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[binutils.git] / libiberty / make-relative-prefix.c
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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.
5 This file is part of libiberty.
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.
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.
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. */
24 @deftypefn Extension {const char*} make_relative_prefix (const char *@var{progname}, const char *@var{bin_prefix}, const char *@var{prefix})
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}.
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.
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/}.
43 The return value is normally allocated via @code{malloc}. If no
44 relative prefix can be found, return @code{NULL}.
46 @end deftypefn
50 #ifdef HAVE_CONFIG_H
51 #include "config.h"
52 #endif
54 #ifdef HAVE_STDLIB_H
55 #include <stdlib.h>
56 #endif
57 #ifdef HAVE_UNISTD_H
58 #include <unistd.h>
59 #endif
61 #include <string.h>
63 #include "ansidecl.h"
64 #include "libiberty.h"
66 #ifndef R_OK
67 #define R_OK 4
68 #define W_OK 2
69 #define X_OK 1
70 #endif
72 #ifndef DIR_SEPARATOR
73 # define DIR_SEPARATOR '/'
74 #endif
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
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
96 #define DIR_UP ".."
98 static char *save_string (const char *, int);
99 static char **split_directories (const char *, int *);
100 static void free_split_directories (char **);
102 static char *
103 save_string (const char *s, int len)
105 char *result = malloc (len + 1);
107 memcpy (result, s, len);
108 result[len] = 0;
109 return result;
112 /* Split a filename into component directories. */
114 static char **
115 split_directories (const char *name, int *ptr_num_dirs)
117 int num_dirs = 0;
118 char **dirs;
119 const char *p, *q;
120 int ch;
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]))
128 p += 3;
129 num_dirs++;
131 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
133 while ((ch = *p++) != '\0')
135 if (IS_DIR_SEPARATOR (ch))
137 num_dirs++;
138 while (IS_DIR_SEPARATOR (*p))
139 p++;
143 dirs = (char **) malloc (sizeof (char *) * (num_dirs + 2));
144 if (dirs == NULL)
145 return NULL;
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]))
153 dirs[num_dirs++] = save_string (p, 3);
154 if (dirs[num_dirs - 1] == NULL)
156 free (dirs);
157 return NULL;
159 p += 3;
161 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
163 q = p;
164 while ((ch = *p++) != '\0')
166 if (IS_DIR_SEPARATOR (ch))
168 while (IS_DIR_SEPARATOR (*p))
169 p++;
171 dirs[num_dirs++] = save_string (q, p - q);
172 if (dirs[num_dirs - 1] == NULL)
174 dirs[num_dirs] = NULL;
175 free_split_directories (dirs);
176 return NULL;
178 q = p;
182 if (p - 1 - q > 0)
183 dirs[num_dirs++] = save_string (q, p - 1 - q);
184 dirs[num_dirs] = NULL;
186 if (dirs[num_dirs - 1] == NULL)
188 free_split_directories (dirs);
189 return NULL;
192 if (ptr_num_dirs)
193 *ptr_num_dirs = num_dirs;
194 return dirs;
197 /* Release storage held by split directories. */
199 static void
200 free_split_directories (char **dirs)
202 int i = 0;
204 while (dirs[i] != NULL)
205 free (dirs[i++]);
207 free ((char *) dirs);
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.
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/.
218 If no relative prefix can be found, return NULL. */
220 char *
221 make_relative_prefix (const char *progname,
222 const char *bin_prefix, const char *prefix)
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;
230 if (progname == NULL || bin_prefix == NULL || prefix == NULL)
231 return NULL;
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)
237 char *temp;
239 temp = getenv ("PATH");
240 if (temp)
242 char *startp, *endp, *nstore;
243 size_t prefixlen = strlen (temp) + 1;
244 if (prefixlen < 2)
245 prefixlen = 2;
247 nstore = (char *) alloca (prefixlen + strlen (progname) + 1);
249 startp = endp = temp;
250 while (1)
252 if (*endp == PATH_SEPARATOR || *endp == 0)
254 if (endp == startp)
256 nstore[0] = '.';
257 nstore[1] = DIR_SEPARATOR;
258 nstore[2] = '\0';
260 else
262 strncpy (nstore, startp, endp - startp);
263 if (! IS_DIR_SEPARATOR (endp[-1]))
265 nstore[endp - startp] = DIR_SEPARATOR;
266 nstore[endp - startp + 1] = 0;
268 else
269 nstore[endp - startp] = 0;
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
278 progname = nstore;
279 break;
282 if (*endp == 0)
283 break;
284 endp = startp = endp + 1;
286 else
287 endp++;
292 full_progname = lrealpath (progname);
293 if (full_progname == NULL)
294 return NULL;
296 prog_dirs = split_directories (full_progname, &prog_num);
297 bin_dirs = split_directories (bin_prefix, &bin_num);
298 free (full_progname);
299 if (bin_dirs == NULL || prog_dirs == NULL)
300 return NULL;
302 /* Remove the program name from comparison of directory names. */
303 prog_num--;
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)
311 for (i = 0; i < bin_num; i++)
313 if (strcmp (prog_dirs[i], bin_dirs[i]) != 0)
314 break;
317 if (prog_num <= 0 || i == bin_num)
319 free_split_directories (prog_dirs);
320 free_split_directories (bin_dirs);
321 prog_dirs = bin_dirs = (char **) 0;
322 return NULL;
326 prefix_dirs = split_directories (prefix, &prefix_num);
327 if (prefix_dirs == NULL)
329 free_split_directories (prog_dirs);
330 free_split_directories (bin_dirs);
331 return NULL;
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++)
338 if (strcmp (bin_dirs[common], prefix_dirs[common]) != 0)
339 break;
342 /* If there are no common directories, there can be no relative prefix. */
343 if (common == 0)
345 free_split_directories (prog_dirs);
346 free_split_directories (bin_dirs);
347 free_split_directories (prefix_dirs);
348 return NULL;
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. */
361 ret = (char *) malloc (needed_len);
362 if (ret == NULL)
363 return NULL;
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]);
370 /* Now build up the ..'s. */
371 ptr = ret + strlen(ret);
372 for (i = common; i < bin_num; i++)
374 strcpy (ptr, DIR_UP);
375 ptr += sizeof (DIR_UP) - 1;
376 *(ptr++) = DIR_SEPARATOR;
378 *ptr = '\0';
380 /* Put in directories to move over to prefix. */
381 for (i = common; i < prefix_num; i++)
382 strcat (ret, prefix_dirs[i]);
384 free_split_directories (prog_dirs);
385 free_split_directories (bin_dirs);
386 free_split_directories (prefix_dirs);
388 return ret;