libiberty/make-relative-prefix.c

   1 /* Relative (relocatable) prefix support.
   2    Copyright (C) 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2006 Free Software Foundation, Inc.
   4
   5 This file is part of libiberty.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22 /*
  23
  24 @deftypefn Extension {const char*} make_relative_prefix (const char *@var{progname}, const char *@var{bin_prefix}, const char *@var{prefix})
  25
  26 Given three paths @var{progname}, @var{bin_prefix}, @var{prefix},
  27 return the path that is in the same position relative to
  28 @var{progname}'s directory as @var{prefix} is relative to
  29 @var{bin_prefix}.  That is, a string starting with the directory
  30 portion of @var{progname}, followed by a relative pathname of the
  31 difference between @var{bin_prefix} and @var{prefix}.
  32
  33 If @var{progname} does not contain any directory separators,
  34 @code{make_relative_prefix} will search @env{PATH} to find a program
  35 named @var{progname}.  Also, if @var{progname} is a symbolic link,
  36 the symbolic link will be resolved.
  37
  38 For example, if @var{bin_prefix} is @code{/alpha/beta/gamma/gcc/delta},
  39 @var{prefix} is @code{/alpha/beta/gamma/omega/}, and @var{progname} is
  40 @code{/red/green/blue/gcc}, then this function will return
  41 @code{/red/green/blue/../../omega/}.
  42
  43 The return value is normally allocated via @code{malloc}.  If no
  44 relative prefix can be found, return @code{NULL}.
  45
  46 @end deftypefn
  47
  48 */
  49
  50 #ifdef HAVE_CONFIG_H
  51 #include "config.h"
  52 #endif
  53
  54 #ifdef HAVE_STDLIB_H
  55 #include <stdlib.h>
  56 #endif
  57 #ifdef HAVE_UNISTD_H
  58 #include <unistd.h>
  59 #endif
  60
  61 #include <string.h>
  62
  63 #include "ansidecl.h"
  64 #include "libiberty.h"
  65
  66 #ifndef R_OK
  67 #define R_OK 4
  68 #define W_OK 2
  69 #define X_OK 1
  70 #endif
  71
  72 #ifndef DIR_SEPARATOR
  73 #  define DIR_SEPARATOR '/'
  74 #endif
  75
  76 #if defined (_WIN32) || defined (__MSDOS__) \
  77     || defined (__DJGPP__) || defined (__OS2__)
  78 #  define HAVE_DOS_BASED_FILE_SYSTEM
  79 #  define HAVE_HOST_EXECUTABLE_SUFFIX
  80 #  define HOST_EXECUTABLE_SUFFIX ".exe"
  81 #  ifndef DIR_SEPARATOR_2
  82 #    define DIR_SEPARATOR_2 '\\'
  83 #  endif
  84 #  define PATH_SEPARATOR ';'
  85 #else
  86 #  define PATH_SEPARATOR ':'
  87 #endif
  88
  89 #ifndef DIR_SEPARATOR_2
  90 #  define IS_DIR_SEPARATOR(ch) ((ch) == DIR_SEPARATOR)
  91 #else
  92 #  define IS_DIR_SEPARATOR(ch) \
  93         (((ch) == DIR_SEPARATOR) || ((ch) == DIR_SEPARATOR_2))
  94 #endif
  95
  96 #define DIR_UP ".."
