On Wed, Aug 31, 2011 at 19:35, Kevin Brott <kevin.br...@gmail.com> wrote:
> On Wed, Aug 31, 2011 at 17:34, Paul Eggert <egg...@cs.ucla.edu> wrote:
>
>> On 08/31/11 07:06, Kevin Brott wrote:
>> > If we do not use fstatat then tar builds and passes almost all of the
>> checks (only the two sparse file ones fail).
>> > If we use fstatat, then almost all of the checks fail - because the
>> resulting binary is dropping zero-byte files into the archives, and doesn't
>> function.
>> >
>> > So either there is a bug or enough of a fundamental difference in the
>> way AIX 7.1's new fstatat call works, that it's not usable with the way the
>> existing GNU tar code is trying to use it.
>>
>> It semmed pretty clear there is a bug there.
>> Unfortunately, the test program does not seem to expose the bug.
>>
>> How about this test program instead? Please run it in a directory
>> where conftest.file has been created via "echo xxx >conftest.file".
>>
>> If this test program works on AIX 7.1, can you modify it in a minor
>> way so that it correctly exposes the AIX bug? There must be some
>> way to do it, since 'tar' is doing it.
>>
>> #include <fcntl.h>
>> #include <sys/stat.h>
>>
>> int
>> main (void)
>> {
>> struct stat a;
>> struct stat b;
>> int fd = open (".", O_RDONLY);
>>
>> if (fd < 0)
>> return 10;
>> if (fstatat (fd, "conftest.file", &a,
>> AT_SYMLINK_NOFOLLOW)
>> != 0)
>> return 1;
>> if (lstat ("conftest.file", &b) != 0)
>> return 2;
>> if (a.st_size != b.st_size) return 3;
>> if (a.st_dev != b.st_dev) return 4;
>> if (a.st_ino != b.st_ino) return 5;
>> if (a.st_mode != b.st_mode) return 6;
>> if (a.st_nlink != b.st_nlink) return 7;
>> if (a.st_uid != b.st_uid) return 8;
>> if (a.st_gid != b.st_gid) return 9;
>> /* Don't check time members, to avoid caching issues. */
>> return 0;
>> }
>>
>
> $ echo xxx > conftest.file
> $ cat conftest.file
> xxx
> $ xlc -o test source.c
> $ ./test ; echo $?
> 0
> $ truss -f ./test
> 12058888: execve("./test", 0x2FF22AA4, 0x200132A8) argc: 1
> 12058888: 16908635: kopen(".", O_RDONLY) = 3
> 12058888: 16908635: statxat(3, "conftest.file", 0x2FF22910, 76, 01) = 0
> 12058888: 16908635: statx("conftest.file", 0x2FF22988, 76, 01) = 0
> 12058888: 16908635: kfcntl(1, F_GETFL, 0x2FF22FFC) = 67110914
> 12058888: 16908635: kfcntl(2, F_GETFL, 0x2FF22FFC) = 67110914
> 12058888: 16908635: _exit(0)
>
> I'm going to rebuild the non-working version of tar and the mostly-working
> version and have them both create a two-file archive and truss both runs.
> Maybe someone less clueless than I will be able to see where the failure
> is.
>
>
$ dd if=/dev/urandom of=$PWD/random-file-10 bs=1024 count=10
$ dd if=/dev/urandom of=$PWD/random-file-100 bs=1024 count=100
$ ls -l
-rw-r--r-- 1 xxxxxx xxxxxxxx 10240 Aug 31 20:09 random-file-10
-rw-r--r-- 1 xxxxxx xxxxxxxx 102400 Aug 31 20:09 random-file-100
-rwxr-xr-x 1 xxxxxx xxxxxxxx 1778388 Aug 31 20:06 tar-fstatat
-rwxr-xr-x 1 xxxxxx xxxxxxxx 1779667 Aug 30 12:53 tar-nofstatat
$ truss -f ./tar-fstatat -cf test-fstatat.tar random* > fstatat.truss 2>&1
$ truss -f ./tar-nofstatat -cf test-nofstatat.tar random* > nofstatat.truss
2>&1
$ ls -l
-rw-r--r-- 1 xxxxxx xxxxxxxx 14715 Aug 31 20:14 fstatat.truss
-rw-r--r-- 1 xxxxxx xxxxxxxx 16725 Aug 31 20:14 nofstatat.truss
-rw-r--r-- 1 xxxxxx xxxxxxxx 10240 Aug 31 20:09 random-file-10
-rw-r--r-- 1 xxxxxx xxxxxxxx 102400 Aug 31 20:09 random-file-100
-rwxr-xr-x 1 xxxxxx xxxxxxxx 1778388 Aug 31 20:06 tar-fstatat
-rwxr-xr-x 1 xxxxxx xxxxxxxx 1779667 Aug 30 12:53 tar-nofstatat
-rw-r--r-- 1 xxxxxx xxxxxxxx 10240 Aug 31 20:14 test-fstatat.tar
-rw-r--r-- 1 xxxxxx xxxxxxxx 122880 Aug 31 20:14 test-nofstatat.tar
$ tar tvf test-fstatat.tar
-rw-r--r-- xxx xxx 0 Aug 31 20:09:57 2011 random-file-10
-rw-r--r-- xxx xxx 0 Aug 31 20:09:39 2011 random-file-100
$ tar tvf test-nofstatat.tar
-rw-r--r-- xxx xxx 10240 Aug 31 20:09:57 2011 random-file-10
-rw-r--r-- xxx xxx 102400 Aug 31 20:09:39 2011 random-file-100
Attached are the full truss outputs. It *looks* like a lot of extra/failed
seeks in the fstatat-enabled tar?
--
# include <stddisclaimer.h>
/* Kevin Brott <kevin.br...@gmail.com> */
fstatat.truss.gz
Description: GNU Zip compressed data
nofstatat.truss.gz
Description: GNU Zip compressed data
