From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 26 Nov 2009 00:59:24 GMT
Subject: Re: [PATCH/RFC 02/11] strbuf: add non-variadic function strbuf_vaddf()
Message-ID: <7vskc2ksnn.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1259196260-3064-3-git-send-email-kusmabite@gmail.com>

Erik Faye-Lund <kusmabite@googlemail.com> writes:

> +void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap)
>  {
>  	int len;
>  
>  	if (!strbuf_avail(sb))
>  		strbuf_grow(sb, 64);
>  	len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
>  	if (len < 0)
>  		die("your vsnprintf is broken");
>  	if (len > strbuf_avail(sb)) {
>  		strbuf_grow(sb, len);
>  		len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
>  		if (len > strbuf_avail(sb)) {
>  			die("this should not happen, your snprintf is broken");
>  		}

Hmm, I would have expected to see va_copy() somewhere in the patch text.
Is it safe to reuse ap like this in two separate invocations of
vsnprintf()?