What has happened to this issue? I can confirm this to be an issue with a
vanilla 2.6.26.7 kernel with
deprecated sysfs files disabled. In addition, it has propagated to Ubuntu 8.10
(Intrepid Ibex), see
https://bugs.launchpad.net/ubuntu/+source/pmount/+bug/281367.
I had already started writing a patch before finding this report, and looking
at the other patch on this bug
report, I believe it to be a better solution, relying on glibc filename
canonicalisation rather than
convoluted string manipulation.
The attached file can be dropped into debian/patches, and is intended to be
applied after the other patch in
there. Also note that the patch hasn't been used extensively, just on my own
system, where it works fine.
Francis Russell
--- sysfsutils-2.1.0/lib/sysfs_utils.c 2008-11-05 18:23:41.000000000 +0000
+++ build-tree/sysfsutils-2.1.0/lib/sysfs_utils.c 2008-11-05 18:22:59.000000000 +0000
@@ -23,6 +23,10 @@
#include "libsysfs.h"
#include "sysfs.h"
#include <mntent.h>
+#include <sys/stat.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
/**
* sysfs_remove_trailing_slash: Removes any trailing '/' in the given path
@@ -138,87 +142,31 @@
*/
int sysfs_get_link(const char *path, char *target, size_t len)
{
- char devdir[SYSFS_PATH_MAX];
- char linkpath[SYSFS_PATH_MAX];
- char temp_path[SYSFS_PATH_MAX];
- char *d = NULL, *s = NULL;
- int slashes = 0, count = 0;
+ struct stat path_stat;
+ char *resolved_path;
if (!path || !target || len == 0) {
errno = EINVAL;
return -1;
}
- memset(devdir, 0, SYSFS_PATH_MAX);
- memset(linkpath, 0, SYSFS_PATH_MAX);
- memset(temp_path, 0, SYSFS_PATH_MAX);
- safestrcpy(devdir, path);
+ /* If path is not a symlink, fail */
+ if (stat(path, &path_stat) != 0 || (path_stat.st_mode & S_IFLNK))
+ return -1;
- if ((readlink(path, linkpath, SYSFS_PATH_MAX)) < 0) {
+ /* Canonicalize the path */
+ resolved_path = canonicalize_file_name(path);
+
+ /* We fail if we cannot find the canonical path, or it is too long to copy */
+ if (resolved_path == NULL || strlen(resolved_path) >= SYSFS_PATH_MAX) {
+ free(resolved_path);
return -1;
}
- d = linkpath;
- /*
- * Three cases here:
- * 1. relative path => format ../..
- * 2. absolute path => format /abcd/efgh
- * 3. relative path _from_ this dir => format abcd/efgh
- */
- switch (*d) {
- case '.':
- /*
- * handle the case where link is of type ./abcd/xxx
- */
- safestrcpy(temp_path, devdir);
- if (*(d+1) == '/')
- d += 2;
- else if (*(d+1) == '.')
- goto parse_path;
- s = strrchr(temp_path, '/');
- if (s != NULL) {
- *(s+1) = '\0';
- safestrcat(temp_path, d);
- } else {
- safestrcpy(temp_path, d);
- }
- safestrcpymax(target, temp_path, len);
- break;
- /*
- * relative path, getting rid of leading "../.."
- */
-parse_path:
- while (*d == '/' || *d == '.') {
- if (*d == '/')
- slashes++;
- d++;
- }
- d--;
- s = &devdir[strlen(devdir)-1];
- while (s != NULL && count != (slashes+1)) {
- s--;
- if (*s == '/')
- count++;
- }
- safestrcpymax(s, d, (SYSFS_PATH_MAX-strlen(devdir)));
- safestrcpymax(target, devdir, len);
- break;
- case '/':
- /* absolute path - copy as is */
- safestrcpymax(target, linkpath, len);
- break;
- default:
- /* relative path from this directory */
- safestrcpy(temp_path, devdir);
- s = strrchr(temp_path, '/');
- if (s != NULL) {
- *(s+1) = '\0';
- safestrcat(temp_path, linkpath);
- } else {
- safestrcpy(temp_path, linkpath);
- }
- safestrcpymax(target, temp_path, len);
+ else {
+ strncpy(target, resolved_path, SYSFS_PATH_MAX);
+ free(resolved_path);
+ return 0;
}
- return 0;
}
/**
