path: root/src/engine/SCons/Script/__init__.py

"""engine.SCons.script

This file implements the main() function used by the scons script.

Architecturally, this *is* the scons script, and will likely only be
called from the external "scons" wrapper.  Consequently, anything here
should not be, or be considered, part of the build engine.  If it's
something that we expect other software to want to use, it should go in
some other module.  If it's specific to the "scons" script invocation,
it goes here.

"""

#
# Copyright (c) 2001, 2002 Steven Knight
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"

import time
start_time = time.time()

import getopt
import os
import os.path
import string
import sys
import traceback
import copy

# Strip the script directory from sys.path() so on case-insensitive
# (WIN32) systems Python doesn't think that the "scons" script is the
# "SCons" package.  Replace it with our own version directory so, if
# if they're there, we pick up the right version of the build engine
# modules.
sys.path = [os.path.join(sys.prefix, 'lib', 'scons-__VERSION__')] + sys.path[1:]

import SCons.Node
import SCons.Node.FS
import SCons.Job
from SCons.Errors import *
import SCons.Sig
import SCons.Sig.MD5
from SCons.Taskmaster import Taskmaster
import SCons.Builder
import SCons.Script.SConscript
import SCons.Warnings


#
# Task control.
#
class BuildTask(SCons.Taskmaster.Task):
    """An SCons build task."""
    def execute(self):
        if self.targets[0].get_state() == SCons.Node.up_to_date:
            if self.top:
                print 'scons: "%s" is up to date.' % str(self.targets[0])
        else:
            try:
                self.targets[0].prepare()
                if print_time:
                    start_time = time.time()
                self.targets[0].build()
                if print_time:
                    finish_time = time.time()
                    global command_time
                    command_time = command_time+finish_time-start_time
                    print "Command execution time: %f seconds"%(finish_time-start_time)
   
            except BuildError, e:
                sys.stderr.write("scons: *** [%s] %s\n" % (e.node, e.errstr))
                if e.errstr == 'Exception':
                    traceback.print_exception(e.args[0], e.args[1],
                                              e.args[2])
                raise
	    except:
		sys.stderr.write("scons: *** %s\n" % sys.exc_value)
		raise

    def executed(self):
        SCons.Taskmaster.Task.executed(self)
        # print the tree here instead of in execute() because
        # this method is serialized, but execute isn't:
        if print_tree and self.top:
            print
            print SCons.Util.render_tree(self.targets[0], get_all_children)
	if print_dtree and self.top:
	    print
	    print SCons.Util.render_tree(self.targets[0], get_derived_children)

    def failed(self):
        global exit_status
        if ignore_errors:
            SCons.Taskmaster.Task.executed(self)
        elif keep_going_on_error:
            SCons.Taskmaster.Task.fail_continue(self)
            exit_status = 2
        else:
            SCons.Taskmaster.Task.fail_stop(self)
            exit_status = 2

class CleanTask(SCons.Taskmaster.Task):
    """An SCons clean task."""
    def show(self):
        if self.targets[0].builder:
            print "Removed " + self.targets[0].path

    def remove(self):
        if self.targets[0].builder:
            try:
                os.unlink(self.targets[0].path)
            except OSError:
                pass
            else:
                print "Removed " + self.targets[0].path
            try:
                for t in self.targets[1:]:
                    try:
                        os.unlink(t.path)
                    except OSError:
                        pass
                    else:
                        print "Removed " + t.path
            except IndexError:
                pass

    execute = remove

class QuestionTask(SCons.Taskmaster.Task):
    """An SCons task for the -q (question) option."""
    def execute(self):
        if self.targets[0].get_state() != SCons.Node.up_to_date:
            global exit_status
            exit_status = 1
            self.tm.stop()

    def executed(self):
        pass

# Global variables

include_dirs = []
num_jobs = 1
scripts = []
task_class = BuildTask	# default action is to build targets
current_func = None
calc = None
ignore_errors = 0
keep_going_on_error = 0
help_option = None
print_tree = 0
print_dtree = 0
print_time = 0
sconscript_time = 0
command_time = 0
climb_up = 0
target_top = None
exit_status = 0 # exit status, assume success by default
profiling = 0
max_drift = None


