From 16c0e4a3c8de3c96d29fd495c1aded36d8935759 Mon Sep 17 00:00:00 2001
From: Mikhail Burakov <mburakov@mailbox.org>
Date: Sun, 25 Dec 2022 13:51:30 +0100
Subject: Use syslog for logging facilities

---
 utils.c | 27 +++++++++++++++++----------
 utils.h | 18 +++++++++++++++---
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/utils.c b/utils.c
index b0f36fa..62f09fa 100644
--- a/utils.c
+++ b/utils.c
@@ -18,26 +18,33 @@
 #include "utils.h"
 
 #include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
+#include <syslog.h>
 #include <threads.h>
 #include <time.h>
 
 static once_flag g_once_flag = ONCE_FLAG_INIT;
-static mtx_t g_log_mutex;
 
-static void InitLogMutex() {
-  if (mtx_init(&g_log_mutex, mtx_plain) != thrd_success) abort();
+static void InitLogging() { openlog(NULL, LOG_PERROR, LOG_USER); }
+
+static int LogLevelToPriority(enum LogLevel log_level) {
+  switch (log_level) {
+    case kLogLevelDebug:
+      return LOG_DEBUG;
+    case kLogLevelInfo:
+      return LOG_INFO;
+    case kLogLevelWarning:
+      return LOG_WARNING;
+    case kLogLevelError:
+      return LOG_ERR;
+  }
 }
 
-void LogImpl(const char* fmt, ...) {
-  call_once(&g_once_flag, InitLogMutex);
-  int status = mtx_lock(&g_log_mutex);
+void LogImpl(enum LogLevel log_level, const char* fmt, ...) {
+  call_once(&g_once_flag, InitLogging);
   va_list args;
   va_start(args, fmt);
-  vfprintf(stderr, fmt, args);
+  vsyslog(LogLevelToPriority(log_level), fmt, args);
   va_end(args);
-  if (status == thrd_success) mtx_unlock(&g_log_mutex);
 }
 
 unsigned long long MillisNow(void) {
diff --git a/utils.h b/utils.h
index 7eb585b..3774e62 100644
--- a/utils.h
+++ b/utils.h
@@ -24,11 +24,23 @@ extern "C" {
 
 #define STR_IMPL(op) #op
 #define STR(op) STR_IMPL(op)
-#define LOG(fmt, ...) \
-  LogImpl(__FILE__ ":" STR(__LINE__) " " fmt "\n", ##__VA_ARGS__)
+#define LOG(log_level, fmt, ...) \
+  LogImpl(level, __FILE__ ":" STR(__LINE__) " " fmt "\n", ##__VA_ARGS__)
+#define LOGD(...) LOG(kLogLevelDebug, __VA_ARGS__)
+#define LOGI(...) LOG(kLogLevelInfo, __VA_ARGS__)
+#define LOGW(...) LOG(kLogLevelWarning, __VA_ARGS__)
+#define LOGE(...) LOG(kLogLevelError, __VA_ARGS__)
 #define LENGTH(op) (sizeof(op) / sizeof *(op))
 
-void LogImpl(const char* fmt, ...) __attribute__((format(printf, 1, 2)));
+enum LogLevel {
+  kLogLevelDebug = 0,
+  kLogLevelInfo,
+  kLogLevelWarning,
+  kLogLevelError,
+};
+
+void LogImpl(enum LogLevel log_level, const char* fmt, ...)
+    __attribute__((format(printf, 2, 3)));
 unsigned long long MillisNow(void);
 
 #ifdef __cplusplus
-- 
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