setup.py

mercurial: implement import hook for handling C/Python modules

There are a handful of modules that have both pure Python and C
extension implementations. Currently, setup.py copies files from
mercurial/pure/*.py to mercurial/ during the install process if C
extensions are not available. This way, "import mercurial.X" will
work whether C extensions are available or not.

This approach has a few drawbacks. First, there aren't run-time checks
verifying the C extensions are loaded when they should be. This could
lead to accidental use of the slower pure Python modules. Second, the
C extensions aren't compatible with PyPy and running Mercurial with
PyPy requires installing Mercurial - you can't run ./hg from a source
checkout. This makes developing while running PyPy somewhat difficult.

This patch implements a PEP-302 import hook for finding and loading the
modules with both C and Python implementations. When a module with dual
implementations is requested for import, its import is handled by our
import hook.

The importer has a mechanism that controls what types of modules we
allow to load. We call this loading behavior the "module load policy."
There are 3 settings:

* Only load C extensions
* Only load pure Python
* Try to load C and fall back to Python

An environment variable allows overriding this policy at run time. This
is mainly useful for developers and for performing actions against the
source checkout (such as installing), which require overriding the
default (strict) policy about requiring C extensions.

The default mode for now is to allow both. This isn't proper and is
technically backwards incompatible. However, it is necessary to
implement a sane patch series that doesn't break the world during
future bisections. The behavior will be corrected in future patch.

We choose the main mercurial/__init__.py module for this code out of
necessity: in a future world, if the custom module importer isn't
registered, we'll fail to find/import certain modules when running
from a pure installation. Without the magical import-time side-effects,
*any* importer of mercurial.* modules would be required to call a
function to register our importer. I'm not a fan of import time side
effects and I initially attempted to do this. However, I was foiled by
our own test harness, which has numerous `python` invoked scripts that
"import mercurial" and fail because the importer isn't registered.
Realizing this problem is probably present in random Python scripts
that have been written over the years, I decided that sacrificing
purity for backwards compatibility is necessary. Plus, if you are
programming Python, "import" should probably "just work."

It's worth noting that now that we have a custom module loader, it
would be possible to hook up demand module proxies at this level
instead of replacing __import__. We leave this work for another time,
if it's even desired.

This patch breaks importing in environments where Mercurial modules
are loaded from a zip file (such as py2exe distributions). This will
be addressed in a subsequent patch.

#
# This is the mercurial setup script.
#
# 'python setup.py install', or
# 'python setup.py --help' for more options

import sys, platform
if getattr(sys, 'version_info', (0, 0, 0)) < (2, 6, 0, 'final'):
    raise SystemExit("Mercurial requires Python 2.6 or later.")

if sys.version_info[0] >= 3:
    def b(s):
        '''A helper function to emulate 2.6+ bytes literals using string
        literals.'''
        return s.encode('latin1')
    printf = eval('print')
    libdir_escape = 'unicode_escape'
else:
    libdir_escape = 'string_escape'
    def b(s):
        '''A helper function to emulate 2.6+ bytes literals using string
        literals.'''
        return s
    def printf(*args, **kwargs):
        f = kwargs.get('file', sys.stdout)
        end = kwargs.get('end', '\n')
        f.write(b(' ').join(args) + end)

# Solaris Python packaging brain damage
try:
    import hashlib
    sha = hashlib.sha1()
except ImportError:
    try:
        import sha
        sha.sha # silence unused import warning
    except ImportError:
        raise SystemExit(
            "Couldn't import standard hashlib (incomplete Python install).")

try:
    import zlib
    zlib.compressobj # silence unused import warning
except ImportError:
    raise SystemExit(
        "Couldn't import standard zlib (incomplete Python install).")

