Date: Fri, 1 Apr 2011 15:40:24 +0400 From: Sergey Kandaurov <pluknet@freebsd.org> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-hackers@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: issue with devstat_buildmatch(3) and certain strings Message-ID: <AANLkTimGGwnAORNPzDYzMD6PoHkri3NdQHht3xyVGytO@mail.gmail.com> In-Reply-To: <AANLkTinK2u4G9m00RXUKK6C%2BBAtO7SdNNX8Er%2BY4YRNL@mail.gmail.com> References: <20110331210349.GA4112@freebsd.org> <AANLkTinK2u4G9m00RXUKK6C%2BBAtO7SdNNX8Er%2BY4YRNL@mail.gmail.com>
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On 1 April 2011 15:37, Sergey Kandaurov <pluknet@freebsd.org> wrote:
> On 1 April 2011 01:03, Alexander Best <arundel@freebsd.org> wrote:
>> hi there,
>>
>> devstat_buildmatch(3) crashes with certain strings. you can test this by
>> doing one of:
>>
>> iostat -t ","
>> iostat -t ",,"
>> iostat -t "da,"
>> iostat -t ",da,"
>> iostat -t ",da"
>> iostat -t "da,scsi,"
>> iostat -t ",da,scsi"
>> iostat -t "da,,scsi"
>
> [Someone told me, -hackers isn't appropriate for patches, Cc: -current.]
>
> The problem is devstat(3) increments num_args regardless if strsep
> returned NULL.
> I think that should work (all your tests pass):
>
> Index: lib/libdevstat/devstat.c
> ===================================================================
> --- lib/libdevstat/devstat.c (revision 220102)
> +++ lib/libdevstat/devstat.c (working copy)
> @@ -1014,11 +1014,12 @@
> * Break the (comma delimited) input string out into separate strings.
> */
> for (tempstr = tstr, num_args = 0;
> - (*tempstr = strsep(&match_str, ",")) != NULL && (num_args < 5);
> - num_args++)
> - if (**tempstr != '\0')
> + (*tempstr = strsep(&match_str, ",")) != NULL && (num_args < 5); )
> + if (**tempstr != '\0') {
> + num_args++;
> if (++tempstr >= &tstr[5])
^^^^
BTW,
this game with pointers might prevent devstat(3) from work on big-endian.
> break;
> + }
>
> /* The user gave us too many type arguments */
> if (num_args > 3) {
>
> Please review, and I will commit the patch.
--
wbr,
pluknet
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