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Message-ID: <CACBMf31KTTcdfn4XExe=QxtW+8RQ396sMy3q4Etg09mnvn48EQ@mail.gmail.com>
Date: Wed, 17 May 2017 11:16:51 -0500
From: John Regan <saxindustries@...il.com>
To: musl@...ts.openwall.com
Subject: Re: Question about setting argv[0] when manually using dynamic linker
On Wed, May 17, 2017 at 11:07 AM, mzpqnxow <musl@...qnxow.com> wrote:
> BTW, the shell built-in "exec" has -a which can be used to set argv[0]
>
> Again though, I'm not entire sure I understand your use, so ignore this if
> it's irrelevant :>
>
> On Wed, May 17, 2017 at 07:00 mzpqnxow <musl@...qnxow.com> wrote:
>
>> Is there any reason you want to avoid simply statically linking the
>> program(s) so that it needs no libc or other shared objects at all?
>>
>> Or did I misunderstand what you're trying to do?
>>
>> On Wed, May 17, 2017 at 05:05 <u-uy74@...ey.se> wrote:
>>
>>> On Tue, May 16, 2017 at 08:38:56PM -0400, John Regan wrote:
>>> > Hi there - I was wondering if it's possible to somehow set argv[0] when
>>> > calling the dynamic linker to load a program.
>>> ...
>>> > I'd like to retain whatever was actually typed on the command line (in
>>> this
>>> > case, set argv[0] to "app"), since many apps look at argv[0] to change
>>> > behavior, ie - gzip vs gunzip.
>>> >
>>> > I tried seeing if there was some switch I could pass to the linker,
>>> etc -
>>> > as far as I can tell, there's no easy way to do this.
>>>
>>> Set argv[0] to whatever you need when you exec*() the dynamic loader,
>>> which is straightforward with a binary wrapper (not with a shell).
>>>
>>> A binary wrapper also adds less overhead then going through a shell.
>>>
>>> There is imho hardly any incentive to put such functionalty into the
>>> loader. I say this even though we are dependent here on such tricks,
>>> to work around programs which insist on guessing things when not asked
>>> to.
>>>
>>> Regards,
>>> Rune
>>>
>>>
Well, if I statically link I'm unable to dynamically load modules (at least
I'm pretty sure that's the case). There's some cases where that might be
useful.
Right now, I'm really just trying to see "is this doable?". It'd be
interesting to be able to distribute a program with its own libc,
libraries, etc, and still have the ability to dynamically load modules.
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