Moving mixxx/* to the root. A new era begins!

1 files changed, 532 insertions, 0 deletions

diff --git a/build/osx/OSConsX.py b/build/osx/OSConsX.py
new file mode 100644
index 0000000000..a194c9b734
--- /dev/null
+++ b/build/osx/OSConsX.py
@@ -0,0 +1,532 @@
+"""OSConsX.py - scons support for building applications on OS X using SCons.
+Functions to build .app bundles and .dmg images, and to use otool(1) to trace out the needed libraries.
+
+usage:
+
+env = Environment(tools = ['OSConsX', toolpath=['path/to/osconsx'])
+env.App('
+
+By <nick@kousu.ca> January 16th 2009
+License: 2-clause BSD (XXX put a proper notice here)
+
+
+Please email me with questions/comments/patches!
+
+TODO:
+-add a CheckFramework() call that looks for a framework (and maybe adds to CXXFLAGS||CPPATH||LINKFLAGS if found)
+"""
+
+
+
+import sys, os, shutil, stat
+import SCons
+from SCons.Builder import Builder
+from SCons.Script import *
+import otool
+
+#Dev info:
+#http://doc.trolltech.com/qq/qq09-mac-deployment.html
+#http://www.scons.org/wiki/MacOSX (not very featureful, but the tip about resource forks might be important (wait did I say important? I meant out of date. see CpMac(1))
+
+#oooh, you can use warnings! just call "warn()"
+
+def system(s):
+    "wrap system() to give us feedback on what it's doing"
+    "anything using this call should be fixed to use SCons's declarative style (once you figure that out, right nick?)"
+    print s,
+    sys.stdout.flush() #ignore line buffering..
+    result = os.system(s)
+    print
+    return result
+
+
+
+def no_sources(target, source, env):
+    "an emitter that forces null sources, so that we don't need to have the user explicitly say there are no dependencies (SCons assumes that if you are building 'X.out' then you need 'X.in')"
+    return target, []
+
+
+
+def InstallDir(target, source, env): #XXX this belongs not in this module
+    "copies the given source dir inside of the given target dir"
+    #XXX could be rewritten better with schemey-recursion as "if source is File: env.Install(), elif source is Dir, scan the dir and recurse"
+    #SCons doesn't really like using directories as targets. Like, at all.
+    #Mkdir(os.path.join(str(target), str(source)))
+    #translate install(a/, b/) to install(a/b/, [files in b])
+    contents = Glob(os.path.join(str(source), "*")) #XXX there's probably a cleaner way that SCons has to do this
+    #print "contents:",contents
+    files = filter(lambda f: isinstance(f, SCons.Node.FS.File), contents)
+    folders = filter(lambda f: isinstance(f, SCons.Node.FS.Dir), contents)
+    #print map(str, folders)
+    name = os.path.basename(str(source))
+
+    #install the files local to this
+    nodes = env.Install(Dir(os.path.join(str(target), name)), files)
+
+    #now recursively install the subfolders
+    for f in folders:
+        nodes+=InstallDir(Dir(os.path.join(str(target), name)), f, env)
+    return nodes
+
+#okay, this works. It could be done better (make better use of SCons's declarativity, look at http://frungy.org/~tpot/weblog/2008/05/02#scons-rpm2 for ideas)
+#Specifically, this does file copying by itself, instead of telling SCons about it.
+#On the other hand, the files it is copying are not really part of the build process, they are tmp files, so maybe it works....
+#BUG: scons doesn't track that it's built the .dmg. It decides it needs to build it every time "because it doesn't exist". Perhaps has to do with the lack s
+def build_dmg(target, source, env):
+    "takes the given source files, makes a temporary directory, copies them all there, and then packages that directory into a .dmg"
+    #TODO: make emit_dmg emit that we are making the Dmg that we are making
+
+    #since we are building into a single .dmg, coerce target to point at the actual name
+    assert len(target) == 1
+    target = target[0]
+
+    # I'm going to let us overwrite the .dmg for now - Albert
+    #if os.path.exists(str(target)+".dmg"): #huhh? why do I have to say +.dmg here? I thought scons was supposed to handle that
+    #    raise Exception(".dmg target already exists.")
+
+    #if 'DMG_DIR' in env: .... etc fill me in please
+    dmg = os.tmpnam()+"-"+env['VOLNAME'].strip()+"-dmg" #create a directory to build the .dmg root from
+
+    #is os.system the best thing for this? Can't we declare that these files need to be moved somehow?
