waitpid doesn't work with WIFSTOPPED

> Quoth Emmanuel Rodriguez:
>> I'm see a strange behavior in the fonction WIFSTOPPED($?) when
>> waitpid($pid, WUNTRACED) is invoked and that the child process
>> receives a stop signal. Under this conditions one would expect that
>> WIFSTOPPED($?) would return a true value, but that's not what is
>> happening. A similar program written in C will have the same macro
>> return true instead of false under the same conditions.
>>
>> I can reproduce this with the default perl provided by Ubuntu 9.10 and
>> OS X 10.6. Which lets me guess that this is not a distro related bug.
>
> This is a documentation error.  POSIX.pod incorrectly claims that
> you can pass the value of $? to WIFEXITED and its relatives.
> You must use the raw status value from ${^CHILD_ERROR_NATIVE} instead.

And here's the patch.  Note that perlvar.pod gets it right already.

/Bo Lindbergh

diff --git a/ext/POSIX/lib/POSIX.pod b/ext/POSIX/lib/POSIX.pod
index 41bbde2..0327d05 100644 (file)
--- a/ext/POSIX/lib/POSIX.pod
+++ b/ext/POSIX/lib/POSIX.pod
@@ -2188,33 +2188,37 @@ WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG
 
 =item WIFEXITED
 
-WIFEXITED($?) returns true if the child process exited normally
-(C<exit()> or by falling off the end of C<main()>)
+WIFEXITED(${^CHILD_ERROR_NATIVE}) returns true if the child process
+exited normally (C<exit()> or by falling off the end of C<main()>)
 
 =item WEXITSTATUS
 
-WEXITSTATUS($?) returns the normal exit status of the child process
-(only meaningful if WIFEXITED($?) is true)
+WEXITSTATUS(${^CHILD_ERROR_NATIVE}) returns the normal exit status of
+the child process (only meaningful if WIFEXITED(${^CHILD_ERROR_NATIVE})
+is true)
 
 =item WIFSIGNALED
 
-WIFSIGNALED($?) returns true if the child process terminated because
-of a signal
+WIFSIGNALED(${^CHILD_ERROR_NATIVE}) returns true if the child process
+terminated because of a signal
 
 =item WTERMSIG
 
-WTERMSIG($?) returns the signal the child process terminated for
-(only meaningful if WIFSIGNALED($?) is true)
+WTERMSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child process
+terminated for (only meaningful if WIFSIGNALED(${^CHILD_ERROR_NATIVE})
+is true)
 
 =item WIFSTOPPED
 
-WIFSTOPPED($?) returns true if the child process is currently stopped
-(can happen only if you specified the WUNTRACED flag to waitpid())
+WIFSTOPPED(${^CHILD_ERROR_NATIVE}) returns true if the child process is
+currently stopped (can happen only if you specified the WUNTRACED flag
+to waitpid())
 
 =item WSTOPSIG
 
-WSTOPSIG($?) returns the signal the child process was stopped for
-(only meaningful if WIFSTOPPED($?) is true)
+WSTOPSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child process
+was stopped for (only meaningful if WIFSTOPPED(${^CHILD_ERROR_NATIVE})
+is true)
 
 =back