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 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, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, 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 strings @var{progname}, @var{bin_prefix}, @var{prefix}, return a string
  27 that gets to @var{prefix} starting with the directory portion of @var{progname} and
  28 a relative pathname of the difference between @var{bin_prefix} and @var{prefix}.
  29
  30 For example, if @var{bin_prefix} is @code{/alpha/beta/gamma/gcc/delta}, @var{prefix}
  31 is @code{/alpha/beta/gamma/omega/}, and @var{progname} is @code{/red/green/blue/gcc},
  32 then this function will return @code{/red/green/blue/../../omega/}.
  33
  34 The return value is normally allocated via @code{malloc}.  If no relative prefix
  35 can be found, return @code{NULL}.
  36
  37 @end deftypefn
  38
  39 */
  40
  41 #ifdef HAVE_CONFIG_H
  42 #include "config.h"
  43 #endif
  44
  45 #ifdef HAVE_STDLIB_H
  46 #include <stdlib.h>
  47 #endif
  48 #ifdef HAVE_UNISTD_H
  49 #include <unistd.h>
  50 #endif
  51
  52 #include <string.h>
  53
  54 #include "ansidecl.h"
  55 #include "libiberty.h"
  56
  57 #ifndef R_OK
  58 #define R_OK 4
  59 #define W_OK 2
  60 #define X_OK 1
  61 #endif
  62
  63 #ifndef DIR_SEPARATOR
  64 #  define DIR_SEPARATOR '/'
  65 #endif
  66
  67 #if defined (_WIN32) || defined (__MSDOS__) \
  68     || defined (__DJGPP__) || defined (__OS2__)
  69 #  define HAVE_DOS_BASED_FILE_SYSTEM
  70 #  define HAVE_HOST_EXECUTABLE_SUFFIX
  71 #  define HOST_EXECUTABLE_SUFFIX ".exe"
  72 #  ifndef DIR_SEPARATOR_2
  73 #    define DIR_SEPARATOR_2 '\\'
  74 #  endif
  75 #  define PATH_SEPARATOR ';'
  76 #else
  77 #  define PATH_SEPARATOR ':'
  78 #endif
  79
  80 #ifndef DIR_SEPARATOR_2
  81 #  define IS_DIR_SEPARATOR(ch) ((ch) == DIR_SEPARATOR)
  82 #else
  83 #  define IS_DIR_SEPARATOR(ch) \
  84         (((ch) == DIR_SEPARATOR) || ((ch) == DIR_SEPARATOR_2))
  85 #endif
  86
  87 #define DIR_UP ".."
  88
  89 static char *save_string PARAMS ((const char *, int));
  90 static char **split_directories PARAMS ((const char *, int *));
  91 static void free_split_directories PARAMS ((char **));
  92
  93 static char *
  94 save_string (s, len)
  95      const char *s;
  96      int len;
  97 {
  98   char *result = malloc (len + 1);
  99
 100   memcpy (result, s, len);
 101   result[len] = 0;
 102   return result;
 103 }
 104
 105 /* Split a filename into component directories.  */
 106
 107 static char **
 108 split_directories (name, ptr_num_dirs)
 109      const char *name;
 110      int *ptr_num_dirs;
 111 {
 112   int num_dirs = 0;
 113   char **dirs;
 114   const char *p, *q;
 115   int ch;
 116
 117   /* Count the number of directories.  Special case MSDOS disk names as part
 118      of the initial directory.  */
 119   p = name;
 120 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
 121   if (name[1] == ':' && IS_DIR_SEPARATOR (name[2]))
 122     {
 123       p += 3;
 124       num_dirs++;
 125     }
 126 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 127
 128   while ((ch = *p++) != '\0')
 129     {
 130       if (IS_DIR_SEPARATOR (ch))
 131         {
 132           num_dirs++;
 133           while (IS_DIR_SEPARATOR (*p))
 134             p++;
 135         }
 136     }
 137
 138   dirs = (char **) malloc (sizeof (char *) * (num_dirs + 2));
 139   if (dirs == NULL)
 140     return NULL;
 141
 142   /* Now copy the directory parts.  */
 143   num_dirs = 0;
 144   p = name;
 145 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
 146   if (name[1] == ':' && IS_DIR_SEPARATOR (name[2]))
 147     {
 148       dirs[num_dirs++] = save_string (p, 3);
 149       if (dirs[num_dirs - 1] == NULL)
 150         {
 151           free (dirs);
 152           return NULL;
 153         }
 154       p += 3;
