#!/usr/bin/env python
#
#    revdep-pax: this file is part of the elfix package
#    Copyright (C) 2011, 2012  Anthony G. Basile
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

#
# Note: This alternative way of doing revdep-pax only
# works on Gentoo systems where NEEDED.ELF.2 all the
# information we need generated by scanelf during emerge.
#
# See /usr/lib/portage/bin/misc-functions.sh ~line 520
# echo "${arch:3};${obj};${soname};${rpath};${needed}" >> \
# "${PORTAGE_BUILDDIR}"/build-info/NEEDED.ELF.2
#

import getopt
import os
import sys
import pax
import re
import portage


def get_input(prompt):
    """ python2/3 compat input """
    if sys.hexversion > 0x03000000:
        return input(prompt)
    else:
        return raw_input(prompt)


class LinkGraph:

    def __init__(self):
        """ Put all the NEEDED.ELF.2 files for all installed packages
        into a dictionary of the form

            { pkg : line_from_NEEDED.ELF.2, ... }

        where the line has the following form:

           echo "${arch:3};${obj};${soname};${rpath};${needed}" >> \
               "${PORTAGE_BUILDDIR}"/build-info/NEEDED.ELF.2

        See /usr/lib/portage/bin/misc-functions.sh ~line 520
        """

        vardb = portage.db[portage.root]["vartree"].dbapi

        self.pkgs = []
        self.pkgs_needed = {}

        for pkg in vardb.cpv_all():
            needed = vardb.aux_get(pkg, ['NEEDED.ELF.2'])[0].strip()
            if needed:  # Some packages have no NEEDED.ELF.2
                self.pkgs.append(pkg)
                for line in re.split('\n', needed):
                    self.pkgs_needed.setdefault(pkg, []).append(re.split(';', line))

    def get_object_needed(self):
        """ Return object_needed dictionary which has structure

            {
                abi1 : { full_path_to_ELF_object : [ soname1, soname2, ... ], ... },
                abi2 : { full_path_to_ELF_object : [ soname1, soname2, ... ], ... },
                ....
            }

        Here the sonames were obtained from the ELF object by scanelf -nm
        (like readelf -d) during emerge.
        """
        object_needed = {}

        for pkg in self.pkgs:
            for link in self.pkgs_needed[pkg]:
                abi = link[0]
                elf = link[1]
                sonames = re.split(',', link[4])
                object_needed.setdefault(abi, {}).update({elf: sonames})

        return object_needed

    def get_libraries(self):
        """ Return library2soname dictionary which has structure

            { full_path_to_library : (soname, abi), ... }

        and its inverse which has structure

            { (soname, abi) : full_path_to_library, ... }
        """
        library2soname = {}
        soname2library = {}

        for pkg in self.pkgs:
            for link in self.pkgs_needed[pkg]:
                abi = link[0]
                elf = link[1]
                soname = link[2]
                if soname:  # no soname => executable
                    library2soname[elf] = (soname, abi)
                    soname2library[(soname, abi)] = elf

        return library2soname, soname2library

    def get_soname_needed(self, object_needed, library2soname):
        """ Return soname_needed dictionary which has structure:

            {
                abi1: { soname: [ soname1, soname2, ... ], .... },
                abi2: { soname: [ soname1, soname2, ... ], .... },
            }

        Here the soname1, soname2,... were obtained from soname's corresponding
        ELF object by scanelf -n during emerge.
        """
        soname_needed = {}

        for abi in object_needed:
            for elf in object_needed[abi]:
                try:
                    (soname, abi_check) = library2soname[elf]
                    # We should get the same abi associated with the soname
                    assert abi == abi_check
                    soname_needed.setdefault(abi, {}).update({soname: object_needed[abi][elf]})
                except KeyError:
                    continue  # no soname, its probably an executable

        return soname_needed

    def expand_linkings(self, object_needed, soname2library):
        """ Expands the object_needed dictionary which has structure