# The base IronPython distribution (as of 2.7.1) doesn't support bz2
isironpython = False
try:
    isironpython = (platform.python_implementation()
                    .lower().find("ironpython") != -1)
except AttributeError:
    pass

if isironpython:
    sys.stderr.write("warning: IronPython detected (no bz2 support)\n")
else:
    try:
        import bz2
        bz2.BZ2Compressor # silence unused import warning
    except ImportError:
        raise SystemExit(
            "Couldn't import standard bz2 (incomplete Python install).")

ispypy = "PyPy" in sys.version

import os, stat, subprocess, time
import re
import shutil
import tempfile
from distutils import log
if 'FORCE_SETUPTOOLS' in os.environ:
    from setuptools import setup
else:
    from distutils.core import setup
from distutils.core import Command, Extension
from distutils.dist import Distribution
from distutils.command.build import build
from distutils.command.build_ext import build_ext
from distutils.command.build_py import build_py
from distutils.command.install_lib import install_lib
from distutils.command.install_scripts import install_scripts
from distutils.spawn import spawn, find_executable
from distutils import file_util
from distutils.errors import CCompilerError, DistutilsExecError
from distutils.sysconfig import get_python_inc, get_config_var
from distutils.version import StrictVersion

convert2to3 = '--c2to3' in sys.argv
if convert2to3:
    try:
        from distutils.command.build_py import build_py_2to3 as build_py
        from lib2to3.refactor import get_fixers_from_package as getfixers
    except ImportError:
        if sys.version_info[0] < 3:
            raise SystemExit("--c2to3 is only compatible with python3.")
        raise
    sys.path.append('contrib')
elif sys.version_info[0] >= 3:
    raise SystemExit("setup.py with python3 needs --c2to3 (experimental)")

scripts = ['hg']
if os.name == 'nt':
    scripts.append('contrib/win32/hg.bat')

# simplified version of distutils.ccompiler.CCompiler.has_function
# that actually removes its temporary files.
def hasfunction(cc, funcname):
    tmpdir = tempfile.mkdtemp(prefix='hg-install-')
    devnull = oldstderr = None
    try:
        fname = os.path.join(tmpdir, 'funcname.c')
        f = open(fname, 'w')
        f.write('int main(void) {\n')
        f.write('    %s();\n' % funcname)
        f.write('}\n')
        f.close()
        # Redirect stderr to /dev/null to hide any error messages
        # from the compiler.
        # This will have to be changed if we ever have to check
        # for a function on Windows.
        devnull = open('/dev/null', 'w')
        oldstderr = os.dup(sys.stderr.fileno())
        os.dup2(devnull.fileno(), sys.stderr.fileno())
        objects = cc.compile([fname], output_dir=tmpdir)
        cc.link_executable(objects, os.path.join(tmpdir, "a.out"))
        return True
    except Exception:
        return False
    finally:
        if oldstderr is not None:
            os.dup2(oldstderr, sys.stderr.fileno())
        if devnull is not None:
            devnull.close()
        shutil.rmtree(tmpdir)

# py2exe needs to be installed to work
try:
    import py2exe
    py2exe.Distribution # silence unused import warning
    py2exeloaded = True
    # import py2exe's patched Distribution class
    from distutils.core import Distribution
except ImportError:
    py2exeloaded = False

def runcmd(cmd, env):
    if (sys.platform == 'plan9'
       and (sys.version_info[0] == 2 and sys.version_info[1] < 7)):
        # subprocess kludge to work around issues in half-baked Python
        # ports, notably bichued/python:
        _, out, err = os.popen3(cmd)
        return str(out), str(err)
    else:
        p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE, env=env)
        out, err = p.communicate()
        return out, err

def runhg(cmd, env):
    out, err = runcmd(cmd, env)
    # If root is executing setup.py, but the repository is owned by
    # another user (as in "sudo python setup.py install") we will get
    # trust warnings since the .hg/hgrc file is untrusted. That is
    # fine, we don't want to load it anyway.  Python may warn about
    # a missing __init__.py in mercurial/locale, we also ignore that.
    err = [e for e in err.splitlines()
           if not e.startswith(b('not trusting file')) \
              and not e.startswith(b('warning: Not importing')) \
              and not e.startswith(b('obsolete feature not enabled'))]
    if err:
        printf("stderr from '%s':" % (' '.join(cmd)), file=sys.stderr)
        printf(b('\n').join([b('  ') + e for e in err]), file=sys.stderr)
        return ''
    return out

version = ''

