On 09/22/2016 11:12 AM, Konrad Rzeszutek Wilk wrote:
On Thu, Sep 22, 2016 at 08:25:33AM +0100, Ross Lagerwall wrote:
On 09/21/2016 08:20 PM, Konrad Rzeszutek Wilk wrote:
. print a better error code.

Reported-by: Andrew Cooper <andrew.coop...@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
 tools/misc/xen-livepatch.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/misc/xen-livepatch.c b/tools/misc/xen-livepatch.c
index 2de04c0..f11e71f07f 100644
--- a/tools/misc/xen-livepatch.c
+++ b/tools/misc/xen-livepatch.c
@@ -100,8 +100,11 @@ static int list_func(int argc, char *argv[])
         rc = xc_livepatch_list(xch, MAX_LEN, idx, info, name, len, &done, 
         if ( rc )
-            fprintf(stderr, "Failed to list %d/%d: %d(%s)!\n",
-                    idx, left, errno, strerror(errno));
+            if ( errno == ENOSYS )
+                fprintf(stderr, "Hypervisor compiled without Xen 
+            else
+                fprintf(stderr, "Failed to list %d/%d: %d(%s)!\n",
+                        idx, left, errno, strerror(errno));
         if ( !idx )

You should save errno since you have an fprintf before you check it.

I am missing something.

Why would fprintf mess up 'errno' ?

If the first fprintf fails for whatever reason (e.g. ENOSPC), then it will set errno and the subsequent check of errno afterwards will serve no purpose.

I have a patch to fix this issue for the rest of xen-livepatch.c, and will send it out shortly.

Ross Lagerwall

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