[RFC] Remove EXIT_UNSUPPORTED in stdlib/test-bz22786 if path is NULL

[Stefan Liebler]

On 4/27/26 15:19, Adhemerval Zanella Netto wrote:
> 
> 
> On 23/04/26 09:43, Stefan Liebler wrote:
>> With commit 6c3a8a9d868a8deddf0d6dcc785b6d120de90523 (2018-08-25), the test
>> used xmalloc instead of malloc and therefore removed the path == NULL check
>> as xmalloc is printing an error message and exit with a fail in this case.
>>
>> On s390-32 this was always a FAIL instead of UNSUPPORTED, thus the previous
>> behaviour was re-enabled with commit 3bad2358d67d371497079bba4f8eca9c0096f4e2
>> five days later on 2018-08-30. Therefore, we don't know if this also happens
>> on other systems.
>>
>> While removing s390-32 with commit b01debcd8f5229860b3224ea135b1b8456281cee
>> I've adjusted the comment and Adhemerval asked whether this can also happen
>> on other systems with little physical memory.  We've decided to remove the
>> EXIT_UNSUPPORTED in this extra commit instead of the large s390-32 removal one.
>> See libc-alpha:
>> https://inbox.sourceware.org/libc-alpha/20260409085102.3475867-1-stli@linux.ibm.com/T/#m28b5375bef4cfb10729b93c7e658b91a14b07b85
>>
>> If this change leads to test fails somewhere, please add a comment about your
>> used system and revert this commit.
>>
>> Nowadays path is allocated with support_blob_repeat_allocate which returns
>> an empty struct in case of malloc/mmap is not able to allocate enough memory.
>> All other tests using support_blob_repeat_allocate
>> (stdlib/tst-strtod-overflow.c, support/tst-support_blob_repeat.c and
>> string/tst-memmove-overflow.c) are properly checking the start or size field
>> directly or indirectly via TEST_COMPARE_BLOB.
>> While the test support/tst-support_blob_repeat.c just prints a warning if
>> allocating the large mappings is not possible, the other tests exit with
>> UNSUPPORTED.
>>
>> At least for the realpath-part, the commit
>> 855a67c3cc81be4fc806c66e3e01b53e352a4e9f introduced support_accept_oom handling.
>> According to the discussion:
>> https://inbox.sourceware.org/libc-alpha/8a1fd5b2-5118-498e-babf-e46c0e6d1cdf@redhat.com/
>> Agreed, test-bz22786 can use a lot of memory.
>> OK. These convert OOM to UNSUPPORTED for the test if there isn't enough memory.
>>
>> In case of not enough memory while allocating path, this change would lead to a
>> segmentation fault instead of UNSUPPORTED. As this is inconsistent compared to
>> the second realpath-part and also to the other tests using
>> support_blob_repeat_allocate, I would prefer keeping UNSUPPORTED if path is NULL.
>> Nevertheless, I've posted this patch for discussion as promised while reviewing
>> the s390-32 removal patch.
> 
> LGTM, thanks.  I think I haven't seem any failure besides s390.
> 
> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 
Okay. Thanks. I've just committed the patch.

Bye,
Stefan
>> ---
>>  stdlib/test-bz22786.c | 7 -------
>>  1 file changed, 7 deletions(-)
>>
>> diff --git a/stdlib/test-bz22786.c b/stdlib/test-bz22786.c
>> index 6e2636d896..494fc2adc7 100644
>> --- a/stdlib/test-bz22786.c
>> +++ b/stdlib/test-bz22786.c
>> @@ -43,13 +43,6 @@ do_test (void)
>>    struct support_blob_repeat repeat
>>      = support_blob_repeat_allocate ("a", 1, path_len);
>>    char *path = repeat.start;
>> -  if (path == NULL)
>> -    {
>> -      printf ("Repeated allocation (%zu bytes): %m\n", path_len);
>> -      /* On systems with little physical memory the test will
>> -	 fail and should be unsupported.  */
>> -      return EXIT_UNSUPPORTED;
>> -    }
>>  
>>    TEST_VERIFY_EXIT (symlink (".", lnk) == 0);
>>  
>