[libvirt] [PATCH 3/5] virfile: Introduce virFileMajMinToName
This function can be used to translate MAJ:MIN device pair into
/dev/blah name.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/libvirt_private.syms | 1 +
src/util/virfile.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++
src/util/virfile.h | 3 +++
3 files changed, 57 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 1bbff72263..a705bfd5ef 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1787,6 +1787,7 @@ virFileLength;
virFileLinkPointsTo;
virFileLock;
virFileLoopDeviceAssociate;
+virFileMajMinToName;
virFileMakeParentPath;
virFileMakePath;
virFileMakePathWithMode;
diff --git a/src/util/virfile.c b/src/util/virfile.c
index f89e4bd823..62620862a1 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -68,6 +68,12 @@
# include <libdevmapper.h>
#endif
+#ifdef MAJOR_IN_MKDEV
+# include <sys/mkdev.h>
+#elif MAJOR_IN_SYSMACROS
+# include <sys/sysmacros.h>
+#endif
+
#include "configmake.h"
#include "intprops.h"
#include "viralloc.h"
@@ -4317,3 +4323,50 @@ virFileGetMPathTargets(const char *path ATTRIBUTE_UNUSED,
return -1;
}
#endif /* ! WITH_DEVMAPPER */
+
+
+/**
+ * virFileMajMinToName:
+ * @device: device (rdev) to translate
+ * @name: returned name
+ *
+ * For given MAJ:MIN pair (stored in one integer like in st_rdev)
+ * fetch device name, e.g. 8:0 is translated to "/dev/sda".
+ * Caller is responsible for freeing @name when no longer needed.
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int
+virFileMajMinToName(unsigned long long device,
+ char **name)
+{
+ struct stat sb;
+ char *sysfsPath = NULL;
+ char *link = NULL;
+ int ret = -1;
+
+ *name = NULL;
+ if (virAsprintf(&sysfsPath, "/sys/dev/block/%u:%u",
+ major(device), minor(device)) < 0)
+ goto cleanup;
+
+ if (lstat(sysfsPath, &sb) < 0)
+ goto cleanup;
+
+ if (!S_ISLNK(sb.st_mode)) {
+ errno = ENXIO;
+ goto cleanup;
+ }
+
+ if (virFileReadLink(sysfsPath, &link) < 0)
+ goto cleanup;
+
+ if (virAsprintf(name, "/dev/%s", last_component(link)) < 0)
+ goto cleanup;
+
+ ret = 0;
+ cleanup:
+ VIR_FREE(link);
+ VIR_FREE(sysfsPath);
+ return ret;
+}
diff --git a/src/util/virfile.h b/src/util/virfile.h
index 0db8bf0b99..390940dc98 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -362,4 +362,7 @@ int virFileGetMPathTargets(const char *path,
unsigned long long **devs,
size_t *ndevs);
+int virFileMajMinToName(unsigned long long device,
+ char **name);
+
#endif /* __VIR_FILE_H */
--
2.16.1