# utility functions

def get_all_children(node): return node.all_children(None)

def get_derived_children(node):
    children = node.all_children(None)
    return filter(lambda x: x.builder, children)

def _scons_syntax_error(e):
    """Handle syntax errors. Print out a message and show where the error
    occurred.
    """
    etype, value, tb = sys.exc_info()
    lines = traceback.format_exception_only(etype, value)
    for line in lines:
        sys.stderr.write(line+'\n')
    sys.exit(2)

def find_deepest_user_frame(tb):
    """
    Find the deepest stack frame that is not part of SCons.

    Input is a "pre-processed" stack trace in the form
    returned by traceback.extract_tb() or traceback.extract_stack()
    """
    
    tb.reverse()

    # find the deepest traceback frame that is not part
    # of SCons:
    for frame in tb:
        filename = frame[0]
        if string.find(filename, os.sep+'SCons'+os.sep) == -1:
            return frame
    return tb[0]

def _scons_user_error(e):
    """Handle user errors. Print out a message and a description of the
    error, along with the line number and routine where it occured. 
    The file and line number will be the deepest stack frame that is
    not part of SCons itself.
    """
    etype, value, tb = sys.exc_info()
    filename, lineno, routine, dummy = find_deepest_user_frame(traceback.extract_tb(tb))
    sys.stderr.write("\nSCons error: %s\n" % value)
    sys.stderr.write('File "%s", line %d, in %s\n' % (filename, lineno, routine))
    sys.exit(2)

def _scons_user_warning(e):
    """Handle user warnings. Print out a message and a description of
    the warning, along with the line number and routine where it occured.
    The file and line number will be the deepest stack frame that is
    not part of SCons itself.
    """
    etype, value, tb = sys.exc_info()
    filename, lineno, routine, dummy = find_deepest_user_frame(traceback.extract_tb(tb))
    sys.stderr.write("\nSCons warning: %s\n" % e)
    sys.stderr.write('File "%s", line %d, in %s\n' % (filename, lineno, routine))

def _scons_internal_warning(e):
    """Slightly different from _scons_user_warning in that we use the
    *current call stack* rather than sys.exc_info() to get our stack trace.
    This is used by the warnings framework to print warnings."""
    filename, lineno, routine, dummy = find_deepest_user_frame(traceback.extract_stack())
    sys.stderr.write("\nSCons warning: %s\n" % e)
    sys.stderr.write('File "%s", line %d, in %s\n' % (filename, lineno, routine))

def _scons_other_errors():
    """Handle all errors but user errors. Print out a message telling
    the user what to do in this case and print a normal trace.
    """
    print 'other errors'
    traceback.print_exc()
    sys.exit(2)


#
# After options are initialized, the following variables are
# filled in:
#
option_list = []	# list of Option objects
short_opts = ""		# string of short (single-character) options
long_opts = []		# array of long (--) options
opt_func = {}		# mapping of option strings to functions

def options_init():
    """Initialize command-line options processing.

    This is in a subroutine mainly so we can easily single-step over
    it in the debugger.
    """

    class Option:
	"""Class for command-line option information.

	This exists to provide a central location for everything
	describing a command-line option, so that we can change
	options without having to update the code to handle the
	option in one place, the -h help message in another place,
	etc.  There are no methods here, only attributes.

	You can initialize an Option with the following:

	func	The function that will be called when this
		option is processed on the command line.
		Calling sequence is:

			func(opt, arg)

		If there is no func, then this Option probably
		stores an optstring to be printed.

	helpline
		The string to be printed in -h output.  If no
		helpline is specified but a help string is
		specified (the usual case), a helpline will be
		constructed automatically from the short, long,
		arg, and help attributes.  (In practice, then,
		setting helpline without setting func allows you
		to print arbitrary lines of text in the -h
		output.)

	short	The string for short, single-hyphen
		command-line options.
		Do not include the hyphen:

			'a' for -a, 'xy' for -x and -y, etc.

	long	An array of strings for long, double-hyphen
		command-line options.  Do not include
		the hyphens:

			['my-option', 'verbose']

	arg	If this option takes an argument, this string
		specifies how you want it to appear in the
		-h output ('DIRECTORY', 'FILE', etc.).

	help	The help string that will be printed for
		this option in the -h output.  Must be
		49 characters or fewer.

	future	If non-zero, this indicates that this feature
		will be supported in a future release, not
		the currently planned one.  SCons will
		recognize the option, but it won't show up
		in the -h output.

