Re: [libvirt] [PATCH 3/3] storage: Fix checking whether source filesystem is mounted

[Erik Skultety]

On Thu, Feb 09, 2017 at 06:05:41PM -0500, John Ferlan wrote:
> 
> 
> On 02/07/2017 09:16 AM, Erik Skultety wrote:
> > Right now, we use simple string comparison both on the source paths
> > (mount's output vs pool's source) and the target (mount's mnt_dir vs
> > pool's target). The problem are symlinks and mount indeed returns
> > symlinks in its output, e.g. /dev/mappper/lvm_symlink. The same goes for
> > the pool's source/target, so in order to successfully compare these two
> > replace plain string comparison with virFileComparePaths which will
> > resolve all symlinks and canonicalize the paths prior to comparison.
> > 
> > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1417203
> > 
> > Signed-off-by: Erik Skultety 
> > ---
> >  src/storage/storage_backend_fs.c | 12 ++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/storage/storage_backend_fs.c 
> > b/src/storage/storage_backend_fs.c
> > index fe4705b..fae1c03 100644
> > --- a/src/storage/storage_backend_fs.c
> > +++ b/src/storage/storage_backend_fs.c
> > @@ -301,6 +301,7 @@ 
> > virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr pool)
> >  FILE *mtab;
> >  struct mntent ent;
> >  char buf[1024];
> > +int rc1, rc2;
> >  
> >  if ((mtab = fopen(_PATH_MOUNTED, "r")) == NULL) {
> >  virReportSystemError(errno,
> > @@ -313,8 +314,15 @@ 
> > virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr pool)
> >  if (!(src = virStorageBackendFileSystemGetPoolSource(pool)))
> >  goto cleanup;
> >  
> > -if (STREQ(ent.mnt_dir, pool->def->target.path) &&
> > -STREQ(ent.mnt_fsname, src)) {
> > +/* compare both mount destinations and sources to be sure the 
> > mounted
> > + * FS pool is really the one we're looking for
> > + */
> > +if ((rc1 = virFileComparePaths(ent.mnt_dir,
> > +   pool->def->target.path)) < 0 ||
> > +(rc2 = virFileComparePaths(ent.mnt_fsname, src)) < 0)
> > +goto cleanup;
> > +
> > +if (rc1 == 0 && rc2 == 0) {
> 
> With changes to previous to return 1 on match, then this gets adjusted
> too...
> 
> ACK - I think you can alter this appropriately

Sure, thanks.

Erik

> 
> John
> >  ret = 1;
> >  goto cleanup;
> >  }
> > 
> 
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Re: [libvirt] [PATCH 3/3] storage: Fix checking whether source filesystem is mounted

[John Ferlan]

On 02/07/2017 09:16 AM, Erik Skultety wrote:
> Right now, we use simple string comparison both on the source paths
> (mount's output vs pool's source) and the target (mount's mnt_dir vs
> pool's target). The problem are symlinks and mount indeed returns
> symlinks in its output, e.g. /dev/mappper/lvm_symlink. The same goes for
> the pool's source/target, so in order to successfully compare these two
> replace plain string comparison with virFileComparePaths which will
> resolve all symlinks and canonicalize the paths prior to comparison.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1417203
> 
> Signed-off-by: Erik Skultety 
> ---
>  src/storage/storage_backend_fs.c | 12 ++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/storage/storage_backend_fs.c 
> b/src/storage/storage_backend_fs.c
> index fe4705b..fae1c03 100644
> --- a/src/storage/storage_backend_fs.c
> +++ b/src/storage/storage_backend_fs.c
> @@ -301,6 +301,7 @@ virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr 
> pool)
>  FILE *mtab;
>  struct mntent ent;
>  char buf[1024];
> +int rc1, rc2;
>  
>  if ((mtab = fopen(_PATH_MOUNTED, "r")) == NULL) {
>  virReportSystemError(errno,
> @@ -313,8 +314,15 @@ 
> virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr pool)
>  if (!(src = virStorageBackendFileSystemGetPoolSource(pool)))
>  goto cleanup;
>  
> -if (STREQ(ent.mnt_dir, pool->def->target.path) &&
> -STREQ(ent.mnt_fsname, src)) {
> +/* compare both mount destinations and sources to be sure the mounted
> + * FS pool is really the one we're looking for
> + */
> +if ((rc1 = virFileComparePaths(ent.mnt_dir,
> +   pool->def->target.path)) < 0 ||
> +(rc2 = virFileComparePaths(ent.mnt_fsname, src)) < 0)
> +goto cleanup;
> +
> +if (rc1 == 0 && rc2 == 0) {

With changes to previous to return 1 on match, then this gets adjusted
too...

ACK - I think you can alter this appropriately

John
>  ret = 1;
>  goto cleanup;
>  }
> 

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[libvirt] [PATCH 3/3] storage: Fix checking whether source filesystem is mounted

[Erik Skultety]

Right now, we use simple string comparison both on the source paths
(mount's output vs pool's source) and the target (mount's mnt_dir vs
pool's target). The problem are symlinks and mount indeed returns
symlinks in its output, e.g. /dev/mappper/lvm_symlink. The same goes for
the pool's source/target, so in order to successfully compare these two
replace plain string comparison with virFileComparePaths which will
resolve all symlinks and canonicalize the paths prior to comparison.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1417203

Signed-off-by: Erik Skultety 
---
 src/storage/storage_backend_fs.c | 12 ++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index fe4705b..fae1c03 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -301,6 +301,7 @@ virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr 
pool)
 FILE *mtab;
 struct mntent ent;
 char buf[1024];
+int rc1, rc2;
 
 if ((mtab = fopen(_PATH_MOUNTED, "r")) == NULL) {
 virReportSystemError(errno,
@@ -313,8 +314,15 @@ virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr 
pool)
 if (!(src = virStorageBackendFileSystemGetPoolSource(pool)))
 goto cleanup;
 
-if (STREQ(ent.mnt_dir, pool->def->target.path) &&
-STREQ(ent.mnt_fsname, src)) {
+/* compare both mount destinations and sources to be sure the mounted
+ * FS pool is really the one we're looking for
+ */
+if ((rc1 = virFileComparePaths(ent.mnt_dir,
+   pool->def->target.path)) < 0 ||
+(rc2 = virFileComparePaths(ent.mnt_fsname, src)) < 0)
+goto cleanup;
+
+if (rc1 == 0 && rc2 == 0) {
 ret = 1;
 goto cleanup;
 }
-- 
2.10.2

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