[GRASS-dev] cppcheck analysis of grass_6.4.0 finds a number of C bugs

[Glynn Clements]

Hamish wrote:

>     * ./display/d.barscale/main.c:171 [error] - Undefined behaviour: cmdbuf is used wrong in call to sprintf or snprintf. Quote: If copying takes place between objects that overlap as a result of a call to sprintf() or snprintf(), the results are undefined.
>     * ./display/d.barscale/main.c:172 [error] - Undefined behaviour: cmdbuf is used wrong in call to sprintf or snprintf. Quote: If copying takes place between objects that overlap as a result of a call to sprintf() or snprintf(), the results are undefined.

	sprintf(cmdbuf, "%s bcolor=%s", cmdbuf, opt1->answer);
	sprintf(cmdbuf, "%s tcolor=%s", cmdbuf, opt2->answer);

This is a fairly common idiom in GRASS. As the tool notes, the
behaviour of using the destination buffer as an argument is undefined. 

This specific case is easy enough to fix; just generate the entire
string in one go. In cases where the append is conditional, safe
alternatives include using buf+strlen(buf) as the destination and
sprintf()ing into a temporary buffer then appending that with
strcat().

-- 
Glynn Clements <glynn at gclements.plus.com>