libmedia: Preserve futex return status in client obtainBuffer
clock_gettime() can change errno if something goes wrong (most
commonly setting EBADF). This failure should not cause a failure
in ClientProxy::obtainBuffer() if the futex returned successfully
or with a known status. Preserve errno before calling clock_gettime
to prevent propagation of an invalid, unexpected error.
authored-by: Leena Winterrowd <lenhardw@codeaurora.org>
Change-Id: Ib69201031a81395ece47dd8ad7c4dcddd2b00153
diff --git a/media/libmedia/AudioTrackShared.cpp b/media/libmedia/AudioTrackShared.cpp
index 666b747..9d5d996 100644
--- a/media/libmedia/AudioTrackShared.cpp
+++ b/media/libmedia/AudioTrackShared.cpp
@@ -240,6 +240,7 @@
errno = 0;
(void) syscall(__NR_futex, &cblk->mFutex,
mClientInServer ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT, old & ~CBLK_FUTEX_WAKE, ts);
+ status_t error = errno; // clock_gettime can affect errno
// update total elapsed time spent waiting
if (measure) {
struct timespec after;
@@ -257,7 +258,7 @@
before = after;
beforeIsValid = true;
}
- switch (errno) {
+ switch (error) {
case 0: // normal wakeup by server, or by binderDied()
case EWOULDBLOCK: // benign race condition with server
case EINTR: // wait was interrupted by signal or other spurious wakeup
@@ -265,7 +266,7 @@
// FIXME these error/non-0 status are being dropped
break;
default:
- status = errno;
+ status = error;
ALOGE("%s unexpected error %s", __func__, strerror(status));
goto end;
}