helpers for locking/unlocking a file

src/misc/lock_file.c

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+///////////////////////////////////////////////////////////////////////////////
+//
+//                          IMPORTANT NOTICE
+//
+// The following open source license statement does not apply to any
+// entity in the Exception List published by FMSoft.
+//
+// For more information, please visit:
+//
+// https://www.fmsoft.cn/exception-list
+//
+//////////////////////////////////////////////////////////////////////////////
+/*
+ *   This file is part of MiniGUI, a mature cross-platform windowing
+ *   and Graphics User Interface (GUI) support system for embedded systems
+ *   and smart IoT devices.
+ *
+ *   Copyright (C) 2023, Beijing FMSoft Technologies Co., Ltd.
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *   Or,
+ *
+ *   As this program is a library, any link to this program must follow
+ *   GNU General Public License version 3 (GPLv3). If you cannot accept
+ *   GPLv3, you need to be licensed from FMSoft.
+ *
+ *   If you have got a commercial license of this program, please use it
+ *   under the terms and conditions of the commercial license.
+ *
+ *   For more information about the commercial license, please refer to
+ *   <http://www.minigui.com/blog/minigui-licensing-policy/>.
+ */
+/*
+** lock_file.c: This file include functions for locking/unlocking a file.
+**
+** Create date: 2023/09/10
+**
+** Current maintainer: Wei Yongming.
+*/
+
+#include "common.h"
+
+#ifndef __NOUNIX__
+
+#include "misc.h"
+
+#include <unistd.h>
+#include <sys/file.h>
+#include <fcntl.h>
+#include <errno.h>
+
+void __mg_lock_file_for_read(int fd)
+{
+    while (flock(fd, LOCK_SH) == -1 && errno == EINTR);
+}
+
+void __mg_unlock_file_for_read(int fd)
+{
+    flock(fd, LOCK_UN);
+}
+
+void __mg_lock_file_for_write(int fd)
+{
+    while (flock(fd, LOCK_EX) == -1 && errno == EINTR);
+}
+
+void __mg_unlock_file_for_write(int fd)
+{
+    flock(fd, LOCK_UN);
+}
+
+#endif /* __NOUNIX__ */