[bug-gawk] GNU Libc2.27 and stdio streams

[Nelson H. F. Beebe]

A posting on the address@hidden list a few minutes ago reported:

>> ...
>> As Gnu libc 2.27 comes online, keep aware that [it] no longer attempts
>> to flush stdio streams on abort.  I wonder if this `might' affect
>> Guile error messages that occur at abort.
>> ...

There have been several recent discussions on the bug-gawk list about
the abort() call, so that heads-up might require a small defensive
coding response.

I suppose that some might view an abort() call mean to "get me out of
here, NOW!  and I don't care how you do, just DO IT".

On the other hand, output buffer flushing is likely usually harmless,
and reduces user surprise.  Perhaps the glibc developer list should be
consulted to understand why they made that change.

I checked my copy of POSIX (the IEEE Std 1003.1-2001 version), and
found little mention of abort(), and nothing on its desired behavior.

Here is what a 2007 draft of the ISO C Standard (ISO/IEC 9899:TC3)
says:

>> ...
>>     7.20.4.1 The abort function
>>     Synopsis
>> 1          #include <stdlib.h>
>>            void abort(void);
>>     Description
>> 2   The abort function causes abnormal program termination to occur, unless 
>> the signal
>>     SIGABRT is being caught and the signal handler does not return. Whether 
>> open streams
>>     with unwritten buffered data are flushed, open streams are closed, or 
>> temporary files are
>>     removed is implementation-defined. An implementation-defined form of the 
>> status
>>     unsuccessful termination is returned to the host environment by means of 
>> the function
>>     call raise(SIGABRT).
>>     Returns
>> 3   The abort function does not return to its caller.
>> ...

Thus, the glibc changes are standard conforming in this area.

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