[PATCH 2/2] avoid relying on ppoll as a cancellation point

[Eric Wong <e@80x24.org>]

While glibc supports ppoll, ppoll is not standardized and
apparently is not a cancellation point in some versions FreeBSD
based on Mykola Golub's bug report.

Reported-by: Mykola Golub <trociny@FreeBSD.org>
ref: <20150309151851.GC2195@gmail.com>
---
 sig.c | 22 ++++------------------
 1 file changed, 4 insertions(+), 18 deletions(-)

diff --git a/sig.c b/sig.c
index cfbffc2..7e1c200 100644
--- a/sig.c
+++ b/sig.c
@@ -27,27 +27,14 @@ void mog_intr_enable(void)
 	CHECK(int, 0, pthread_sigmask(SIG_SETMASK, &mog_emptyset, NULL));
 }
 
-/*
- * favor ppoll if available since this is our only pselect user and
- * would increase the size of the executable
- */
-#ifdef HAVE_PPOLL
-static int sleeper(struct timespec *tsp, const sigset_t *sigmask)
-{
-	int err = 0;
-
-	if (ppoll(NULL, 0, tsp, sigmask) < 0) {
-		err = errno;
-		assert((err == EINTR || err == ENOMEM) &&
-		       "BUG in ppoll usage");
-	}
-	return err;
-}
-#else /* PSELECT */
 static int sleeper(struct timespec *tsp, const sigset_t *sigmask)
 {
 	int err = 0;
 
+	/*
+	 * pselect is a cancellation point,
+	 * ppoll is not POSIX and is only a cancellation point on glibc.
+	 */
 	if (pselect(0, NULL, NULL, NULL, tsp, sigmask) < 0) {
 		err = errno;
 		assert((err == EINTR || err == ENOMEM) &&
@@ -55,7 +42,6 @@ static int sleeper(struct timespec *tsp, const sigset_t *sigmask)
 	}
 	return err;
 }
-#endif /* PSELECT */
 
 /* thread-safe, interruptible sleep, negative seconds -> sleep forever */
 int mog_sleep(long seconds)
-- 
EW