Re: [BUG]? Strange return values of close()

[Andrew J. Schorr]

Hi Arnold,

I added a test case and pushed it. I considered an alternative
patch to gawk_pclose to call sanitize_exit_status there, but
it seemed inconsistent to save struct redirect status values
in some cases pre-sanitization and other cases post-sanitization.
That being said, nothing else seems to use those saved values,
so the result should be the same either way.

By the way, in io.c:close_rp, there's a spot where it says:
                status = sanitize_exit_status(pclose(rp->output.fp));
Is it OK to call sanitize_exit_status on the value returned by pclose?
>From the pclose man page:
       The pclose() function returns -1 if wait4(2) returns an error, or  some
       other error is detected.  In the event of an error, these functions set
       errno to indicate the cause of the error.

Regards,
Andy

On Thu, Feb 10, 2022 at 01:31:48AM -0700, arnold@skeeve.com wrote:
> Jakub, thanks for the for the report.
> 
> Andy, that patch looks good, please push it to gawk-5.1-stable. You 
> may need to pull first. If you can add a test, that'd be great.
> 
> Eli Z., the code in wait_any supposedly gets the exit status properly
> for Win32; please review.
> 
> Thanks all!
> 
> Arnold
> 
> "Andrew J. Schorr" <aschorr@telemetry-investments.com> wrote:
> 
> > Hi,
> >
> > Thanks for the bug report. The problem is that the exit status of a 
> > previously
> > reaped process is not being handled properly. The attached patch seems to 
> > fix
> > the issue for me, but I'm not able to test the Mingw32 piece of it. We 
> > should
> > probably add a test case and check that it works on all platforms.
> >
> > Regards,
> > Andy
> >
> > On Wed, Feb 09, 2022 at 03:44:03PM +0100, Jakub Martisko wrote:
> > > Hello,
> > > 
> > > there seems to be some strange behaviour with the close (reproducer is
> > > attached in case the formatting gets messed). Is the RC echo=2304 expected
> > > or is this a bug? I've tested the same thing with the gawk-4.0.2 (i.e.
> > > before the change described in) and it returns 2304 in all four cases.
> > > 
> > > Thanks,
> > > Jakub
> > > 
> > > [1]:
> > > https://www.gnu.org/software/gawk/manual/html_node/Close-Files-And-Pipes.html#FOOT29
> > > 
> > > $ ls
> > > gwk_prog
> > > $ gawk -f ./gwk_prog
> > > RC Empty=9 #this is the expected value based on unzip's return values
> > > RC echo=9
> > > $ unzip -o ./test.zip 2>/dev/null; echo $?
> > > 9
> > > 
> > > $ touch ./test.zip
> > > 
> > > $ ls
> > > 
> > > gwk_prog  test.zip
> > > $ gawk -f ./gwk_prog
> > > RC Empty=9
> > > RC echo=2304 # this is 256*9 btw
> > > $ unzip -o ./test.zip 2>/dev/null; echo $?
> > > 
> > > Archive:  ./test.zip
> > > 9
> > > 
> > > $ cat gwk_prog
> > > #!/usr/bin/gawk -f
> > > 
> > > BEGIN{
> > > rc=0;
> > > 
> > > extract_file="unzip -o ./test.zip 2>/dev/null";
> > > 
> > > #Just an empty cycle - returns 9 as expected
> > > while (extract_file|getline){
> > > continue;
> > > }
> > > rc=close(extract_file);
> > > print "RC Empty="rc;
> > > 
> > > 
> > > #Non empty cycle - extract_file should return 9
> > > while (extract_file|getline){
> > > cmd="echo"
> > > cmd|getline
> > > close(cmd)
> > > }
> > > rc=close(extract_file);
> > > print "RC echo="rc;
> > > }
> >
> > > 
> > > #!/usr/bin/gawk -f
> > > 
> > > BEGIN{
> > > rc=0;
> > > 
> > > extract_file="unzip -o ./test.zip 2>/dev/null";
> > > 
> > > #Just an empty cycle - returns 9 as expected
> > > while (extract_file|getline){
> > > continue;
> > > }
> > > rc=close(extract_file);
> > > print "RC Empty="rc;
> > > 
> > > 
> > > #Non empty cycle - extract_file should return 9
> > > while (extract_file|getline){
> > >   cmd="echo"
> > >   cmd|getline
> > >   close(cmd)
> > > }
> > > rc=close(extract_file);
> > > print "RC echo="rc;
> > > 
> > > }
> 

-- 
Andrew Schorr                      e-mail: aschorr@telemetry-investments.com
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