On Tue, Dec 11, 2012 at 04:07:03PM +0400, Gleb Smirnoff wrote:
> On Tue, Dec 11, 2012 at 12:21:20PM +0200, Artyom Mirgorodskiy wrote:
> A> Gleb, when I reset errno at the begin of fiboptlist_csv()
> A> everything work as expected.
> Artyom,
> can you please test attached patch?
> Index: route.c
> ===================================================================
> --- route.c (revision 244082)
> +++ route.c (working copy)
> @@ -271,8 +271,7 @@
> case 0:
> case 1:
> fib[i] = strtol(token, &endptr, 0);
> - if (*endptr != '\0' || (fib[i] == 0 &&
> - (errno == EINVAL || errno == ERANGE)))
> + if (*endptr != '\0')
> error = 1;
> break;
> default:
> @@ -336,8 +335,7 @@
> goto fiboptlist_csv_ret;
> } else {
> fib = strtol(token, &endptr, 0);
> - if (*endptr != '\0' || (fib == 0 &&
> - (errno == EINVAL || errno == ERANGE))) {
> + if (*endptr != '\0') {
> error = 1;
> goto fiboptlist_csv_ret;
> }
This patch will avoid erroneously failing but will let through certain
invalid strings. The empty string will silently be treated as 0 and
values outside the range [LONG_MIN, LONG_MAX] will be clamped silently
(the latter was already broken in most cases because [ERANGE] happens
only with a return value of LONG_MIN or LONG_MAX).
Other invalid strings that were and are let through (with unexpected
results) are ones containing a number that fits in a long but not in an
int.
To fix the range detection, errno should be set to 0 before the call and
checked afterwards; in a library function (this is an application),
errno should be saved and restored around that to avoid setting errno to
0 as a side effect of the function. The empty string needs a specific
check.
I don't insist on this being fixed but it shows that strtol() is too
hard to use correctly. The non-standard strtonum() looks easier but has
other problems (such as returning an English string in an API that
should be language-neutral).
--
Jilles Tjoelker
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