Ian Lepore wrote: >On Sun, 2019-08-11 at 09:12 -0600, Alan Somers wrote: >> On Sun, Aug 11, 2019 at 8:57 AM Ian Lepore <i...@freebsd.org> wrote: >> > >> > On Sun, 2019-08-11 at 09:04 +0200, Gary Jennejohn wrote: >> > > On Sun, 11 Aug 2019 02:03:10 +0000 >> > > Rick Macklem <rmack...@uoguelph.ca> wrote: >> > > >> > > > Hi, >> > > > >> > > > I've noticed that, if you do a lseek(SEEK_DATA/SEEK_HOLE) on a >> > > > file >> > > > that >> > > > resides in a file system that does not support holes, ENOTTY is >> > > > returned. >> > > > >> > > > This error isn't listed for lseek() and seems a liitle weird. >> > > > >> > > >> > > ENOTTY is the standard error return for an unimplemented >> > > ioctl(2), >> > > and SEEK_HOLE ultimately becomes a call to fo_ioctl(). >> > > >> > > > I can see a couple of alternatives to this: >> > > > 1 - Return a different error. Maybe ENXIO? >> > > > or >> > > > 2 - Have lseek() do the trivial implementation when the >> > > > VOP_IOCTL() >> > > > fails. >> > > > - For SEEK_DATA, just return the offset given as argument >> > > > and >> > > > for SEEK_HOLE >> > > > return the file's size as the offset. >> > > > >> > > > What do others think? rick >> > > > ps: The man page should be updated, whatever is done w.r.t. >> > > > this. >> > > > >> > > >> > > I also vote for option 2 >> > > >> > >> > If SEEK_DATA and SEEK_HOLE don't return the standard "ioctl not >> > supported" error code and return a fake result, how are you >> > supposed to >> > determine at runtime whether SEEK_HOLE is supported or not? >> > >> > -- Ian >> >> pathconf(2) will tell you. >> > >Ahh, I wasn't aware of that. > >For option 2, lseek() has to not just return the info, but must also >actually set the file position accordingly, and has to treat offset >= >filesize as an error.
I have put a patch for this at https://reviews.freebsd.org/D21299 I listed markj@ as a reviewer, but anyone is welcome to review it, if they'd like. Since vn_bmap_seekhole() can return ENOTTY, the above patch follows that convention as well. I also have a trivial patch to map errnos not specified for lseek() to EINVAL. https://reviews.freebsd.org/D21300. Ditto above w.r.t. to reviewing it. rick _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
