[PATCH] gdb: testsuite: fix wrong expected result in attach-pie-noexec.exp

[Tom de Vries]

On 11/23/21 4:39 AM, Tiezhu Yang wrote:
> If /proc/sys/kernel/yama/ptrace_scope is 1, when execute attach-pie-noexec.exp
> without superuser, the gdb.log shows the following info:
> 
>     (gdb) attach 6500
>     Attaching to process 6500
>     ptrace: Operation not permitted.
>     (gdb) PASS: gdb.base/attach-pie-noexec.exp: attach
> 
> It is obviously wrong, the expected result should be FAIL in such a case.
> 

Agreed, PASS is incorrect, I suppose though that UNTESTED or UNSUPPORTED
would be better than FAIL.

Anyway, looking earlier in the test-case I see:
...
if {![can_spawn_for_attach]} {
    return 0
}
...
and in gdb/testsuite/lib/gdb.exp I see:
...
# Return true if we can spawn a program on the target and attach to

# it.


proc can_spawn_for_attach { } {
...

So, is it not a more complete fix to make can_spawn_for_attach to return
false for this case?  It would have to setup a small test-case, compile
it to exec, spawn it and try to attach to it.  This is much more work
than it's currently doing, so it would have to become a
gdb_caching_proc.  For an example, look for instance at
target_supports_scheduler_locking .

Thanks,
- Tom

> With this patch:
> 
>     (gdb) attach 6600
>     Attaching to process 6600
>     ptrace: Operation not permitted.
>     (gdb) FAIL: gdb.base/attach-pie-noexec.exp: attach (please check privileges and try again)
> > When check this log info if failed, we can do the following processes
to test:
> (1) set ptrace_scope as 0
>     $ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
>     $ make check-gdb TESTS="gdb.base/attach-pie-noexec.exp"
> (2) use sudo to test
>     $ sudo make check-gdb TESTS="gdb.base/attach-pie-noexec.exp"
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  gdb/testsuite/gdb.base/attach-pie-noexec.exp | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/testsuite/gdb.base/attach-pie-noexec.exp b/gdb/testsuite/gdb.base/attach-pie-noexec.exp
> index 85161fa..c029003 100644
> --- a/gdb/testsuite/gdb.base/attach-pie-noexec.exp
> +++ b/gdb/testsuite/gdb.base/attach-pie-noexec.exp
> @@ -59,7 +59,15 @@ set testpid [spawn_id_get_pid $test_spawn_id]
>  
>  gdb_start
>  file delete -- $binfile
> -gdb_test "attach $testpid" "Attaching to process $testpid\r\n.*" "attach"
> +set test "attach"
> +gdb_test_multiple "attach $testpid" $test {
> +    -re "Attaching to process $testpid\r\n.*No executable file now.*\r\n$gdb_prompt $" {
> +	pass $test
> +    }
> +    -re "Attaching to process $testpid\r\n.*ptrace: Operation not permitted\\.\r\n$gdb_prompt $" {
> +	fail "$test (please check privileges and try again)"
> +    }
> +}
>  gdb_test "set architecture $arch" "The target architecture is set to \"$arch\"\\."
>  gdb_test "info shared" "From\[ \t\]+To\[ \t\]+Syms Read\[ \t\]+Shared Object Library\r\n0x.*"
>  
>