[haiku-development] Re: POSIX error code

  • From: kaoutsis <kaoutsis@xxxxxx>
  • To: haiku-development@xxxxxxxxxxxxx
  • Date: Wed, 21 May 2008 21:31:23 +0300

Ingo Weinhold wrote:
On 2008-05-21 at 17:43:38 [+0200], kaoutsis <kaoutsis@xxxxxx> wrote:
Ingo Weinhold wrote:
On 2008-05-21 at 01:05:51 [+0200], kaoutsis <kaoutsis@xxxxxx> wrote:
Ingo Weinhold wrote:
Anyway, it certainly doesn't harm to try, but I have little hope that this
will have any effect. If the standard maintainers consider the request,
they are in a dilemma. Undoing the Issue 6 error codes change means that
all the applications that relied on it would become non-conforming.
I agree.
I had an idea how to tackle the problem, may be good, may be bad:
The main problem is not binary compatibility. The problem is that the Be API
requires that error codes be negative. E.g. create_sem() returns a
non-negative value (the sem_id) when successful, a negative error code
otherwise. A good deal of other functions/methods use the same strategy, and so does third party code. Making our error codes positive will break them all.

Changing concerned API functions to return -1 and set errno would be an
option, but that would be quite a bit of work and third party software would
have to be changed as well. Personally I don't even find this option very

Also, i didn't find this idea very appealing and that was the 'easy part';
i forgot the 'hard part' :-), just for the record here it is:
all the functions that returns semIds, areaIds etc, they would
check for errors like this:
area_id areaSpaceId;
areaSpaceId = create_area("AreaSpace",...

if  (areaSpaceId < B_OK) {

a) In all similar current code places, the 0 should be replaced with B_OK
b) There must be an assurance that
the valid ids should not conflict with the error codes.

If you really define B_OK to LONG_MAX, the number of valid IDs is *very* limited. :-)

It looks like, in my mind, above the LONG_MAX, there is another
set to use of  VERY_LONG_MAX :-D
Even, if you pick a smaller number, a non-null B_OK doesn't sound like that good an idea. The "no error" error code has traditionally been 0. By changing that all code relying on it will break -- the checks you mentioned above, but also the "status_t error = ...; if (error) {...}" kinds of checks, and we would need to translate the error codes for the newer POSIX APIs that directly return an error code.

Now i understood the full moto :
"_We_ making standards work, but the nightmare is _yours_" :-D

good bye,

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