tools/moveconfig.py

#!/usr/bin/env python2
#
# Author: Masahiro Yamada <yamada.masahiro@socionext.com>
#
# SPDX-License-Identifier:	GPL-2.0+
#

"""
Move config options from headers to defconfig files.

Since Kconfig was introduced to U-Boot, we have worked on moving
config options from headers to Kconfig (defconfig).

This tool intends to help this tremendous work.


Usage
-----

First, you must edit the Kconfig to add the menu entries for the configs
you are moving.

And then run this tool giving CONFIG names you want to move.
For example, if you want to move CONFIG_CMD_USB and CONFIG_SYS_TEXT_BASE,
simply type as follows:

  $ tools/moveconfig.py CONFIG_CMD_USB CONFIG_SYS_TEXT_BASE

The tool walks through all the defconfig files and move the given CONFIGs.

The log is also displayed on the terminal.

The log is printed for each defconfig as follows:

<defconfig_name>
    <action1>
    <action2>
    <action3>
    ...

<defconfig_name> is the name of the defconfig.

<action*> shows what the tool did for that defconfig.
It looks like one of the following:

 - Move 'CONFIG_... '
   This config option was moved to the defconfig

 - CONFIG_... is not defined in Kconfig.  Do nothing.
   The entry for this CONFIG was not found in Kconfig.  The option is not
   defined in the config header, either.  So, this case can be just skipped.

 - CONFIG_... is not defined in Kconfig (suspicious).  Do nothing.
   This option is defined in the config header, but its entry was not found
   in Kconfig.
   There are two common cases:
     - You forgot to create an entry for the CONFIG before running
       this tool, or made a typo in a CONFIG passed to this tool.
     - The entry was hidden due to unmet 'depends on'.
   The tool does not know if the result is reasonable, so please check it
   manually.

 - 'CONFIG_...' is the same as the define in Kconfig.  Do nothing.
   The define in the config header matched the one in Kconfig.
   We do not need to touch it.

 - Compiler is missing.  Do nothing.
   The compiler specified for this architecture was not found
   in your PATH environment.
   (If -e option is passed, the tool exits immediately.)

 - Failed to process.
   An error occurred during processing this defconfig.  Skipped.
   (If -e option is passed, the tool exits immediately on error.)

Finally, you will be asked, Clean up headers? [y/n]:

If you say 'y' here, the unnecessary config defines are removed
from the config headers (include/configs/*.h).
It just uses the regex method, so you should not rely on it.
Just in case, please do 'git diff' to see what happened.


How does it work?
-----------------

This tool runs configuration and builds include/autoconf.mk for every
defconfig.  The config options defined in Kconfig appear in the .config
file (unless they are hidden because of unmet dependency.)
On the other hand, the config options defined by board headers are seen
in include/autoconf.mk.  The tool looks for the specified options in both
of them to decide the appropriate action for the options.  If the given
config option is found in the .config, but its value does not match the
one from the board header, the config option in the .config is replaced
with the define in the board header.  Then, the .config is synced by
"make savedefconfig" and the defconfig is updated with it.

For faster processing, this tool handles multi-threading.  It creates
separate build directories where the out-of-tree build is run.  The
temporary build directories are automatically created and deleted as
needed.  The number of threads are chosen based on the number of the CPU
cores of your system although you can change it via -j (--jobs) option.


Toolchains
----------

Appropriate toolchain are necessary to generate include/autoconf.mk
for all the architectures supported by U-Boot.  Most of them are available
at the kernel.org site, some are not provided by kernel.org.

The default per-arch CROSS_COMPILE used by this tool is specified by
the list below, CROSS_COMPILE.  You may wish to update the list to
use your own.  Instead of modifying the list directly, you can give
them via environments.


Available options
-----------------

 -c, --color
   Surround each portion of the log with escape sequences to display it
   in color on the terminal.

 -d, --defconfigs
  Specify a file containing a list of defconfigs to move

 -n, --dry-run
   Perform a trial run that does not make any changes.  It is useful to
   see what is going to happen before one actually runs it.

 -e, --exit-on-error
   Exit immediately if Make exits with a non-zero status while processing
   a defconfig file.

 -s, --force-sync
   Do "make savedefconfig" forcibly for all the defconfig files.
   If not specified, "make savedefconfig" only occurs for cases
   where at least one CONFIG was moved.

 -H, --headers-only
   Only cleanup the headers; skip the defconfig processing

 -j, --jobs
   Specify the number of threads to run simultaneously.  If not specified,
   the number of threads is the same as the number of CPU cores.

 -r, --git-ref
   Specify the git ref to clone for building the autoconf.mk. If unspecified
   use the CWD. This is useful for when changes to the Kconfig affect the
   default values and you want to capture the state of the defconfig from
   before that change was in effect. If in doubt, specify a ref pre-Kconfig
   changes (use HEAD if Kconfig changes are not committed). Worst case it will
   take a bit longer to run, but will always do the right thing.

