On Mar 31 09:24, Eric Blake wrote: > On 03/31/2016 07:30 AM, Björn Stabel wrote: > > Am 31.03.2016 um 15:01 schrieb Cristian: > >> I noted that exit codes returned by CMD and other apps (msiexec) are > >> truncated to 1 byte (0 .. 255). > > This matches Linux, but not POSIX.
Why? Does bash use waitid? > >> Windows exit codes are represented using 32 bits, so is this limitation > >> intentional? > > Part intentional (we do what Linux does), and part accidental (Cygwin > handles the return status slightly different than Windows, and that > handling makes it impossible to easily preserve all 32-bits, even if > Linux were to be patched to obey POSIX). I don't quite understand this. Right now the exitcode value is truncated to 8 bits to fit into the 32 bit status value as defined for wait/waitpid, but this is not set in stone. We could change the communication between parent and child to allow preserving the full 32 bit value for waitid. But... > > POSIX specifies that the lower 8 bits of the exit status be made > > available to the caller of wait/waitpid: > > http://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html > > Correct: wait() and waitpid() can only return 8 bits; but POSIX states > that waitid() MUST be able to access all 32-bits untruncated; this is > where Linux gets it wrong (Linux truncates during exit(), so waitid() > can only return 8 bits; other operating systems do NOT truncate during > exit, but preserve all 32 bits; if you use wait() or waitpid() you only > get 8 bits, but if you use waitid() you can see the full 32 bits). ...that only makes sense if we implement waitid at all. SHTDI and all that... Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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