[libvirt] [PATCH] qemu-ns: Detect /dev/* mount point duplicates better

[Michal Privoznik]

https://bugzilla.redhat.com/show_bug.cgi?id=1495511

When creating new /dev for domain ran in namespace we try to
preserve all sub-mounts of /dev. Well, not quite all. For
instance if /dev/foo/bar and /dev/foo are both mount points, only
/dev/foo needs preserving. /dev/foo/bar is preserved with it too.
Now, to identify such cases like this one STRPREFIX() is used.
That is not good enough. While it works for [/dev/foo/bar;
/dev/foo] case, it fails for [/dev/prefix; /dev/prefix2] where
the strings share the same prefix but are in fact two different
paths. The solution is to use STRSKIP().

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_domain.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 05e8b96aa..8aa66c69c 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -8182,7 +8182,9 @@ qemuDomainGetPreservedMounts(virQEMUDriverConfigPtr cfg,
     for (i = 1; i < nmounts; i++) {
         j = i + 1;
         while (j < nmounts) {
-            if (STRPREFIX(mounts[j], mounts[i])) {
+            char *c = STRSKIP(mounts[j], mounts[i]);
+
+            if (c && *c == '/') {
                 VIR_DEBUG("Dropping path %s because of %s", mounts[j], mounts[i]);
                 VIR_DELETE_ELEMENT(mounts, j, nmounts);
             } else {
-- 
2.13.6