Re: [PATCH 1/2] Reinstate ftime and move define it for POSIX.1-2001 or older

[Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>]

On 21/10/2020 02:17, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> diff --git a/NEWS b/NEWS
>> index 6eb577a669..6105eb0b3e 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -37,10 +37,8 @@ Deprecated and removed features, and other changes affecting compatibility:
>>    implementations from HWCAP subdirectories are no longer loaded.
>>    Instead, the default implementation is used.
>>  
>> -* The deprecated <sys/timeb.h> header and the ftime function have been
>> -  removed.  To support old binaries, the ftime function continue to exist
>> -  as a compatibility symbol (on those architectures which had it).  All
>> -  programs should use gettimeofday or clock_gettime instead.
>> +* The deprecated ftime function is now only declared for POSIX.1-2001 or
>> +  older standard.
> 
> It is also declared for _GNU_SOURCE, so the NEWS entry is not correct.

I removed the entry.

> 
>> diff --git a/include/features.h b/include/features.h
>> index f3e62d3362..aec149ed10 100644
>> --- a/include/features.h
>> +++ b/include/features.h
>> @@ -143,6 +143,7 @@
>>  #undef	__GLIBC_USE_ISOC2X
>>  #undef	__GLIBC_USE_DEPRECATED_GETS
>>  #undef	__GLIBC_USE_DEPRECATED_SCANF
>> +#undef	__GLIBC_USE_DEPRECATED_FTIME
>>  
>>  /* Suppress kernel-name space pollution unless user expressedly asks
>>     for it.  */
>> @@ -438,6 +439,15 @@
>>  # define __GLIBC_USE_DEPRECATED_SCANF 0
>>  #endif
>>  
>> +/* The function 'ftime' appeared in Version 7 AT&T UNIX, it was marked
>> +   as LEGACY on IEEE 1003.1-2004, and removed on IEEE 1003.1-2008.  */
>> +#if (defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) <= 200112L) \
>> +    || defined _XOPEN_SOURCE_EXTENDED
>> +# define __GLIBC_USE_DEPRECATED_FTIME 1
>> +#else
>> +# define __GLIBC_USE_DEPRECATED_FTIME 0
>> +#endif
> 
> Due to the _XOPEN_SOURCE_EXTENDED part, this does not seem particularly
> useful.

Not a strong position here, I will remove since it will defined anyway
for most scenarios.

> 
>> diff --git a/time/sys/timeb.h b/time/sys/timeb.h
>> new file mode 100644
>> index 0000000000..be7b46c178
>> --- /dev/null
>> +++ b/time/sys/timeb.h
>> @@ -0,0 +1,48 @@
>> +/* Copyright (C) 1994-2020 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/>.  */
>> +
>> +#ifndef _SYS_TIMEB_H
>> +#define _SYS_TIMEB_H	1
>> +
>> +#include <features.h>
>> +
>> +#include <bits/types/time_t.h>
>> +
>> +__BEGIN_DECLS
>> +
>> +#if __GLIBC_USE (DEPRECATED_FTIME)
> 
> I'm not sure if that #if is particularly useful.  For later POSIX, this
> is a non-standard header, so there is no conformance issue.

Indeed.

> 
>> +
>> +/* Structure returned by the `ftime' function.  */
>> +
>> +struct timeb
>> +  {
>> +    time_t time;		/* Seconds since epoch, as from `time'.  */
>> +    unsigned short int millitm;	/* Additional milliseconds.  */
>> +    short int timezone;		/* Minutes west of GMT.  */
>> +    short int dstflag;		/* Nonzero if Daylight Savings Time used.  */
>> +  };
> 
> Missing __attribute_deprecated_msg__.

Ack.

> 
>> +
>> +/* Fill in TIMEBUF with information about the current time.  */
>> +
>> +extern int ftime (struct timeb *__timebuf)
>> +  __nonnull ((1)) __attribute_deprecated__;
> 
> Please use __attribute_deprecated_msg__, pointing towards clock_gettime.
> 
> Should these deprecations be disabled for older POSIX?

I think we should enforce these interface are really deprecated, and
clock_gettime is provided with _POSIX_C_SOURCE >= 199309L.

> 
> Thanks,
> Florian
>