 -v, --verbose
   Show any build errors as boards are built

To see the complete list of supported options, run

  $ tools/moveconfig.py -h

"""

import copy
import difflib
import filecmp
import fnmatch
import multiprocessing
import optparse
import os
import re
import shutil
import subprocess
import sys
import tempfile
import time

SHOW_GNU_MAKE = 'scripts/show-gnu-make'
SLEEP_TIME=0.03

# Here is the list of cross-tools I use.
# Most of them are available at kernel.org
# (https://www.kernel.org/pub/tools/crosstool/files/bin/), except the following:
# arc: https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/releases
# blackfin: http://sourceforge.net/projects/adi-toolchain/files/
# nds32: http://osdk.andestech.com/packages/nds32le-linux-glibc-v1.tgz
# nios2: https://sourcery.mentor.com/GNUToolchain/subscription42545
# sh: http://sourcery.mentor.com/public/gnu_toolchain/sh-linux-gnu
#
# openrisc kernel.org toolchain is out of date, download latest one from
# http://opencores.org/or1k/OpenRISC_GNU_tool_chain#Prebuilt_versions
CROSS_COMPILE = {
    'arc': 'arc-linux-',
    'aarch64': 'aarch64-linux-',
    'arm': 'arm-unknown-linux-gnueabi-',
    'avr32': 'avr32-linux-',
    'blackfin': 'bfin-elf-',
    'm68k': 'm68k-linux-',
    'microblaze': 'microblaze-linux-',
    'mips': 'mips-linux-',
    'nds32': 'nds32le-linux-',
    'nios2': 'nios2-linux-gnu-',
    'openrisc': 'or1k-elf-',
    'powerpc': 'powerpc-linux-',
    'sh': 'sh-linux-gnu-',
    'sparc': 'sparc-linux-',
    'x86': 'i386-linux-',
    'xtensa': 'xtensa-linux-'
}

STATE_IDLE = 0
STATE_DEFCONFIG = 1
STATE_AUTOCONF = 2
STATE_SAVEDEFCONFIG = 3

ACTION_MOVE = 0
ACTION_NO_ENTRY = 1
ACTION_NO_ENTRY_WARN = 2
ACTION_NO_CHANGE = 3

COLOR_BLACK        = '0;30'
COLOR_RED          = '0;31'
COLOR_GREEN        = '0;32'
COLOR_BROWN        = '0;33'
COLOR_BLUE         = '0;34'
COLOR_PURPLE       = '0;35'
COLOR_CYAN         = '0;36'
COLOR_LIGHT_GRAY   = '0;37'
COLOR_DARK_GRAY    = '1;30'
COLOR_LIGHT_RED    = '1;31'
COLOR_LIGHT_GREEN  = '1;32'
COLOR_YELLOW       = '1;33'
COLOR_LIGHT_BLUE   = '1;34'
COLOR_LIGHT_PURPLE = '1;35'
COLOR_LIGHT_CYAN   = '1;36'
COLOR_WHITE        = '1;37'

### helper functions ###
def get_devnull():
    """Get the file object of '/dev/null' device."""
    try:
        devnull = subprocess.DEVNULL # py3k
    except AttributeError:
        devnull = open(os.devnull, 'wb')
    return devnull

def check_top_directory():
    """Exit if we are not at the top of source directory."""
    for f in ('README', 'Licenses'):
        if not os.path.exists(f):
            sys.exit('Please run at the top of source directory.')

def check_clean_directory():
    """Exit if the source tree is not clean."""
    for f in ('.config', 'include/config'):
        if os.path.exists(f):
            sys.exit("source tree is not clean, please run 'make mrproper'")

def get_make_cmd():
    """Get the command name of GNU Make.

    U-Boot needs GNU Make for building, but the command name is not
    necessarily "make". (for example, "gmake" on FreeBSD).
    Returns the most appropriate command name on your system.
    """
    process = subprocess.Popen([SHOW_GNU_MAKE], stdout=subprocess.PIPE)
    ret = process.communicate()
    if process.returncode:
        sys.exit('GNU Make not found')
    return ret[0].rstrip()

def get_all_defconfigs():
    """Get all the defconfig files under the configs/ directory."""
    defconfigs = []
    for (dirpath, dirnames, filenames) in os.walk('configs'):
        dirpath = dirpath[len('configs') + 1:]
        for filename in fnmatch.filter(filenames, '*_defconfig'):
            defconfigs.append(os.path.join(dirpath, filename))

    return defconfigs

def color_text(color_enabled, color, string):
    """Return colored string."""
    if color_enabled:
        # LF should not be surrounded by the escape sequence.
        # Otherwise, additional whitespace or line-feed might be printed.
        return '\n'.join([ '\033[' + color + 'm' + s + '\033[0m' if s else ''
                           for s in string.split('\n') ])
    else:
        return string

def show_diff(a, b, file_path, color_enabled):
    """Show unidified diff.