# Execute hg out of this directory with a custom environment which takes care
# to not use any hgrc files and do no localization.
env = {'HGMODULEPOLICY': 'py',
       'HGRCPATH': '',
       'LANGUAGE': 'C'}
if 'LD_LIBRARY_PATH' in os.environ:
    env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
if 'SystemRoot' in os.environ:
    # Copy SystemRoot into the custom environment for Python 2.6
    # under Windows. Otherwise, the subprocess will fail with
    # error 0xc0150004. See: http://bugs.python.org/issue3440
    env['SystemRoot'] = os.environ['SystemRoot']

if os.path.isdir('.hg'):
    cmd = [sys.executable, 'hg', 'log', '-r', '.', '--template', '{tags}\n']
    numerictags = [t for t in runhg(cmd, env).split() if t[0].isdigit()]
    hgid = runhg([sys.executable, 'hg', 'id', '-i'], env).strip()
    if numerictags: # tag(s) found
        version = numerictags[-1]
        if hgid.endswith('+'): # propagate the dirty status to the tag
            version += '+'
    else: # no tag found
        ltagcmd = [sys.executable, 'hg', 'parents', '--template',
                   '{latesttag}']
        ltag = runhg(ltagcmd, env)
        changessincecmd = [sys.executable, 'hg', 'log', '-T', 'x\n', '-r',
                           "only(.,'%s')" % ltag]
        changessince = len(runhg(changessincecmd, env).splitlines())
        version = '%s+%s-%s' % (ltag, changessince, hgid)
    if version.endswith('+'):
        version += time.strftime('%Y%m%d')
elif os.path.exists('.hg_archival.txt'):
    kw = dict([[t.strip() for t in l.split(':', 1)]
               for l in open('.hg_archival.txt')])
    if 'tag' in kw:
        version =  kw['tag']
    elif 'latesttag' in kw:
        if 'changessincelatesttag' in kw:
            version = '%(latesttag)s+%(changessincelatesttag)s-%(node).12s' % kw
        else:
            version = '%(latesttag)s+%(latesttagdistance)s-%(node).12s' % kw
    else:
        version = kw.get('node', '')[:12]

if version:
    f = open("mercurial/__version__.py", "w")
    f.write('# this file is autogenerated by setup.py\n')
    f.write('version = "%s"\n' % version)
    f.close()


try:
    from mercurial import __version__
    version = __version__.version
except ImportError:
    version = 'unknown'

class hgbuild(build):
    # Insert hgbuildmo first so that files in mercurial/locale/ are found
    # when build_py is run next.
    sub_commands = [('build_mo', None),

    # We also need build_ext before build_py. Otherwise, when 2to3 is
    # called (in build_py), it will not find osutil & friends,
    # thinking that those modules are global and, consequently, making
    # a mess, now that all module imports are global.

                    ('build_ext', build.has_ext_modules),
                   ] + build.sub_commands

class hgbuildmo(build):

    description = "build translations (.mo files)"

    def run(self):
        if not find_executable('msgfmt'):
            self.warn("could not find msgfmt executable, no translations "
                     "will be built")
            return

        podir = 'i18n'
        if not os.path.isdir(podir):
            self.warn("could not find %s/ directory" % podir)
            return

        join = os.path.join
        for po in os.listdir(podir):
            if not po.endswith('.po'):
                continue
            pofile = join(podir, po)
            modir = join('locale', po[:-3], 'LC_MESSAGES')
            mofile = join(modir, 'hg.mo')
            mobuildfile = join('mercurial', mofile)
            cmd = ['msgfmt', '-v', '-o', mobuildfile, pofile]
            if sys.platform != 'sunos5':
                # msgfmt on Solaris does not know about -c
                cmd.append('-c')
            self.mkpath(join('mercurial', modir))
            self.make_file([pofile], mobuildfile, spawn, (cmd,))


class hgdist(Distribution):
    pure = ispypy

    global_options = Distribution.global_options + \
                     [('pure', None, "use pure (slow) Python "
                        "code instead of C extensions"),
                      ('c2to3', None, "(experimental!) convert "
                        "code with 2to3"),
                     ]

    def has_ext_modules(self):
        # self.ext_modules is emptied in hgbuildpy.finalize_options which is
        # too late for some cases
        return not self.pure and Distribution.has_ext_modules(self)

class hgbuildext(build_ext):

