add logging

include/stk_log.h

@@ -0,0 +1,16 @@
+#ifndef STK_LOG_H
+#define STK_LOG_H
+
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void stk_log(FILE *fp, const char *fmt, ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* STK_LOG_H */

src/stk.c

@@ -1,14 +1,14 @@
 #include "stk.h"
-#include <stdio.h>
+#include "stk_log.h"
 
 int stk_init(void)
 {
-	printf("stk initialized v%s\n", STK_VERSION_STRING);
+	stk_log(stdout, "[stk] stk initialized v%s!", STK_VERSION_STRING);
 	return 0;
 }
 
 int stk_shutdown(void)
 {
-	printf("stk shutdown\n");
+	stk_log(stdout, "stk shutdown");
 	return 0;
 }

src/stk_log.c

@@ -0,0 +1,14 @@
+#include "stk_log.h"
+#include <stdarg.h>
+#include <stdio.h>
+
+void stk_log_file(FILE *fp, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+
+	vfprintf(fp, fmt, args);
+	fputc('\n', fp);
+
+	va_end(args);
+}