	The following attribute is derived from the supplied attributes:

	optstring
		A string, with hyphens, describing the flags
		for this option, as constructed from the
		specified short, long and arg attributes.

	All Option objects are stored in the global option_list list,
	in the order in which they're created.  This is the list
	that's used to generate -h output, so the order in which the
	objects are created is the order in which they're printed.

	The upshot is that specifying a command-line option and having
	everything work correctly is a matter of defining a function to
	process its command-line argument (set the right flag, update
	the right value), and then creating an appropriate Option object
	at the correct point in the code below.
	"""

	def __init__(self, func = None, helpline = None,
		 short = None, long = None, arg = None,
		 help = None, future = None):
	    self.func = func
	    self.short = short
	    self.long = long
	    self.arg = arg
	    self.help = help
	    opts = []
	    if self.short:
		for c in self.short:
		    if arg:
			c = c + " " + arg
		    opts = opts + ['-' + c]
	    if self.long:
		l = self.long
		if arg:
		    l = map(lambda x,a=arg: x + "=" + a, self.long)
		opts = opts + map(lambda x: '--' + x, l)
	    self.optstring = string.join(opts, ', ')
	    if helpline:
		self.helpline = helpline
	    elif help and not future:
		if len(self.optstring) <= 26:
		    sep = " " * (28 - len(self.optstring))
		else:
		    sep = self.helpstring = "\n" + " " * 30
		self.helpline = "  " + self.optstring + sep + self.help
	    else:
		self.helpline = None
	    global option_list
	    option_list.append(self)

    # Generic routine for to-be-written options, used by multiple
    # options below.

    def opt_not_yet(opt, arg):
        sys.stderr.write("Warning:  the %s option is not yet implemented\n"
			  % opt)

    # In the following instantiations, the help string should be no
    # longer than 49 characters.  Use the following as a guide:
    #	help = "1234567890123456789012345678901234567890123456789"

    def opt_ignore(opt, arg):
	sys.stderr.write("Warning:  ignoring %s option\n" % opt)

    Option(func = opt_ignore,
	short = 'bmSt', long = ['no-keep-going', 'stop', 'touch'],
	help = "Ignored for compatibility.")

    def opt_c(opt, arg):
        global task_class, calc
        task_class = CleanTask
        class CleanCalculator:
            def bsig(self, node):
                return None
            def csig(self, node):
                return None
            def current(self, node, sig):
                return 0
            def write(self):
                pass
        calc = CleanCalculator()

    Option(func = opt_c,
	short = 'c', long = ['clean', 'remove'],
	help = "Remove specified targets and dependencies.")

    Option(func = opt_not_yet, future = 1,
	long = ['cache-disable', 'no-cache'],
	help = "Do not retrieve built targets from Cache.")

    Option(func = opt_not_yet, future = 1,
	long = ['cache-force', 'cache-populate'],
	help = "Copy already-built targets into the Cache.")

    Option(func = opt_not_yet, future = 1,
	long = ['cache-show'],
	help = "Print what would have built Cached targets.")

    def opt_C(opt, arg):
	try:
	    os.chdir(arg)
	except:
	    sys.stderr.write("Could not change directory to 'arg'\n")

    Option(func = opt_C,
	short = 'C', long = ['directory'], arg = 'DIRECTORY',
	help = "Change to DIRECTORY before doing anything.")

