[Libguestfs] [PATCH] New API: is-lv: check if a block device is a logical volume (RHBZ#619793)
Richard W.M. Jones
rjones at redhat.com
Fri Jul 30 15:40:06 UTC 2010
Fix for:
https://bugzilla.redhat.com/show_bug.cgi?id=619793
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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-------------- next part --------------
>From 6280ac9b987c14f89749b4b4fdfec5a647567432 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at redhat.com>
Date: Fri, 30 Jul 2010 16:32:35 +0100
Subject: [PATCH] New API: is-lv: check if a block device is a logical volume (RHBZ#619793)
This adds a new API, guestfs_is_lv (g, device), which returns true iff
the named device is an LVM2 logical volume.
A sample guestfish session:
><fs> lvs
/dev/vg_f13x64/lv_root
/dev/vg_f13x64/lv_swap
><fs> list-devices
/dev/vda
><fs> list-partitions
/dev/vda1
/dev/vda2
><fs> is-lv /dev/vg_f13x64/lv_root
true
><fs> is-lv /dev/vg_f13x64/lv_swap
true
><fs> is-lv /dev/vda
false
><fs> is-lv /dev/vda1
false
><fs> is-lv /dev/vda2
false
---
daemon/lvm.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
src/MAX_PROC_NR | 2 +-
src/generator.ml | 10 ++++++++++
3 files changed, 58 insertions(+), 1 deletions(-)
diff --git a/daemon/lvm.c b/daemon/lvm.c
index 70c3c90..0df27e2 100644
--- a/daemon/lvm.c
+++ b/daemon/lvm.c
@@ -23,6 +23,7 @@
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
+#include <sys/stat.h>
#include "daemon.h"
#include "c-ctype.h"
@@ -662,3 +663,49 @@ do_vgscan (void)
free (err);
return 0;
}
+
+/* Test if a device is a logical volume (RHBZ#619793).
+ *
+ * This is harder than it should be. A LV device like /dev/VG/LV is
+ * really a symlink to a device-mapper device like /dev/dm-0. However
+ * at the device-mapper (kernel) level, nothing is really known about
+ * LVM (a userspace concept). Therefore we use a convoluted method to
+ * determine this, by listing out known LVs and checking whether the
+ * rdev (major/minor) of the device we are passed matches any of them.
+ *
+ * Note use of 'stat' instead of 'lstat' so that symlinks are fully
+ * resolved.
+ */
+int
+do_is_lv (const char *device)
+{
+ struct stat stat1, stat2;
+
+ int r = stat (device, &stat1);
+ if (r == -1) {
+ reply_with_perror ("stat: %s", device);
+ return -1;
+ }
+
+ char **lvs = do_lvs ();
+ if (lvs == NULL)
+ return -1;
+
+ size_t i;
+ for (i = 0; lvs[i] != NULL; ++i) {
+ r = stat (lvs[i], &stat2);
+ if (r == -1) {
+ reply_with_perror ("stat: %s", lvs[i]);
+ free_strings (lvs);
+ return -1;
+ }
+ if (stat1.st_rdev == stat2.st_rdev) { /* found it */
+ free_strings (lvs);
+ return 1;
+ }
+ }
+
+ /* not found */
+ free_strings (lvs);
+ return 0;
+}
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 175b6c5..10b0c0d 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-263
+264
diff --git a/src/generator.ml b/src/generator.ml
index d537945..20f7ac0 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -4953,6 +4953,16 @@ This command deletes the key in key slot C<keyslot> from the
encrypted LUKS device C<device>. C<key> must be one of the
I<other> keys.");
+ ("is_lv", (RBool "lvflag", [Device "device"]), 264, [Optional "lvm2"],
+ [InitBasicFSonLVM, IfAvailable "lvm2", TestOutputTrue (
+ [["is_lv"; "/dev/VG/LV"]]);
+ InitBasicFSonLVM, IfAvailable "lvm2", TestOutputFalse (
+ [["is_lv"; "/dev/sda1"]])],
+ "test if device is a logical volume",
+ "\
+This command tests whether C<device> is a logical volume, and
+returns true iff this is the case.");
+
]
let all_functions = non_daemon_functions @ daemon_functions
--
1.7.1
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