Messages in this thread | | | Date | Fri, 23 Jan 2004 13:53:44 +0000 | From | Dave Jones <> | Subject | Re: logic error in radeonfb. |
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On Fri, Jan 23, 2004 at 11:24:44AM +0000, John Levon wrote:
> > Back then someone came up with a cool one-liner that grepped for > > suspicious if's with !'s, it seems no-one ever did the same for 2.6, > > as there were a few others (see seperate mails for patches). > > Actually I did make a one-liner for 2.6, and found rather a lot (15 or > so if I remember correctly). I also went as far as hacking up something > in gcc, but it was too flaky to go in and I haven't got round to fixing > it up yet. > > Some of them were right under our noses for ages: > http://linus.bkbits.net:8080/linux-2.5/user=levon/patch@1.889.272.4?nav=!-|index.html|stats|!+|index.html|ChangeSet|cset@1.889.272.4 > If you like I can see if I can dig up the gcc patch or the one-liner.
Yep, that's where I got the idea for this (seems no-one did the same for the 2.6 tree). Here's the one-liner.. find ${1:-.} -name "*.c" -type f | xargs grep -En '![a-zA-Z0-9_ ]+(\|[^|]|\&[^&])|([^|]\||[^&]\&) *!' | grep -v SCCS
As well as the misplaced brackets, it also catches if (foo & bar) where && was probably intended (ditto | instead of ||). It does miss some cases though. Whereas this..
find ${1:-.} -name "*.c" -type f | xargs grep -En 'if[\ ]\(' | grep -v SCCS | grep \)[\ ]\[\|\&][\ ]
turns up a few more, but also a lot more false positives.
And if you think the number of bugs it turned up in the kernel is unfunny, you should see the results when you run it on a source tree of an unpacked distro. It's Un-be-lievable how common this problem is. It's not every week you get to do patches to ~80 projects in 3 days 8-)
I tried coming up with some regexps for other 'stupid errors', things like if (foo); bar
or the likes, I got 1-2 real hits out of zillions of lines of code as opposed to the few dozen misplaced brackets and '|' instead of '||'
Fun.
Dave
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