Re: [libvirt] [PATCH v2] storage: Sanitize pool target paths
On 05/21/2010 11:05 AM, Cole Robinson wrote:
Spurious / in a pool target path makes life difficult for apps using
the
GetVolByPath, and doing other path based comparisons with pools. This
has caused a few issues for virt-manager users:
https://bugzilla.redhat.com/show_bug.cgi?id=494005
https://bugzilla.redhat.com/show_bug.cgi?id=593565
Add a new util API which removes spurious /, virFileSanitizePath. Sanitize
target paths when parsing pool XML, and for paths passed to GetVolByPath.
v2: Leading // must be preserved, properly sanitize path=/, sanitize
away /./ -> /
Nice - you caught one case that my review did not ("/" as the entire path).
+/* Remove spurious / characters from a path. The result must be
freed */
+char *
+virFileSanitizePath(const char *path)
+{
+ const char *cur = path;
+ char *cleanpath;
+ int idx = 0;
+
+ cleanpath = strdup(path);
+ if (!cleanpath) {
+ virReportOOMError();
+ return NULL;
+ }
+
+ /* Starting with // is valid posix, but ///foo == /foo */
+ if (cur[0] == '/' && cur[1] == '/' && cur[2] !=
'/') {
+ cleanpath[0] = '/';
+ cleanpath[1] = '/';
Delete these two lines; since cleanpath was created by strdup(), they
are redundant assignments.
+ idx = 2;
+ cur += 2;
+ }
+
+ /* Sanitize path in place */
+ while (*cur != '\0') {
+ if (*cur != '/') {
+ cleanpath[idx++] = *cur++;
+ continue;
+ }
+
+ /* Skip all extra / */
+ while (*cur == '/') {
+ cur++;
+
+ /* Resolve away /./ to just / */
+ if (cur[0] == '.' && cur[1] == '/')
+ cur++;
+ }
That doesn't simplify "./a" to "a", nor "b/." to
"b"
+
+ /* Don't add a trailing / unless path is only made of / */
+ if (idx != 0 && *cur == '\0')
+ break;
This incorrectly collapses plain "//" to "/".
+
+ cleanpath[idx++] = '/';
+ }
Maybe a better approach is this pseudo-code:
if (2 leading slashes) {
advance 2
if (end) return
} else if (leading slash)
advance 1
do {
advance past all slashes - they are redundant from previous round
if (./ or .-end) advance 1 and continue
copy all non-slashes
copy one slash
} while (!end)
if (trailing slash)
back up 1
+ cleanpath[idx] = '\0';
+
+ return cleanpath;
+}
+
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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