
 145 enum { FOREGROUND, BACKGROUND };
 146
 147 static const struct {
 148     struct color const *entries;
 149     unsigned int count;
 150     const char *desc;
 151 } tables[] = {
 152     { fg_colors, sizeof (fg_colors) / sizeof (struct color), "foreground" },
 153     { bg_colors, sizeof (bg_colors) / sizeof (struct color), "background" },
 154 };
 155
 156 enum stream_mode { SCAN_FIRST = 1, SCAN_ALWAYS };
 157
 158 struct ending {
 159     unsigned int flags;
 160     const char newline[3];
 161 };
 162
 163 static const struct ending endings[] = {
 164     { CR & LF, "\r\n" },
 165     { CR,      "\r"   },
 166     { LF,      "\n"   },
 167 };
 168
 169 static FILE *stream = NULL;
 170
 171 static unsigned int stacked_vars = 0;
 172 static void **vars_list = NULL;
 173
 174 static char *exclude = NULL;
 175
 176 static const char *program_name;
 177
 178 static void print_help (void);
 179 static void print_version (void);
 180 static void cleanup (void);
 181 static void free_color_names (struct color_name **);
 182 static void process_options (unsigned int, char **, bool *, const struct color **, const char **, FILE **);
 183 static void read_print_stream (bool, const struct color **, const char *, FILE *, enum stream_mode);
 184 static void find_color_entries (struct color_name **, const struct color **);
 185 static void find_color_entry (const char *const, unsigned int, const struct color **);
 186 static void print_line (const struct color **, bool, const char * const, unsigned int);
 187 static void *malloc_wrap (size_t, const char *, unsigned int);
 188 static void *realloc_wrap (void *, size_t, const char *, unsigned int);
 189 static char *strdup_wrap (const char *, const char *, unsigned int);
 190 static void vfprintf_fail (const char *, ...);
 191 static void stack_var (void ***, unsigned int *, unsigned int, void *);
 192 static void release_var (void **, unsigned int, void **);
 193
 194 extern char *optarg;
 195 extern int optind;
 196
 197 int
 198 main (int argc, char **argv)
 199 {
 200     unsigned int arg_cnt = 0;
 201
 202     bool invalid_opt = false;
 203
 204     int opt;
 205     struct option long_opts[] = {
 206         { "exclude-random", required_argument, NULL, 'e' },
 207         { "help",           no_argument,       NULL, 'h' },
 208         { "version",        no_argument,       NULL, 'v' },
 209         {  0,               0,                 0,     0  },
 210     };
 211
 212     bool bold = false;
 213
 214     const struct color *colors[2] = {
 215         NULL, /* foreground */
 216         NULL, /* background */
 217     };
 218
 219     const char *file;
 220
 221     enum stream_mode mode = SCAN_FIRST;
 222
 223     program_name = argv[0];
 224     atexit (cleanup);
 225
 226     setvbuf (stdout, NULL, _IOLBF, 0);
 227
 228     while ((opt = getopt_long (argc, argv, "hv", long_opts, NULL)) != -1)
 229       {
 230         switch (opt)
 231           {
 232             case 'e': {
 233               char *p;
 234               exclude = xstrdup (optarg);
 235               STACK_VAR (exclude);
 236               for (p = exclude; *p; p++)
 237                 *p = tolower (*p);
 238               if (streq (exclude, "random"))
 239                 vfprintf_fail (formats[FMT_GENERIC], "--exclude-random switch must be provided a color");
 240               break;
 241             }
 242             case 'h':
 243               print_help ();
 244               exit (EXIT_SUCCESS);
 245             case 'v':
 246               print_version ();
 247               exit (EXIT_SUCCESS);
 248             case '?':
 249               invalid_opt = true;
 250               break;
 251             default: /* never reached */
 252               ABORT_TRACE ();
 253           }
 254       }
 255
 256     arg_cnt = argc - optind;
 257
 258     if (arg_cnt == 0 || arg_cnt > 2 || invalid_opt)
 259       {
 260         print_help ();
 261         exit (EXIT_FAILURE);
 262       }
 263
 264     process_options (arg_cnt, &argv[optind], &bold, colors, &file, &stream);
 265     read_print_stream (bold, colors, file, stream, mode);
 266
 267     RELEASE_VAR (exclude);
 268
 269     exit (EXIT_SUCCESS);
 270 }