  97
  98 static char *save_string (const char *, int);
  99 static char **split_directories (const char *, int *);
 100 static void free_split_directories (char **);
 101
 102 static char *
 103 save_string (const char *s, int len)
 104 {
 105   char *result = (char *) malloc (len + 1);
 106
 107   memcpy (result, s, len);
 108   result[len] = 0;
 109   return result;
 110 }
 111
 112 /* Split a filename into component directories.  */
 113
 114 static char **
 115 split_directories (const char *name, int *ptr_num_dirs)
 116 {
 117   int num_dirs = 0;
 118   char **dirs;
 119   const char *p, *q;
 120   int ch;
 121
 122   /* Count the number of directories.  Special case MSDOS disk names as part
 123      of the initial directory.  */
 124   p = name;
 125 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
 126   if (name[1] == ':' && IS_DIR_SEPARATOR (name[2]))
 127     {
 128       p += 3;
 129       num_dirs++;
 130     }
 131 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 132
 133   while ((ch = *p++) != '\0')
 134     {
 135       if (IS_DIR_SEPARATOR (ch))
 136         {
 137           num_dirs++;
 138           while (IS_DIR_SEPARATOR (*p))
 139             p++;
 140         }
 141     }
 142
 143   dirs = (char **) malloc (sizeof (char *) * (num_dirs + 2));
 144   if (dirs == NULL)
 145     return NULL;
 146
 147   /* Now copy the directory parts.  */
 148   num_dirs = 0;
 149   p = name;
 150 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
 151   if (name[1] == ':' && IS_DIR_SEPARATOR (name[2]))
 152     {
 153       dirs[num_dirs++] = save_string (p, 3);
 154       if (dirs[num_dirs - 1] == NULL)
 155         {
 156           free (dirs);
 157           return NULL;
 158         }
 159       p += 3;
 160     }
 161 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 162
 163   q = p;
 164   while ((ch = *p++) != '\0')
 165     {
 166       if (IS_DIR_SEPARATOR (ch))
 167         {
 168           while (IS_DIR_SEPARATOR (*p))
 169             p++;
 170
 171           dirs[num_dirs++] = save_string (q, p - q);
 172           if (dirs[num_dirs - 1] == NULL)
 173             {
 174               dirs[num_dirs] = NULL;
 175               free_split_directories (dirs);
 176               return NULL;
 177             }
 178           q = p;
 179         }
 180     }
 181
 182   if (p - 1 - q > 0)
 183     dirs[num_dirs++] = save_string (q, p - 1 - q);
 184   dirs[num_dirs] = NULL;
 185
 186   if (dirs[num_dirs - 1] == NULL)
 187     {
 188       free_split_directories (dirs);
 189       return NULL;
 190     }
 191
 192   if (ptr_num_dirs)
 193     *ptr_num_dirs = num_dirs;
 194   return dirs;
 195 }
 196
 197 /* Release storage held by split directories.  */
 198
 199 static void
 200 free_split_directories (char **dirs)
 201 {
 202   int i = 0;
 203
 204   while (dirs[i] != NULL)
 205     free (dirs[i++]);
 206
 207   free ((char *) dirs);
 208 }
 209
 210 /* Given three strings PROGNAME, BIN_PREFIX, PREFIX, return a string that gets
 211    to PREFIX starting with the directory portion of PROGNAME and a relative
 212    pathname of the difference between BIN_PREFIX and PREFIX.
 213
 214    For example, if BIN_PREFIX is /alpha/beta/gamma/gcc/delta, PREFIX is
 215    /alpha/beta/gamma/omega/, and PROGNAME is /red/green/blue/gcc, then this
 216    function will return /red/green/blue/../../omega/.
 217
 218    If no relative prefix can be found, return NULL.  */
 219
 220 static char *
 221 make_relative_prefix_1 (const char *progname, const char *bin_prefix,
 222                         const char *prefix, const int resolve_links)
 223 {
 224   char **prog_dirs, **bin_dirs, **prefix_dirs;
 225   int prog_num, bin_num, prefix_num;
 226   int i, n, common;
 227   int needed_len;
 228   char *ret, *ptr, *full_progname = NULL;
 229
 230   if (progname == NULL || bin_prefix == NULL || prefix == NULL)
 231     return NULL;
 232
 233   /* If there is no full pathname, try to find the program by checking in each
 234      of the directories specified in the PATH environment variable.  */
 235   if (lbasename (progname) == progname)
 236     {
 237       char *temp;
 238
 239       temp = getenv ("PATH");
 240       if (temp)
 241         {
 242           char *startp, *endp, *nstore;
 243           size_t prefixlen = strlen (temp) + 1;
 244           if (prefixlen < 2)
 245             prefixlen = 2;
 246
 247           nstore = (char *) alloca (prefixlen + strlen (progname) + 1);
 248
 249           startp = endp = temp;
 250           while (1)
 251             {
 252               if (*endp == PATH_SEPARATOR || *endp == 0)
 253                 {
 254                   if (endp == startp)
 255                     {
 256                       nstore[0] = '.';
 257                       nstore[1] = DIR_SEPARATOR;
 258                       nstore[2] = '\0';
 259                     }
 260                   else
 261                     {
 262                       strncpy (nstore, startp, endp - startp);
 263                       if (! IS_DIR_SEPARATOR (endp[-1]))
 264                         {
 265                           nstore[endp - startp] = DIR_SEPARATOR;
 266                           nstore[endp - startp + 1] = 0;