            {
                abi1 : { full_path_to_ELF_object : [ soname1, soname2, ... ], ... },
                abi2 : { full_path_to_ELF_object : [ soname1, soname2, ... ], ... },
                ....
            }

        such that the soname's are traced all the way to the end of
        the link chain.  Here the sonames should be the same as those
        obtained from the ELF object by ldd.
        """
        for abi in object_needed:
            for elf in object_needed[abi]:
                while True:
                    found_new_soname = False
                    # For all the first links ...
                    for so in object_needed[abi][elf]:
                        try:
                            # go to the next links ...
                            for sn in object_needed[abi][soname2library[(so, abi)]]:
                                # skip if already included ...
                                if sn in object_needed[abi][elf]:
                                    continue
                                # skip if vdso ...
                                if not (sn, abi) in soname2library:
                                    continue

                        # This appends to the object_needed and soname_needed lists.  No copy was
                        # done so its the same lists in memory for both, and its modified for both.

                                # otherwise collapse it back into
                                object_needed[abi][elf].append(sn)
                                # first links of the chain.
                                found_new_soname = True

                        except KeyError:  # Not all nodes in the chain have a next node
                            continue

                    if not found_new_soname:             # We're done, that last iteration found
                        break                            # no new nodes

    def get_object_reverse_linkings(self, object_linkings):
        """ Return object_reverse_linkings dictionary which has structure

            {
                abi1 : { soname : [ path_to_elf1, path_to_elf2, ... ], ... },
                abi2 : { soname : [ path_to_elf3, path_to_elf4, ... ], ... },
                ....
            }
        """
        object_reverse_linkings = {}

        for abi in object_linkings:
            for elf in object_linkings[abi]:
                for soname in object_linkings[abi][elf]:
                    object_reverse_linkings.setdefault(abi, {}).setdefault(soname, []).append(elf)

        return object_reverse_linkings

    def get_graph(self):
        """ Generate the full forward and reverse links using the above functions """

        # After get_object_needed() and get_soname_needed(), both object_linkings and
        # soname_linkings are only one step into the entire link chain.

        object_linkings = self.get_object_needed()
        (library2soname, soname2library) = self.get_libraries()
        soname_linkings = self.get_soname_needed(object_linkings, library2soname)

        # After the appending in expand_linkings(), forward_linkings and soname_linkings
        # have been extended through the entire chain of linking.  expand_linkings() is
        # a "side-effect" function, so we note it here.
        self.expand_linkings(soname_linkings, soname2library)
        object_reverse_linkings = self.get_object_reverse_linkings(object_linkings)

        return object_linkings, object_reverse_linkings, library2soname, soname2library


def print_problems(sonames_missing_library):
    sonames_missing_library = set(sonames_missing_library)
    print('\n**** SONAMES without any library files ****')
    for m in sonames_missing_library:
        print('\t%s' % m)


def run_forward(verbose):
    (object_linkings, object_reverse_linkings,
     library2soname, soname2library) = LinkGraph().get_graph()

    sonames_missing_library = []

    for abi in object_linkings:
        for elf in object_linkings[abi]:
            try:
                (elf_str_flags, elf_bin_flags) = pax.getflags(elf)
                sv = '%s :%s ( %s )' % (elf, abi, elf_str_flags)
            except (pax.PaxError, RuntimeError, TypeError, NameError):
                #because this is a pax error (likely), we need to set elf_str_flags
                #elf_str_flags and sv are used a few lines down
                elf_str_flags = '****'
                sv = '%s :%s ( %s )' % (elf, abi, elf_str_flags)
                continue
            s = sv

            count = 0
            for soname in object_linkings[abi][elf]:
                try:
                    library = soname2library[(soname, abi)]
                    try:
                        (library_str_flags, library_bin_flags) = pax.getflags(library)
                    except pax.PaxError:
                        library_str_flags = '****'
                    sv = '%s\n\t%s\t%s ( %s )' % (sv, soname, library, library_str_flags)
                    if elf_str_flags != library_str_flags:
                        s = '%s\n\t%s\t%s ( %s )' % (s, soname, library, library_str_flags)
                        count += 1
                except KeyError:
                    sonames_missing_library.append(soname)

            if verbose:
                print('%s\n' % sv)
                if count == 0:
                    print('\tNo mismatches\n\n')
                else:
                    print('\tMismatches\n\n')
            else:
                if count != 0:
                    print('%s\n\n' % s)

    if verbose:
        print_problems(sonames_missing_library)