    Option(func = opt_not_yet,
	short = 'd',
	help = "Print file dependency information.")

    def opt_D(opt, arg):
        global climb_up
        climb_up = 2

    Option(func = opt_D,
        short = 'D',
        help = "Search up directory tree for SConstruct.")

    def opt_debug(opt, arg):
        global print_tree
        global print_dtree
        global print_time
        if arg == "pdb":
            args = [ sys.executable, "pdb.py" ] + \
                     filter(lambda x: x != "--debug=pdb", sys.argv)
            if sys.platform == 'win32':
                args[1] = os.path.join(sys.exec_prefix, "lib", "pdb.py")
                sys.exit(os.spawnve(os.P_WAIT, args[0], args, os.environ))
            else:
                args[1] = os.path.join(sys.exec_prefix,
                                       "lib",
                                       "python" + sys.version[0:3],
				       "pdb.py")
                os.execvpe(args[0], args, os.environ)
        elif arg == "tree":
            print_tree = 1
        elif arg == "dtree":
            print_dtree = 1
        elif arg == "time":
            print_time = 1
        else:
            sys.stderr.write("Warning:  %s is not a valid debug type\n"
                             % arg)

    Option(func = opt_debug,
           long = ['debug'], arg='TYPE',
           help = "Print various types of debugging information.")

    Option(func = opt_not_yet, future = 1,
	short = 'e', long = ['environment-overrides'],
	help = "Environment variables override makefiles.")

    def opt_f(opt, arg):
	global scripts
        scripts.append(arg)

    Option(func = opt_f,
	short = 'f', long = ['file', 'makefile', 'sconstruct'], arg = 'FILE',
	help = "Read FILE as the top-level SConstruct file.")

    def opt_help(opt, arg):
	global help_option
        help_option = 'h'
	SCons.Script.SConscript.print_help = 1

    Option(func = opt_help,
	short = 'h', long = ['help'],
	help = "Print defined help message, or this one.")

    def opt_help_options(opt, arg):
	global help_option
        help_option = 'H'

    Option(func = opt_help_options,
	short = 'H', long = ['help-options'],
	help = "Print this message and exit.")

    def opt_i(opt, arg):
        global ignore_errors
        ignore_errors = 1

    Option(func = opt_i,
	short = 'i', long = ['ignore-errors'],
	help = "Ignore errors from build actions.")

    def opt_I(opt, arg):
	global include_dirs
	include_dirs = include_dirs + [arg]

    Option(func = opt_I,
	short = 'I', long = ['include-dir'], arg = 'DIRECTORY',
	help = "Search DIRECTORY for imported Python modules.")

    def opt_implicit_cache(opt, arg):
        import SCons.Node
        SCons.Node.implicit_cache = 1

    Option(func = opt_implicit_cache,
        long = ['implicit-cache'],
        help = "Cache implicit dependencies")

    def opt_j(opt, arg):
	global num_jobs
	try:
            num_jobs = int(arg)
	except:
            print UsageString()
            sys.exit(1)

	if num_jobs <= 0:
            print UsageString()
            sys.exit(1)

    Option(func = opt_j,
	short = 'j', long = ['jobs'], arg = 'N',
	help = "Allow N jobs at once.")

    def opt_k(opt, arg):
        global keep_going_on_error
        keep_going_on_error = 1

    Option(func = opt_k,
	short = 'k', long = ['keep-going'],
	help = "Keep going when a target can't be made.")

    Option(func = opt_not_yet, future = 1,
	short = 'l', long = ['load-average', 'max-load'], arg = 'N',
	help = "Don't start multiple jobs unless load is below N.")

    Option(func = opt_not_yet, future = 1,
	long = ['list-derived'],
	help = "Don't build; list files that would be built.")

    Option(func = opt_not_yet, future = 1,
	long = ['list-actions'],
	help = "Don't build; list files and build actions.")

    Option(func = opt_not_yet, future = 1,
	long = ['list-where'],
	help = "Don't build; list files and where defined.")

    def opt_max_drift(opt, arg):
        global max_drift
        try:
            max_drift = int(arg)
        except ValueError:
            raise UserError, "The argument for --max-drift must be an integer."