    Arguments:
      a: A list of lines (before)
      b: A list of lines (after)
      file_path: Path to the file
      color_enabled: Display the diff in color
    """

    diff = difflib.unified_diff(a, b,
                                fromfile=os.path.join('a', file_path),
                                tofile=os.path.join('b', file_path))

    for line in diff:
        if line[0] == '-' and line[1] != '-':
            print color_text(color_enabled, COLOR_RED, line),
        elif line[0] == '+' and line[1] != '+':
            print color_text(color_enabled, COLOR_GREEN, line),
        else:
            print line,

def update_cross_compile(color_enabled):
    """Update per-arch CROSS_COMPILE via environment variables

    The default CROSS_COMPILE values are available
    in the CROSS_COMPILE list above.

    You can override them via environment variables
    CROSS_COMPILE_{ARCH}.

    For example, if you want to override toolchain prefixes
    for ARM and PowerPC, you can do as follows in your shell:

    export CROSS_COMPILE_ARM=...
    export CROSS_COMPILE_POWERPC=...

    Then, this function checks if specified compilers really exist in your
    PATH environment.
    """
    archs = []

    for arch in os.listdir('arch'):
        if os.path.exists(os.path.join('arch', arch, 'Makefile')):
            archs.append(arch)

    # arm64 is a special case
    archs.append('aarch64')

    for arch in archs:
        env = 'CROSS_COMPILE_' + arch.upper()
        cross_compile = os.environ.get(env)
        if not cross_compile:
            cross_compile = CROSS_COMPILE.get(arch, '')

        for path in os.environ["PATH"].split(os.pathsep):
            gcc_path = os.path.join(path, cross_compile + 'gcc')
            if os.path.isfile(gcc_path) and os.access(gcc_path, os.X_OK):
                break
        else:
            print >> sys.stderr, color_text(color_enabled, COLOR_YELLOW,
                 'warning: %sgcc: not found in PATH.  %s architecture boards will be skipped'
                                            % (cross_compile, arch))
            cross_compile = None

        CROSS_COMPILE[arch] = cross_compile

def extend_matched_lines(lines, matched, pre_patterns, post_patterns, extend_pre,
                         extend_post):
    """Extend matched lines if desired patterns are found before/after already
    matched lines.

    Arguments:
      lines: A list of lines handled.
      matched: A list of line numbers that have been already matched.
               (will be updated by this function)
      pre_patterns: A list of regular expression that should be matched as
                    preamble.
      post_patterns: A list of regular expression that should be matched as
                     postamble.
      extend_pre: Add the line number of matched preamble to the matched list.
      extend_post: Add the line number of matched postamble to the matched list.
    """
    extended_matched = []

    j = matched[0]

    for i in matched:
        if i == 0 or i < j:
            continue
        j = i
        while j in matched:
            j += 1
        if j >= len(lines):
            break

        for p in pre_patterns:
            if p.search(lines[i - 1]):
                break
        else:
            # not matched
            continue

        for p in post_patterns:
            if p.search(lines[j]):
                break
        else:
            # not matched
            continue

        if extend_pre:
            extended_matched.append(i - 1)
        if extend_post:
            extended_matched.append(j)

    matched += extended_matched
    matched.sort()

def cleanup_one_header(header_path, patterns, options):
    """Clean regex-matched lines away from a file.

    Arguments:
      header_path: path to the cleaned file.
      patterns: list of regex patterns.  Any lines matching to these
                patterns are deleted.
      options: option flags.
    """
    with open(header_path) as f:
        lines = f.readlines()

    matched = []
    for i, line in enumerate(lines):
        if i - 1 in matched and lines[i - 1][-2:] == '\\\n':
            matched.append(i)
            continue
        for pattern in patterns:
            if pattern.search(line):
                matched.append(i)
                break

    if not matched:
        return

    # remove empty #ifdef ... #endif, successive blank lines
    pattern_if = re.compile(r'#\s*if(def|ndef)?\W') #  #if, #ifdef, #ifndef
    pattern_elif = re.compile(r'#\s*el(if|se)\W')   #  #elif, #else
    pattern_endif = re.compile(r'#\s*endif\W')      #  #endif
    pattern_blank = re.compile(r'^\s*$')            #  empty line

    while True:
        old_matched = copy.copy(matched)
        extend_matched_lines(lines, matched, [pattern_if],
                             [pattern_endif], True, True)
        extend_matched_lines(lines, matched, [pattern_elif],
                             [pattern_elif, pattern_endif], True, False)
        extend_matched_lines(lines, matched, [pattern_if, pattern_elif],
                             [pattern_blank], False, True)
        extend_matched_lines(lines, matched, [pattern_blank],
                             [pattern_elif, pattern_endif], True, False)
        extend_matched_lines(lines, matched, [pattern_blank],
                             [pattern_blank], True, False)
        if matched == old_matched:
            break

    tolines = copy.copy(lines)

    for i in reversed(matched):
        tolines.pop(i)

    show_diff(lines, tolines, header_path, options.color)

    if options.dry_run:
        return

    with open(header_path, 'w') as f:
        for line in tolines:
            f.write(line)

def cleanup_headers(configs, options):
    """Delete config defines from board headers.

