[Monetdb-developers] [PATCH] Mx Io.c more specific errors

Sjoerd Mullender sjoerd at acm.org
Thu Aug 3 14:32:21 CEST 2006

On 2006-08-03 13:57, Fabian Groffen wrote:
> On 03-08-2006 13:51:58 +0200, Stefan Manegold wrote:
>> Hi,
>> I'd stongly vote for checking your changes in --- detailed and informative
>> error messages are more than "handy" for both developers (debugging!) and
>> users --- in case there are any Windows related problems, we should find and
>> solve them, not try to avoid them.
>> I'm not sure about the error.h (it's never used (directly) in the whole
> errno.h
> it's effect can be mimicked by "extern int errno;", but that is a bit
> dirty.  It is necessary to be able to access the errno variable that at
> least all io related functions set.

No, you can't use extern int errno; instead of including errno.h.  errno
could be declared in some weird way, especially in environments that
allow multi-threaded programs, so that it *looks* like a simple int but
is in fact something else.  The C99 standard has this in a footnote:

The macro errno need not be the identifier of an object. It might expand
to a modifiable lvalue resulting from a function call (for example,

Sjoerd Mullender

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