Re: [PATCH v2 15/25] y2038: Use a common definition for semid_ds

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 04/06/2021 16:38, Carlos O'Donell wrote:
> On 5/18/21 4:56 PM, Adhemerval Zanella wrote:
>> Instead of replicate the same definitions from struct_semid64_ds.h
>> on the multiple struct_semid_ds.h, use a common header which is included
>> when required (struct_semid64_ds_helper.h).
>>
>> The __USE_TIME_BITS64 is not defined internally yet, although the
>> internal header is used when building the 64-bit semctl implementation.
> 
> Requesting a v3 please.
> 
> Similar to 14/25, we should add the __glibc_reserved* members to the
> structure to preserve maximum compatibility with the kernel structure.
> 
> The original struct semid_ds is 64 bytes on i686 with high-low time pairs
> and only 56 bytes in the 64-bit time_t version. With the two reserved
> members added back it's 64 bytes in both ABIs.

Ack.

> 
> We could add some static asserts if we really want to be thorough about
> the alignment of __time64_t.

I think there is no need, this would bsaically verify the expected ABI
already set by the compiler (since we do not need to actually follow
kernel expected internal layout).

> 
>> ---
>>  sysdeps/unix/sysv/linux/Makefile              |  3 ++-
>>  .../sysv/linux/bits/types/struct_semid64_ds.h |  5 +---
>>  .../bits/types/struct_semid64_ds_helper.h     | 23 +++++++++++++++++++
>>  .../sysv/linux/bits/types/struct_semid_ds.h   | 10 +++++---
>>  .../linux/hppa/bits/types/struct_semid_ds.h   |  4 ++++
>>  .../linux/mips/bits/types/struct_semid_ds.h   |  4 ++++
>>  .../powerpc/bits/types/struct_semid_ds.h      | 10 +++++---
>>  .../linux/sparc/bits/types/struct_semid_ds.h  | 10 +++++---
>>  .../linux/x86/bits/types/struct_semid_ds.h    |  4 ++++
>>  9 files changed, 59 insertions(+), 14 deletions(-)
>>  create mode 100644 sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds_helper.h
>>
>> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
>> index 193b7c46b9..b599c423ed 100644
>> --- a/sysdeps/unix/sysv/linux/Makefile
>> +++ b/sysdeps/unix/sysv/linux/Makefile
>> @@ -102,7 +102,8 @@ sysdep_headers += sys/mount.h sys/acct.h \
>>  		  bits/ipc-perm.h \
>>  		  bits/struct_stat.h \
>>  		  bits/struct_stat_time64_helper.h \
>> -		  bits/types/struct_msqid64_ds_helper.h
>> +		  bits/types/struct_msqid64_ds_helper.h \
>> +		  bits/types/struct_semid64_ds_helper.h
> 
> OK. Add helper.
> 
>>  
>>  tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
>>  	 tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
>> diff --git a/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h
>> index 7263e50bbf..adaee3eb9e 100644
>> --- a/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h
>> +++ b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds.h
>> @@ -25,9 +25,6 @@
>>  #else
>>  struct __semid64_ds
>>  {
>> -  struct ipc_perm sem_perm;		/* operation permission struct */
>> -  __time64_t sem_otime;			/* last semop() time */
>> -  __time64_t sem_ctime;			/* last time changed by semctl() */
>> -  __syscall_ulong_t sem_nsems;		/* number of semaphores in set */
>> +# include <bits/types/struct_semid64_ds_helper.h>
> 
> OK. Use helper.
> 
>>  };
>>  #endif
>> diff --git a/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds_helper.h b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds_helper.h
>> new file mode 100644
>> index 0000000000..ea60b671f1
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/bits/types/struct_semid64_ds_helper.h
>> @@ -0,0 +1,23 @@
>> +/* Common definitions for struct semid_ds with 64 bit time.
>> +   Copyright (C) 2020-2021 Free Software Foundation, Inc.
>> +   This file is part of the GNU C Library.
>> +
>> +   The GNU C Library is free software; you can redistribute it and/or
>> +   modify it under the terms of the GNU Lesser General Public
>> +   License as published by the Free Software Foundation; either
>> +   version 2.1 of the License, or (at your option) any later version.
>> +
>> +   The GNU C Library is distributed in the hope that it will be useful,
>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> +   Lesser General Public License for more details.
>> +
>> +   You should have received a copy of the GNU Lesser General Public
>> +   License along with the GNU C Library; if not, see
>> +   <https://www.gnu.org/licenses/>.  */
>> +
>> +  /* Content of internal __semid64_ds.  */
>> +  struct ipc_perm sem_perm;		/* operation permission struct */
>> +  __time64_t sem_otime;			/* last semop() time */
>> +  __time64_t sem_ctime;			/* last time changed by semctl() */
>> +  __syscall_ulong_t sem_nsems;		/* number of semaphores in set */
> 
> Definitions look good.
> 
> Needs __glibc_reserved3 and __glibc_reserved4.

Ack.