Re: [gentoo-musl] realpath() gives wrong result on a chroot musl system

[Lei Zhang]

2016-06-07 8:19 GMT+08:00 Lei Zhang <zhanglei.april@×××××.com>:
> 2016-06-07 6:04 GMT+08:00 Felix Janda <felix.janda@××××××.de>:
>> Lei Zhang wrote:
>>> Hi,
>>>
>>> I was trying to run clang (built specifically for musl) on a chroot
>>> musl system, and met some strange issue. After some investigation, it
>>> turns out the function realpath() is giving me wrong results.
>>>
>>> I can reproduce the error with the following code snippet:
>>>
>>> #include <stdio.h>
>>> #include <stdlib.h>
>>> #include <limits.h>
>>>
>>> int main(int argc, char** argv) {
>>>     const char* path = "/usr/bin/clang"; // suppose this is a valid path
>>>     char resolved[PATH_MAX];
>>>     char* ret = realpath(path, resolved);
>>>
>>>     if (ret)
>>>         printf("%s\n", ret);
>>> }
>>>
>>> If I build it against musl, it gives correct result on my host, but
>>> wrong result on chroot; If I build it against glibc (statically, since
>>> there's no glibc on chroot), it gives correct results on both
>>> environments. So it looks like musl is to blame on the chroot
>>> environment. I haven't yet confirmed if it's a bug.
>>>
>>> Any thoughts?
>>
>> With musl, realpath() (and some other things) depend on having a
>> mounted /proc.
>
> You're right!
>
> After mounting /proc on the chroot system, the issue is resolved. At
> this point I'm really not sure if this is musl's bug. Is it legit to
> unconditionally depends on the presence of a mounted /proc?

Answer from musl's mailing list: www.openwall.com/lists/musl/2016/06/07/2


Lei