Re: [ITP] libfakesu 1.0

[Christian Franke <Christian dot Franke at t-online dot de>]

D. Boland wrote:
> Hi Christian,
>
> Christian Franke wrote:
> > ...
> > BTW: All these variables except root_uid/gid are not needed as static
> > globals:
> >
> > my_uid is only used to pass the uid from uid_get/set() to get/set(e)uid().
> >
> > my_pw and str255 are only needed because su_getpwnam() calls
> > getpwnam_r() instead of getpwnam().
> I did that to avoid writing into 'external' memory. Would calling getpwnam directly
> be thread-safe?

No and this cannot be fixed because the function interface itself uses 
on a static pwd buffer as return value (and TLS is not allowed). As a 
consequence, the su_getpwnam() is also not thread safe. Calling 
thread-safe su_getpwnam_r() with a static result buffer makes the result 
thread-unsafe.

This would work without any extra buffers and is as thread-unsafe as the 
current version:

struct passwd *su_getpwnam(const char *name)
{
    struct passwd *pwd = getpwnam(name);
    if (!pwd)
        return NULL;
    if (pwd->pw_uid == root_uid)
        pwd->pw_uid = 0;
    if (pwd->pw_gid == root_gid)
        pwd->pw_gid = 0;
    return pwd;
}


Christian