misc: life_mngr: add log module

In the log module, the following functions are implemented:
- open_log
Provide one interface to open log file;

-close_log
Provide one interface to close log file;

- LOG_PRINTF LOG_WRITE
Provide interfaces to write log message to log file.

v1-->v3:
	Add timestamp in the log message.

Tracked-On: #6652

Signed-off-by: Xiangyang Wu <xiangyang.wu@intel.com>
Reviewed-by: fei1.li@intel.com

misc/services/life_mngr/log.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C)2021 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef _LOG_H_
+#define _LOG_H_
+#include <time.h>
+
+extern FILE *log_fd;
+static inline void output_timestamp(void)
+{
+	struct tm *t;
+	time_t tt;
+
+	time(&tt);
+	t = localtime(&tt);
+	fprintf(log_fd, "[%4d-%02d-%02d %02d:%02d:%02d]", t->tm_year + 1900, \
+		t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
+}
+#define LOG_PRINTF(format, args...) \
+do { output_timestamp(); \
+	fprintf(log_fd, format, args); \
+	fflush(log_fd); } while (0)
+
+#define LOG_WRITE(args) \
+do { output_timestamp(); \
+	fwrite(args, 1, sizeof(args), log_fd); \
+	fflush(log_fd); } while (0)
+
+static inline bool open_log(const char *path)
+{
+	bool ret = false;
+
+	log_fd = fopen("/var/log/life_mngr.log", "a+");
+	if (log_fd != NULL)
+		ret = true;
+	return ret;
+}
+static inline void close_log(void)
+{
+	if (log_fd != NULL)
+		fclose(log_fd);
+}
+#endif