Add gsr_log logging module with log level and overridable log handler

1 files changed, 28 insertions, 0 deletions

diff --git a/include/log.h b/include/log.h
new file mode 100644
index 0000000..71be585
--- /dev/null
+++ b/include/log.h
@@ -0,0 +1,28 @@
+#ifndef GSR_LOG_H
+#define GSR_LOG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+    GSR_LOG_LEVEL_DEBUG,
+    GSR_LOG_LEVEL_INFO,
+    GSR_LOG_LEVEL_WARNING,
+    GSR_LOG_LEVEL_ERROR
+} gsr_log_level;
+
+/* The handler may be called from any thread. |message| has no prefix, level name or trailing newline */
+typedef void (*gsr_log_handler)(gsr_log_level level, const char *message, void *userdata);
+
+void gsr_log(gsr_log_level level, const char *fmt, ...) __attribute__((format(printf, 2, 3)));
+/* Messages below |level| are discarded */
+void gsr_log_set_level(gsr_log_level level);
+/* A NULL |handler| restores the default handler which prints "gsr <level>: <message>" to stderr */
+void gsr_log_set_handler(gsr_log_handler handler, void *userdata);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GSR_LOG_H */