GNU bug report logs - #18065
guile hangs if strerror is called with invalid (non-int) argument

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Glenn Michaels" <gmichaels <at> Safe-mail.net>
To: bug-guile <at> gnu.org
Subject: guile hangs if strerror is called with invalid (non-int) argument
Date: Sun, 20 Jul 2014 11:25:11 -0400

Calling strerror with a non-integer argument causes guile to hang.
e.g.:

(strerror 1.5)

It's a locking issue, which is solved by the following trivial patch:

--- a/libguile/error.c
+++ b/libguile/error.c
@@ -121,10 +121,12 @@ SCM_DEFINE (scm_strerror, "strerror", 1, 0, 0,
 #define FUNC_NAME s_scm_strerror
 {
   SCM ret;
+  int errnum;
   scm_dynwind_begin (0);
+  errnum = scm_to_int (err);
   scm_i_dynwind_pthread_mutex_lock (&scm_i_misc_mutex);
 
-  ret = scm_from_locale_string (strerror (scm_to_int (err)));
+  ret = scm_from_locale_string (strerror (errnum));
 
   scm_dynwind_end ();
   return ret;

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ian Price <ianprice90 <at> googlemail.com>
To: bug-guile <at> gnu.org
Cc: 18065 <at> debbugs.gnu.org
Subject: Re: bug#18065: guile hangs if strerror is called with invalid
 (non-int) argument
Date: Fri, 01 Aug 2014 20:47:02 +0100

Your patch does solve this issue, but I'm not 100% why the problem
occurs in the first place, as the lock should have been unlocked when
the throw occurred.

If I catch the wrong type error explicitly, then there is no problem.

scheme@(guile-user)> (catch #t (lambda () (strerror 1.5)) list)
$1 = (wrong-type-arg #f "Wrong type (expecting ~A): ~S" ("exact integer" 1.5) (1.5))

My thinking is that the a pre-unwind handler in the repl tries to lock
the same mutex, but I haven't looked into this deeply enough.

-- 
Ian Price -- shift-reset.com

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"

Message #16 received at 18065-done <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: "Glenn Michaels" <gmichaels <at> Safe-mail.net>
Cc: 18065-done <at> debbugs.gnu.org
Subject: Re: bug#18065: guile hangs if strerror is called with invalid
 (non-int) argument
Date: Wed, 12 Nov 2014 01:05:53 -0500

Fixed in fda17c20a3d088fccab1671c8881bd217d83d5f6 on the stable-2.0
branch, which will become Guile 2.0.12.

     Thanks,
       Mark

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