[libvirt] [PATCH] virFileInData: Preserve errno on error

[Martin Kletzander]

On Thu, Oct 18, 2018 at 05:12:33PM +0200, Michal Privoznik wrote:
>The virFileInData() function should return to the caller if the
>current position the passed file is in is a data section or a
>hole (and also how long the current section is). At any rate,
>upon return from this function (be it successful or not) the
>original position in the file is restored. This may mess up with
>errno which might have been set earlier. Save the errno into a
>local variable so it can be restored for the caller's sake.
>

Reviewed-by: Martin Kletzander <mkletzan at redhat.com>

>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> src/util/virfile.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
>diff --git a/src/util/virfile.c b/src/util/virfile.c
>index e09992e41a..f6f01ec1e1 100644
>--- a/src/util/virfile.c
>+++ b/src/util/virfile.c
>@@ -4072,11 +4072,18 @@ virFileInData(int fd,
>     ret = 0;
>  cleanup:
>     /* At any rate, reposition back to where we started. */
>-    if (cur != (off_t) -1 &&
>-        lseek(fd, cur, SEEK_SET) == (off_t) -1) {
>-        virReportSystemError(errno, "%s",
>-                             _("unable to restore position in file"));
>-        ret = -1;
>+    if (cur != (off_t) -1) {
>+        int theerrno = errno;
>+
>+        if (lseek(fd, cur, SEEK_SET) == (off_t) -1) {
>+            virReportSystemError(errno, "%s",
>+                                 _("unable to restore position in file"));
>+            ret = -1;
>+            if (theerrno == 0)
>+                theerrno = errno;
>+        }
>+
>+        errno = theerrno;
>     }
>     return ret;
> }
>-- 
>2.18.1
>
>--
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