On Thu, Sep 25, 2008 at 08:15:05AM -0600, Brad Nicholes wrote:
> <[EMAIL PROTECTED]> wrote:
> > if (strcasecmp(cb->name, metric_info[i].name) == 0)
> > {
> > - sprintf (modular_desc, "%s (module %s)",
> > metric_info[i].desc, cb->modp->module_name);
> > + snprintf (modular_desc, sizeof(modular_desc),
> > + "%s (module %s)",
> > + metric_info[i].desc,
> > + cb->modp->module_name);
> > +
> > desc = (char*)modular_desc;
> > break;
> > }
>
> When copying into the buffer, shouldn't the length be sizeof(modular_desc)-1
> rather than the full length of the buffer?
the length is the maximum allowed number of bytes that will be written in the
buffer so sizeof(modular_desc) is a more natural fit since otherwise the
buffer will be artificially restricted by 1 byte.
> It needs to allow for a NULL terminator.
snprintf is defined with C99 and I don't have an specification handy but the
man page for it in Linux says :
"The functions snprintf() and vsnprintf() write at most size bytes
(including the trailing null byte ('\0')) to str."
so the NULL terminator should be included in the length requested, and a quick
test with gcc 4.1.2 and the following code shows that it is indeed terminating
the buffer and truncating the result as needed to do so.
#include <string.h>
#include <stdio.h>
#define BUFFSIZE 4
int main(int argc, char *argv[])
{
char buffer[BUFFSIZE];
char *source = "test";
int n;
for (n =0 ; n < BUFFSIZE; n++)
buffer[n] = 'A';
printf("%s\n", buffer);
snprintf(buffer, sizeof(buffer), "%s", source);
printf("%s\n", buffer);
printf("%d\n", buffer[BUFFSIZE]);
return (0);
}
to avoid truncation modular_desc should be large enough but now is 1024
bytes long and most likely big enough already (if probably too big)
Carlo
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