def run_reverse(verbose, executable_only):
    (object_linkings, object_reverse_linkings,
     library2soname, soname2library) = LinkGraph().get_graph()

    shell_path = os.getenv('PATH').split(':')

    sonames_missing_library = []

    for abi in object_reverse_linkings:
        for soname in object_reverse_linkings[abi]:
            try:
                library = soname2library[(soname, abi)]
                try:
                    (library_str_flags, library_bin_flags) = pax.getflags(library)
                except pax.PaxError:
                    library_str_flags = '****'
            except KeyError:
                sonames_missing_library.append(soname)
                library = 'unknown_library'
                library_str_flags = '****'
            #always gets set, and dependant variables always get set, no need to
            #be in a try statement
            sv = '%s\t%s :%s ( %s )' % (soname, library, abi, library_str_flags)
            s = sv

            count = 0
            for elf in object_reverse_linkings[abi][soname]:
                try:
                    (elf_str_flags, elf_bin_flags) = pax.getflags(elf)
                except pax.PaxError:
                    elf_str_flags = '****'
                if executable_only:
                    if os.path.dirname(elf) in shell_path:
                        sv = '%s\n\t%s ( %s )' % (sv, elf, elf_str_flags)
                        if library_str_flags != elf_str_flags:
                            s = '%s\n\t%s ( %s )' % (s, elf, elf_str_flags)
                            count += 1
                else:
                    sv = '%s\n\t%s ( %s )' % (sv, elf, elf_str_flags)
                    if library_str_flags != elf_str_flags:
                        s = '%s\n\t%s ( %s )' % (s, elf, elf_str_flags)
                        count += 1

            if verbose:
                print('%s\n' % sv)
                if count == 0:
                    print('\tNo mismatches\n\n')
                else:
                    print('\tMismatches\n\n')
            else:
                if count != 0:
                    print('%s\n\n' % s)

    if verbose:
        print_problems(sonames_missing_library)


def migrate_flags(importer, exporter_str_flags, exporter_bin_flags):
    # We implement the following logic for setting the pax flags
    # on the target elf object, the IMPORTER, given that the flags
    # from the elf object we want it to match to, the EXPORTER.
    #
    #    EXPORTER    IMPORTER    RESULT
    #       On          On         On
    #       On          Off        On + Warn
    #       On          -          On
    #       Off         On         On + Warn
    #       Off         Off        Off
    #       Off         -          Off
    #       -           On         On
    #       -           Off        Off
    #       -           -          -

    #See /usr/include/elf.h for these values
    pf_flags = {
        'P': 1 << 4, 'p': 1 << 5,
        'S': 1 << 6, 's': 1 << 7,
        'M': 1 << 8, 'm': 1 << 9,
        'X': 1 << 10, 'x': 1 << 11,
        'E': 1 << 12, 'e': 1 << 13,
        'R': 1 << 14, 'r': 1 << 15
    }

    try:
        (importer_str_flags, importer_bin_flags) = pax.getflags(importer)
    except pax.PaxError:
        # The importer has no flags, so just set them
        pax.setbinflags(importer, exporter_bin_flags)
        return

    # Start with the exporter's flags
    result_bin_flags = exporter_bin_flags

    for i in range(len(importer_str_flags)):

        # The exporter's flag contradicts the importer's flag, so do nothing
        if (exporter_str_flags[i].isupper() and importer_str_flags[i].islower()) or \
           (exporter_str_flags[i].islower() and importer_str_flags[i].isupper()):

            # Revert the exporter's flag, use the importer's flag and warn
            result_bin_flags = result_bin_flags ^ pf_flags[exporter_str_flags[i]]
            result_bin_flags = result_bin_flags | pf_flags[importer_str_flags[i]]
            print('\t\tWarning: %s has %s, refusing to set to %s' % (
                importer, importer_str_flags[i], exporter_str_flags[i])),

