Fixed bug #79000

Don't report EAGAIN/EWOULDBLOCK as errors for fwrite on
non-blocking socket streams. This matches behavior for fread,
as well as behavior for plain file streams.

Closes GH-5026.

Author: nikic

NEWS

@@ -28,6 +28,10 @@ PHP                                                                        NEWS
 - Spl:
   . Fixed bug #78976 (SplFileObject::fputcsv returns -1 on failure). (cmb)
 
+- Standard:
+  . Fixed bug #79000 (Non-blocking socket stream reports EAGAIN as error).
+    (Nikita)
+
 18 Dec 2019, PHP 7.4.1
 
 - Core:

ext/standard/tests/streams/bug79000.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Bug #79000: Non-blocking socket stream reports EAGAIN as error
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY == 'Windows') die('skip Not for Windows');
+?>
+--FILE--
+<?php
+
+[$sock1, $sock2] = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
+$str = str_repeat('a', 1000000);
+stream_set_blocking($sock1, false);
+var_dump(fwrite($sock1, $str));
+var_dump(fwrite($sock1, $str));
+
+?>
+--EXPECTF--
+int(%d)
+int(%d)

main/streams/xp_socket.c

@@ -75,30 +75,36 @@ static ssize_t php_sockop_write(php_stream *stream, const char *buf, size_t coun
 	didwrite = send(sock->socket, buf, XP_SOCK_BUF_SIZE(count), (sock->is_blocked && ptimeout) ? MSG_DONTWAIT : 0);
 
 	if (didwrite <= 0) {
-		int err = php_socket_errno();
 		char *estr;
+		int err = php_socket_errno();
+		if (err == EWOULDBLOCK || err == EAGAIN) {
+			if (sock->is_blocked) {
+				int retval;
 
-		if (sock->is_blocked && (err == EWOULDBLOCK || err == EAGAIN)) {
-			int retval;
-
-			sock->timeout_event = 0;
+				sock->timeout_event = 0;
 
-			do {
-				retval = php_pollfd_for(sock->socket, POLLOUT, ptimeout);
+				do {
+					retval = php_pollfd_for(sock->socket, POLLOUT, ptimeout);
 
-				if (retval == 0) {
-					sock->timeout_event = 1;
-					break;
-				}
+					if (retval == 0) {
+						sock->timeout_event = 1;
+						break;
+					}
 
-				if (retval > 0) {
-					/* writable now; retry */
-					goto retry;
-				}
+					if (retval > 0) {
+						/* writable now; retry */
+						goto retry;
+					}
 
-				err = php_socket_errno();
-			} while (err == EINTR);
+					err = php_socket_errno();
+				} while (err == EINTR);
+			} else {
+				/* EWOULDBLOCK/EAGAIN is not an error for a non-blocking stream.
+				 * Report zero byte write instead. */
+				return 0;
+			}
 		}
+
 		estr = php_socket_strerror(err, NULL, 0);
 		php_error_docref(NULL, E_NOTICE, "send of " ZEND_LONG_FMT " bytes failed with errno=%d %s",
 				(zend_long)count, err, estr);