pr_log: a new module that provides a simple run-time controlled logging interface

[ccan] / ccan / pr_log / pr_log.c

diff --git a/ccan/pr_log/pr_log.c b/ccan/pr_log/pr_log.c
new file mode 100644 (file)
index 0000000..1de8cb9
--- /dev/null
+++ b/ccan/pr_log/pr_log.c
@@ -0,0 +1,48 @@
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+#include "pr_log.h"
+
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+
+#include <ccan/str/str.h>
+
+#define DEBUG_NEED_INIT INT_MIN
+static int debug = DEBUG_NEED_INIT;
+
+bool debug_is(int lvl)
+{
+       return lvl <= debug_level();
+}
+
+int debug_level(void)
+{
+       if (debug != DEBUG_NEED_INIT)
+               return debug;
+       char *c = getenv("DEBUG");
+       if (!c) {
+               debug = CCAN_PR_LOG_DEFAULT_LEVEL;
+               return debug;
+       }
+
+       debug = atoi(c);
+       return debug;
+}
+
+void pr_log_(char const *fmt, ...)
+{
+       int level = INT_MIN;
+       if (fmt[0] == '<' && cisdigit(fmt[1]) && fmt[2] == '>')
+               level = fmt[1] - '0';
+
+       if (!debug_is(level))
+               return;
+
+       va_list va;
+       va_start(va, fmt);
+       vfprintf(stderr, fmt, va);
+       va_end(va);
+}