        # The exporter's flags is off, so use the importer's flag
        if (exporter_str_flags[i] == '-') and (importer_str_flags[i] != '-'):
            result_bin_flags = result_bin_flags | pf_flags[importer_str_flags[i]]

    pax.setbinflags(importer, result_bin_flags)


def run_elf(elf, verbose, mark, allyes):
    if not os.path.exists(elf):
        print('%s\tNo such OBJECT' % elf)
        return

    try:
        (elf_str_flags, elf_bin_flags) = pax.getflags(elf)
        print('%s (%s)\n' % (elf, elf_str_flags))
    except pax.PaxError:
        print('%s: No PAX flags found\n' % elf)
        return

    (object_linkings, object_reverse_linkings,
     library2soname, soname2library) = LinkGraph().get_graph()

    mismatched_libraries = []

    for abi in object_linkings:
        if not elf in object_linkings[abi]:  # There may be no elf for that abi
            continue
        for soname in object_linkings[abi][elf]:
            try:
                library = soname2library[(soname, abi)]
                try:
                    (library_str_flags, library_bin_flags) = pax.getflags(library)
                except pax.PaxError:
                    library_str_flags = '****'
                if verbose:
                    print('\t%s\t%s :%s ( %s )' % (soname, library, abi, library_str_flags))
                if elf_str_flags != library_str_flags:
                    mismatched_libraries.append(library)
                    if not verbose:
                        print('\t%s\t%s :%s ( %s )' % (soname, library, abi, library_str_flags))
            except KeyError:
                print('%s :%s: file for soname not found' % (soname, abi))

        if len(mismatched_libraries) == 0:
            if not verbose:
                print('\tNo mismatches\n')
        else:
            print('')
            if mark:
                print('\tWill mark libraries with %s\n' % elf_str_flags)
                for library in mismatched_libraries:
                    do_marking = False
                    while True:
                        if allyes:
                            ans = 'y'
                        else:
                            ans = get_input('\tSet flags for %s :%s (y/n): ' % (library, abi))
                        if ans == 'y':
                            do_marking = True
                            break
                        elif ans == 'n':
                            do_marking = False
                            break
                        else:
                            print('\t\tPlease enter y or n')

                    if do_marking:
                        try:
                            migrate_flags(library, elf_str_flags, elf_bin_flags)
                        except pax.PaxError:
                            print('\n\tCould not set PAX flags on %s, text maybe busy' % library)

                        try:
                            (library_str_flags, library_bin_flags) = pax.getflags(library)
                            print('\n\t\t%s ( %s )\n' % (library, library_str_flags))
                        except pax.PaxError:
                            print('\n\t\t%s: Could not read PAX flags')


def run_soname(name, verbose, use_soname, mark, allyes, executable_only):
    shell_path = os.getenv('PATH').split(':')

    (object_linkings, object_reverse_linkings,
     library2soname, soname2library) = LinkGraph().get_graph()

    if use_soname:
        soname = name
        abi_list = object_reverse_linkings.keys()
        for abi in abi_list:
            # There must be at least on abi with that soname
            if soname in object_reverse_linkings[abi]:
                break
        else:
            print('%s\tNo such SONAME' % soname)
            return
    else:
        try:
            (soname, abi) = library2soname[name]
            abi_list = [abi]
        except KeyError:
            print('%s\tNo such LIBRARY' % name)
            return

    mismatched_elfs = []

    for abi in abi_list:
        # An soname can belong to one or more abis
        if not soname in object_reverse_linkings[abi]:
            continue

        library = soname2library[(soname, abi)]

        try:
            (library_str_flags, library_bin_flags) = pax.getflags(library)
            print('%s\t%s :%s (%s)\n' % (soname, library, abi, library_str_flags))
        except pax.PaxError:
            print('%s :%s : No PAX flags found\n' % (library, abi))
            continue

        for elf in object_reverse_linkings[abi][soname]:
            try:
                (elf_str_flags, elf_bin_flags) = pax.getflags(elf)
            except pax.PaxError:
                elf_str_flags = '****'
            if verbose:
                if executable_only:
                    if os.path.dirname(elf) in shell_path:
                        print('\t%s ( %s )' % (elf, elf_str_flags))
                else:
                    print('\t%s ( %s )' % (elf, elf_str_flags))
            if library_str_flags != elf_str_flags:
                if executable_only:
                    if os.path.dirname(elf) in shell_path:
                        mismatched_elfs.append(elf)
                        if not verbose:
                            print('\t%s ( %s )' % (elf, elf_str_flags))
                else:
                    mismatched_elfs.append(elf)
                    if not verbose:
                        print('\t%s ( %s )' % (elf, elf_str_flags))

