linux-kernel - Re: execve for script don't return ENOEXEC, bug ?

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Message-ID: <435973.80037.qm@web110306.mail.gq1.yahoo.com>
Date:	Sat, 20 Mar 2010 05:56:06 -0700 (PDT)
From:	Valery Reznic <valery_reznic@...oo.com>
To:	David Newall <davidn@...idnewall.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: execve for script don't return ENOEXEC, bug ?



--- On Sat, 3/20/10, David Newall <davidn@...idnewall.com> wrote:

> From: David Newall <davidn@...idnewall.com>
> Subject: Re: execve for script don't return ENOEXEC, bug ?
> To: "Valery Reznic" <valery_reznic@...oo.com>
> Cc: linux-kernel@...r.kernel.org
> Date: Saturday, March 20, 2010, 11:41 AM
> Valery Reznic wrote:
> > [valery@...alhost ~]$ cat a.sh #!/bin/sh
> > echo "It's a.sh"
> > [valery@...alhost ~]$ cat b.sh #! ./a.sh
> > echo "It's b.sh"
> > [valery@...alhost ~]$ [valery@...alhost ~]$ strace -f
> -e execve setarch i386 ./b.sh execve("/usr/bin/setarch",
> ["setarch", "i386", "./b.sh"], [/* 40 vars */]) = 0
> > execve("./b.sh", ["./b.sh"], [/* 40 vars */]) = 0
> > It's a.sh
> >   
> 
> That is the correct output for a script which is being
> interpreted by a.sh, when a.sh prints "It's a.sh" using
> /bin/sh as its interpreter.  Remember, you didn't ask
> /bin/sh to interpret b.sh, you asked a.sh to do it, and a.sh
> is a simple echo statement, not an interpreter.  There
> is no error here.

execve's man page state that script's interprtert should not be 
interpreter itself:
------------------------------------------------------
   Interpreter scripts
       An  interpreter  script  is  a  text  file  that has execute permission
       enabled and whose first line is of the form:

           #! interpreter [optional-arg]

       The interpreter must be a valid pathname for an executable which is not
       itself  a  script. 
------------------------------------------------------

I.e, execve should return ENOEXEC. And it did it at least in Fedora 8 and earlier.

To me it looks like  execve and it's man page disagree. Do you know is it new intended behaviour of execve and just man page wasn't update or it's a bug in execve ?

Valery.
> 


      
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