 271
 272 static void
 273 print_help (void)
 274 {
 275     unsigned int i;
 276
 277     printf ("Usage: %s (foreground) OR (foreground)/(background) [-|file]\n\n", program_name);
 278     printf ("\tColors (foreground) (background)\n");
 279     for (i = 0; i < tables[FOREGROUND].count; i++)
 280       {
 281         const struct color *entry = &tables[FOREGROUND].entries[i];
 282         const char *name = entry->name;
 283         const char *code = entry->code;
 284         if (code)
 285           printf ("\t\t{\033[%s#\033[0m} [%c%c]%s%*s%s\n",
 286                    code, toupper (*name), *name, name + 1, 10 - (int)strlen (name), " ", name);
 287         else
 288           printf ("\t\t{-} %s%*s%s\n", name, 13 - (int)strlen (name), " ", name);
 289       }
 290     printf ("\t\t{*} [Rr]%s%*s%s [--exclude-random=<foreground color>]\n", "andom", 10 - (int)strlen ("random"), " ", "random");
 291
 292     printf ("\n\tFirst character of color name in upper case denotes increased intensity,\n");
 293     printf ("\twhereas for lower case colors will be of normal intensity.\n");
 294
 295     printf ("\n\tOptions\n");
 296     printf ("\t\t-h, --help\n");
 297     printf ("\t\t-v, --version\n\n");
 298 }
 299
 300 static void
 301 print_version (void)
 302 {
 303     const char *c_flags;
 304     printf ("%s v%s (compiled at %s, %s)\n", "colorize", VERSION, __DATE__, __TIME__);
 305 #ifdef CFLAGS
 306     c_flags = to_str (CFLAGS);
 307 #else
 308     c_flags = "unknown";
 309 #endif
 310     printf ("Compiler flags: %s\n", c_flags);
 311     printf ("Buffer size: %d bytes\n", BUF_SIZE - 1);
 312 }
 313
 314 static void
 315 cleanup (void)
 316 {
 317     free_color_names (color_names);
 318
 319     if (stream && fileno (stream) != STDIN_FILENO)
 320       fclose (stream);
 321
 322     if (vars_list)
 323       {
 324         unsigned int i;
 325         for (i = 0; i < stacked_vars; i++)
 326           if (vars_list[i])
 327             {
 328               free (vars_list[i]);
 329               vars_list[i] = NULL;
 330             }
 331         free (vars_list);
 332         vars_list = NULL;
 333       }
 334 }
 335
 336 static void
 337 free_color_names (struct color_name **color_names)
 338 {
 339     unsigned int i;
 340     for (i = 0; color_names[i]; i++)
 341       {
 342         free (color_names[i]->name);
 343         color_names[i]->name = NULL;
 344         free (color_names[i]->orig);
 345         color_names[i]->orig = NULL;
 346         free (color_names[i]);
 347         color_names[i] = NULL;
 348       }
 349 }
 350
 351 static void
 352 process_options (unsigned int arg_cnt, char **option_strings, bool *bold, const struct color **colors, const char **file, FILE **stream)
 353 {
 354     int ret;
 355     unsigned int index;
 356     char *color, *p, *str;
 357     struct stat sb;
 358
 359     const char *color_string = arg_cnt >= 1 ? option_strings[0] : NULL;
 360     const char *file_string  = arg_cnt == 2 ? option_strings[1] : NULL;
 361
 362     assert (color_string);
 363
 364     if (streq (color_string, "-"))
 365       {
 366         if (file_string)
 367           vfprintf_fail (formats[FMT_GENERIC], "hyphen cannot be used as color string");
 368         else
 369           vfprintf_fail (formats[FMT_GENERIC], "hyphen must be preceeded by color string");
 370       }
 371
 372     ret = stat (color_string, &sb);
 373
 374     /* Ensure that we don't fail if there's a file with one or more
 375        color names in its path.  */
 376     if (ret != -1)
 377       {
 378         bool have_file;
 379         unsigned int c;
 380         const char *color = color_string;
 381
 382         for (c = 1; c <= 2 && *color; c++)
 383           {
 384             bool matched = false;
 385             unsigned int i;
 386             for (i = 0; i < tables[FOREGROUND].count; i++)
 387               {
 388                 const struct color *entry = &tables[FOREGROUND].entries[i];
 389                 char *p;
 390                 if ((p = strstr (color, entry->name)) && p == color)
 391                   {
 392                     color = p + strlen (entry->name);
 393                     matched = true;
