#!/bin/env python
#
# compare: a tool to compare kernel config files
#
# Marc E. Fiuczynski <mef@cs.princeton.edu>
# Copyright (C) 2006 The Trustees of Princeton University
#
# $Id: kread,v 1.1 2006/12/01 16:21:13 mef Exp $
#

import sys, re, os, stat
import cStringIO, cPickle

currentconfig = ""
files = []
configs = {}
meta = None

def _config(parts,fb):
    global currentconfig
    currentconfig = parts[1]
    return None

def _help(parts,fb):
    global currentconfig
    helptxt = ""
    lineno = 0
    while True:
        line = fb.readline()
        lineno = lineno + 1
        if len(line)==0: break
        if not line[0].isspace(): break
        if len(line)>1: newline = line.lstrip()
        else: newline = line
        helptxt = helptxt+newline

    configs[currentconfig]=helptxt
    return line

def _source(parts,fb):
    filename = "".join(parts[1:])
    if filename[0]=='"' or filename[0]=='\'':
        filename=filename[1:]
    if filename[-1]=='"' or filename[-1]=='\'':
        filename=filename[:-1]
    process(filename)
    return None

def _noop(parts,fb):
    return None

keywords = {"config":_config,
            "help":_help,
            "---help---":_help,
            "source":_source}

def process(filename):
    files.append((filename,os.stat(filename)[stat.ST_MTIME])) 
    fb = open(filename)
    lineno = 0
    line = fb.readline()
    while True:
        lineno = lineno + 1
        if len(line)==0:break

        line  = line.strip()
        parts = line.split()
        if len(parts)==0:
            line = fb.readline()
        else:
            func  = keywords.get(parts[0],_noop)
            line = func(parts,fb)
            if line == None:
                line = fb.readline()

    fb.close()

def init(force):
    global configs
    global files
    ARCH=os.getenv("ARCH","i386")
    reprocess = True
    try:
        f = open(".kread.db","r")
        meta = cPickle.load(f)
        f.close()
        configs, files = meta
        reprocess = False
        try:
            for file, mtime in files:
                cur_mtime = os.stat(file)[stat.ST_MTIME]
                if mtime <> cur_mtime:
                    reprocess = True
                    break
        except:
            pass
    except IOError, e:
        pass
    if reprocess or force:
        meta = (configs, files)
        process("arch/%s/Kconfig" % ARCH)
    try:
        f = open(".kread.db.tmp","w")
        cPickle.dump(meta,f,True)
        f.close()
        os.rename(".kread.db.tmp", ".kread.db")
    except IOError, e:
        pass
            
def gethelp(option):
    if option[:len("CONFIG_")] == "CONFIG_":
        option=option[len("CONFIG_"):]
    helptxt = configs.get(option,"")
    return helptxt


if __name__ == '__main__':
    if len(sys.argv) == 1:
        print """USAGE\n%s configoptionname""" % os.path.basename(sys.argv[0])
    else:
	if sys.argv[1] == "-f" and len(sys.argv)>=2:
            force = True
            options=sys.argv[2:]
        else:
            options = sys.argv[1:]
            force = False

        init(force)
        for option in options:
            helptxt = gethelp(option)
            print "CONFIG_%s:\n%s" % (option,helptxt)