# Authors: Karl MacMillan <kmacmillan@mentalrootkit.com>
#
# Copyright (C) 2006 Red Hat 
# see file 'COPYING' for use and warranty information
#
# 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; version 2 only
#
# 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#

"""
Utilities for dealing with the compilation of modules and creation
of module tress.
"""

import defaults

import selinux

import re
import tempfile
import commands
import os
import os.path
import subprocess
import shutil

def is_valid_name(modname):
    """Check that a module name is valid.
    """
    m = re.findall("[^a-zA-Z0-9_\-\.]", modname)
    if len(m) == 0 and modname[0].isalpha():
        return True
    else:
        return False

class ModuleTree:
    def __init__(self, modname):
        self.modname = modname
        self.dirname = None

    def dir_name(self):
        return self.dirname

    def te_name(self):
        return self.dirname + "/" + self.modname + ".te"

    def fc_name(self):
        return self.dirname + "/" + self.modname + ".fc"

    def if_name(self):
        return self.dirname + "/" + self.modname + ".if"

    def package_name(self):
        return self.dirname + "/" + self.modname + ".pp"

    def makefile_name(self):
        return self.dirname + "/Makefile"

    def create(self, parent_dirname, makefile_include=None):
        self.dirname = parent_dirname + "/" + self.modname
        os.mkdir(self.dirname)
        fd = open(self.makefile_name(), "w")
        if makefile_include:
            fd.write("include " + makefile_include)
        else:
            fd.write("include " + defaults.refpolicy_makefile())
        fd.close()

        # Create empty files for the standard refpolicy
        # module files
        open(self.te_name(), "w").close()
        open(self.fc_name(), "w").close()
        open(self.if_name(), "w").close()

def modname_from_sourcename(sourcename):
    return os.path.splitext(os.path.split(sourcename)[1])[0]

class ModuleCompiler:
    """ModuleCompiler eases running of the module compiler.

    The ModuleCompiler class encapsulates running the commandline
    module compiler (checkmodule) and module packager (semodule_package).
    You are likely interested in the create_module_package method.
    
    Several options are controlled via paramaters (only effects the 
    non-refpol builds):
    
     .mls          [boolean] Generate an MLS module (by passed -M to
                   checkmodule). True to generate an MLS module, false
                   otherwise.
                   
     .module       [boolean] Generate a module instead of a base module.
                   True to generate a module, false to generate a base.
                   
     .checkmodule  [string] Fully qualified path to the module compiler.
                   Default is /usr/bin/checkmodule.
                   
     .semodule_package [string] Fully qualified path to the module
                   packager. Defaults to /usr/bin/semodule_package.
     .output       [file object] File object used to write verbose
                   output of the compililation and packaging process.
    """
    def __init__(self, output=None):
        """Create a ModuleCompiler instance, optionally with an
        output file object for verbose output of the compilation process.
        """
        self.mls = selinux.is_selinux_mls_enabled()
        self.module = True
        self.checkmodule = "/usr/bin/checkmodule"
        self.semodule_package = "/usr/bin/semodule_package"
        self.output = output
        self.last_output = ""
        self.refpol_makefile = defaults.refpolicy_makefile()
        self.make = "/usr/bin/make"

    def o(self, str):
        if self.output:
            self.output.write(str + "\n")
        self.last_output = str

    def run(self, command):
        self.o(command)
        rc, output = commands.getstatusoutput(command)
        self.o(output)
        
        return rc
    
    def gen_filenames(self, sourcename):
        """Generate the module and policy package filenames from
        a source file name. The source file must be in the form
        of "foo.te". This will generate "foo.mod" and "foo.pp".
        
        Returns a tuple with (modname, policypackage).
        """
        splitname = sourcename.split(".")
        if len(splitname) < 2:
            raise RuntimeError("invalid sourcefile name %s (must end in .te)", sourcename)
        # Handle other periods in the filename correctly
        basename = ".".join(splitname[0:-1])
        modname = basename + ".mod"
        packagename = basename + ".pp"
        
        return (modname, packagename)

    def create_module_package(self, sourcename, refpolicy=True):
        """Create a module package saved in a packagename from a
        sourcename.

        The create_module_package creates a module package saved in a
        file named sourcename (.pp is the standard extension) from a
        source file (.te is the standard extension). The source file
        should contain SELinux policy statements appropriate for a
        base or non-base module (depending on the setting of .module).

        Only file names are accepted, not open file objects or
        descriptors because the command line SELinux tools are used.

        On error a RuntimeError will be raised with a descriptive
        error message.
        """
        if refpolicy:
            self.refpol_build(sourcename)
        else:
            modname, packagename = self.gen_filenames(sourcename)
            self.compile(sourcename, modname)
            self.package(modname, packagename)
            os.unlink(modname)
            
    def refpol_build(self, sourcename):
        # Compile
        command = self.make + " -f " + self.refpol_makefile
        rc = self.run(command)

        # Raise an error if the process failed
        if rc != 0:
            raise RuntimeError("compilation failed:\n%s" % self.last_output)
        
    def compile(self, sourcename, modname):
        s = [self.checkmodule]
        if self.mls:
            s.append("-M")
        if self.module:
            s.append("-m")
        s.append("-o")
        s.append(modname)
        s.append(sourcename)

        rc = self.run(" ".join(s))
        if rc != 0:
            raise RuntimeError("compilation failed:\n%s" % self.last_output)

    def package(self, modname, packagename):
        s = [self.semodule_package]
        s.append("-o")
        s.append(packagename)
        s.append("-m")
        s.append(modname)
        
        rc = self.run(" ".join(s))
        if rc != 0:
            raise RuntimeError("packaging failed [%s]" % self.last_output)