ext/standard: Check file truncation

NEWS

@@ -230,6 +230,8 @@ PHP                                                                        NEWS
     properties). (Lazizbek Ergashev)
 
 - Standard:
+  . Fixed file_put_contents() with LOCK_EX ignoring truncation failures on
+    regular files. (Ilia Alshanetsky)
   . Fixed bug GH-24308 (Request shutdown calls closelog() even when syslog
     was not opened by PHP). (lazerg)
   . Fixed bug GH-24399 (usleep() and time_nanosleep() ignore queued APCs on

ext/standard/file.c

@@ -493,8 +493,24 @@ PHP_FUNCTION(file_put_contents)
 		RETURN_FALSE;
 	}
 
-	if (mode[0] == 'c') {
-		php_stream_truncate_set_size(stream, 0);
+	if (mode[0] == 'c' && php_stream_truncate_set_size(stream, 0) != PHP_STREAM_OPTION_RETURN_OK) {
+		bool non_regular = false;
+		if (php_stream_is(stream, PHP_STREAM_IS_STDIO)) {
+#ifdef PHP_WIN32
+			php_socket_t fd;
+			if (php_stream_cast(stream, PHP_STREAM_AS_FD, (void **) &fd, 0) == SUCCESS) {
+				DWORD file_type = GetFileType((HANDLE) _get_osfhandle((int) fd));
+				non_regular = file_type == FILE_TYPE_CHAR || file_type == FILE_TYPE_PIPE;
+			}
+#else
+			php_stream_statbuf ssb;
+			non_regular = php_stream_stat(stream, &ssb) == 0 && !S_ISREG(ssb.sb.st_mode);
+#endif
+		}
+		if (!non_regular) {
+			php_stream_close(stream);
+			RETURN_FALSE;
+		}
 	}
 
 	switch (Z_TYPE_P(data)) {

ext/standard/tests/file/file_put_contents_lock_ex_device.phpt

@@ -0,0 +1,11 @@
+--TEST--
+file_put_contents() LOCK_EX permits writes to a device that cannot be truncated
+--FILE--
+<?php
+$device = PHP_OS_FAMILY === 'Windows' ? 'NUL' : '/dev/null';
+var_dump(file_put_contents($device, 'data', LOCK_EX));
+var_dump(file_put_contents($device, '', LOCK_EX));
+?>
+--EXPECT--
+int(4)
+int(0)

ext/standard/tests/file/file_put_contents_lock_ex_truncate_failure.phpt

@@ -0,0 +1,88 @@
+--TEST--
+file_put_contents() LOCK_EX stops writing after a wrapper truncation failure
+--FILE--
+<?php
+class FailingTruncateWrapper
+{
+    public $context;
+    public static bool $truncateResult = false;
+
+    public function stream_open($path, $mode, $options, &$openedPath)
+    {
+        return true;
+    }
+
+    public function stream_lock($operation)
+    {
+        return true;
+    }
+
+    public function stream_truncate($newSize)
+    {
+        echo "truncate: $newSize\n";
+        return self::$truncateResult;
+    }
+
+    public function stream_write($data)
+    {
+        echo "write\n";
+        return strlen($data);
+    }
+
+    public function stream_close()
+    {
+        echo "close\n";
+    }
+}
+
+$source = fopen('php://memory', 'w+');
+fwrite($source, 'data');
+rewind($source);
+
+var_dump(stream_wrapper_unregister('file'));
+var_dump(stream_wrapper_register('file', FailingTruncateWrapper::class));
+foreach (['string' => 'data', 'empty' => '', 'array' => ['data'], 'stream' => $source] as $label => $data) {
+    echo "$label:\n";
+    var_dump(file_put_contents('file:///test', $data, LOCK_EX));
+}
+echo "source position: ", ftell($source), "\n";
+fclose($source);
+
+echo "successful truncation:\n";
+FailingTruncateWrapper::$truncateResult = true;
+var_dump(file_put_contents('file:///test', 'data', LOCK_EX));
+
+echo "append:\n";
+FailingTruncateWrapper::$truncateResult = false;
+var_dump(file_put_contents('file:///test', 'data', FILE_APPEND | LOCK_EX));
+stream_wrapper_restore('file');
+?>
+--EXPECT--
+bool(true)
+bool(true)
+string:
+truncate: 0
+close
+bool(false)
+empty:
+truncate: 0
+close
+bool(false)
+array:
+truncate: 0
+close
+bool(false)
+stream:
+truncate: 0
+close
+bool(false)
+source position: 0
+successful truncation:
+truncate: 0
+write
+close
+int(4)
+append:
+write
+close
+int(4)