From: Martin Mares <mj@ucw.cz>
Date: Wed, 14 Sep 2005 09:19:17 +0000 (+0000)
Subject: Another thing about the C standard I didn't know: passing a va_list to
X-Git-Tag: holmes-import~743
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=2bdb8362f6969384d1c2a4c0ee6bfef5e60e85c5;p=libucw.git

Another thing about the C standard I didn't know: passing a va_list to
a library function (e.g., snprintf()) can destroy it. Need to call va_copy() here.
---

diff --git a/lib/ff-printf.c b/lib/ff-printf.c
index fe9c9642..aff49eb2 100644
--- a/lib/ff-printf.c
+++ b/lib/ff-printf.c
@@ -17,11 +17,13 @@ vbprintf(struct fastbuf *b, char *msg, va_list args)
 {
   byte *buf;
   int len, r;
+  va_list args2;
 
   len = bdirect_write_prepare(b, &buf);
   if (len >= 16)
     {
-      r = vsnprintf(buf, len, msg, args);
+      va_copy(args2, args);
+      r = vsnprintf(buf, len, msg, args2);
       if (r < 0)
 	len = 256;
       else if (r < len)
@@ -38,7 +40,8 @@ vbprintf(struct fastbuf *b, char *msg, va_list args)
   while (1)
     {
       buf = alloca(len);
-      r = vsnprintf(buf, len, msg, args);
+      va_copy(args2, args);
+      r = vsnprintf(buf, len, msg, args2);
       if (r < 0)
 	len += len;
       else if (r < len)