 394                     break;
 395                   }
 396               }
 397             if (matched && *color == '/' && *(color + 1))
 398               color++;
 399             else
 400               break;
 401           }
 402
 403         have_file = (*color != '\0');
 404
 405         if (have_file)
 406           vfprintf_fail (formats[FMT_GENERIC], "file must be preceeded by color string");
 407       }
 408
 409     if ((p = strchr (color_string, '/')))
 410       {
 411         if (p == color_string)
 412           vfprintf_fail (formats[FMT_GENERIC], "foreground color missing");
 413         else if (p == color_string + strlen (color_string) - 1)
 414           vfprintf_fail (formats[FMT_GENERIC], "background color missing");
 415         else if (strchr (++p, '/'))
 416           vfprintf_fail (formats[FMT_GENERIC], "one color pair allowed only");
 417       }
 418
 419     str = xstrdup (color_string);
 420     STACK_VAR (str);
 421
 422     for (index = 0, color = str; *color; index++, color = p)
 423       {
 424         char *ch, *sep;
 425         if ((sep = strchr (color, '/')))
 426           {
 427             *sep = '\0';
 428             p = sep + 1;
 429           }
 430         else
 431           p = color + strlen (color);
 432
 433         for (ch = color; *ch; ch++)
 434           if (!isalpha (*ch))
 435             vfprintf_fail (formats[FMT_COLOR], tables[index].desc, color, "cannot be made of non-alphabetic characters");
 436
 437         for (ch = color + 1; *ch; ch++)
 438           if (!islower (*ch))
 439             vfprintf_fail (formats[FMT_COLOR], tables[index].desc, color, "cannot be in mixed lower/upper case");
 440
 441         if (streq (color, "None"))
 442           vfprintf_fail (formats[FMT_COLOR], tables[index].desc, color, "cannot be bold");
 443
 444         if (isupper (*color))
 445           {
 446             switch (index)
 447               {
 448                 case FOREGROUND:
 449                   *bold = true;
 450                   break;
 451                 case BACKGROUND:
 452                   vfprintf_fail (formats[FMT_COLOR], tables[BACKGROUND].desc, color, "cannot be bold");
 453                   break;
 454                 default: /* never reached */
 455                   ABORT_TRACE ();
 456               }
 457           }
 458
 459         color_names[index] = xmalloc (sizeof (struct color_name));
 460
 461         color_names[index]->orig = xstrdup (color);
 462
 463         for (ch = color; *ch; ch++)
 464           *ch = tolower (*ch);
 465
 466         color_names[index]->name = xstrdup (color);
 467       }
 468
 469     RELEASE_VAR (str);
 470
 471     assert (color_names[FOREGROUND]);
 472
 473     if (color_names[BACKGROUND])
 474       {
 475         unsigned int i;
 476         unsigned int color_sets[2][2] = { { FOREGROUND, BACKGROUND }, { BACKGROUND, FOREGROUND } };
 477         for (i = 0; i < 2; i++)
 478           {
 479             unsigned int color1 = color_sets[i][0];
 480             unsigned int color2 = color_sets[i][1];
 481             if (CHECK_COLORS_RANDOM (color1, color2))
 482               vfprintf_fail (formats[FMT_RANDOM], tables[color1].desc, color_names[color1]->orig, "cannot be combined with", color_names[color2]->orig);
 483           }
 484       }
 485
 486     find_color_entries (color_names, colors);
 487     free_color_names (color_names);
 488
 489     if (!colors[FOREGROUND]->code && colors[BACKGROUND] && colors[BACKGROUND]->code)
 490       find_color_entry ("default", FOREGROUND, colors);
 491
 492     if (file_string)
 493       {
 494         if (streq (file_string, "-"))
 495           *stream = stdin;
 496         else
 497           {
 498             FILE *s;
 499             const char *file = file_string;
 500             struct stat sb;
 501             int errno, ret;
 502
 503             errno = 0;
 504             ret = stat (file, &sb);
 505
 506             if (ret == -1)
 507               vfprintf_fail (formats[FMT_FILE], file, strerror (errno));
 508
 509             if (!(S_ISREG (sb.st_mode) || S_ISLNK (sb.st_mode) || S_ISFIFO (sb.st_mode)))
 510               vfprintf_fail (formats[FMT_FILE], file, "unrecognized file type");
