Libguestfs - Jul 2011 - hivex patch to solve device or resource busy error when access Windows directory while open system hive

I have found a strange issue related to hivex/ntfs-3g. After opening a system
hive on a volume mounted by ntfs-3g, any access to the Windows directory results
device or resource busy error. The patch below fix it by closing the hive file
handle in hivex_open() call in the writable path because the handle never been
used after its content been read into memory.

--- hivex-1.2.5.orig/lib/hivex.c    2011-04-13 06:04:49.000000000 -0700
+++ hivex-1.2.5/lib/hivex.c   2011-07-07 09:10:06.927429068 -0700
@@ -321,6 +321,8 @@
     if (full_read (h->fd, h->addr, h->size) < h->size)
       goto error;
+    close(h->fd);
+    h->fd = -1;
   }
   /* Check header. */
@@ -541,7 +543,10 @@
     munmap (h->addr, h->size);
   else
     free (h->addr);
-  r = close (h->fd);
+  if (h->fd >= 0)
+       r = close (h->fd);
+  else
+       r = 0;
   free (h->filename);
   free (h);

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On Thu, Jul 07, 2011 at 06:18:46PM +0000, Michael Huang
wrote:
> I have found a strange issue related to hivex/ntfs-3g. After opening a
system hive on a volume mounted by ntfs-3g, any access to the Windows directory
results device or resource busy error. The patch below fix it by closing the
hive file handle in hivex_open() call in the writable path because the handle
never been used after its content been read into memory.
> 
> --- hivex-1.2.5.orig/lib/hivex.c    2011-04-13 06:04:49.000000000 -0700
> +++ hivex-1.2.5/lib/hivex.c   2011-07-07 09:10:06.927429068 -0700
> @@ -321,6 +321,8 @@
>      if (full_read (h->fd, h->addr, h->size) < h->size)
>        goto error;
> +    close(h->fd);
> +    h->fd = -1;
>    }
>    /* Check header. */
> @@ -541,7 +543,10 @@
>      munmap (h->addr, h->size);
>    else
>      free (h->addr);
> -  r = close (h->fd);
> +  if (h->fd >= 0)
> +       r = close (h->fd);
> +  else
> +       r = 0;
>    free (h->filename);
>    free (h);
> 
Yes, I think from a preliminary look, this is correct.  I will take a
closer look, test it, and apply it on Monday.

Thanks,

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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On Thu, Jul 07, 2011 at 06:18:46PM +0000, Michael Huang
wrote:
> I have found a strange issue related to hivex/ntfs-3g. After opening a
system hive on a volume mounted by ntfs-3g, any access to the Windows directory
results device or resource busy error. The patch below fix it by closing the
hive file handle in hivex_open() call in the writable path because the handle
never been used after its content been read into memory.
> 
> --- hivex-1.2.5.orig/lib/hivex.c    2011-04-13 06:04:49.000000000 -0700
> +++ hivex-1.2.5/lib/hivex.c   2011-07-07 09:10:06.927429068 -0700
> @@ -321,6 +321,8 @@
>      if (full_read (h->fd, h->addr, h->size) < h->size)
>        goto error;
> +    close(h->fd);
> +    h->fd = -1;
>    }
>    /* Check header. */
> @@ -541,7 +543,10 @@
>      munmap (h->addr, h->size);
>    else
>      free (h->addr);
> -  r = close (h->fd);
> +  if (h->fd >= 0)
> +       r = close (h->fd);
> +  else
> +       r = 0;
>    free (h->filename);
>    free (h);
> 

I've pushed this, slightly modified.

Thanks for your contribution!

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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software inside the virtual machine.  Supports Linux and Windows.
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