    Arguments:
      configs: A list of CONFIGs to remove.
      options: option flags.
    """
    while True:
        choice = raw_input('Clean up headers? [y/n]: ').lower()
        print choice
        if choice == 'y' or choice == 'n':
            break

    if choice == 'n':
        return

    patterns = []
    for config in configs:
        patterns.append(re.compile(r'#\s*define\s+%s\W' % config))
        patterns.append(re.compile(r'#\s*undef\s+%s\W' % config))

    for dir in 'include', 'arch', 'board':
        for (dirpath, dirnames, filenames) in os.walk(dir):
            if dirpath == os.path.join('include', 'generated'):
                continue
            for filename in filenames:
                if not fnmatch.fnmatch(filename, '*~'):
                    cleanup_one_header(os.path.join(dirpath, filename),
                                       patterns, options)

def cleanup_one_extra_option(defconfig_path, configs, options):
    """Delete config defines in CONFIG_SYS_EXTRA_OPTIONS in one defconfig file.

    Arguments:
      defconfig_path: path to the cleaned defconfig file.
      configs: A list of CONFIGs to remove.
      options: option flags.
    """

    start = 'CONFIG_SYS_EXTRA_OPTIONS="'
    end = '"\n'

    with open(defconfig_path) as f:
        lines = f.readlines()

    for i, line in enumerate(lines):
        if line.startswith(start) and line.endswith(end):
            break
    else:
        # CONFIG_SYS_EXTRA_OPTIONS was not found in this defconfig
        return

    old_tokens = line[len(start):-len(end)].split(',')
    new_tokens = []

    for token in old_tokens:
        pos = token.find('=')
        if not (token[:pos] if pos >= 0 else token) in configs:
            new_tokens.append(token)

    if new_tokens == old_tokens:
        return

    tolines = copy.copy(lines)

    if new_tokens:
        tolines[i] = start + ','.join(new_tokens) + end
    else:
        tolines.pop(i)

    show_diff(lines, tolines, defconfig_path, options.color)

    if options.dry_run:
        return

    with open(defconfig_path, 'w') as f:
        for line in tolines:
            f.write(line)

def cleanup_extra_options(configs, options):
    """Delete config defines in CONFIG_SYS_EXTRA_OPTIONS in defconfig files.

    Arguments:
      configs: A list of CONFIGs to remove.
      options: option flags.
    """
    while True:
        choice = raw_input('Clean up CONFIG_SYS_EXTRA_OPTIONS? [y/n]: ').lower()
        print choice
        if choice == 'y' or choice == 'n':
            break

    if choice == 'n':
        return

    configs = [ config[len('CONFIG_'):] for config in configs ]

    defconfigs = get_all_defconfigs()

    for defconfig in defconfigs:
        cleanup_one_extra_option(os.path.join('configs', defconfig), configs,
                                 options)

### classes ###
class Progress:

    """Progress Indicator"""

    def __init__(self, total):
        """Create a new progress indicator.

        Arguments:
          total: A number of defconfig files to process.
        """
        self.current = 0
        self.total = total

    def inc(self):
        """Increment the number of processed defconfig files."""

        self.current += 1

    def show(self):
        """Display the progress."""
        print ' %d defconfigs out of %d\r' % (self.current, self.total),
        sys.stdout.flush()

class KconfigParser:

    """A parser of .config and include/autoconf.mk."""

    re_arch = re.compile(r'CONFIG_SYS_ARCH="(.*)"')
    re_cpu = re.compile(r'CONFIG_SYS_CPU="(.*)"')

    def __init__(self, configs, options, build_dir):
        """Create a new parser.

        Arguments:
          configs: A list of CONFIGs to move.
          options: option flags.
          build_dir: Build directory.
        """
        self.configs = configs
        self.options = options
        self.dotconfig = os.path.join(build_dir, '.config')
        self.autoconf = os.path.join(build_dir, 'include', 'autoconf.mk')
        self.config_autoconf = os.path.join(build_dir, 'include', 'config',
                                            'auto.conf')
        self.defconfig = os.path.join(build_dir, 'defconfig')

    def get_cross_compile(self):
        """Parse .config file and return CROSS_COMPILE.

