[libvirt] [PATCH 1/6 v2] Add virFileIsMountPoint function
From: "Daniel P. Berrange" <berrange(a)redhat.com>
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(a)redhat.com>
---
src/libvirt_private.syms | 1 +
src/util/virfile.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
src/util/virfile.h | 2 ++
3 files changed, 53 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 84c1c28..fff91ca 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1187,6 +1187,7 @@ virFileIsAbsPath;
virFileIsDir;
virFileIsExecutable;
virFileIsLink;
+virFileIsMountPoint;
virFileLinkPointsTo;
virFileLock;
virFileLoopDeviceAssociate;
diff --git a/src/util/virfile.c b/src/util/virfile.c
index e10de5a..b93fa87 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -1513,6 +1513,56 @@ 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))
+ return false;
+
+ 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 {
--
1.8.3.1