From 5a6f9558a980c6c7d3d08379edcde85dd85b5190 Mon Sep 17 00:00:00 2001

From: Richard Jones <rjones@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

(cherry picked from commit 6280ac9b987c14f89749b4b4fdfec5a647567432)

---

 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 8675828..b5da6cf 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