From: Richard Jones <rjones@redhat.com>
Date: Tue, 17 Nov 2009 17:02:45 +0000 (+0000)
Subject: fuse: Fix read for empty files.
X-Git-Tag: 1.0.79~5
X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=336275ee6dbff5efa2152a4f67ef354b81d15d59;p=libguestfs.git

fuse: Fix read for empty files.

Error handling for the guestfs_pread call was incorrect, which
meant that empty files could produce spurious error messages.
---

diff --git a/fuse/guestmount.c b/fuse/guestmount.c
index baf2b66..ba0d626 100644
--- a/fuse/guestmount.c
+++ b/fuse/guestmount.c
@@ -620,8 +620,14 @@ fg_read (const char *path, char *buf, size_t size, off_t offset,
   if (size > limit)
     size = limit;
 
+  /* Note the correct error handling here is tricky, because in the
+   * case where the call returns a zero-length buffer, it might return
+   * NULL.  However it won't adjust rsize along the error path, so we
+   * can set rsize to something beforehand and use that as a flag.
+   */
+  rsize = 1;
   r = guestfs_pread (g, path, size, offset, &rsize);
-  if (r == NULL)
+  if (rsize == 1 && r == NULL)
     return error ();
 
   /* This should never happen, but at least it stops us overflowing