log: Create `log.{c,h}`, and add `vprintlog()`

`vprintlog()` prints out the provided string to either syslog, stderr,
or stdout depending on the output type.

2 files changed, 46 insertions, 0 deletions

diff --git a/log.c b/log.c
new file mode 100644
index 0000000..12898f4
--- /dev/null
+++ b/log.c
@@ -0,0 +1,28 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include "log.h"
+#include "misc.h"
+
+void vprintlog(log_output output_type, int priority, const char *fmt, va_list args) {
+	char *buf = calloc(vformat_len_copy(fmt, args)+1, sizeof(char));
+	vsprintf(buf, fmt, args);
+
+	switch (output_type) {
+		case LOG_OUT_SYSLOG: {
+			syslog(priority, "%s", buf);
+			break;
+		}
+		case LOG_OUT_STDERR:
+		case LOG_OUT_STDOUT: {
+			FILE *output = (output_type == LOG_OUT_STDOUT) ? stdout : stderr;
+			fprintf(output, "%s\n", buf);
+			break;
+		}
+		default:
+			break;
+	}
+	free(buf);
+}
diff --git a/log.h b/log.h
new file mode 100644
index 0000000..08477e9
--- /dev/null
+++ b/log.h
@@ -0,0 +1,18 @@
+#ifndef LOG_H
+#define LOG_H
+
+#include <stdarg.h>
+
+typedef enum log_output log_output;
+
+enum log_output {
+	LOG_OUT_SYSLOG,
+	LOG_OUT_STDERR,
+	LOG_OUT_STDOUT,
+	LOG_OUT_NONE,
+};
+
+extern void vprintlog(log_output output_type, int priority, const char *fmt, va_list args);
+
+#endif
+