NetBSD Problem Report #39574

From www@NetBSD.org  Wed Sep 17 22:23:35 2008
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Date: Wed, 17 Sep 2008 22:23:34 +0000 (UTC)
From: eravin@panix.com
Reply-To: eravin@panix.com
To: gnats-bugs@NetBSD.org
Subject: /bin/echo always exits zero even when it encounters I/O errors
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>Number:         39574
>Category:       bin
>Synopsis:       /bin/echo always exits zero even when it encounters I/O errors
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    dholland
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Sep 17 22:25:00 +0000 2008
>Closed-Date:    Wed Nov 19 05:46:12 +0000 2008
>Last-Modified:  Wed Nov 19 05:46:12 +0000 2008
>Originator:     Ed Ravin
>Release:        4.0
>Organization:
Public Access Networks Corp
>Environment:
NetBSD panix5.panix.com 4.0 NetBSD 4.0 (PANIX-XEN3U-USER) #1: Tue Apr  1 23:24:49 EDT 2008  root@juggler.panix.com:/misc2/obj/misc2/devel/netbsd/4.0/src/sys/arch/i386/compile/PANIX-XEN3U-USER i386

>Description:
We are having trouble with a shell script that loops on stdin, prompting users for information, that goes into infinite loop when the tty is revoked.

One of the problems seems to be that /bin/echo always exits with zero, even if it encounters I/O errors trying to write to stdout.  This is bad practice, and it also contravenes the documentation:

   EXIT STATUS
   The echo utility exits 0 on success, and >0 if an error occurs.


>How-To-Repeat:
Confirmed by reading src/bin/echo.c (a very short program) that the return value from printf() and putchar() is never checked and that it always exits with zero.
>Fix:

>Release-Note:

>Audit-Trail:
From: Ed Ravin <eravin@panix.com>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: bin/39574: /bin/echo always exits zero even when it encounters
	I/O errors
Date: Wed, 17 Sep 2008 22:18:53 -0400

 On Wed, Sep 17, 2008 at 10:25:00PM +0000, gnats-admin@netbsd.org wrote:
 > >Category:       bin
 > >Responsible:    bin-bug-people
 > >Synopsis:       /bin/echo always exits zero even when it encounters I/O errors
 > >Arrival-Date:   Wed Sep 17 22:25:00 +0000 2008

 This might be a patch to fix the problem:

 --- echo.c      2003-11-24 22:40:18.000000000 -0500
 +++ echoiochk.c 2008-09-17 22:17:06.000000000 -0400
 @@ -65,12 +65,13 @@
                 nflag = 0;

         while (*argv) {
 -               (void)printf("%s", *argv);
 +               if (printf("%s", *argv) < 0) exit(1);
                 if (*++argv)
 -                       (void)putchar(' ');
 +                       if (putchar(' ') == EOF) exit(1);
 +
         }
         if (nflag == 0)
 -               (void)putchar('\n');
 +               if (putchar('\n') == EOF) exit(1);
         exit(0);
         /* NOTREACHED */
  }

From: "David A. Holland" <dholland@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/39574 CVS commit: src/bin/echo
Date: Thu, 18 Sep 2008 05:42:08 +0000 (UTC)

 Module Name:	src
 Committed By:	dholland
 Date:		Thu Sep 18 05:42:08 UTC 2008

 Modified Files:
 	src/bin/echo: echo.c

 Log Message:
 Check ferror(stdout) and exit(1) if there's been a problem.
 Fixes PR bin/39574 from Ed Ravin, but with a simpler patch.


 To generate a diff of this commit:
 cvs rdiff -r1.17 -r1.18 src/bin/echo/echo.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->pending-pullups
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Thu, 18 Sep 2008 05:52:04 +0000
State-Changed-Why:
Fixed in -current. I want to make sure it doesn't make the world explode
before filing the pullup.


State-Changed-From-To: pending-pullups->analyzed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Sun, 12 Oct 2008 01:41:34 +0000
State-Changed-Why:
overoptimistic.


Responsible-Changed-From-To: bin-bug-people->dholland
Responsible-Changed-By: dholland@NetBSD.org
Responsible-Changed-When: Sun, 12 Oct 2008 01:42:17 +0000
Responsible-Changed-Why:
I've been handling it.


From: "David A. Holland" <dholland@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/39574 CVS commit: src/bin/sh
Date: Sun, 12 Oct 2008 01:40:37 +0000 (UTC)

 Module Name:	src
 Committed By:	dholland
 Date:		Sun Oct 12 01:40:37 UTC 2008

 Modified Files:
 	src/bin/sh: output.c output.h
 	src/bin/sh/bltin: bltin.h echo.c

 Log Message:
 output.c output.h: expose OUTPUT_ERR (flag for an exposed flags variable)
 bltin.h: support ferror()
 echo.c: use ferror() to fail on output write errors

 Another piece of PR bin/39574.


 To generate a diff of this commit:
 cvs rdiff -r1.29 -r1.30 src/bin/sh/output.c
 cvs rdiff -r1.18 -r1.19 src/bin/sh/output.h
 cvs rdiff -r1.12 -r1.13 src/bin/sh/bltin/bltin.h
 cvs rdiff -r1.13 -r1.14 src/bin/sh/bltin/echo.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: analyzed->pending-pullups
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Sun, 09 Nov 2008 05:06:06 +0000
State-Changed-Why:
Both changes filed as pullup-4 #1232. I think I'm not going to request
pullup to 3.x; if anyone needs it (or wants to test it) let me know.


From: Manuel Bouyer <bouyer@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/39574 CVS commit: [netbsd-4] src/bin
Date: Tue, 18 Nov 2008 22:17:04 +0000 (UTC)

 Module Name:	src
 Committed By:	bouyer
 Date:		Tue Nov 18 22:17:04 UTC 2008

 Modified Files:
 	src/bin/echo [netbsd-4]: echo.c
 	src/bin/sh [netbsd-4]: output.c output.h
 	src/bin/sh/bltin [netbsd-4]: bltin.h echo.c

 Log Message:
 Pull up following revision(s) (requested by dholland in ticket #1232):
 	bin/echo/echo.c: revision 1.18
 	bin/sh/bltin/bltin.h: revision 1.13
 	bin/sh/bltin/echo.c: revision 1.14
 	bin/sh/output.c: revision 1.30
 	bin/sh/output.h: revision 1.19
 Check ferror(stdout) and exit(1) if there's been a problem.
 Fixes PR bin/39574 from Ed Ravin, but with a simpler patch.
 output.c output.h: expose OUTPUT_ERR (flag for an exposed flags variable)
 bltin.h: support ferror()
 echo.c: use ferror() to fail on output write errors
 Another piece of PR bin/39574.


 To generate a diff of this commit:
 cvs rdiff -r1.15 -r1.15.16.1 src/bin/echo/echo.c
 cvs rdiff -r1.29 -r1.29.4.1 src/bin/sh/output.c
 cvs rdiff -r1.17 -r1.17.16.1 src/bin/sh/output.h
 cvs rdiff -r1.11 -r1.11.16.1 src/bin/sh/bltin/bltin.h
 cvs rdiff -r1.12 -r1.12.10.1 src/bin/sh/bltin/echo.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: pending-pullups->closed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Wed, 19 Nov 2008 05:46:12 +0000
State-Changed-Why:
Fixed and pulled up; thanks for reporting it.


>Unformatted:

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