[PATCH] waitpid should not crash on error

[PATCH] waitpid should not crash on error

[Nala Ginrut]

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hi guys!
I realized that "waitpid" in Guile will cause my program crash while
"waitpid" actually returned -1. I believe it's unnecessary. I think the
better way is we deal with it by ourselves if "waitpid in POSIX" returned
-1. The SCM_SYSERROR bother me a lot. I hope my program get robustness other
than crash.

Yes I can wrap my own "waipid" for my program if no one get interested in
this patch. Just a suggestion. ;-)
What you guys think?

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From 0e4b65ee6b8dfc6cfba01a9a91aa49babaa5d7c7 Mon Sep 17 00:00:00 2001
From: NalaGinrut <NalaGinrut@gmail.com>
Date: Sun, 16 Oct 2011 11:30:25 +0800
Subject: [PATCH] waitpid should return false on error

---
 libguile/posix.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/libguile/posix.c b/libguile/posix.c
index 2923dc6..5b8f849 100644
--- a/libguile/posix.c
+++ b/libguile/posix.c
@@ -731,7 +731,7 @@ SCM_DEFINE (scm_waitpid, "waitpid", 1, 1, 0,
     }
   SCM_SYSCALL (i = waitpid (scm_to_int (pid), &status, ioptions));
   if (i == -1)
-    SCM_SYSERROR;
+      return SCM_BOOL_F;
   return scm_cons (scm_from_int (i), scm_from_int (status));
 }
 #undef FUNC_NAME
-- 
1.7.0.4

Re: [PATCH] waitpid should not crash on error

[Mark H Weaver]

Nala Ginrut <nalaginrut@gmail.com> writes:
> I realized that "waitpid" in Guile will cause my program crash while
> "waitpid" actually returned -1. I believe it's unnecessary. I think
> the better way is we deal with it by ourselves if "waitpid in POSIX"
> returned -1. The SCM_SYSERROR bother me a lot. I hope my program
> get robustness other than crash. 

The proper way to deal with this is to catch the system error, e.g.:

(catch 'system-error
  (lambda () (waitpid the-pid))
  (lambda (key . args) 'waitpid-failed))

     Best,
      Mark

Re: [PATCH] waitpid should not crash on error

[Nala Ginrut]

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On Tue, Oct 18, 2011 at 1:00 AM, Mark H Weaver <mhw@netris.org> wrote:

> Nala Ginrut <nalaginrut@gmail.com> writes:
> > I realized that "waitpid" in Guile will cause my program crash while
> > "waitpid" actually returned -1. I believe it's unnecessary. I think
> > the better way is we deal with it by ourselves if "waitpid in POSIX"
> > returned -1. The SCM_SYSERROR bother me a lot. I hope my program
> > get robustness other than crash.
>
> The proper way to deal with this is to catch the system error, e.g.:
>
> (catch 'system-error
>  (lambda () (waitpid the-pid))
>  (lambda (key . args) 'waitpid-failed))
>
>     Best,
>       Mark
>

Oh thanks ,that's what I need.
But how can I find the error message like 'waitpid-failed? I can't find it
in the manual.

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Re: [PATCH] waitpid should not crash on error

[Andy Wingo]

On Tue 18 Oct 2011 04:22, Nala Ginrut <nalaginrut@gmail.com> writes:

> On Tue, Oct 18, 2011 at 1:00 AM, Mark H Weaver <mhw@netris.org> wrote:
>
>     (catch 'system-error
>      (lambda () (waitpid the-pid))
>      (lambda (key . args) 'waitpid-failed))
>
> But how can I find the error message like 'waitpid-failed? I can't
> find it in the manual. 

That's not an error message, it's the return value of the catch handler.

Andy
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