Re: [gentoo-user] A question about emerge --info

["Joshua Murphy" <poisonbl@gmail.com>]

On Wed, Oct 29, 2008 at 7:51 PM, Andrey Vul <andrey.vul@gmail.com> wrote:
<snip>
>    elif system in ('Linux',):
>        # Linux based systems
>        distname,distversion,distid = dist('')
>        if distname and not terse:
>            platform = _platform(system,release,machine,processor,
>                                 'with',
>                                 distname,distversion,distid)
>        else:
>            # If the distribution name is unknown check for libc vs. glibc
>            libcname,libcversion = libc_ver(sys.executable)
>            platform = _platform(system,release,machine,processor,
>                                 'with',
>                                 libcname+libcversion)
<snip>

Hrm. I know just enough about python to get myself in trouble here...
but it looks like a python bug in magicking up the libc name and
version... but the below is WAY outside my level of practice with
python (it'll take re-reading and digging elsewhere a good few times
if I'm ever to make sense of it...

------------------
def libc_ver(executable=sys.executable,lib='',version='',

             chunksize=2048):

    """ Tries to determine the libc version that the file executable
        (which defaults to the Python interpreter) is linked against.

        Returns a tuple of strings (lib,version) which default to the
        given parameters in case the lookup fails.

        Note that the function has intimate knowledge of how different
        libc versions add symbols to the executable and thus is probably
        only useable for executables compiled using gcc.

        The file is read and scanned in chunks of chunksize bytes.

    """
    f = open(executable,'rb')
    binary = f.read(chunksize)
    pos = 0
    while 1:
        m = _libc_search.search(binary,pos)
        if not m:
            binary = f.read(chunksize)
            if not binary:
                break
            pos = 0
            continue
        libcinit,glibc,glibcversion,so,threads,soversion = m.groups()
        if libcinit and not lib:
            lib = 'libc'
        elif glibc:
            if lib != 'glibc':
                lib = 'glibc'
                version = glibcversion
            elif glibcversion > version:
                version = glibcversion
        elif so:
            if lib != 'glibc':
                lib = 'libc'
                if soversion > version:
                    version = soversion
                if threads and version[-len(threads):] != threads:
                    version = version + threads
        pos = m.end()
    f.close()
    return lib,version
------------------

It parses the header of an executable and guesses, but... the how is
too many directions from this that I'm not seeing it with my haphazard
abuse of grep. I'd presume anything that might care what platform it's
running on (underneath python itself) would be susceptible, so a word
thrown in the direction of upstream python would be the main way to
go... though it looks like emerge didn't used to use that call...

Portage 2.1.4.5 (default/linux/x86/2008.0, gcc-4.1.2, glibc-2.6.1-r0,
2.6.25-gentoo-r7-mahain i686)
=================================================================
System uname: 2.6.25-gentoo-r7-mahain i686 AMD Athlon(tm) MP 2400+

is my output, based on a call in emerge to "uname -mrp" .. not
platform.platform()

Looks like gentoo-dev aimed to drop that dependency in newer versions after all.

-- 
Poison [BLX]
Joshua M. Murphy