 511
 512             errno = 0;
 513
 514             s = fopen (file, "r");
 515             if (!s)
 516               vfprintf_fail (formats[FMT_FILE], file, strerror (errno));
 517             *stream = s;
 518           }
 519         *file = file_string;
 520       }
 521     else
 522       {
 523         *stream = stdin;
 524         *file = "stdin";
 525       }
 526
 527     assert (*stream);
 528 }
 529
 530 static void
 531 read_print_stream (bool bold, const struct color **colors, const char *file, FILE *stream, enum stream_mode mode)
 532 {
 533     char buf[BUF_SIZE];
 534     unsigned int flags = 0;
 535     bool first = false, always = false;
 536
 537     switch (mode)
 538       {
 539         case SCAN_FIRST:
 540           first = true;
 541           break;
 542         case SCAN_ALWAYS:
 543           always = true;
 544           break;
 545         default: /* never reached */
 546           ABORT_TRACE ();
 547       }
 548
 549     while (!feof (stream))
 550       {
 551         size_t bytes_read;
 552         char *eol;
 553         const char *line;
 554         memset (buf, '\0', BUF_SIZE);
 555         bytes_read = fread (buf, 1, BUF_SIZE - 1, stream);
 556         if (bytes_read != (BUF_SIZE - 1) && ferror (stream))
 557           vfprintf_fail (formats[FMT_ERROR], BUF_SIZE - 1, "read");
 558         line = buf;
 559         LOOP: while ((eol = strpbrk (line, "\n\r")))
 560           {
 561             char *p;
 562             if (first || always)
 563               {
 564                 first = false;
 565                 flags &= ~(CR|LF);
 566                 if (*eol == '\r')
 567                   {
 568                     flags |= CR;
 569                     if (*(eol + 1) == '\n')
 570                       flags |= LF;
 571                   }
 572                 else if (*eol == '\n')
 573                   flags |= LF;
 574                 else
 575                   vfprintf_fail (formats[FMT_FILE], file, "unrecognized line ending");
 576               }
 577             if (always)
 578               p = eol + SKIP_LINE_ENDINGS (flags);
 579             else /* first */
 580               {
 581                 unsigned int i;
 582                 unsigned int count = sizeof (endings) / sizeof (struct ending);
 583                 for (i = 0; i < count; i++)
 584                   {
 585                     if (flags & endings[i].flags)
 586                       {
 587                         char *p;
 588                         if ((p = strstr (eol, endings[i].newline)) && p == eol)
 589                           break;
 590                         else
 591                           {
 592                             always = true;
 593                             goto LOOP;
 594                           }
 595                       }
 596                   }
 597                 p = eol + SKIP_LINE_ENDINGS (flags);
 598               }
 599             *eol = '\0';
 600             print_line (colors, bold, line, flags);
 601             line = p;
 602           }
 603         print_line (colors, bold, line, 0);
 604       }
 605 }
 606
 607 static void
 608 find_color_entries (struct color_name **color_names, const struct color **colors)
 609 {
 610     struct timeval tv;
 611     unsigned int index;
 612
 613     /* randomness */
 614     gettimeofday (&tv, NULL);
 615     srand (tv.tv_usec * tv.tv_sec);
 616
 617     for (index = 0; color_names[index]; index++)
 618       {
 619         const char *color_name = color_names[index]->name;
 620
 621         const unsigned int count                = tables[index].count;
 622         const struct color *const color_entries = tables[index].entries;
 623
 624         if (streq (color_name, "random"))
 625           {
 626             bool excludable;
 627             unsigned int i;
 628             do {
 629               excludable = false;
 630               i = rand() % (count - 2) + 1; /* omit color none and default */
 631               switch (index)
 632                 {
 633                   case FOREGROUND:
 634                     /* --exclude-random */
