On Mon, 01 Oct 2012 13:49:28 +0200 Michal Hlavinka wrote:
> > #if _lib_posix_spawn < 2
> > if (waitpid(pid, &err, WNOHANG|WNOWAIT) == pid && EXIT_STATUS(err) ==
> > 127)
> > {
> > while (waitpid(pid, NiL, 0) == -1 && errno == EINTR);
> > if (!access(path, X_OK))
> > errno = ENOEXEC;
> > pid = -1;
> > }
> > #endif
> It will fail with EINVAL, because of WNOWAIT. This option is not
> supported in waitpid. It's supported only in waitid().
> so you'd have to use something like
> pid_t pid;
> siginfo_t err;
> if (!waitid(P_PID, pid, &err, WEXITED|WNOHANG|WNOWAIT) && err.si_status
> == 127)
thanks for pointing out the WNOWAIT misuse
alas even with the correct waitid() usage it does not solve the problem
with all posix-spawn() implementations that use exit code 127 as a catch all for
posix_spawn() related problems in the child process
in the particular case of how shell implementations *portably* determine
"binary executable" vs "shell script" (exec fails with ENOEXEC)
such posix_spawn() implementations are useless
e.g. a shell calling posix_spawn() must be able to differentiate
EAGAIN retry in case some resources become free
E2BIG diagnostic or apply xargs algorithm if appropriate
ENOEXEC either a shell script or a diagnostic
and you can't get that from exit status 127
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