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

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Date:	Fri, 19 Mar 2010 23:42:41 -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, 2:37 AM
> On Thu, 11 Mar 2010 02:56:16 -0800
> (PST) Valery Reznic <valery_reznic@...oo.com>
> wrote:
> > Hi,
> > 
> > I Have following to scripts:
> > 
> > a.sh
> > #!/bin/sh
> > echo "It's a.sh
> > 
> > and b.sh:
> > #! ./b.sh
> > echo "It's b.sh"
> >   
> [...]
> > When I run same scripts on Fedora 12 x86_64 box with
> stock kernel 2.6.31.5-127.fc12.x86_64 I got following:
> > 
> > strace -f -e execve setarch i386  ./b.sh
> execve("/usr/bin/setarch", ["setarch", "i386", "./b.sh"],
> [/* 41 vars */]) = 0
> > execve("./b.sh", ["./b.sh"], [/* 41 vars */]) = 0
> > It's a.sh
> 
> I see no circumstance which would make b.sh invoke a.sh
> (and thus emit "It's a.sh"). Are you sure these are the
> actual scripts and output?

Of course you are right. Somehow I messed up b.sh
(OK, this file is so long and complicated, so no wonder :)
Anyway my bad, sorry.

In the b.sh interpreter should be ./a.sh

Another attempt to provide correct data:

[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
[valery@...alhost ~]$ 




> 
> On the other hand, if the output was "It's b.sh", this is
> compatible with many historical versions of UNIX, which
> assumed /bin/sh to be the script interpreter. On
> 2.6.28-16-generic #55-Ubuntu SMP i686 GNU/Linux I get
> successful output for the following variants of "x.sh":
> 
> :
> echo worked
> 
> and
> 
> #!
> echo worked
> 
> and
> 
> #! ./x.sh
> echo worked
My problem is not incorrect output, but successful execve, when script's interpreter is interpreter itself.

Somewhere between Fedora 8 and Fedora 12 execve's behaviour changed.

@Andrew:
When b.sh has interpreter ./b.sh I got expected ENOEXEC, same as you.

Regards,
Valery.

> 


      
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