Re: xfs mount opts (was: More better in mount(2))
hi, On Jan 5, 3:51pm, Daniel Phillips wrote: > Subject: Re: More better in mount(2) > Nathan Scott wrote: > > On Jan 5, 3:26am, Daniel Phillips wrote: > > > ... > > > This filesystem mount option parsing code is completely ad hoc, and uses > > > strtok which is horribly horribly broken. (Do man strtok and read the > > > 'Bugs' section.) > > > > > > It would be worth thinking about how to do this better. > > > > hmm ... can't claim I wrote this code, just looked at it. > > are you saying the kernel strtok is horribly broken or just > > the way its being used here? (and why?) > > >From the man page: > ... yup, I did see that. I've gone through the code and I can't see anything wrong with it (tell me if I've missed something). If the problem is simply that its using strtok, then this must just be a perceived problem rather than an actual problem (the data is copied, and noone uses it other than the parsing code, afaict). >From a look through how the other filesystems do this, it seems most use strtok (including ext2). cheers. -- Nathan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: More better in mount(2)
Daniel writes: > [re strtok for mount option parsing] > > BUGSNever use this function. If you do, note that: > This function modifies its first argument. > The identity of the delimiting character is lost. > This functions cannot be used on constant strings. > The strtok() function uses a static buffer while > parsing, so it's not thread safe. Use strtok_r() > if this matters to you. Luckily, when mount(8) is trying to mount a filesystem, it passes the mount options into the kernel each time, which does copy_from_user(), so the fact that strtok() breaks the data is OK. The only time this is bad is with Stephen's ext3 rootflags option... Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: More better in mount(2)
Nathan Scott wrote: > On Jan 5, 3:26am, Daniel Phillips wrote: > > ... > > This filesystem mount option parsing code is completely ad hoc, and uses > > strtok which is horribly horribly broken. (Do man strtok and read the > > 'Bugs' section.) > > > > It would be worth thinking about how to do this better. > > hmm ... can't claim I wrote this code, just looked at it. > are you saying the kernel strtok is horribly broken or just > the way its being used here? (and why?) >From the man page: BUGSNever use this function. If you do, note that: This function modifies its first argument. The identity of the delimiting character is lost. This functions cannot be used on constant strings. The strtok () function uses a static buffer while parsing, so it's not thread safe. Use strtok_r () if this matters to you. -- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
