1 files changed, 38 insertions, 0 deletions
diff --git a/src/stdio/vfprintf_s.c b/src/stdio/vfprintf_s.c
new file mode 100644
index 00000000..e2d94c71
--- /dev/null
+++ b/src/stdio/vfprintf_s.c
@@ -0,0 +1,38 @@
+#include "stdio.h"
+#include "__stdio.h"
+#include <stdarg.h>
+
+/** write formatted output to a file stream **/
+int vfprintf_s(FILE * restrict stream, const char * restrict format, va_list arg)
+{
+	__C_EXT(1, 201112L);
+	va_list ap;
+	va_copy(ap, arg);
+	int len = vsnprintf(NULL, 0, format, arg);
+	char *buf = malloc(len + 1);
+	len = vsnprintf(buf, len, format, ap);
+	va_end(ap);
+	len = (int)fwrite(buf, sizeof(*buf), len, stream);
+	free(buf);
+	return len;
+}
+
+/***
+The fn(vfprintf) function is equivalent to fn(fprintf), but with a type(va_list)
+argument instead of variadic arguments. The argument arg(arg) must be
+initialized with fnmacro(va_start) prior to calling fn(vfprintf). The
+fn(vfprintf) function does not call fnmacro(va_end), so the calling function is
+responsible for this.
+***/
+
+/* UNSPECIFIED: ??? */
+/* UNDEFINED: ??? */
+/* IMPLEMENTATION: ??? */
+/* LOCALE: ??? */
+
+/* RETURN(NEG): an error occurred */
+/* RETURN: the number of characters written */
+
+/*
+CEXT1(201112)
+*/