Libguestfs - Jun 2010 - [PATCH] file: Fix file command on /dev/VG/LV paths (RHBZ#582484).

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Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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>From ba39ced8804765705f4c61a92db0fddb8d672c7d Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at redhat.com>
Date: Tue, 8 Jun 2010 16:04:01 +0100
Subject: [PATCH] file: Fix file command on /dev/VG/LV paths (RHBZ#582484).

Previous commit 4df593496e116dfb635731c058b7627e81fc179c broke the
"file" command on logical volume paths, since these are symbolic
links.  We *should* follow these (only).

This inadvertantly broke virt-inspector too, which indicates that
we need more regression testing in this area.  Since carrying whole
Fedora images around could make the distribution even larger than
now, I'm not sure at the moment how to do this.

Thanks to Matt Booth for diagnosing this bug.
---
 daemon/file.c    |    7 ++++++-
 src/generator.ml |    2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/daemon/file.c b/daemon/file.c
index a55c606..da899b6 100644
--- a/daemon/file.c
+++ b/daemon/file.c
@@ -581,8 +581,13 @@ do_file (const char *path)
     }
   }
 
+  /* Which flags to use?  For /dev paths, follow links because
+   * /dev/VG/LV is a symbolic link.
+   */
+  const char *flags = is_dev ? "-zbsL" : "-zb";
+
   char *out, *err;
-  int r = command (&out, &err, "file", "-zbs",
path, NULL);
+  int r = command (&out, &err, "file", flags, path, NULL);
   free (buf);
 
   if (r == -1) {
diff --git a/src/generator.ml b/src/generator.ml
index 37d63f2..0ffd3c7 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -1645,7 +1645,7 @@ the type or contents of the file.
 This call will also transparently look inside various types
 of compressed file.
 
-The exact command which runs is C<file -zbs path>.  Note in
+The exact command which runs is C<file -zb path>.  Note in
 particular that the filename is not prepended to the output
 (the C<-b> option).
 
-- 
1.6.6.1

On 08/06/10 16:07, Richard W.M. Jones wrote:
>> From ba39ced8804765705f4c61a92db0fddb8d672c7d Mon Sep 17 00:00:00 2001
> From: Richard Jones<rjones at redhat.com>
> Date: Tue, 8 Jun 2010 16:04:01 +0100
> Subject: [PATCH] file: Fix file command on /dev/VG/LV paths (RHBZ#582484).
>
> Previous commit 4df593496e116dfb635731c058b7627e81fc179c broke the
> "file" command on logical volume paths, since these are symbolic
> links.  We*should*  follow these (only).
>
> This inadvertantly broke virt-inspector too, which indicates that
> we need more regression testing in this area.  Since carrying whole
> Fedora images around could make the distribution even larger than
> now, I'm not sure at the moment how to do this.
>
> Thanks to Matt Booth for diagnosing this bug.
> ---
>   daemon/file.c    |    7 ++++++-
>   src/generator.ml |    2 +-
>   2 files changed, 7 insertions(+), 2 deletions(-)
ACK.

However, as discussed on IRC this call is now a bit of a mess. Could we 
please deprecate it in favour of a new one?

On a related note, perhaps we should update virt-inspector to use 
vfs_type instead of file.

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

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