    def build_extension(self, ext):
        try:
            build_ext.build_extension(self, ext)
        except CCompilerError:
            if not getattr(ext, 'optional', False):
                raise
            log.warn("Failed to build optional extension '%s' (skipping)",
                     ext.name)

class hgbuildpy(build_py):
    if convert2to3:
        fixer_names = sorted(set(getfixers("lib2to3.fixes") +
                                 getfixers("hgfixes")))

    def finalize_options(self):
        build_py.finalize_options(self)

        if self.distribution.pure:
            if self.py_modules is None:
                self.py_modules = []
            for ext in self.distribution.ext_modules:
                if ext.name.startswith("mercurial."):
                    self.py_modules.append("mercurial.pure.%s" % ext.name[10:])
            self.distribution.ext_modules = []
        else:
            h = os.path.join(get_python_inc(), 'Python.h')
            if not os.path.exists(h):
                raise SystemExit('Python headers are required to build '
                                 'Mercurial but weren\'t found in %s' % h)

    def find_modules(self):
        modules = build_py.find_modules(self)
        for module in modules:
            if module[0] == "mercurial.pure":
                if module[1] != "__init__":
                    yield ("mercurial", module[1], module[2])
            else:
                yield module

class buildhgextindex(Command):
    description = 'generate prebuilt index of hgext (for frozen package)'
    user_options = []
    _indexfilename = 'hgext/__index__.py'

    def initialize_options(self):
        pass

    def finalize_options(self):
        pass

    def run(self):
        if os.path.exists(self._indexfilename):
            f = open(self._indexfilename, 'w')
            f.write('# empty\n')
            f.close()

        # here no extension enabled, disabled() lists up everything
        code = ('import pprint; from mercurial import extensions; '
                'pprint.pprint(extensions.disabled())')
        out, err = runcmd([sys.executable, '-c', code], env)
        if err:
            raise DistutilsExecError(err)

        f = open(self._indexfilename, 'w')
        f.write('# this file is autogenerated by setup.py\n')
        f.write('docs = ')
        f.write(out)
        f.close()

class buildhgexe(build_ext):
    description = 'compile hg.exe from mercurial/exewrapper.c'

    def build_extensions(self):
        if os.name != 'nt':
            return
        if isinstance(self.compiler, HackedMingw32CCompiler):
            self.compiler.compiler_so = self.compiler.compiler # no -mdll
            self.compiler.dll_libraries = [] # no -lmsrvc90
        hv = sys.hexversion
        pythonlib = 'python%d%d' % (hv >> 24, (hv >> 16) & 0xff)
        f = open('mercurial/hgpythonlib.h', 'wb')
        f.write('/* this file is autogenerated by setup.py */\n')
        f.write('#define HGPYTHONLIB "%s"\n' % pythonlib)
        f.close()
        objects = self.compiler.compile(['mercurial/exewrapper.c'],
                                         output_dir=self.build_temp)
        dir = os.path.dirname(self.get_ext_fullpath('dummy'))
        target = os.path.join(dir, 'hg')
        self.compiler.link_executable(objects, target,
                                      libraries=[],
                                      output_dir=self.build_temp)

class hginstalllib(install_lib):
    '''
    This is a specialization of install_lib that replaces the copy_file used
    there so that it supports setting the mode of files after copying them,
    instead of just preserving the mode that the files originally had.  If your
    system has a umask of something like 027, preserving the permissions when
    copying will lead to a broken install.

    Note that just passing keep_permissions=False to copy_file would be
    insufficient, as it might still be applying a umask.
    '''

    def run(self):
        realcopyfile = file_util.copy_file
        def copyfileandsetmode(*args, **kwargs):
            src, dst = args[0], args[1]
            dst, copied = realcopyfile(*args, **kwargs)
            if copied:
                st = os.stat(src)
                # Persist executable bit (apply it to group and other if user
                # has it)
                if st[stat.ST_MODE] & stat.S_IXUSR:
                    setmode = int('0755', 8)
                else:
                    setmode = int('0644', 8)
                m = stat.S_IMODE(st[stat.ST_MODE])
                m = (m & ~int('0777', 8)) | setmode
                os.chmod(dst, m)
        file_util.copy_file = copyfileandsetmode
        try:
            install_lib.run(self)
        finally:
            file_util.copy_file = realcopyfile