        Returns:
          A string storing the compiler prefix for the architecture.
          Return a NULL string for architectures that do not require
          compiler prefix (Sandbox and native build is the case).
          Return None if the specified compiler is missing in your PATH.
          Caller should distinguish '' and None.
        """
        arch = ''
        cpu = ''
        for line in open(self.dotconfig):
            m = self.re_arch.match(line)
            if m:
                arch = m.group(1)
                continue
            m = self.re_cpu.match(line)
            if m:
                cpu = m.group(1)

        if not arch:
            return None

        # fix-up for aarch64
        if arch == 'arm' and cpu == 'armv8':
            arch = 'aarch64'

        return CROSS_COMPILE.get(arch, None)

    def parse_one_config(self, config, dotconfig_lines, autoconf_lines):
        """Parse .config, defconfig, include/autoconf.mk for one config.

        This function looks for the config options in the lines from
        defconfig, .config, and include/autoconf.mk in order to decide
        which action should be taken for this defconfig.

        Arguments:
          config: CONFIG name to parse.
          dotconfig_lines: lines from the .config file.
          autoconf_lines: lines from the include/autoconf.mk file.

        Returns:
          A tupple of the action for this defconfig and the line
          matched for the config.
        """
        not_set = '# %s is not set' % config

        for line in autoconf_lines:
            line = line.rstrip()
            if line.startswith(config + '='):
                new_val = line
                break
        else:
            new_val = not_set

        for line in dotconfig_lines:
            line = line.rstrip()
            if line.startswith(config + '=') or line == not_set:
                old_val = line
                break
        else:
            if new_val == not_set:
                return (ACTION_NO_ENTRY, config)
            else:
                return (ACTION_NO_ENTRY_WARN, config)

        # If this CONFIG is neither bool nor trisate
        if old_val[-2:] != '=y' and old_val[-2:] != '=m' and old_val != not_set:
            # tools/scripts/define2mk.sed changes '1' to 'y'.
            # This is a problem if the CONFIG is int type.
            # Check the type in Kconfig and handle it correctly.
            if new_val[-2:] == '=y':
                new_val = new_val[:-1] + '1'

        return (ACTION_NO_CHANGE if old_val == new_val else ACTION_MOVE,
                new_val)

    def update_dotconfig(self):
        """Parse files for the config options and update the .config.

        This function parses the generated .config and include/autoconf.mk
        searching the target options.
        Move the config option(s) to the .config as needed.

        Arguments:
          defconfig: defconfig name.

        Returns:
          Return a tuple of (updated flag, log string).
          The "updated flag" is True if the .config was updated, False
          otherwise.  The "log string" shows what happend to the .config.
        """

        results = []
        updated = False
        suspicious = False

        with open(self.dotconfig) as f:
            dotconfig_lines = f.readlines()

        with open(self.autoconf) as f:
            autoconf_lines = f.readlines()

        for config in self.configs:
            result = self.parse_one_config(config, dotconfig_lines,
                                           autoconf_lines)
            results.append(result)

        log = ''

        for (action, value) in results:
            if action == ACTION_MOVE:
                actlog = "Move '%s'" % value
                log_color = COLOR_LIGHT_GREEN
            elif action == ACTION_NO_ENTRY:
                actlog = "%s is not defined in Kconfig.  Do nothing." % value
                log_color = COLOR_LIGHT_BLUE
            elif action == ACTION_NO_ENTRY_WARN:
                actlog = "%s is not defined in Kconfig (suspicious).  Do nothing." % value
                log_color = COLOR_YELLOW
                suspicious = True
            elif action == ACTION_NO_CHANGE:
                actlog = "'%s' is the same as the define in Kconfig.  Do nothing." \
                         % value
                log_color = COLOR_LIGHT_PURPLE
            else:
                sys.exit("Internal Error. This should not happen.")

            log += color_text(self.options.color, log_color, actlog) + '\n'

        with open(self.dotconfig, 'a') as f:
            for (action, value) in results:
                if action == ACTION_MOVE:
                    f.write(value + '\n')
                    updated = True

        self.results = results
        os.remove(self.config_autoconf)
        os.remove(self.autoconf)

        return (updated, suspicious, log)

    def check_defconfig(self):
        """Check the defconfig after savedefconfig

        Returns:
          Return additional log if moved CONFIGs were removed again by
          'make savedefconfig'.
        """

        log = ''

        with open(self.defconfig) as f:
            defconfig_lines = f.readlines()

        for (action, value) in self.results:
            if action != ACTION_MOVE:
                continue
            if not value + '\n' in defconfig_lines:
                log += color_text(self.options.color, COLOR_YELLOW,
                                  "'%s' was removed by savedefconfig.\n" %
                                  value)

        return log

class Slot:

    """A slot to store a subprocess.

