[PATCH]: Thread safe stdio with cygwin
Jeff Johnston
jjohnstn@redhat.com
Thu Jan 15 19:15:00 GMT 2004
I should have added that there is no reason not to check in your patch
which I have just done.
I can add the initialization/closing in __sbprintf().
-- Jeff J.
Jeff Johnston wrote:
> Thomas Pfaff wrote:
>
>> Jeff,
>>
>> memset makes only sure that _lock does not contain random data before
>> __lock_init_recursive. __lock_init_recursive is called later when the
>> file is really opened.
>
>
> I assumed you were worried about something accessing the file pointer
> before fopen/freopen returned the file pointer so it would then make
> sense just to initialize it earlier. Otherwise, the
> __lock_init_recursive should initialize the lock without need for
> pre-initialization.
>
>>
>> __sbprintf is a special case because it generates a fake FILE pointer
>> and its associated buf on the stack, therefore there is no need to
>> lock it fo thread safety.
>
>
> There may be no need to lock, but the VFPRINTF code attempts a lock
> and unlock anyway. It then makes sense to ensure that the lock is
> validly initialized/closed for any platform's lock implementation.
> -- Jeff J.
>
>> Thomas
>>
>> Jeff Johnston wrote:
>>
>>> Thomas,
>>>
>>> You should be using __lock_init_recursive to initialize the locks
>>> rather than zeroing them out.
>>> The code in __sbprintf should probably be closing the lock after the
>>> call to VFPRINTF as well.
>>>
>>> -- Jeff J.
>>>
>>> Thomas Pfaff wrote:
>>>
>>>> This patch adds support for thread safe stdio for Cygwin.
>>>>
>>>> Cygwin uses dynamic mutexes for locking, therefore it is
>>>> necessary to:
>>>>
>>>> 1. Initialize FILE pointers _lock properly.
>>>> 2. Destroy the lock when it is no longer needed.
>>>>
>>>> Regards,
>>>>
>>>> Thomas
>>>>
>>>> 2004-01-12 Thomas Pfaff <tpfaff@gmx.net>
>>>>
>>>> * libc/stdio/fclose.c: Include sys/lock.h.
>>>> (fclose): Destroy lock when file is closed.
>>>> * libc/stdio/findfp.c (__sfp): Initialize file pointers _lock
>>>> member.
>>>> * libc/stdio/freopen.c: Include sys/lock.h.
>>>> (_freopen_r): Destroy lock when file is closed.
>>>> * libc/stdio/vfprintf.c (__sbprintf): Initialize file pointers
>>>> _lock member.
>>>>
>>>>
>>>>
>>>
>>
>
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