Fix some issues with zlog stream unbuffered write

Author: bukka

sapi/fpm/fpm/zlog.c

@@ -323,7 +323,8 @@ static inline ssize_t zlog_stream_unbuffered_write(struct zlog_stream *stream, c
 {
 	int finished = 0;
 	const char *append;
-	size_t append_len;
+	size_t append_len = 0;
+	ssize_t written;
 
 	if (stream->len + len >= zlog_limit) {
 		if (stream->wrap) {
@@ -347,15 +348,27 @@ static inline ssize_t zlog_stream_unbuffered_write(struct zlog_stream *stream, c
 				zlog_stream_direct_write_ex(stream, buf, len, append, append_len);
 			}
 			/* TODO: use loop to speed it up */
-			return len + zlog_stream_unbuffered_write(stream, buf + len, len);
+			written = zlog_stream_unbuffered_write(stream, buf + len, len);
+			if (written > 0) {
+				return len + written;
+			}
+
+			return written;
 		}
 		stream->finished = finished = 1;
 		append = (stream->len + len == zlog_limit) ? "\n" : "...\n";
 		append_len = sizeof(append) - 1;
 		len = zlog_limit - stream->len - append_len;
 	}
 
-	return zlog_stream_direct_write_ex(stream, buf, len, append, append_len);
+	written = zlog_stream_direct_write_ex(stream, buf, len, append, append_len);
+	if (written > 0) {
+		/* currently written will be always len as the write is blocking
+		 * - this should be address if we change to non-blocking write */
+		stream->len += written;
+	}
+
+	return written;
 }
 /* }}} */
 
@@ -460,10 +473,11 @@ ssize_t zlog_stream_set_wrapping_prefix(struct zlog_stream *stream, const char *
 	va_end(args);
 
 	stream->wrap_prefix = malloc(len);
-	if (stream->wrap_prefix != NULL) {
+	if (stream->wrap_prefix == NULL) {
 		return -1;
 	}
 	memcpy(stream->wrap_prefix, buf, len);
+	stream->wrap_prefix_len = len;
 
 	return len;
 }