Re: execve for script don't return ENOEXEC, bug ?
From: David Newall
Date: Sat Mar 20 2010 - 13:57:22 EST
Valery Reznic wrote:
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 ?
Code and man pages do sometimes disagree. I shan't address what the
correct behaviour is, because if you ask three people you're sure to get
four different answers, rather let's discuss what is desirable. Without
looking at how it works, we observe that a.sh can be executed without
error. If a.out were written in C it would qualify as an acceptable
interpreter according to the man page, so why should it not qualify if
it is interpreted? I think it's desirable that it does qualify. There
could be sound reasons why only one level of interpreter can be
invoked. Perhaps loading a script interpreter is done as an exception
in exec, and it's too ugly to allow recursive exceptions. That would be
a fair reason. But if there's no reason, then don't have the
restriction*. Linux now apparently does permit interpreted
interpreters, and I say that is the desirable result.
*Newall's second rule of programming: A program should impose no
unnecessary restriction on its user.
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