ensure that async_run() and async_run_sync() always preserve errno.

3 files changed, 27 insertions, 13 deletions

diff --git a/lib/libc/asr/asr.c b/lib/libc/asr/asr.c
index 48460d31ac0..d4db4ed2606 100644
--- a/lib/libc/asr/asr.c
+++ b/lib/libc/asr/asr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: asr.c,v 1.3 2012/04/15 22:25:14 eric Exp $	*/
+/*	$OpenBSD: asr.c,v 1.4 2012/08/18 16:48:17 eric Exp $	*/
 /*
  * Copyright (c) 2010-2012 Eric Faurot <eric@openbsd.org>
  *
@@ -159,7 +159,7 @@ async_abort(struct async *as)
 int
 async_run(struct async *as, struct async_res *ar)
 {
-	int	r;
+	int	r, saved_errno = errno;
 
 #ifdef DEBUG
 	asr_printf("asr: async_run(%p, %p) %s ctx=[%p]\n",
@@ -182,6 +182,8 @@ async_run(struct async *as, struct async_res *ar)
 	if (r == ASYNC_DONE)
 		async_free(as);
 
+	errno = saved_errno;
+
 	return (r);
 }
 
@@ -191,8 +193,8 @@ async_run(struct async *as, struct async_res *ar)
 int
 async_run_sync(struct async *as, struct async_res *ar)
 {
-	struct pollfd		 fds[1];
-	int			 r;
+	struct pollfd	 fds[1];
+	int		 r, saved_errno = errno;
 
 	while((r = async_run(as, ar)) == ASYNC_COND) {
 		fds[0].fd = ar->ar_fd;
@@ -201,10 +203,14 @@ async_run_sync(struct async *as, struct async_res *ar)
 		r = poll(fds, 1, ar->ar_timeout);
 		if (r == -1 && errno == EINTR)
 			goto again;
-		if (r == -1) /* XXX Is it possible? and what to do if so? */
-			err(1, "poll");
+		/*
+		 * Otherwise, just ignore the error and let async_run()
+		 * catch the failure.
+		 */
 	}
 
+	errno = saved_errno;
+
 	return (r);
 }
 
diff --git a/lib/libc/asr/asr_resolver.c b/lib/libc/asr/asr_resolver.c
index ab996fd97b6..acebcbd6753 100644
--- a/lib/libc/asr/asr_resolver.c
+++ b/lib/libc/asr/asr_resolver.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: asr_resolver.c,v 1.7 2012/08/18 13:49:13 eric Exp $	*/
+/*	$OpenBSD: asr_resolver.c,v 1.8 2012/08/18 16:48:17 eric Exp $	*/
 /*
  * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
  *
@@ -237,7 +237,6 @@ getrrsetbyname(const char *name, unsigned int class, unsigned int type,
 
 	async_run_sync(as, &ar);
 
-	errno = saved_errno;
 	*res = ar.ar_rrsetinfo;
 
 	return (ar.ar_rrset_errno);
@@ -490,7 +489,8 @@ getaddrinfo(const char *hostname, const char *servname,
 	async_run_sync(as, &ar);
 
 	*res = ar.ar_addrinfo;
-	errno = (ar.ar_gai_errno == EAI_SYSTEM) ? ar.ar_errno : saved_errno;
+	if (ar.ar_gai_errno == EAI_SYSTEM)
+		errno = ar.ar_errno;
 
 	return (ar.ar_gai_errno);
 }
@@ -514,8 +514,8 @@ getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
 	}
 
 	async_run_sync(as, &ar);
-
-	errno = (ar.ar_gai_errno == EAI_SYSTEM) ? ar.ar_errno : saved_errno;
+	if (ar.ar_gai_errno == EAI_SYSTEM)
+		errno = ar.ar_errno;
 
 	return (ar.ar_gai_errno);
 }
diff --git a/lib/libc/asr/async_resolver.3 b/lib/libc/asr/async_resolver.3
index 2fa4204abe7..81ae9f92e23 100644
--- a/lib/libc/asr/async_resolver.3
+++ b/lib/libc/asr/async_resolver.3
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: async_resolver.3,v 1.2 2012/04/15 15:08:12 jmc Exp $
+.\"	$OpenBSD: async_resolver.3,v 1.3 2012/08/18 16:48:17 eric Exp $
 .\"
 .\" Copyright (c) 2012, Eric Faurot <eric@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: April 15 2012 $
+.Dd $Mdocdate: August 18 2012 $
 .Dt ASYN_RESOLVER 3
 .Os
 .Sh NAME
@@ -212,6 +212,13 @@ are set accordingly and the resolving process can be resumed by calling
 .Fn async_run .
 .El
 .Pp
+Note that although the query itself may fail (the error being properly reported
+in the
+.Fa ar
+structure), the
+.Fn async_run
+function itself cannot fail and it always preserves errno.
+.Pp
 The
 .Fn async_run_sync
 function is a wrapper around
@@ -220,6 +227,7 @@ that handles the read/write conditions, thus falling back to a blocking
 interface.
 It only returns partial and complete results through ASYNC_YIELD and ASYNC_DONE
 respectively.
+It also preserves errno.
 .Pp
 The
 .Fn async_abort