    Each instance of this class handles one subprocess.
    This class is useful to control multiple threads
    for faster processing.
    """

    def __init__(self, configs, options, progress, devnull, make_cmd, reference_src_dir):
        """Create a new process slot.

        Arguments:
          configs: A list of CONFIGs to move.
          options: option flags.
          progress: A progress indicator.
          devnull: A file object of '/dev/null'.
          make_cmd: command name of GNU Make.
          reference_src_dir: Determine the true starting config state from this
                             source tree.
        """
        self.options = options
        self.progress = progress
        self.build_dir = tempfile.mkdtemp()
        self.devnull = devnull
        self.make_cmd = (make_cmd, 'O=' + self.build_dir)
        self.reference_src_dir = reference_src_dir
        self.parser = KconfigParser(configs, options, self.build_dir)
        self.state = STATE_IDLE
        self.failed_boards = set()
        self.suspicious_boards = set()

    def __del__(self):
        """Delete the working directory

        This function makes sure the temporary directory is cleaned away
        even if Python suddenly dies due to error.  It should be done in here
        because it is guaranteed the destructor is always invoked when the
        instance of the class gets unreferenced.

        If the subprocess is still running, wait until it finishes.
        """
        if self.state != STATE_IDLE:
            while self.ps.poll() == None:
                pass
        shutil.rmtree(self.build_dir)

    def add(self, defconfig):
        """Assign a new subprocess for defconfig and add it to the slot.

        If the slot is vacant, create a new subprocess for processing the
        given defconfig and add it to the slot.  Just returns False if
        the slot is occupied (i.e. the current subprocess is still running).

        Arguments:
          defconfig: defconfig name.

        Returns:
          Return True on success or False on failure
        """
        if self.state != STATE_IDLE:
            return False

        self.defconfig = defconfig
        self.log = ''
        self.current_src_dir = self.reference_src_dir
        self.do_defconfig()
        return True

    def poll(self):
        """Check the status of the subprocess and handle it as needed.

        Returns True if the slot is vacant (i.e. in idle state).
        If the configuration is successfully finished, assign a new
        subprocess to build include/autoconf.mk.
        If include/autoconf.mk is generated, invoke the parser to
        parse the .config and the include/autoconf.mk, moving
        config options to the .config as needed.
        If the .config was updated, run "make savedefconfig" to sync
        it, update the original defconfig, and then set the slot back
        to the idle state.

        Returns:
          Return True if the subprocess is terminated, False otherwise
        """
        if self.state == STATE_IDLE:
            return True

        if self.ps.poll() == None:
            return False

        if self.ps.poll() != 0:
            self.handle_error()
        elif self.state == STATE_DEFCONFIG:
            if self.reference_src_dir and not self.current_src_dir:
                self.do_savedefconfig()
            else:
                self.do_autoconf()
        elif self.state == STATE_AUTOCONF:
            if self.current_src_dir:
                self.current_src_dir = None
                self.do_defconfig()
            else:
                self.do_savedefconfig()
        elif self.state == STATE_SAVEDEFCONFIG:
            self.update_defconfig()
        else:
            sys.exit("Internal Error. This should not happen.")

        return True if self.state == STATE_IDLE else False

    def handle_error(self):
        """Handle error cases."""

        self.log += color_text(self.options.color, COLOR_LIGHT_RED,
                               "Failed to process.\n")
        if self.options.verbose:
            self.log += color_text(self.options.color, COLOR_LIGHT_CYAN,
                                   self.ps.stderr.read())
        self.finish(False)

    def do_defconfig(self):
        """Run 'make <board>_defconfig' to create the .config file."""

        cmd = list(self.make_cmd)
        cmd.append(self.defconfig)
        self.ps = subprocess.Popen(cmd, stdout=self.devnull,
                                   stderr=subprocess.PIPE,
                                   cwd=self.current_src_dir)
        self.state = STATE_DEFCONFIG

    def do_autoconf(self):
        """Run 'make include/config/auto.conf'."""

        self.cross_compile = self.parser.get_cross_compile()
        if self.cross_compile is None:
            self.log += color_text(self.options.color, COLOR_YELLOW,
                                   "Compiler is missing.  Do nothing.\n")
            self.finish(False)
            return

        cmd = list(self.make_cmd)
        if self.cross_compile:
            cmd.append('CROSS_COMPILE=%s' % self.cross_compile)
        cmd.append('KCONFIG_IGNORE_DUPLICATES=1')
        cmd.append('include/config/auto.conf')
        self.ps = subprocess.Popen(cmd, stdout=self.devnull,
                                   stderr=subprocess.PIPE,
                                   cwd=self.current_src_dir)
        self.state = STATE_AUTOCONF

    def do_savedefconfig(self):
        """Update the .config and run 'make savedefconfig'."""

