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-rw-r--r--stdlib/canonicalize.c196
1 files changed, 196 insertions, 0 deletions
diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c
new file mode 100644
index 0000000000..55ac1bcf1d
--- /dev/null
+++ b/stdlib/canonicalize.c
@@ -0,0 +1,196 @@
+/* Return the canonical absolute name of a given file.
+Copyright (C) 1996 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+/* Return the canonical absolute name of file NAME. The last file name
+ component need not exist, and may be a symlink to a nonexistent file.
+ If RESOLVED is null, the result is malloc'd; otherwise, if the canonical
+ name is PATH_MAX chars or more, returns null with `errno' set to
+ ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, returns the
+ name in RESOLVED. */
+
+static char *
+canonicalize (const char *name, char *resolved)
+{
+ struct stat st;
+ const char *p;
+ long int path_max;
+ char *result, *dir, *end;
+ size_t namelen;
+
+ if (! resolved)
+ path_max = 0;
+ else
+ {
+#ifdef PATH_MAX
+ path_max = PATH_MAX;
+#else
+ path_max = sysconf (_SC_PATH_MAX);
+ if (path_max <= 0)
+ path_max = 1024;
+#endif
+ }
+
+ p = strrchr (name, '/');
+ if (!p)
+ {
+ dir = (char *) ".";
+ p = name;
+ }
+ else
+ {
+ if (p++ == name)
+ dir = (char *) "/";
+ else
+ {
+ dir = __alloca (p - name);
+ memcpy (dir, name, p - name - 1);
+ dir[p - name] = '\0';
+ }
+ }
+
+ result = __canonicalize_directory_name_internal (dir, resolved, path_max);
+ if (!result)
+ return NULL;
+
+ /* Reconstruct the file name in the canonicalized directory. */
+ namelen = strlen (name);
+ end = strchr (result, '\0');
+ if (resolved)
+ {
+ /* Make sure the name is not too long. */
+ if (end - result + namelen > path_max)
+ {
+ errno = ENAMETOOLONG;
+ return NULL;
+ }
+ }
+ else
+ {
+ /* The name is dynamically allocated. Extend it. */
+ char *new = realloc (result, end - result + namelen + 1);
+ if (! new)
+ {
+ free (result);
+ return NULL;
+ }
+ end = new + (end - result);
+ result = new;
+ }
+ memcpy (end, name, namelen + 1);
+
+ while (__lstat (result, &st) == 0 && S_ISLNK (st.st_mode))
+ {
+ /* The file is a symlink. Read its contents. */
+ ssize_t n;
+ read_link_contents:
+ n = readlink (result, end,
+ resolved ? result + path_max - end : namelen + 1);
+ if (n < 0)
+ /* Error reading the link contents. */
+ return NULL;
+
+ if (end[0] == '/')
+ {
+ /* Absolute symlink. */
+ if (resolved ? (end + n < result + path_max) : (n < namelen + 1))
+ {
+ /* It fit in our buffer, so we have the whole thing. */
+ memcpy (result, end, n);
+ result[n] = '\0';
+ }
+ else if (resolved)
+ {
+ /* It didn't fit in the remainder of the buffer. Either it
+ fits in the entire buffer, or it doesn't. Copy back the
+ unresolved name onto the canonical directory and try once
+ more. */
+ memcpy (end, name, namelen + 1);
+ n = readlink (result, result, path_max);
+ if (n < 0)
+ return NULL;
+ if (n == path_max)
+ {
+ errno = ENAMETOOLONG;
+ return NULL;
+ }
+ result[n] = '\0';
+ }
+ else
+ /* Try again with a bigger buffer. */
+ goto extend_buffer;
+
+ /* Check the resolved name for being a symlink too. */
+ continue;
+ }
+
+ if (resolved)
+ {
+ if (end + n == result + path_max)
+ {
+ /* The link contents we read fill the buffer completely.
+ There may be even more to read, and there is certainly no
+ space for the null terminator. */
+ errno = ENAMETOOLONG;
+ return NULL;
+ }
+ }
+ else if (n == namelen + 1)
+ extend_buffer:
+ {
+ /* The name buffer is dynamically allocated. Extend it. */
+ char *new;
+
+ /* Copy back the unresolved name onto the canonical directory. */
+ memcpy (end, name, namelen + 1);
+
+ /* Make more space for readlink. */
+ namelen *= 2;
+ new = realloc (result, end - result + namelen + 1);
+ if (! new)
+ {
+ free (result);
+ return NULL;
+ }
+ end = new + (end - result);
+ result = new;
+
+ goto read_link_contents;
+ }
+
+ /* Terminate the string; readlink does not. */
+ end[n] = '\0';
+ }
+
+ return result;
+}
+
+weak_alias (canonicalize, realpath)
+
+char *
+canonicalize_file_name (const char *name)
+{
+ return canonicalize (name, NULL);
+}