 267                         }
 268                       else
 269                         nstore[endp - startp] = 0;
 270                     }
 271                   strcat (nstore, progname);
 272                   if (! access (nstore, X_OK)
 273 #ifdef HAVE_HOST_EXECUTABLE_SUFFIX
 274                       || ! access (strcat (nstore, HOST_EXECUTABLE_SUFFIX), X_OK)
 275 #endif
 276                       )
 277                     {
 278                       progname = nstore;
 279                       break;
 280                     }
 281
 282                   if (*endp == 0)
 283                     break;
 284                   endp = startp = endp + 1;
 285                 }
 286               else
 287                 endp++;
 288             }
 289         }
 290     }
 291
 292   if ( resolve_links )
 293     {
 294       full_progname = lrealpath (progname);
 295       if (full_progname == NULL)
 296         return NULL;
 297     }
 298   else
 299     full_progname = strdup(progname);
 300
 301   prog_dirs = split_directories (full_progname, &prog_num);
 302   bin_dirs = split_directories (bin_prefix, &bin_num);
 303   free (full_progname);
 304   if (bin_dirs == NULL || prog_dirs == NULL)
 305     return NULL;
 306
 307   /* Remove the program name from comparison of directory names.  */
 308   prog_num--;
 309
 310   /* If we are still installed in the standard location, we don't need to
 311      specify relative directories.  Also, if argv[0] still doesn't contain
 312      any directory specifiers after the search above, then there is not much
 313      we can do.  */
 314   if (prog_num == bin_num)
 315     {
 316       for (i = 0; i < bin_num; i++)
 317         {
 318           if (strcmp (prog_dirs[i], bin_dirs[i]) != 0)
 319             break;
 320         }
 321
 322       if (prog_num <= 0 || i == bin_num)
 323         {
 324           free_split_directories (prog_dirs);
 325           free_split_directories (bin_dirs);
 326           prog_dirs = bin_dirs = (char **) 0;
 327           return NULL;
 328         }
 329     }
 330
 331   prefix_dirs = split_directories (prefix, &prefix_num);
 332   if (prefix_dirs == NULL)
 333     {
 334       free_split_directories (prog_dirs);
 335       free_split_directories (bin_dirs);
 336       return NULL;
 337     }
 338
 339   /* Find how many directories are in common between bin_prefix & prefix.  */
 340   n = (prefix_num < bin_num) ? prefix_num : bin_num;
 341   for (common = 0; common < n; common++)
 342     {
 343       if (strcmp (bin_dirs[common], prefix_dirs[common]) != 0)
 344         break;
 345     }
 346
 347   /* If there are no common directories, there can be no relative prefix.  */
 348   if (common == 0)
 349     {
 350       free_split_directories (prog_dirs);
 351       free_split_directories (bin_dirs);
 352       free_split_directories (prefix_dirs);
 353       return NULL;
 354     }
 355
 356   /* Two passes: first figure out the size of the result string, and
 357      then construct it.  */
 358   needed_len = 0;
 359   for (i = 0; i < prog_num; i++)
 360     needed_len += strlen (prog_dirs[i]);
 361   needed_len += sizeof (DIR_UP) * (bin_num - common);
 362   for (i = common; i < prefix_num; i++)
 363     needed_len += strlen (prefix_dirs[i]);
 364   needed_len += 1; /* Trailing NUL.  */
 365
 366   ret = (char *) malloc (needed_len);
 367   if (ret == NULL)
 368     return NULL;
 369
 370   /* Build up the pathnames in argv[0].  */
 371   *ret = '\0';
 372   for (i = 0; i < prog_num; i++)
 373     strcat (ret, prog_dirs[i]);
 374
 375   /* Now build up the ..'s.  */
 376   ptr = ret + strlen(ret);
 377   for (i = common; i < bin_num; i++)
 378     {
 379       strcpy (ptr, DIR_UP);
 380       ptr += sizeof (DIR_UP) - 1;
 381       *(ptr++) = DIR_SEPARATOR;
 382     }
 383   *ptr = '\0';
 384
 385   /* Put in directories to move over to prefix.  */
 386   for (i = common; i < prefix_num; i++)
 387     strcat (ret, prefix_dirs[i]);
 388
 389   free_split_directories (prog_dirs);
 390   free_split_directories (bin_dirs);
 391   free_split_directories (prefix_dirs);
 392
 393   return ret;
 394 }
 395
 396
 397 /* Do the full job, including symlink resolution.
 398    This path will find files installed in the same place as the
 399    program even when a soft link has been made to the program
 400    from somwhere else. */
 401
 402 char *
 403 make_relative_prefix (progname, bin_prefix, prefix)
 404      const char *progname;
 405      const char *bin_prefix;
 406      const char *prefix;
 407 {
 408   return make_relative_prefix_1 (progname, bin_prefix, prefix, 1);
 409 }
 410
 411 /* Make the relative pathname without attempting to resolve any links.
 412    '..' etc may also be left in the pathname.
 413    This will find the files the user meant the program to find if the
 414    installation is patched together with soft links. */
 415
 416 char *
 417 make_relative_prefix_ignore_links (progname, bin_prefix, prefix)
 418      const char *progname;
 419      const char *bin_prefix;
 420      const char *prefix;
 421 {
 422   return make_relative_prefix_1 (progname, bin_prefix, prefix, 0);
 423 }
 424