class hginstallscripts(install_scripts):
    '''
    This is a specialization of install_scripts that replaces the @LIBDIR@ with
    the configured directory for modules. If possible, the path is made relative
    to the directory for scripts.
    '''

    def initialize_options(self):
        install_scripts.initialize_options(self)

        self.install_lib = None

    def finalize_options(self):
        install_scripts.finalize_options(self)
        self.set_undefined_options('install',
                                   ('install_lib', 'install_lib'))

    def run(self):
        install_scripts.run(self)

        if (os.path.splitdrive(self.install_dir)[0] !=
            os.path.splitdrive(self.install_lib)[0]):
            # can't make relative paths from one drive to another, so use an
            # absolute path instead
            libdir = self.install_lib
        else:
            common = os.path.commonprefix((self.install_dir, self.install_lib))
            rest = self.install_dir[len(common):]
            uplevel = len([n for n in os.path.split(rest) if n])

            libdir =  uplevel * ('..' + os.sep) + self.install_lib[len(common):]

        for outfile in self.outfiles:
            fp = open(outfile, 'rb')
            data = fp.read()
            fp.close()

            # skip binary files
            if b('\0') in data:
                continue

            data = data.replace(b('@LIBDIR@'), libdir.encode(libdir_escape))
            fp = open(outfile, 'wb')
            fp.write(data)
            fp.close()

cmdclass = {'build': hgbuild,
            'build_mo': hgbuildmo,
            'build_ext': hgbuildext,
            'build_py': hgbuildpy,
            'build_hgextindex': buildhgextindex,
            'install_lib': hginstalllib,
            'install_scripts': hginstallscripts,
            'build_hgexe': buildhgexe,
            }

packages = ['mercurial', 'mercurial.hgweb', 'mercurial.httpclient',
            'hgext', 'hgext.convert', 'hgext.highlight', 'hgext.zeroconf',
            'hgext.largefiles']

common_depends = ['mercurial/util.h']

osutil_ldflags = []

if sys.platform == 'darwin':
    osutil_ldflags += ['-framework', 'ApplicationServices']

extmodules = [
    Extension('mercurial.base85', ['mercurial/base85.c'],
              depends=common_depends),
    Extension('mercurial.bdiff', ['mercurial/bdiff.c'],
              depends=common_depends),
    Extension('mercurial.diffhelpers', ['mercurial/diffhelpers.c'],
              depends=common_depends),
    Extension('mercurial.mpatch', ['mercurial/mpatch.c'],
              depends=common_depends),
    Extension('mercurial.parsers', ['mercurial/dirs.c',
                                    'mercurial/manifest.c',
                                    'mercurial/parsers.c',
                                    'mercurial/pathencode.c'],
              depends=common_depends),
    Extension('mercurial.osutil', ['mercurial/osutil.c'],
              extra_link_args=osutil_ldflags,
              depends=common_depends),
    ]

try:
    from distutils import cygwinccompiler

    # the -mno-cygwin option has been deprecated for years
    compiler = cygwinccompiler.Mingw32CCompiler

    class HackedMingw32CCompiler(cygwinccompiler.Mingw32CCompiler):
        def __init__(self, *args, **kwargs):
            compiler.__init__(self, *args, **kwargs)
            for i in 'compiler compiler_so linker_exe linker_so'.split():
                try:
                    getattr(self, i).remove('-mno-cygwin')
                except ValueError:
                    pass

    cygwinccompiler.Mingw32CCompiler = HackedMingw32CCompiler
except ImportError:
    # the cygwinccompiler package is not available on some Python
    # distributions like the ones from the optware project for Synology
    # DiskStation boxes
    class HackedMingw32CCompiler(object):
        pass

packagedata = {'mercurial': ['locale/*/LC_MESSAGES/hg.mo',
                             'help/*.txt',
                             'default.d/*.rc',
                             'dummycert.pem']}

def ordinarypath(p):
    return p and p[0] != '.' and p[-1] != '~'

for root in ('templates',):
    for curdir, dirs, files in os.walk(os.path.join('mercurial', root)):
        curdir = curdir.split(os.sep, 1)[1]
        dirs[:] = filter(ordinarypath, dirs)
        for f in filter(ordinarypath, files):
            f = os.path.join(curdir, f)
            packagedata['mercurial'].append(f)