 635                     if (exclude && streq (exclude, color_entries[i].name))
 636                       excludable = true;
 637                     else if (color_names[BACKGROUND] && streq (color_names[BACKGROUND]->name, color_entries[i].name))
 638                       excludable = true;
 639                     break;
 640                   case BACKGROUND:
 641                     if (streq (colors[FOREGROUND]->name, color_entries[i].name))
 642                       excludable = true;
 643                     break;
 644                   default: /* never reached */
 645                     ABORT_TRACE ();
 646                  }
 647             } while (excludable);
 648             colors[index] = (struct color *)&color_entries[i];
 649           }
 650         else
 651           find_color_entry (color_name, index, colors);
 652       }
 653 }
 654
 655 static void
 656 find_color_entry (const char *const color_name, unsigned int index, const struct color **colors)
 657 {
 658     bool found = false;
 659     unsigned int i;
 660
 661     const unsigned int count                = tables[index].count;
 662     const struct color *const color_entries = tables[index].entries;
 663
 664     for (i = 0; i < count; i++)
 665       if (streq (color_name, color_entries[i].name))
 666         {
 667           colors[index] = (struct color *)&color_entries[i];
 668           found = true;
 669           break;
 670         }
 671     if (!found)
 672       vfprintf_fail (formats[FMT_COLOR], tables[index].desc, color_name, "not recognized");
 673 }
 674
 675 static void
 676 print_line (const struct color **colors, bool bold, const char *const line, unsigned int flags)
 677 {
 678     if (colors[BACKGROUND] && colors[BACKGROUND]->code)
 679       printf ("\033[%s", colors[BACKGROUND]->code);
 680     if (colors[FOREGROUND]->code)
 681       printf ("\033[%s%s%s\033[0m", bold ? "1;" : "", colors[FOREGROUND]->code, line);
 682     else
 683       printf (formats[FMT_GENERIC], line);
 684     if (flags & CR)
 685       putchar ('\r');
 686     if (flags & LF)
 687       putchar ('\n');
 688 }
 689
 690 static void *
 691 malloc_wrap (size_t size, const char *file, unsigned int line)
 692 {
 693     void *p = malloc (size);
 694     if (!p)
 695       MEM_ALLOC_FAIL (file, line);
 696     return p;
 697 }
 698
 699 static void *
 700 realloc_wrap (void *ptr, size_t size, const char *file, unsigned int line)
 701 {
 702     void *p = realloc (ptr, size);
 703     if (!p)
 704       MEM_ALLOC_FAIL (file, line);
 705     return p;
 706 }
 707
 708 static char *
 709 strdup_wrap (const char *str, const char *file, unsigned int line)
 710 {
 711     const unsigned int len = strlen (str) + 1;
 712     char *p = malloc (len);
 713     if (!p)
 714       MEM_ALLOC_FAIL (file, line);
 715     strncpy (p, str, len);
 716     return p;
 717 }
 718
 719 static void
 720 vfprintf_fail (const char *fmt, ...)
 721 {
 722     va_list ap;
 723     fprintf (stderr, "%s: ", program_name);
 724     va_start (ap, fmt);
 725     vfprintf (stderr, fmt, ap);
 726     va_end (ap);
 727     fprintf (stderr, "\n");
 728     exit (EXIT_FAILURE);
 729 }
 730
 731 static void
 732 stack_var (void ***list, unsigned int *stacked, unsigned int index, void *ptr)
 733 {
 734     /* nothing to stack */
 735     if (ptr == NULL)
 736       return;
 737     if (!*list)
 738       *list = xmalloc (sizeof (void *));
 739     else
 740       {
 741         unsigned int i;
 742         for (i = 0; i < *stacked; i++)
 743           if (!(*list)[i])
 744             {
 745               (*list)[i] = ptr;
 746               return; /* reused */
 747             }
 748         *list = xrealloc (*list, (*stacked + 1) * sizeof (void *));
 749       }
 750     (*list)[index] = ptr;
 751     (*stacked)++;
 752 }
 753
 754 static void
 755 release_var (void **list, unsigned int stacked, void **ptr)
 756 {
 757     unsigned int i;
 758     /* nothing to release */
 759     if (*ptr == NULL)
 760       return;
 761     for (i = 0; i < stacked; i++)
 762       if (list[i] == *ptr)
 763         {
 764           free (*ptr);
 765           *ptr = NULL;
 766           list[i] = NULL;
 767           return;
 768         }
 769 }