Re: [Bug-tar] [GNU tar 1.26] testsuite: 39 failed

[Jez Wain]

Paul you guessed correctly:

bash-4.2# touch file

bash-4.2# ln -s file symlink

bash-4.2# ./symlink-test 

bash-4.2# echo $?

1

bash-4.2# truss ./symlink-test

execve("./symlink-test", 0x2FF22CD4, 0x20013588)  argc: 1

kopenxat(-2, "symlink", O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR, 0) = 3

kfcntl(1, F_GETFL, 0x2FF22FFC)                  = 2

kfcntl(2, F_GETFL, 0x2FF22FFC)                  = 2

_exit(1)

bash-4.2# 

On 26 Jul 2012, at 18:27, Paul Eggert wrote:

On 07/26/2012 03:33 AM, Jez Wain wrote:

On the new server, which produced the erroneous result,

fcntl.h defines both O_NOFOLLOW and AT_SYMLINK_NOFOLLOW

OK, thanks, but why do you later mention
_XOPEN_SOURCE?  Is that relevant?

 _XOPEN_SOURCE is only relevant in that the O_NOFOLLOW definition depends on _XOPEN_SOURCE as being defined as > 700:

bash-4.2# grep -p O_NOFOLLOW /usr/include/fcntl.h 

#if _XOPEN_SOURCE >= 700

#define O_CLOEXEC       _FCLOEXEC       /* sets FD_CLOEXEC on open      */

#define O_NOFOLLOW      _FNOFOLLOW      /* do not follow symlinks       */

#define O_TTY_INIT      _FTTYINIT       /* sets conforming tty state    */

#endif /* _XOPEN_SOURCE >= 700 */

Recall that the O_NOFOLLOW has been introduced only in the latest version of AIX.  Early versions of AIXv7, 6, 5, and 4 don't have this definition. 

Jez

It sounds like we need to add a test for this AIX bug,
and then put a workaround into tar.  Let's start with the
test.  Suppose you compile the following test program:

 #include <fcntl.h>

 int
 main (void)
 {
   int flags = O_NOFOLLOW | O_WRONLY | O_CREAT;
   mode_t perms = S_IRUSR | S_IWUSR;
   return openat (AT_FDCWD, "symlink", flags, perms) < 0 ? 0 : 1;
 }

Put this into a.out, and then run these shell commands:

  rm -f file symlink
  touch file
  ln -s file symlink
  truss ./a.out

What does the tail end of the "truss" output say,
starting with the first mention of "symlink"?
On a working system, openat should fail and the
program should exit with status 0.  My guess is
that on AIX openat succeeds, and the program exits
with status 1.