3 Jan
2017
3 Jan
'17
6:51 p.m.
Random832 <random832(a)fastmail.com> wrote:
In SUSv2, it did just describes the waitid() interface without mentioning that
there is a mask. People at that time seem to believe that everybody knows that
si_status is a full int.
Note that the WEXITSTATUS() macro does not apply to waitid().
Later, the wrong masking text has been added.
POSIX never introduced own inventions, but rather standardizes existing
features. The siginfo/waitid() interface has been introduced by SVr4 in 1989
and platforms that correctly implement SVr4 compliance of course all return the
full int.
Apple seem to have known that the compliance test did only check for
"more than 8 bits"
by using a 16 bit exit() value in the tests...
Jörg
--
EMail:joerg@schily.net (home) Jörg Schilling D-13353 Berlin
joerg.schilling(a)fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
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On Tue, Jan 3, 2017, at 10:08, Joerg Schilling wrote:
This has now been worded to make it obvious that masking off bits is not
permitted - except for the historic UNIX wait()/waitpid() interfaces.
Random832 <random832(a)fastmail.com> wrote:
Is there some other text you have in mind other than "The exit value in
si_status shall be equal to the full exit value (that is, the value
passed to _exit(), _Exit(), or exit(), or returned from main()); it
shall not be limited to the least significant eight bits of the value."
in the description of signal.h (not present in Issue 6 or SUSv2)? Or
maybe something from "2.13. Status Information" (whole section is new in
Issue 7). However, OSX only claims compliance to Issue 6
(unistd.h _XOPEN_VERSION
600), and the text requiring that the full 32-bit value be preserved is
new to Issue 7.
The text requiring the full 32-bit value is not new.... In SUSv2, the text of exit() states "If the
parent process of the
calling process is executing a wait(), wait3(), waitid() or waitpid(),
[...] it is notified of the calling process' termination and the
low-order eight bits (that is, bits 0377) of status are made available
to it." with no indication of any of these functions allowing the parent
process to get more bits of status. More or less the same text appears
in Issue 6, with some rearrangement due to waitid being part of the XSI
option.
SUSv2 is the standard with the correct text:
Here is a part of it's wait() description:
WEXITSTATUS(stat_val)
If the value of WIFEXITED(stat_val) is non-zero, this macro evaluates to
the low-order 8 bits of the status argument that the child process passed to
_exit() or exit(), or the value the child process returned from main().
from the signal.h description:
int si_status exit value or signal
So masking is only mentioned for wait() and waitpid()
It was
required in 1996 already, but then somebody introduced a bug into
the text and that was not aligned with the expected behavior.
Oh, so there was a bug in *the text*. That would be the text of the
standard that OSX conforms to?