Ben: I think the pvfs getxattr is fashioned after the getfattr command, not the xattr command, which is probably why you are seeing this difference.
Becky On Fri, May 8, 2015 at 9:45 AM, Ben Collins <be...@servergy.com> wrote: > I’m trying to switch from using sycall/kernel-driver to direct pvfs_*() > functions. A major issue is that pvfs_getxattr() returns a length 1 byte > longer than syscalls, as shown: > > > svy@papp1:~$ sudo attr -l /srv/data/cyphre-v2/user0 > Attribute "cyphre.owner" has a 6 byte value for /srv/data/cyphre-v2/user0 > > svy@papp1:~$ sudo ./attr-test /srv/data/cyphre-v2/user0 > user.cyphre.owner is 7 bytes > > Note that 6 is the correct answer. It’s the length I set with setxattr(). > > The second program was a quick one I write using pvfs_getxattr() where as > the first one is using the attr program, so it uses getxattr() syscall > directly, and goes through the kernel driver. > > If I do something like: > > len = pvfs_getxattr(path, key, NULL, 0); > len—; // True length > buf = malloc(len); > len = pvfs_getxattr(path, key, buf, len); > > I get data that is, technically, the right length, but truncated by one > byte (last byte is ‘\0’). My assumption (without digging too deep) is that > the pvfs function adds an extra byte to null terminate the buffer, but it > definitely shouldn’t do this (keys, sure, but not values). > > Either way, this makes the pvfs wrapper incompatible with the posix > functions. > > —— > Ben Collins > Cyphre Champion > —————————————— > VP of Engineering > Servergy, Inc. > > _______________________________________________ > Pvfs2-developers mailing list > Pvfs2-developers@beowulf-underground.org > http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers > > -- Becky Ligon Research Associate Clemson University Clemson, SC
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