    Option(func = opt_max_drift,
        long = ['max-drift'],
        arg = 'SECONDS',
        help = "Set the maximum system clock drift to be SECONDS.")

    def opt_n(opt, arg):
	SCons.Action.execute_actions = None
	CleanTask.execute = CleanTask.show

    Option(func = opt_n,
	short = 'n', long = ['no-exec', 'just-print', 'dry-run', 'recon'],
	help = "Don't build; just print commands.")

    Option(func = opt_not_yet, future = 1,
	short = 'o', long = ['old-file', 'assume-old'], arg = 'FILE',
	help = "Consider FILE to be old; don't rebuild it.")

    Option(func = opt_not_yet, future = 1,
	long = ['override'], arg = 'FILE',
	help = "Override variables as specified in FILE.")

    Option(func = opt_not_yet, future = 1,
	short = 'p',
	help = "Print internal environments/objects.")

    def opt_profile(opt, arg):
        global profiling
        if not profiling:
            profiling = 1
            import profile
            profile.run('SCons.Script.main()', arg)
            sys.exit(exit_status)

    Option(func = opt_profile,
	long = ['profile'], arg = 'FILE',
	help = "Profile SCons and put results in FILE.")

    def opt_q(opt, arg):
        global task_class
        task_class = QuestionTask

    Option(func = opt_q, future = 1,
	short = 'q', long = ['question'],
	help = "Don't build; exit status says if up to date.")

    Option(func = opt_not_yet, future = 1,
	short = 'rR', long = ['no-builtin-rules', 'no-builtin-variables'],
	help = "Clear default environments and variables.")

    Option(func = opt_not_yet, future = 1,
	long = ['random'],
	help = "Build dependencies in random order.")

    def opt_s(opt, arg):
	SCons.Action.print_actions = None

    Option(func = opt_s,
	short = 's', long = ['silent', 'quiet'],
	help = "Don't print commands.")

    def opt_u(opt, arg):
        global climb_up
        climb_up = 1

    Option(func = opt_u,
	short = 'u', long = ['up', 'search-up'],
	help = "Search up directory tree for SConstruct.")

    def opt_U(opt, arg):
        global climb_up
        climb_up = 3

    Option(func = opt_U,
        short = 'U',
        help = "Search up directory tree for SConstruct.")

    def option_v(opt, arg):
        import SCons
	print "SCons by Steven Knight et al.:"
	print "\tscript version __VERSION__"
	print "\tbuild engine version %s" % SCons.__version__
	print "Copyright 2001, 2002 Steven Knight"
	sys.exit(0)

    Option(func = option_v,
	short = 'v', long = ['version'],
	help = "Print the SCons version number and exit.")

    Option(func = opt_not_yet, future = 1,
	short = 'w', long = ['print-directory'],
	help = "Print the current directory.")

    Option(func = opt_not_yet, future = 1,
	long = ['no-print-directory'],
	help = "Turn off -w, even if it was turned on implicitly.")

    Option(func = opt_not_yet, future = 1,
	long = ['write-filenames'], arg = 'FILE',
	help = "Write all filenames examined into FILE.")

    Option(func = opt_not_yet, future = 1,
	short = 'W', long = ['what-if', 'new-file', 'assume-new'], arg = 'FILE',
	help = "Consider FILE to be changed.")

    def opt_warn(opt, arg):
        """The --warn option.  An argument to this option
        should be of the form <warning-class> or no-<warning-class>.
        The warning class is munged in order to get an actual class
        name from the SCons.Warnings module to enable or disable.
        The supplied <warning-class> is split on hyphens, each element
        is captialized, then smushed back together.  Then the string
        "SCons.Warnings." is added to the front and "Warning" is added
        to the back to get the fully qualified class name.

        For example, --warn=deprecated will enable the
        SCons.Warnings.DeprecatedWarning class.

        --warn=no-dependency will disable the
        SCons.Warnings.DependencyWarning class.

