Fix GH-16800: ftp functions can abort with EINTR

This adds wrappers around recv(), send(), and php_pollfd_for_ms() to
handle EINTR.

This is a bit hard to test on its own, but it is testable manually using
the following script:
```php
pcntl_signal(SIGUSR1, function() {
    var_dump(func_get_args());
}, false);

var_dump(getmypid());
sleep(10);

$ftp = ftp_connect('127.0.0.1');
ftp_login($ftp, 'user', 'pass');
ftp_put($ftp, 'testfile', 'testfile');
```

in combination with an infinite while loop that sends SIGUSR1 to the
process.

Closes GH-17327.

NEWS

@@ -2,6 +2,8 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.3.17
 
+- FTP:
+  . Fixed bug GH-16800 (ftp functions can abort with EINTR). (nielsdos)
 
 02 Jan 2025, PHP 8.3.16RC1
 

ext/ftp/ftp.c

@@ -1387,6 +1387,22 @@ ftp_getresp(ftpbuf_t *ftp)
 }
 /* }}} */
 
+static ssize_t my_send_wrapper_with_restart(php_socket_t fd, const void *buf, size_t size, int flags) {
+	ssize_t n;
+	do {
+		n = send(fd, buf, size, flags);
+	} while (n == -1 && php_socket_errno() == EINTR);
+	return n;
+}
+
+static ssize_t my_recv_wrapper_with_restart(php_socket_t fd, void *buf, size_t size, int flags) {
+	ssize_t n;
+	do {
+		n = recv(fd, buf, size, flags);
+	} while (n == -1 && php_socket_errno() == EINTR);
+	return n;
+}
+
 int single_send(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t size) {
 #ifdef HAVE_FTP_SSL
 	int err;
@@ -1402,7 +1418,7 @@ int single_send(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t size) {
 		handle = ftp->data->ssl_handle;
 		fd = ftp->data->fd;
 	} else {
-		return send(s, buf, size, 0);
+		return my_send_wrapper_with_restart(s, buf, size, 0);
 	}
 
 	do {
@@ -1441,8 +1457,33 @@ int single_send(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t size) {
 	} while (retry);
 	return sent;
 #else
-	return send(s, buf, size, 0);
+	return my_send_wrapper_with_restart(s, buf, size, 0);
+#endif
+}
+
+static int my_poll(php_socket_t fd, int events, int timeout) {
+	int n;
+	zend_hrtime_t timeout_hr = (zend_hrtime_t) timeout * 1000000;
+
+	while (true) {
+		zend_hrtime_t start_ns = zend_hrtime();
+		n = php_pollfd_for_ms(fd, events, (int) (timeout_hr / 1000000));
+
+		if (n == -1 && php_socket_errno() == EINTR) {
+			zend_hrtime_t delta_ns = zend_hrtime() - start_ns;
+			if (delta_ns > timeout_hr) {
+#ifndef PHP_WIN32
+				errno = ETIMEDOUT;
 #endif
+				break;
+			}
+			timeout_hr -= delta_ns;
+		} else {
+			break;
+		}
+	}
+
+	return n;
 }
 
 /* {{{ my_send */
@@ -1454,7 +1495,7 @@ my_send(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t len)
 
 	size = len;
 	while (size) {
-		n = php_pollfd_for_ms(s, POLLOUT, ftp->timeout_sec * 1000);
+		n = my_poll(s, POLLOUT, ftp->timeout_sec * 1000);
 
 		if (n < 1) {
 			char buf[256];
@@ -1493,7 +1534,7 @@ my_recv(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t len)
 	SSL *handle = NULL;
 	php_socket_t fd;
 #endif
-	n = php_pollfd_for_ms(s, PHP_POLLREADABLE, ftp->timeout_sec * 1000);
+	n = my_poll(s, PHP_POLLREADABLE, ftp->timeout_sec * 1000);
 	if (n < 1) {
 		char buf[256];
 		if (n == 0) {
@@ -1553,7 +1594,7 @@ my_recv(ftpbuf_t *ftp, php_socket_t s, void *buf, size_t len)
 		} while (retry);
 	} else {
 #endif
-		nr_bytes = recv(s, buf, len, 0);
+		nr_bytes = my_recv_wrapper_with_restart(s, buf, len, 0);
 #ifdef HAVE_FTP_SSL
 	}
 #endif
@@ -1567,7 +1608,7 @@ data_available(ftpbuf_t *ftp, php_socket_t s)
 {
 	int		n;
 
-	n = php_pollfd_for_ms(s, PHP_POLLREADABLE, 1000);
+	n = my_poll(s, PHP_POLLREADABLE, 1000);
 	if (n < 1) {
 		char buf[256];
 		if (n == 0) {
@@ -1590,7 +1631,7 @@ data_writeable(ftpbuf_t *ftp, php_socket_t s)
 {
 	int		n;
 
-	n = php_pollfd_for_ms(s, POLLOUT, 1000);
+	n = my_poll(s, POLLOUT, 1000);
 	if (n < 1) {
 		char buf[256];
 		if (n == 0) {
@@ -1614,7 +1655,7 @@ my_accept(ftpbuf_t *ftp, php_socket_t s, struct sockaddr *addr, socklen_t *addrl
 {
 	int		n;
 
-	n = php_pollfd_for_ms(s, PHP_POLLREADABLE, ftp->timeout_sec * 1000);
+	n = my_poll(s, PHP_POLLREADABLE, ftp->timeout_sec * 1000);
 	if (n < 1) {
 		char buf[256];
 		if (n == 0) {