-#if defined(USE_REALPATH)
- char *rp = realpath (filename, buf);
- return xstrdup (rp ? rp : filename);
-#elif defined(HAVE_CANONICALIZE_FILE_NAME)
- return canonicalize_file_name (filename);
-#else
+ /* Method 2: The host system (i.e., GNU) has the function
+ canonicalize_file_name() which malloc's a chunk of memory and
+ returns that, use that. */
+#if defined(HAVE_CANONICALIZE_FILE_NAME)
+ {
+ char *rp = canonicalize_file_name (filename);
+ if (rp == NULL)
+ return xstrdup (filename);
+ else
+ return rp;
+ }
+#endif
+
+ /* FIXME: cagney/2002-11-13:
+
+ Method 2a: Use realpath() with a NULL buffer. Some systems, due
+ to the problems described in in method 3, have modified their
+ realpath() implementation so that it will allocate a buffer when
+ NULL is passed in. Before this can be used, though, some sort of
+ configure time test would need to be added. Otherwize the code
+ will likely core dump. */
+
+ /* Method 3: Now we're getting desperate! The system doesn't have a
+ compile time buffer size and no alternative function. Query the
+ OS, using pathconf(), for the buffer limit. Care is needed
+ though, some systems do not limit PATH_MAX (return -1 for
+ pathconf()) making it impossible to pass a correctly sized buffer
+ to realpath() (it could always overflow). On those systems, we
+ skip this. */
+#if defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H) && defined(HAVE_ALLOCA)
+ {
+ /* Find out the max path size. */
+ long path_max = pathconf ("/", _PC_PATH_MAX);
+ if (path_max > 0)
+ {
+ /* PATH_MAX is bounded. */
+ char *buf = alloca (path_max);
+ char *rp = realpath (filename, buf);
+ return xstrdup (rp ? rp : filename);
+ }
+ }
+#endif
+
+ /* This system is a lost cause, just dup the buffer. */