Vaclav Petras wrote:
> how should the C module check if the subprocess succeeded, i.e. what is
> subprocess return code.
>
> I just committed fix for r.mode (1) and before the fix, r.mode was
> pretending that everything is all right although it was not (r.reclass
> failed and printed help). Now the r.reclass does not fail and r.mode works,
> however there is still the check of return code missing.
>
> So, the question is, how to deal with the failed subprocess when using
> G_popen_write and G_popen_close function as in case of r.mode.
> Unfortunately, ./lib/gis/popen.c does not contain any documentation, so
> that's why I'm asking.
Currently, that isn't possible.
Consider replacing G_popen_close() with:
int G_popen_close(struct Popen *state)
{
if (state->fp)
fclose(state->fp);
if (state->pid == -1)
return -1;
return G_wait(state->pid);
}
But bear in mind that the same issue applies to r.rescale, r.mode,
r.statistics, r.coin and the functions in lib/gis/pager.c.
An alternative would be for G_popen_close() to raise a fatal error if
the child process terminates with a non-zero exit status or on a
signal.
FWIW, the Unix pclose() function returns -1 and sets errno in the
event of an error.
Also G_wait (in spawn.c) probably needs:
else if (WIFSIGNALED(status))
- return WTERMSIG(status);
+ return -WTERMSIG(status);
Currently, there's no way to distinguish between an exit status and a
signal.
--
Glynn Clements <[email protected]>
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