        As a special case, --warn=all and --warn=no-all
        will enable or disable (respectively) the base
        class of all warnings, which is SCons.Warning.Warning."""
        
        elems = string.split(string.lower(arg), '-')
        enable = 1
        if elems[0] == 'no':
            enable = 0
            del elems[0]

        if len(elems) == 1 and elems[0] == 'all':
            class_name = "Warning"
        else:
            class_name = string.join(map(string.capitalize, elems), '') + \
                         "Warning"
        try:
            clazz = getattr(SCons.Warnings, class_name)
        except AttributeError:
            sys.stderr.write("No warning type: '%s'\n" % arg)
        else:
            if enable:
                SCons.Warnings.enableWarningClass(clazz)
            else:
                SCons.Warnings.suppressWarningClass(clazz)

    Option(func = opt_warn,
           long = [ 'warn', 'warning' ], arg='WARNING-SPEC',
           help = "Enable or disable warnings.")


    # We want to preserve the --warn-undefined-variables option for
    # compatibility with GNU Make.  Unfortunately, this conflicts with
    # the --warn=type option that we're using for our own warning
    # control.  The getopt module reports "--warn not a unique prefix"
    # when both are defined.  We may be able to support both in the
    # future with a more robust getopt solution.
    #
    #Option(func = opt_not_yet, future = 1,
    #    long = ['warn-undefined-variables'],
    #    help = "Warn when an undefined variable is referenced.")

    Option(func = opt_not_yet, future = 1,
	short = 'Y', long = ['repository'], arg = 'REPOSITORY',
	help = "Search REPOSITORY for source and target files.")

    global short_opts
    global long_opts
    global opt_func
    for o in option_list:
	if o.short:
	    if o.func:
		for c in o.short:
		    opt_func['-' + c] = o.func
	    short_opts = short_opts + o.short
	    if o.arg:
		short_opts = short_opts + ":"
	if o.long:
	    if o.func:
		for l in o.long:
		    opt_func['--' + l] = o.func
	    if o.arg:
		long_opts = long_opts + map(lambda a: a + "=", o.long)
	    else:
		long_opts = long_opts + o.long

options_init()



def _SConstruct_exists(dirname=''):
    """This function checks that an SConstruct file exists in a directory.
    If so, it returns the path of the file. By default, it checks the
    current directory.
    """
    for file in ['SConstruct', 'Sconstruct', 'sconstruct']:
        sfile = os.path.join(dirname, file)
        if os.path.isfile(sfile):
            return sfile
    return None


def UsageString():
    help_opts = filter(lambda x: x.helpline, option_list)
    s = "Usage: scons [OPTION] [TARGET] ...\n" + "Options:\n" + \
	string.join(map(lambda x: x.helpline, help_opts), "\n") + "\n"
    return s



def _main():
    global scripts, num_jobs, task_class, calc, target_top

    targets = []

    # It looks like 2.0 changed the name of the exception class
    # raised by getopt.
    try:
	getopt_err = getopt.GetoptError
    except:
	getopt_err = getopt.error

    # Enable deprecated warnings by default.
    SCons.Warnings._warningOut = _scons_internal_warning
    SCons.Warnings.enableWarningClass(SCons.Warnings.DeprecatedWarning)

    try:
	cmd_opts, t = getopt.getopt(string.split(os.environ['SCONSFLAGS']),
					  short_opts, long_opts)
    except KeyError:
	# It's all right if there's no SCONSFLAGS environment variable.
	pass
    except getopt_err, x:
	_scons_user_warning("SCONSFLAGS " + str(x))
    else:
	for opt, arg in cmd_opts:
	    opt_func[opt](opt, arg)

    try:
        cmd_opts, args = getopt.getopt(sys.argv[1:], short_opts, long_opts)
    except getopt_err, x:
	_scons_user_error(x)
    else:
	for opt, arg in cmd_opts:
	    opt_func[opt](opt, arg)
        xmit_args = []
        for a in args:
            if '=' in a:
                xmit_args.append(a)
            else:
                targets.append(a)
        SCons.Script.SConscript._scons_add_args(xmit_args)

    if climb_up:
        target_top = '.'  # directory to prepend to targets
        script_dir = os.getcwd()  # location of script
        while script_dir and not _SConstruct_exists(script_dir):
            script_dir, last_part = os.path.split(script_dir)
            if last_part:
                target_top = os.path.join(last_part, target_top)
            else:
                script_dir = ''
        if script_dir:
	    print "scons: Entering directory %s" % script_dir
            os.chdir(script_dir)
        else:
            raise UserError, "No SConstruct file found."

