Ben: I think those values are stored as a character string in both cases, the kernel version and our version; however, pvfs is not reporting the correct length, from a posix point of view. We will put that on our "todo" list. Thanks for bringing that to our attention, although, be aware that pvfs is not totally posix compliant and you may find other issues like this.
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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