1 files changed, 53 insertions, 0 deletions
diff --git a/src/log.c b/src/log.c
new file mode 100644
index 0000000..3886a1a
--- /dev/null
+++ b/src/log.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2023 Egor Tensin <Egor.Tensin@gmail.com>
+ * This file is part of the "cimple" project.
+ * For details, see https://github.com/egor-tensin/cimple.
+ * Distributed under the MIT License.
+ */
+
+#include "log.h"
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include <unistd.h>
+
+int g_log_lvl = LOG_LVL_INFO;
+
+static inline void log_prefix_timestamp(FILE *dest)
+{
+	struct timeval tv;
+	struct tm tm;
+	char buf[64];
+	size_t used = 0;
+
+	if (gettimeofday(&tv, NULL) < 0)
+		return;
+	if (!gmtime_r(&tv.tv_sec, &tm))
+		return;
+
+	buf[0] = '\0';
+	used += strftime(buf + used, sizeof(buf) - used, "%F %T", &tm);
+	used += snprintf(buf + used, sizeof(buf) - used, ".%03ld | ", tv.tv_usec / 1000);
+	fprintf(dest, "%s", buf);
+}
+
+static inline void log_prefix_thread_id(FILE *dest)
+{
+	fprintf(dest, "%d | ", gettid());
+}
+
+int log_entry_start(int lvl, FILE *dest)
+{
+	if (lvl < g_log_lvl)
+		return 0;
+	flockfile(dest);
+	log_prefix_timestamp(dest);
+	log_prefix_thread_id(dest);
+	return 1;
+}
+
+void log_entry_end(FILE *dest)
+{
+	funlockfile(dest);
+}