        (updated, suspicious, log) = self.parser.update_dotconfig()
        if suspicious:
            self.suspicious_boards.add(self.defconfig)
        self.log += log

        if not self.options.force_sync and not updated:
            self.finish(True)
            return
        if updated:
            self.log += color_text(self.options.color, COLOR_LIGHT_GREEN,
                                   "Syncing by savedefconfig...\n")
        else:
            self.log += "Syncing by savedefconfig (forced by option)...\n"

        cmd = list(self.make_cmd)
        cmd.append('savedefconfig')
        self.ps = subprocess.Popen(cmd, stdout=self.devnull,
                                   stderr=subprocess.PIPE)
        self.state = STATE_SAVEDEFCONFIG

    def update_defconfig(self):
        """Update the input defconfig and go back to the idle state."""

        log = self.parser.check_defconfig()
        if log:
            self.suspicious_boards.add(self.defconfig)
            self.log += log
        orig_defconfig = os.path.join('configs', self.defconfig)
        new_defconfig = os.path.join(self.build_dir, 'defconfig')
        updated = not filecmp.cmp(orig_defconfig, new_defconfig)

        if updated:
            self.log += color_text(self.options.color, COLOR_LIGHT_BLUE,
                                   "defconfig was updated.\n")

        if not self.options.dry_run and updated:
            shutil.move(new_defconfig, orig_defconfig)
        self.finish(True)

    def finish(self, success):
        """Display log along with progress and go to the idle state.

        Arguments:
          success: Should be True when the defconfig was processed
                   successfully, or False when it fails.
        """
        # output at least 30 characters to hide the "* defconfigs out of *".
        log = self.defconfig.ljust(30) + '\n'

        log += '\n'.join([ '    ' + s for s in self.log.split('\n') ])
        # Some threads are running in parallel.
        # Print log atomically to not mix up logs from different threads.
        print >> (sys.stdout if success else sys.stderr), log

        if not success:
            if self.options.exit_on_error:
                sys.exit("Exit on error.")
            # If --exit-on-error flag is not set, skip this board and continue.
            # Record the failed board.
            self.failed_boards.add(self.defconfig)

        self.progress.inc()
        self.progress.show()
        self.state = STATE_IDLE

    def get_failed_boards(self):
        """Returns a set of failed boards (defconfigs) in this slot.
        """
        return self.failed_boards

    def get_suspicious_boards(self):
        """Returns a set of boards (defconfigs) with possible misconversion.
        """
        return self.suspicious_boards - self.failed_boards

class Slots:

    """Controller of the array of subprocess slots."""

    def __init__(self, configs, options, progress, reference_src_dir):
        """Create a new slots controller.

        Arguments:
          configs: A list of CONFIGs to move.
          options: option flags.
          progress: A progress indicator.
          reference_src_dir: Determine the true starting config state from this
                             source tree.
        """
        self.options = options
        self.slots = []
        devnull = get_devnull()
        make_cmd = get_make_cmd()
        for i in range(options.jobs):
            self.slots.append(Slot(configs, options, progress, devnull,
                                   make_cmd, reference_src_dir))

    def add(self, defconfig):
        """Add a new subprocess if a vacant slot is found.

        Arguments:
          defconfig: defconfig name to be put into.

        Returns:
          Return True on success or False on failure
        """
        for slot in self.slots:
            if slot.add(defconfig):
                return True
        return False

    def available(self):
        """Check if there is a vacant slot.

        Returns:
          Return True if at lease one vacant slot is found, False otherwise.
        """
        for slot in self.slots:
            if slot.poll():
                return True
        return False

    def empty(self):
        """Check if all slots are vacant.

        Returns:
          Return True if all the slots are vacant, False otherwise.
        """
        ret = True
        for slot in self.slots:
            if not slot.poll():
                ret = False
        return ret

    def show_failed_boards(self):
        """Display all of the failed boards (defconfigs)."""
        boards = set()
        output_file = 'moveconfig.failed'

        for slot in self.slots:
            boards |= slot.get_failed_boards()

        if boards:
            boards = '\n'.join(boards) + '\n'
            msg = "The following boards were not processed due to error:\n"
            msg += boards
            msg += "(the list has been saved in %s)\n" % output_file
            print >> sys.stderr, color_text(self.options.color, COLOR_LIGHT_RED,
                                            msg)

            with open(output_file, 'w') as f:
                f.write(boards)

    def show_suspicious_boards(self):
        """Display all boards (defconfigs) with possible misconversion."""
        boards = set()
        output_file = 'moveconfig.suspicious'

        for slot in self.slots:
            boards |= slot.get_suspicious_boards()

        if boards:
            boards = '\n'.join(boards) + '\n'
            msg = "The following boards might have been converted incorrectly.\n"
            msg += "It is highly recommended to check them manually:\n"
            msg += boards
            msg += "(the list has been saved in %s)\n" % output_file
            print >> sys.stderr, color_text(self.options.color, COLOR_YELLOW,
                                            msg)

            with open(output_file, 'w') as f:
                f.write(boards)

class ReferenceSource:

    """Reference source against which original configs should be parsed."""

    def __init__(self, commit):
        """Create a reference source directory based on a specified commit.