        if len(mismatched_elfs) == 0:
            if not verbose:
                print('\tNo mismatches\n')
        else:
            print('')
            if mark:
                print('\tWill mark elf with %s\n' % library_str_flags)
                for elf in mismatched_elfs:
                    if executable_only:
                        if not os.path.dirname(elf) in shell_path:
                            continue
                    do_marking = False
                    while True:
                        if allyes:
                            ans = 'y'
                        else:
                            ans = get_input('\tSet flags for %s (y/n): ' % elf)
                        if ans == 'y':
                            do_marking = True
                            break
                        elif ans == 'n':
                            do_marking = False
                            break
                        else:
                            print('\t\tPlease enter y or n')
                    if do_marking:
                        try:
                            migrate_flags(elf, library_str_flags, library_bin_flags)
                        except pax.PaxError:
                            print('\n\tCould not set pax flags on %s, file is probably busy' % elf)
                            print('\tShut down all processes that use it and try again')
                        (elf_str_flags, elf_bin_flags) = pax.getflags(elf)
                        print('\n\t\t%s ( %s )\n' % (elf, elf_str_flags))


def run_usage():
    usage = '''Package Name : elfix
Bug Reports  : http://bugs.gentoo.org/
Program Name : revdep-pax
Description  : Get or set pax flags on an ELF object

Usage        : revdep-pax -f [-v]             print all forward mappings for all system ELF objects
             : revdep-pax -r [-ve]            print all reverse mappings for all system sonames
             : revdep-pax -b OBJECT  [-myv]   print all forward mappings only for OBJECT
             : revdep-pax -s SONAME  [-myve]  print all reverse mappings only for SONAME
             : revdep-pax -l LIBRARY [-myve]  print all reverse mappings only for LIBRARY file
             : revdep-pax [-h]                print this help
             : -v                             verbose, otherwise just print mismatching objects
             : -e                             only print executables in shell $PATH
             : -m                             don\'t just report, but mark the mismatching objects
             : -y                             assume "yes" to all prompts for marking (BE CAREFULL)
'''
    print(usage)


def main():
    # Are we root?
    uid = os.getuid()
    if uid != 0:
        print('This program must be run as root')
        sys.exit(1)

    try:
        opts, args = getopt.getopt(sys.argv[1:], 'hfrb:s:l:vemy')
    except getopt.GetoptError as err:
        print(str(err))  # will print something like 'option -a not recognized'
        run_usage()
        sys.exit(1)

    if len(opts) == 0:
        run_usage()
        sys.exit(1)

    do_usage = False
    do_forward = False
    do_reverse = False

    elf = None
    soname = None
    library = None

    verbose = False
    executable_only = False
    mark = False
    allyes = False

    opt_count = 0

    for o, a in opts:
        if o == '-h':
            do_usage = True
            opt_count += 1
        elif o == '-f':
            do_forward = True
            opt_count += 1
        elif o == '-r':
            do_reverse = True
            opt_count += 1
        elif o == '-b':
            elf = a
            opt_count += 1
        elif o == '-s':
            soname = a
            opt_count += 1
        elif o == '-l':
            library = a
            opt_count += 1
        elif o == '-v':
            verbose = True
        elif o == '-e':
            executable_only = True
        elif o == '-m':
            mark = True
        elif o == '-y':
            allyes = True
        else:
            print('Option included in getopt but not handled here!')
            print('Please file a bug')
            sys.exit(1)

    # Only allow one of -h, -f -r -b -s
    if opt_count > 1 or do_usage:
        run_usage()
    elif do_forward:
        run_forward(verbose)
    elif do_reverse:
        run_reverse(verbose, executable_only)
    elif elf is not None:
        run_elf(elf, verbose, mark, allyes)
    elif soname is not None:
        run_soname(soname, verbose, True, mark, allyes, executable_only)
    elif library is not None:
        library = os.path.realpath(library)
        run_soname(library, verbose, False, mark, allyes, executable_only)


if __name__ == '__main__':
    main()