Re: git segfaults on older Solaris releases

[Jeff King <peff@peff.net>]

On Thu, Apr 07, 2016 at 12:37:53PM -0700, Junio C Hamano wrote:

> -- >8 --
> Subject: setup.c: do not feed NULL to "%.*s" even with the precision 0
> 
> A recent update 75faa45a (replace trivial malloc + sprintf / strcpy
> calls with xstrfmt, 2015-09-24) rewrote
> 
> 	prepare an empty buffer
> 	if (len)
>         	append the first len bytes of "prefix" to the buffer
> 	append "path" to the buffer
> 
> that computed "path", optionally prefixed by "prefix", into
> 
> 	xstrfmt("%.*s%s", len, prefix, path);
> 
> However, passing a NULL pointer to the printf(3) family of functions
> to format it with %s conversion, even with the precision 0, i.e.
> 
> 	xstrfmt("%.*s", 0, NULL)
> 
> yields undefined results, at least on some platforms.  
> 
> Avoid this problem by substituting prefix with "" when len==0, as
> prefix can legally be NULL in that case.  This would mimick the
> intent of the original code better.
> 
> Reported-by: "Tom G. Christensen" <tgc@jupiterrise.com>
> Helped-by: Jeff King <peff@peff.net>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---

Nicely explained.

Acked-by: Jeff King <peff@peff.net>

Thanks.

-Peff