1 files changed, 40 insertions, 0 deletions

diff --git a/src/ot_fmt.c b/src/ot_fmt.c
new file mode 100644
index 0000000..362c9b5
--- /dev/null
+++ b/src/ot_fmt.c
@@ -0,0 +1,40 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+/* Opentracker */
+#include "ot_fmt.h"
+
+void fmt_append(char **cursor, const char *end, const char *format, ...) {
+  va_list arguments;
+  size_t  room;
+  int     written;
+
+  if (*cursor >= end) {
+    *cursor = (char *)end;
+    return;
+  }
+
+  room = (size_t)(end - *cursor);
+  va_start(arguments, format);
+  written = vsnprintf(*cursor, room, format, arguments);
+  va_end(arguments);
+
+  if (written < 0)
+    return;
+  *cursor = (size_t)written >= room ? (char *)end : *cursor + written;
+}
+
+void fmt_bytes(char **cursor, const char *end, const void *bytes, size_t length) {
+  if (*cursor >= end || (size_t)(end - *cursor) < length) {
+    *cursor = (char *)end;
+    return;
+  }
+
+  memcpy(*cursor, bytes, length);
+  *cursor += length;
+}