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.
