From cc6955130dfd090c2f24f787b9aacfd444f5ed45 Mon Sep 17 00:00:00 2001

Message-Id: <cc6955130dfd090c2f24f787b9aacfd444f5ed45.1386348946.git.jdenemar@redhat.com>

From: "Daniel P. Berrange" <berrange@redhat.com>

Date: Mon, 2 Dec 2013 13:39:10 +0000

Subject: [PATCH] Add virFileIsMountPoint function

For

  https://bugzilla.redhat.com/show_bug.cgi?id=1035403

Add a function for efficiently checking if a path is a filesystem

mount point.

NB will not work for bind mounts, only true filesystem mounts.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

(cherry picked from commit ccacd4fe3b7c9de7a4b6bb10220193fc4ba41221)

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

---

 src/libvirt_private.syms |  1 +

 src/util/virfile.c       | 52 ++++++++++++++++++++++++++++++++++++++++++++++++

 src/util/virfile.h       |  2 ++

 3 files changed, 55 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms

index 6821352..fa36b31 100644

--- a/src/libvirt_private.syms

+++ b/src/libvirt_private.syms

@@ -1385,6 +1385,7 @@ virFileIsAbsPath;

 virFileIsDir;

 virFileIsExecutable;

 virFileIsLink;

+virFileIsMountPoint;

 virFileLinkPointsTo;

 virFileLock;

 virFileLoopDeviceAssociate;

diff --git a/src/util/virfile.c b/src/util/virfile.c

index 33a8a6d..b396b16 100644

--- a/src/util/virfile.c

+++ b/src/util/virfile.c

@@ -1440,6 +1440,58 @@ virFileIsExecutable(const char *file)

     return false;

 }

+

+/*

+ * Check that a file refers to a mount point. Trick is that for

+ * a mount point, the st_dev field will differ from the parent

+ * directory.

+ *

+ * Note that this will not detect bind mounts of dirs/files,

+ * only true filesystem mounts.

+ */

+int virFileIsMountPoint(const char *file)

+{

+    char *parent = NULL;

+    int ret = -1;

+    struct stat sb1, sb2;

+

+    if (!(parent = mdir_name(file))) {

+        virReportOOMError();

+        goto cleanup;

+    }

+

+    VIR_DEBUG("Comparing '%s' to '%s'", file, parent);

+

+    if (stat(file, &sb1) < 0) {

+        if (errno == ENOENT)

+            ret = 0;

+        else

+            virReportSystemError(errno,

+                                 _("Cannot stat '%s'"),

+                                 file);

+        goto cleanup;

+    }

+

+    if (stat(parent, &sb2) < 0) {

+        virReportSystemError(errno,

+                             _("Cannot stat '%s'"),

+                             parent);

+        goto cleanup;

+    }

+

+    if (!S_ISDIR(sb1.st_mode)) {

+        ret = 0;

+        goto cleanup;

+    }

+

+    ret = sb1.st_dev != sb2.st_dev;

+    VIR_DEBUG("Is mount %d", ret);

+

+ cleanup:

+    VIR_FREE(parent);

+    return ret;

+}

+

 #ifndef WIN32

 /* Check that a file is accessible under certain

  * user & gid.

diff --git a/src/util/virfile.h b/src/util/virfile.h

index 72d35ce..ff84719 100644

--- a/src/util/virfile.h

+++ b/src/util/virfile.h

@@ -156,6 +156,8 @@ bool virFileIsDir (const char *file) ATTRIBUTE_NONNULL(1);

 bool virFileExists(const char *file) ATTRIBUTE_NONNULL(1);

 bool virFileIsExecutable(const char *file) ATTRIBUTE_NONNULL(1);

+int virFileIsMountPoint(const char *file) ATTRIBUTE_NONNULL(1);

+

 char *virFileSanitizePath(const char *path);

 enum {

-- 

1.8.4.5