 155     }
 156 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 157
 158   q = p;
 159   while ((ch = *p++) != '\0')
 160     {
 161       if (IS_DIR_SEPARATOR (ch))
 162         {
 163           while (IS_DIR_SEPARATOR (*p))
 164             p++;
 165
 166           dirs[num_dirs++] = save_string (q, p - q);
 167           if (dirs[num_dirs - 1] == NULL)
 168             {
 169               dirs[num_dirs] = NULL;
 170               free_split_directories (dirs);
 171               return NULL;
 172             }
 173           q = p;
 174         }
 175     }
 176
 177   if (p - 1 - q > 0)
 178     dirs[num_dirs++] = save_string (q, p - 1 - q);
 179   dirs[num_dirs] = NULL;
 180
 181   if (dirs[num_dirs - 1] == NULL)
 182     {
 183       free_split_directories (dirs);
 184       return NULL;
 185     }
 186
 187   if (ptr_num_dirs)
 188     *ptr_num_dirs = num_dirs;
 189   return dirs;
 190 }
 191
 192 /* Release storage held by split directories.  */
 193
 194 static void
 195 free_split_directories (dirs)
 196      char **dirs;
 197 {
 198   int i = 0;
 199
 200   while (dirs[i] != NULL)
 201     free (dirs[i++]);
 202
 203   free ((char *) dirs);
 204 }
 205
 206 /* Given three strings PROGNAME, BIN_PREFIX, PREFIX, return a string that gets
 207    to PREFIX starting with the directory portion of PROGNAME and a relative
 208    pathname of the difference between BIN_PREFIX and PREFIX.
 209
 210    For example, if BIN_PREFIX is /alpha/beta/gamma/gcc/delta, PREFIX is
 211    /alpha/beta/gamma/omega/, and PROGNAME is /red/green/blue/gcc, then this
 212    function will return /red/green/blue/../../omega/.
 213
 214    If no relative prefix can be found, return NULL.  */
 215
 216 char *
 217 make_relative_prefix (progname, bin_prefix, prefix)
 218      const char *progname;
 219      const char *bin_prefix;
 220      const char *prefix;
 221 {
 222   char **prog_dirs, **bin_dirs, **prefix_dirs;
 223   int prog_num, bin_num, prefix_num;
 224   int i, n, common;
 225   int needed_len;
 226   char *ret, *ptr;
 227
 228   if (progname == NULL || bin_prefix == NULL || prefix == NULL)
 229     return NULL;
 230
 231   prog_dirs = split_directories (progname, &prog_num);
 232   bin_dirs = split_directories (bin_prefix, &bin_num);
 233   if (bin_dirs == NULL || prog_dirs == NULL)
 234     return NULL;
 235
 236   /* If there is no full pathname, try to find the program by checking in each
 237      of the directories specified in the PATH environment variable.  */
 238   if (prog_num == 1)
 239     {
 240       char *temp;
 241
 242       temp = getenv ("PATH");
 243       if (temp)
 244         {
 245           char *startp, *endp, *nstore;
 246           size_t prefixlen = strlen (temp) + 1;
 247           if (prefixlen < 2)
 248             prefixlen = 2;
 249
 250           nstore = (char *) alloca (prefixlen + strlen (progname) + 1);
 251
 252           startp = endp = temp;
 253           while (1)
 254             {
 255               if (*endp == PATH_SEPARATOR || *endp == 0)
 256                 {
 257                   if (endp == startp)
 258                     {
 259                       nstore[0] = '.';
 260                       nstore[1] = DIR_SEPARATOR;
 261                       nstore[2] = '\0';
 262                     }
 263                   else
 264                     {
 265                       strncpy (nstore, startp, endp - startp);
 266                       if (! IS_DIR_SEPARATOR (endp[-1]))
 267                         {
 268                           nstore[endp - startp] = DIR_SEPARATOR;
 269                           nstore[endp - startp + 1] = 0;
 270                         }
 271                       else
 272                         nstore[endp - startp] = 0;
 273                     }
 274                   strcat (nstore, progname);