datafiles = []
setupversion = version
extra = {}

if py2exeloaded:
    extra['console'] = [
        {'script':'hg',
         'copyright':'Copyright (C) 2005-2015 Matt Mackall and others',
         'product_version':version}]
    # sub command of 'build' because 'py2exe' does not handle sub_commands
    build.sub_commands.insert(0, ('build_hgextindex', None))
    # put dlls in sub directory so that they won't pollute PATH
    extra['zipfile'] = 'lib/library.zip'

if os.name == 'nt':
    # Windows binary file versions for exe/dll files must have the
    # form W.X.Y.Z, where W,X,Y,Z are numbers in the range 0..65535
    setupversion = version.split('+', 1)[0]

if sys.platform == 'darwin' and os.path.exists('/usr/bin/xcodebuild'):
    version = runcmd(['/usr/bin/xcodebuild', '-version'], {})[0].splitlines()
    if version:
        version = version[0]
        if sys.version_info[0] == 3:
            version = version.decode('utf-8')
        xcode4 = (version.startswith('Xcode') and
                  StrictVersion(version.split()[1]) >= StrictVersion('4.0'))
        xcode51 = re.match(r'^Xcode\s+5\.1', version) is not None
    else:
        # xcodebuild returns empty on OS X Lion with XCode 4.3 not
        # installed, but instead with only command-line tools. Assume
        # that only happens on >= Lion, thus no PPC support.
        xcode4 = True
        xcode51 = False

    # XCode 4.0 dropped support for ppc architecture, which is hardcoded in
    # distutils.sysconfig
    if xcode4:
        os.environ['ARCHFLAGS'] = ''

    # XCode 5.1 changes clang such that it now fails to compile if the
    # -mno-fused-madd flag is passed, but the version of Python shipped with
    # OS X 10.9 Mavericks includes this flag. This causes problems in all
    # C extension modules, and a bug has been filed upstream at
    # http://bugs.python.org/issue21244. We also need to patch this here
    # so Mercurial can continue to compile in the meantime.
    if xcode51:
        cflags = get_config_var('CFLAGS')
        if cflags and re.search(r'-mno-fused-madd\b', cflags) is not None:
            os.environ['CFLAGS'] = (
                os.environ.get('CFLAGS', '') + ' -Qunused-arguments')

setup(name='mercurial',
      version=setupversion,
      author='Matt Mackall and many others',
      author_email='[e-mail]',
      url='https://mercurial-scm.org/',
      download_url='https://mercurial-scm.org/release/',
      description=('Fast scalable distributed SCM (revision control, version '
                   'control) system'),
      long_description=('Mercurial is a distributed SCM tool written in Python.'
                        ' It is used by a number of large projects that require'
                        ' fast, reliable distributed revision control, such as '
                        'Mozilla.'),
      license='GNU GPLv2 or any later version',
      classifiers=[
          'Development Status :: 6 - Mature',
          'Environment :: Console',
          'Intended Audience :: Developers',
          'Intended Audience :: System Administrators',
          'License :: OSI Approved :: GNU General Public License (GPL)',
          'Natural Language :: Danish',
          'Natural Language :: English',
          'Natural Language :: German',
          'Natural Language :: Italian',
          'Natural Language :: Japanese',
          'Natural Language :: Portuguese (Brazilian)',
          'Operating System :: Microsoft :: Windows',
          'Operating System :: OS Independent',
          'Operating System :: POSIX',
          'Programming Language :: C',
          'Programming Language :: Python',
          'Topic :: Software Development :: Version Control',
      ],
      scripts=scripts,
      packages=packages,
      ext_modules=extmodules,
      data_files=datafiles,
      package_data=packagedata,
      cmdclass=cmdclass,
      distclass=hgdist,
      options={'py2exe': {'packages': ['hgext', 'email']},
               'bdist_mpkg': {'zipdist': False,
                              'license': 'COPYING',
                              'readme': 'contrib/macosx/Readme.html',
                              'welcome': 'contrib/macosx/Welcome.html',
                              },
               },
      **extra)