Re: [libvirt] [PATCH 3/6] Fix error handling of readdir() in virFileLoopDeviceOpen

From: "Daniel P. Berrange" <berrange(a)redhat.com&gt; To correctly handle errors from readdir() you must set 'errno' to zero before invoking it & check its value afterwards to distinguish error from EOF. Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/util/virfile.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/util/virfile.c b/src/util/virfile.c index 25a0501..9363468 100644 --- a/src/util/virfile.c +++ b/src/util/virfile.c @@ -531,6 +531,7 @@ static int virFileLoopDeviceOpen(char **dev_name) goto cleanup; } + errno = 0; while ((de = readdir(dh)) != NULL) { if (!STRPREFIX(de->d_name, "loop")) continue; @@ -562,10 +563,15 @@ static int virFileLoopDeviceOpen(char **dev_name) /* Oh well, try the next device */ VIR_FORCE_CLOSE(fd); VIR_FREE(looppath); + errno = 0; } - virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Unable to find a free loop device in /dev")); + if (errno != 0) + virReportSystemError(errno, "%s", + _("Unable to iterate over loop devices")); + else + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("Unable to find a free loop device in /dev")); cleanup: if (fd != -1) {