On Thu, 15 Nov 2012, Eitan Adler wrote:
On 15 November 2012 10:30, Konstantin Belousov <kostik...@gmail.com> wrote:
On Thu, Nov 15, 2012 at 03:06:03PM +0000, Eitan Adler wrote:
Author: eadler
Date: Thu Nov 15 15:06:03 2012
New Revision: 243076
URL: http://svnweb.freebsd.org/changeset/base/243076
Log:
Check the range of the gid
Approved by: cperciva
MFC after: 1 week
Modified:
head/usr.sbin/chkgrp/chkgrp.c
Modified: head/usr.sbin/chkgrp/chkgrp.c
==============================================================================
--- head/usr.sbin/chkgrp/chkgrp.c Thu Nov 15 15:06:00 2012 (r243075)
+++ head/usr.sbin/chkgrp/chkgrp.c Thu Nov 15 15:06:03 2012 (r243076)
@@ -30,7 +30,10 @@
__FBSDID("$FreeBSD$");
#include <err.h>
+#include <errno.h>
#include <ctype.h>
+#include <limits.h>
+#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -150,6 +153,18 @@ main(int argc, char *argv[])
warnx("%s: line %d: GID is not numeric", gfn, n);
e++;
}
+
+ /* check the range of the group id */
+ errno = 0;
+ unsigned long groupid = strtoul(f[2], NULL, 10);
And this violates style.
I see about 5 style violations here and 5 in other lines.
The checks for strtoul failure are not exhaustive.
from the strtoul man page:
====
... In all cases, errno is set to ERANGE.
If no conversion could be performed, 0 is returned and
the global variable errno is set to EINVAL (the last feature is not por-
table across all platforms).
===
What is missing? Is there a case where strtoul fails but errno == 0 ?
strtoul("1garbage", NULL, 10) succeeds and returns value 1, but the input
is garbage.
As the man page says, the EINVAL feature is unportable. It is almost
useless, since to detect garbage after the number you have to pass an
endptr to strtoul(), and then the check for no conversion (that is,
for garbage at the beginning) is just as easy as the check for garbage
at the end.
The error handling is poor. First, warnx() is used instead of warn() so
as to not tell the user about the errno that we are depending on. Fully
correct and laborious strto*() error reporting has to use warnx() only
for the case(s) where the input is garbage but strtoul() doesn't set
errno. High quality strto*() error reporting also avoids using
strerror(errno) in other cases to get a uniform style of error messages.
The only portable other case is ERANGE for a range error. strerror(errno)
is quite good for that. However, we do another range check later and
should use the same error message for both. strerror(EINVAL) is cryptic
for garbage at the beginning of the input as well as unportable. Second,
we continue using the garbage value after detecting that it is garbage.
strtonum() and expand_number() handle some of these problems internally
but create others. For example, if you don't like the error string created
by strtonum(), then you have to parse it to see what it says in order to
write a better one. This is much more work than doing your own range
checking.
Bruce
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