 275                   if (! access (nstore, X_OK)
 276 #ifdef HAVE_HOST_EXECUTABLE_SUFFIX
 277                       || ! access (strcat (nstore, HOST_EXECUTABLE_SUFFIX), X_OK)
 278 #endif
 279                       )
 280                     {
 281                       free_split_directories (prog_dirs);
 282                       progname = nstore;
 283                       prog_dirs = split_directories (progname, &prog_num);
 284                       if (prog_dirs == NULL)
 285                         {
 286                           free_split_directories (bin_dirs);
 287                           return NULL;
 288                         }
 289                       break;
 290                     }
 291
 292                   if (*endp == 0)
 293                     break;
 294                   endp = startp = endp + 1;
 295                 }
 296               else
 297                 endp++;
 298             }
 299         }
 300     }
 301
 302   /* Remove the program name from comparison of directory names.  */
 303   prog_num--;
 304
 305   /* If we are still installed in the standard location, we don't need to
 306      specify relative directories.  Also, if argv[0] still doesn't contain
 307      any directory specifiers after the search above, then there is not much
 308      we can do.  */
 309   if (prog_num == bin_num)
 310     {
 311       for (i = 0; i < bin_num; i++)
 312         {
 313           if (strcmp (prog_dirs[i], bin_dirs[i]) != 0)
 314             break;
 315         }
 316
 317       if (prog_num <= 0 || i == bin_num)
 318         {
 319           free_split_directories (prog_dirs);
 320           free_split_directories (bin_dirs);
 321           prog_dirs = bin_dirs = (char **) 0;
 322           return NULL;
 323         }
 324     }
 325
 326   prefix_dirs = split_directories (prefix, &prefix_num);
 327   if (prefix_dirs == NULL)
 328     {
 329       free_split_directories (prog_dirs);
 330       free_split_directories (bin_dirs);
 331       return NULL;
 332     }
 333
 334   /* Find how many directories are in common between bin_prefix & prefix.  */
 335   n = (prefix_num < bin_num) ? prefix_num : bin_num;
 336   for (common = 0; common < n; common++)
 337     {
 338       if (strcmp (bin_dirs[common], prefix_dirs[common]) != 0)
 339         break;
 340     }
 341
 342   /* If there are no common directories, there can be no relative prefix.  */
 343   if (common == 0)
 344     {
 345       free_split_directories (prog_dirs);
 346       free_split_directories (bin_dirs);
 347       free_split_directories (prefix_dirs);
 348       return NULL;
 349     }
 350
 351   /* Two passes: first figure out the size of the result string, and
 352      then construct it.  */
 353   needed_len = 0;
 354   for (i = 0; i < prog_num; i++)
 355     needed_len += strlen (prog_dirs[i]);
 356   needed_len += sizeof (DIR_UP) * (bin_num - common);
 357   for (i = common; i < prefix_num; i++)
 358     needed_len += strlen (prefix_dirs[i]);
 359   needed_len += 1; /* Trailing NUL.  */
 360
 361   ret = (char *) malloc (needed_len);
 362   if (ret == NULL)
 363     return NULL;
 364
 365   /* Build up the pathnames in argv[0].  */
 366   *ret = '\0';
 367   for (i = 0; i < prog_num; i++)
 368     strcat (ret, prog_dirs[i]);
 369
 370   /* Now build up the ..'s.  */
 371   ptr = ret + strlen(ret);
 372   for (i = common; i < bin_num; i++)
 373     {
 374       strcpy (ptr, DIR_UP);
 375       ptr += sizeof (DIR_UP) - 1;
 376       *(ptr++) = DIR_SEPARATOR;
 377     }
 378   *ptr = '\0';
 379
 380   /* Put in directories to move over to prefix.  */
 381   for (i = common; i < prefix_num; i++)
 382     strcat (ret, prefix_dirs[i]);
 383
 384   free_split_directories (prog_dirs);
 385   free_split_directories (bin_dirs);
 386   free_split_directories (prefix_dirs);
 387
 388   return ret;
 389 }