socket: sendmsg/recvmsg only retries blocking on errors

* ext/socket/ancdata.c (bsock_sendmsg_internal): only retry on error
  (bsock_recvmsg_internal): ditto
* test/socket/test_unix.rb: test above for infinite loop

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45066 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 37 insertions, 10 deletions

diff --git a/ChangeLog b/ChangeLog
index 2b548567f4..1e95deb350 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Feb 21 09:48:56 2014  Eric Wong  <e@80x24.org>
+
+	* ext/socket/ancdata.c (bsock_sendmsg_internal): only retry on error
+	  (bsock_recvmsg_internal): ditto
+	* test/socket/test_unix.rb: test above for infinite loop
+
 Fri Feb 21 08:27:19 2014  Eric Wong  <e@80x24.org>
 
 	* include/ruby/ruby.h (RB_GC_GUARD):
diff --git a/ext/socket/ancdata.c b/ext/socket/ancdata.c
index 7054d654ea..218085d5ce 100644
--- a/ext/socket/ancdata.c
+++ b/ext/socket/ancdata.c
@@ -1282,12 +1282,11 @@ bsock_sendmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
 
     ss = rb_sendmsg(fptr->fd, &mh, flags);
 
-    if (!nonblock && rb_io_wait_writable(fptr->fd)) {
-        rb_io_check_closed(fptr);
-        goto retry;
-    }
-
     if (ss == -1) {
+        if (!nonblock && rb_io_wait_writable(fptr->fd)) {
+            rb_io_check_closed(fptr);
+            goto retry;
+        }
         if (nonblock && (errno == EWOULDBLOCK || errno == EAGAIN))
             rb_readwrite_sys_fail(RB_IO_WAIT_WRITABLE, "sendmsg(2) would block");
 	rb_sys_fail("sendmsg(2)");
@@ -1601,12 +1600,11 @@ bsock_recvmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
 
     ss = rb_recvmsg(fptr->fd, &mh, flags);
 
-    if (!nonblock && rb_io_wait_readable(fptr->fd)) {
-        rb_io_check_closed(fptr);
-        goto retry;
-    }
-
     if (ss == -1) {
+        if (!nonblock && rb_io_wait_readable(fptr->fd)) {
+            rb_io_check_closed(fptr);
+            goto retry;
+        }
         if (nonblock && (errno == EWOULDBLOCK || errno == EAGAIN))
             rb_readwrite_sys_fail(RB_IO_WAIT_READABLE, "recvmsg(2) would block");
 #if defined(HAVE_STRUCT_MSGHDR_MSG_CONTROL)
diff --git a/test/socket/test_unix.rb b/test/socket/test_unix.rb
index ada614c23f..a6879bbfe4 100644
--- a/test/socket/test_unix.rb
+++ b/test/socket/test_unix.rb
@@ -5,6 +5,7 @@ end
 
 require "test/unit"
 require "tempfile"
+require "timeout"
 require "tmpdir"
 require "thread"
 require "io/nonblock"
@@ -369,6 +370,28 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
     s2.close if s2
   end
 
+  def test_dgram_pair_sendrecvmsg_errno_set
+    s1, s2 = to_close = UNIXSocket.pair(Socket::SOCK_DGRAM)
+    pipe = IO.pipe
+    to_close.concat(pipe)
+    set_errno = lambda do
+      begin
+        pipe[0].read_nonblock(1)
+        fail
+      rescue => e
+        assert(IO::EAGAINWaitReadable === e)
+      end
+    end
+    Timeout.timeout(10) do
+      set_errno.call
+      assert_equal(2, s1.sendmsg("HI"))
+      set_errno.call
+      assert_equal("HI", s2.recvmsg[0])
+    end
+  ensure
+    to_close.each(&:close) if to_close
+  end
+
   def test_epipe # [ruby-dev:34619]
     s1, s2 = UNIXSocket.pair
     s1.shutdown(Socket::SHUT_WR)