preprocessor runs once

src/buffer.cpp

@@ -0,0 +1,25 @@
+#include "buffer.hpp"
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+Buf *buf_sprintf(const char *format, ...) {
+    va_list ap, ap2;
+    va_start(ap, format);
+    va_copy(ap2, ap);
+
+    int len1 = vsnprintf(nullptr, 0, format, ap);
+    assert(len1 >= 0);
+
+    size_t required_size = len1 + 1;
+
+    Buf *buf = buf_alloc_fixed(len1);
+
+    int len2 = vsnprintf(buf_ptr(buf), required_size, format, ap2);
+    assert(len2 == len1);
+
+    va_end(ap2);
+    va_end(ap);
+
+    return buf;
+}