1 files changed, 67 insertions, 0 deletions
diff --git a/lib/log.c b/lib/log.c
new file mode 100644
index 0000000..4924782
--- /dev/null
+++ b/lib/log.c
@@ -0,0 +1,67 @@
+#include <string.h>
+#include <time.h>
+#include "log.h"
+
+/* TODO: replace this with something thread-safe later. */
+
+static unsigned log_level = LOG_INFO;
+
+void vl_log_setlevel(unsigned level)
+{
+  log_level = level;
+}
+
+#define MAX_LOGLEN ((size_t)4096)
+#define MAX_LOGTIMELEN ((size_t)64) /* december 999th of 10000 A.D. at 100 o'clock */
+
+static const char *const log_names[] = {
+  "TRACE",
+  "DEBUG",
+  "INFO",
+  "WARN",
+  "ERROR",
+  NULL
+};
+
+static FILE *log_stream(unsigned level)
+{
+  switch (level) {
+    case LOG_TRACE:
+    case LOG_DEBUG:
+    case LOG_INFO:
+      return stdout;
+    default:
+      return stderr;
+  }
+}
+
+void vl_logv(unsigned level, const char *fmt, va_list args)
+{
+  char buf[MAX_LOGLEN];
+  char datebuf[MAX_LOGTIMELEN];
+  time_t now;
+  struct tm now_tm;
+
+  if (log_level > level) return;
+  if (level > LOG_ERROR) return;
+
+  vsnprintf(buf, MAX_LOGLEN, fmt, args);
+  strcpy(buf + MAX_LOGLEN - 4, "...");
+
+  now = time(NULL);
+  localtime_r(&now, &now_tm);
+
+  if (!strftime(datebuf, MAX_LOGTIMELEN, "%H:%M:%S", &now_tm)) {
+    strcpy(datebuf, "???");
+  }
+
+  fprintf(log_stream(level), "[%s] %s: %s\n", datebuf, log_names[level], buf);
+}
+
+void vl_log(unsigned level, const char *fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  vl_logv(level, fmt, args);
+  va_end(args);
+}