From: Jan Maria Matejka <mq@ucw.cz>
Date: Wed, 22 Aug 2018 12:58:53 +0000 (+0200)
Subject: Lib: recursive printf
X-Git-Tag: v2.0.3~57
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=64c5ad58d276d8a0463aa9ad2b34f75b7d1f4108;p=thirdparty%2Fbird.git

Lib: recursive printf

Use like this:

void func(const char *msg, va_list args) {
  ...
  bvsnprintf(buf, len, "file %s, line %d: %V (foo %d, bar %d)", file, line, msg, &args, foo, bar);
  ...
}
---

diff --git a/lib/printf.c b/lib/printf.c
index 533a1300b..cafeeb931 100644
--- a/lib/printf.c
+++ b/lib/printf.c
@@ -270,6 +270,17 @@ int bvsnprintf(char *buf, int size, const char *fmt, va_list args)
 				*str++ = ' ';
 			continue;
 
+		case 'V': {
+			const char *vfmt = va_arg(args, const char *);
+			va_list *vargs = va_arg(args, va_list *);
+			int res = bvsnprintf(str, size, vfmt, *vargs);
+			if (res < 0)
+				return -1;
+			str += res;
+			size -= res;
+			continue;
+			}
+
 		case 'p':
 			if (field_width == -1) {
 				field_width = 2*sizeof(void *);