Re: No "cannot execute binary file" for x86 binaries?

[Martin Pool <mbp@samba.org>]

On  8 Jun 2004, Matthew Wilcox <willy@debian.org> wrote:
> On Fri, Jun 04, 2004 at 01:59:19PM -0600, Bob Proulx wrote:
> > On an ia64 machine running Bdale's ia64 kernel build of linux 2.4.19
> > and bash 2.05b-2woody3:
> > 
> >   $ ./hppa/executable ; echo $?
> >   -bash: ./hppa/executable: cannot execute binary file
> >   126
> > 
> > All well and good and expected.  But the following is different:
> > 
> >   $ ./ia32/executable ; echo $?
> >   127
> > 
> > There is no message.  Shouldn't this produce a similar error to the
> > one above?  Note that I do not have an emulation layer installed.
> 
> Right, but I bet you have CONFIG_IA32_SUPPORT turned on.  So the code
> path is rather different (see fs/exec.c:search_binary_handler()).  For
> the PA code, you're getting -ENOEXEC back.  For the x86 code, this is
> a simple matter of not finding the dynamic loader / libs required for
> this executable.  I don't know why bash isn't printing an error message
> for this case -- possibly stracing might help?

strace on RHEL3 with /emul blocked off shows

  $ strace ./hello
  execve("./hello", ["./hello"], [/* 22 vars */]) = 0
  strace: exec: No such file or directory

This is the path in bash-2.05b

      /* Execve expects the command name to be in args[0].  So we
	 leave it there, in the same format that the user used to
	 type it in. */
      args = strvec_from_word_list (words, 0, 0, (int *)NULL);
      exit (shell_execve (command, args, export_env));

shell_execve ought to print a message for this case.  I am not sure
why it doesn't.  In some cases there is a useful error:

  $ sh -c ./hello
  sh: line 1: ./hello: No such file or directory
  $ echo $?
  127

but this is strange

  $ sh -x -c ./hello
  + ./hello
  $ echo $?
  127

-- 
Martin