    SCons.Node.FS.default_fs.set_toplevel_dir(os.getcwd())

    if not scripts:
        sfile = _SConstruct_exists()
        if sfile:
            scripts.append(sfile)

    if help_option == 'H':
	print UsageString()
	sys.exit(0)

    if not scripts:
        if help_option == 'h':
            # There's no SConstruct, but they specified -h.
            # Give them the options usage now, before we fail
            # trying to read a non-existent SConstruct file.
	    print UsageString()
	    sys.exit(0)
	else:
	    raise UserError, "No SConstruct file found."

    class Unbuffered:
        def __init__(self, file):
            self.file = file
        def write(self, arg):
            self.file.write(arg)
            self.file.flush()
        def __getattr__(self, attr):
            return getattr(self.file, attr)

    sys.stdout = Unbuffered(sys.stdout)

    sys.path = include_dirs + sys.path

    start_time = time.time()
    for script in scripts:
        SCons.Script.SConscript.SConscript(script)
    global sconscript_time
    sconscript_time = time.time() - start_time

    SCons.Node.FS.default_fs.chdir(SCons.Node.FS.default_fs.Top)

    if help_option == 'h':
	# They specified -h, but there was no Help() inside the
	# SConscript files.  Give them the options usage.
	print UsageString()
	sys.exit(0)

    if target_top:
        target_top = SCons.Node.FS.default_fs.Dir(target_top)
        
        if climb_up == 2 and not targets:
            # -D with default targets
            target_top = None
        elif climb_up == 3 and not targets:
            # -U with default targets
            default_targets = SCons.Script.SConscript.default_targets
            default_targets = filter(lambda x: x.cwd.srcpath == str(target_top),
                                     default_targets)
            SCons.Script.SConscript.default_targets = default_targets
            target_top = None

    if not targets:
        targets = SCons.Script.SConscript.default_targets

    def Entry(x, top = target_top):
        if isinstance(x, SCons.Node.Node):
            node = x
        else:
            try:
                node = SCons.Node.Alias.default_ans.lookup(x)
                if node is None:
                    node = SCons.Node.FS.default_fs.Entry(x,
                                                          directory = top,
                                                          create = 0)
            except UserError:
                string = "scons: *** Do not know how to make target `%s'." % x
                if not keep_going_on_error:
                    sys.stderr.write(string + "  Stop.\n")
                    sys.exit(2)
                sys.stderr.write(string + "\n")
                node = None
        if top and not node.is_under(top):
            if isinstance(node, SCons.Node.FS.Dir) and top.is_under(node):
                node = top
            else:
                node = None
        return node

    nodes = filter(lambda x: x is not None, map(Entry, targets))

    if not calc:
        if max_drift is not None:
            SCons.Sig.default_calc = SCons.Sig.Calculator(SCons.Sig.MD5,
                                                          max_drift)

        calc = SCons.Sig.default_calc

    taskmaster = SCons.Taskmaster.Taskmaster(nodes, task_class, calc)

    jobs = SCons.Job.Jobs(num_jobs, taskmaster)

    try:
        jobs.run()
    finally:
        SCons.Sig.write()

def main():
    try:
	_main()
    except SystemExit:
        pass
    except KeyboardInterrupt:
        print "Build interrupted."
        sys.exit(2)
    except SyntaxError, e:
        _scons_syntax_error(e)
    except UserError, e:
        _scons_user_error(e)
    except:
        _scons_other_errors()

    if print_time:
        total_time = time.time()-start_time
        scons_time = total_time-sconscript_time-command_time
        print "Total build time: %f seconds"%total_time
        print "Total SConscript file execution time: %f seconds"%sconscript_time
        print "Total SCons execution time: %f seconds"%scons_time
        print "Total command execution time: %f seconds"%command_time

    sys.exit(exit_status)