[PATCH]: Thread safe stdio with cygwin

[Jeff Johnston]

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.
>>>>
>>>>  
>>>>
>>>
>>
>