[Xen-changelog] [xen-unstable] libxl: correct error path in libxl_userdata_retrieve

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
# Date 1296233033 0
# Node ID 4fea7664a6fbc0299f813d40395f5b50491314a4
# Parent  722f7b7678dcdf3d522d7875a26491e2272aa66d
libxl: correct error path in libxl_userdata_retrieve

Firstly, if libxl_read_file_contents fails, it doesn't really leave
*data and *datalen_r undefined - it leaves them unchanged.  Tighten up
the spec for the benefit of libxl_userdata_retrieve.

Secondly, libxl_userdata_retrieve ignored errors, assuming they were
all ENOENT.  Instead it should fail on unexpected errors.

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Acked-by: Jim Fehlig <jfehlig@xxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl_dom.c   |    5 ++++-
 tools/libxl/libxl_utils.h |    2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff -r 722f7b7678dc -r 4fea7664a6fb tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c   Fri Jan 28 11:08:49 2011 +0000
+++ b/tools/libxl/libxl_dom.c   Fri Jan 28 16:43:53 2011 +0000
@@ -671,7 +671,10 @@ int libxl_userdata_retrieve(libxl_ctx *c
     }
 
     e = libxl_read_file_contents(ctx, filename, data_r ? &data : 0, &datalen);
-
+    if (e && errno != ENOENT) {
+        rc = ERROR_FAIL;
+        goto out;
+    }
     if (!e && !datalen) {
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "userdata file %s is empty", 
filename);
         if (data_r) assert(!*data_r);
diff -r 722f7b7678dc -r 4fea7664a6fb tools/libxl/libxl_utils.h
--- a/tools/libxl/libxl_utils.h Fri Jan 28 11:08:49 2011 +0000
+++ b/tools/libxl/libxl_utils.h Fri Jan 28 16:43:53 2011 +0000
@@ -36,7 +36,7 @@ int libxl_read_file_contents(libxl_ctx *
   /* Reads the contents of the plain file filename into a mallocd
    * buffer.  Returns 0 or errno.  Any errors other than ENOENT are logged.
    * If the file is empty, *data_r and *datalen_r are set to 0.
-   * On error, *data_r and *datalen_r are undefined.
+   * On error, *data_r and *datalen_r are unchanged.
    * data_r and/or datalen_r may be 0.
    */
 

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