        Arguments:
          commit: commit to git-clone
        """
        self.src_dir = tempfile.mkdtemp()
        print "Cloning git repo to a separate work directory..."
        subprocess.check_output(['git', 'clone', os.getcwd(), '.'],
                                cwd=self.src_dir)
        print "Checkout '%s' to build the original autoconf.mk." % \
            subprocess.check_output(['git', 'rev-parse', '--short', commit]).strip()
        subprocess.check_output(['git', 'checkout', commit],
                                stderr=subprocess.STDOUT, cwd=self.src_dir)

    def __del__(self):
        """Delete the reference source directory

        This function makes sure the temporary directory is cleaned away
        even if Python suddenly dies due to error.  It should be done in here
        because it is guaranteed the destructor is always invoked when the
        instance of the class gets unreferenced.
        """
        shutil.rmtree(self.src_dir)

    def get_dir(self):
        """Return the absolute path to the reference source directory."""

        return self.src_dir

def move_config(configs, options):
    """Move config options to defconfig files.

    Arguments:
      configs: A list of CONFIGs to move.
      options: option flags
    """
    if len(configs) == 0:
        if options.force_sync:
            print 'No CONFIG is specified. You are probably syncing defconfigs.',
        else:
            print 'Neither CONFIG nor --force-sync is specified. Nothing will happen.',
    else:
        print 'Move ' + ', '.join(configs),
    print '(jobs: %d)\n' % options.jobs

    if options.git_ref:
        reference_src = ReferenceSource(options.git_ref)
        reference_src_dir = reference_src.get_dir()
    else:
        reference_src_dir = None

    if options.defconfigs:
        defconfigs = [line.strip() for line in open(options.defconfigs)]
        for i, defconfig in enumerate(defconfigs):
            if not defconfig.endswith('_defconfig'):
                defconfigs[i] = defconfig + '_defconfig'
            if not os.path.exists(os.path.join('configs', defconfigs[i])):
                sys.exit('%s - defconfig does not exist. Stopping.' %
                         defconfigs[i])
    else:
        defconfigs = get_all_defconfigs()

    progress = Progress(len(defconfigs))
    slots = Slots(configs, options, progress, reference_src_dir)

    # Main loop to process defconfig files:
    #  Add a new subprocess into a vacant slot.
    #  Sleep if there is no available slot.
    for defconfig in defconfigs:
        while not slots.add(defconfig):
            while not slots.available():
                # No available slot: sleep for a while
                time.sleep(SLEEP_TIME)

    # wait until all the subprocesses finish
    while not slots.empty():
        time.sleep(SLEEP_TIME)

    print ''
    slots.show_failed_boards()
    slots.show_suspicious_boards()

def main():
    try:
        cpu_count = multiprocessing.cpu_count()
    except NotImplementedError:
        cpu_count = 1

    parser = optparse.OptionParser()
    # Add options here
    parser.add_option('-c', '--color', action='store_true', default=False,
                      help='display the log in color')
    parser.add_option('-d', '--defconfigs', type='string',
                      help='a file containing a list of defconfigs to move')
    parser.add_option('-n', '--dry-run', action='store_true', default=False,
                      help='perform a trial run (show log with no changes)')
    parser.add_option('-e', '--exit-on-error', action='store_true',
                      default=False,
                      help='exit immediately on any error')
    parser.add_option('-s', '--force-sync', action='store_true', default=False,
                      help='force sync by savedefconfig')
    parser.add_option('-H', '--headers-only', dest='cleanup_headers_only',
                      action='store_true', default=False,
                      help='only cleanup the headers')
    parser.add_option('-j', '--jobs', type='int', default=cpu_count,
                      help='the number of jobs to run simultaneously')
    parser.add_option('-r', '--git-ref', type='string',
                      help='the git ref to clone for building the autoconf.mk')
    parser.add_option('-v', '--verbose', action='store_true', default=False,
                      help='show any build errors as boards are built')
    parser.usage += ' CONFIG ...'

    (options, configs) = parser.parse_args()

    if len(configs) == 0 and not options.force_sync:
        parser.print_usage()
        sys.exit(1)

    # prefix the option name with CONFIG_ if missing
    configs = [ config if config.startswith('CONFIG_') else 'CONFIG_' + config
                for config in configs ]

    check_top_directory()

    if not options.cleanup_headers_only:
        check_clean_directory()
        update_cross_compile(options.color)
        move_config(configs, options)

    if configs:
        cleanup_headers(configs, options)
        cleanup_extra_options(configs, options)

if __name__ == '__main__':
    main()