+    #aah there must be a more SCons-ey (i.e. declarative) way to do all this; the trouble with doing
+    os.mkdir(dmg)
+    for f in source:
+        print "Copying",f
+        a, b = str(f), os.path.join(dmg, os.path.basename(str(f.path)))
+        if isinstance(f, SCons.Node.FS.Dir): #XXX there's a lot of cases that could throw this off, particularly if you try to pass in subdirs
+            copier = shutil.copytree
+        elif isinstance(f, SCons.Node.FS.File):
+            copier = shutil.copy
+        else:
+            raise Exception("%s is neither Dir nor File node? Bailing out." % f)
+
+        try:
+            copier(a, b)
+        except Exception, e:
+            print "ERRRR", e
+            raise Exception("Error copying %s: " % (a,), e)
+
+    # Symlink Applications to /Applications
+    os.system('ln -s /Applications %s' % os.path.join(dmg, 'Applications'))
+
+    if env['ICON']:
+        env['ICON'] = File(str(env['ICON'])) #make sure the given file is an icon; scons does this wrapping for us on sources and targets but not on environment vars (obviously, that would be stupid).
+        #XXX this doesn't seem to work, at least not on MacOS 10.5
+        #the MacFUSE people have solved it, though, see "._" in http://www.google.com/codesearch/p?hl=en#OXKFx3-7cSY/tags/macfuse-1.0.0/filesystems-objc/FUSEObjC/FUSEFileSystem.m&q=volumeicon
+        #appearently it requires making a special volume header file named "._$VOLNAME" with a binary blob in it
+        #But also the Qt4 dmg has a working icon, and it has no ._$VOLNAME file
+        shutil.copy(str(env['ICON']), os.path.join(dmg, ".VolumeIcon.icns")) #XXX bug: will crash if not given an icon file
+        system('SetFile -a C "%s"' % dmg) #is there an sconsey way to declare this? Would be nice so that it could write what
+
+
+    if system("hdiutil create -srcfolder %s -format UDBZ -ov -volname %s %s" % (dmg, env['VOLNAME'], target)):
+        raise Exception("hdiutil create failed")
+
+    shutil.rmtree(dmg)
+
+Dmg = Builder(action = build_dmg, suffix=".dmg")
+
+class Bundle(SCons.Node.Node):
+    "until SCons gets its shit together and is able to handle having directories as targets, we use this"
+    def __init__(self, path):
+        path = str(path) #decast the object from being a File or a Dir
+        self.path = path
+        SCons.Node.Node.__init__(self)
+        self.clear()
+        assert self.path == path, "Node constructor overwrote .path :("
+    def __str__(self):
+        return self.path
+    def __repr__(self):
+        return 'Bundle("%s")' % self.path
+
+
+
+def write_file(target, source, env):
+    data = env['DATA']
+    for t in target:
+        f = open(str(t), "wb")
+        f.write(data)
+        f.close()
+
+
+#should be in a different module, really
+Writer = Builder(action = write_file, emitter = no_sources)
+
+
+
+
+
+def build_app(target, source, env):
+    """
+
+    PLUGINS - a list of plugins to install; as a feature/hack/bug (inspired by Qt, but probably needed by other libs) you can pass a tuple where the first is the file/node and the second is the folder under PlugIns/ that you want it installed to
+    """
+    #TODO: make it strip(1) the installed binary (saves about 1Mb)
+
+    #EEEP: this code is pretty flakey because I can't figure out how to force; have asked the scons list about it
+
+
+    #This doesn't handle Frameworks correctly, only .dylibs
+    #useful to know: http://developer.apple.com/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/FrameworkAnatomy.html#//apple_ref/doc/uid/20002253
+     #^ so you do have to copy in and _entire_ framework to be sure...
+     #but for some frameworks it's okay to pretend they are regular
+
+
+    bundle = target[0]
+    binary = source[0]
+
+    #this is copied from emit_app, which is unfortunate
+    contents = Dir(os.path.join(str(bundle), "Contents"))
+    MacOS = Dir(os.path.join(str(contents), "MacOS/"))
+    frameworks = Dir(os.path.join(str(contents), "Frameworks")) #we put both frameworks and standard unix sharedlibs in here
+    plugins = Dir(os.path.join(str(contents), "PlugIns"))
+
+    #installed_bin = source[-1] #env['APP_INSTALLED_BIN']
+    installed_bin = os.path.join(str(MacOS), os.path.basename(str(binary)))
+
+    strip = bool(env.get('STRIP',False))
+
+    otool_local_paths = env.get('OTOOL_LOCAL_PATHS', [])
+    otool_system_paths = env.get('OTOOL_SYSTEM_PATHS', [])
+
+    "todo: expose the ability to override the list of System dirs"
+    #ugh, I really don't like this... I wish I could package it up nicer. I could use a Builder but then I would have to pass in to the builder installed_bin which seems backwards since
+
+
+    #could we use patch_lib on the initial binary itself????
+
+    def embed_lib(abs):
+        "get the path to embed library abs in the bundle"
+        name = os.path.basename(abs)
+        return os.path.join(str(frameworks), name)
+
+    def relative(emb):
+        "compute the path of the given embedded binary relative to the binary, i.e. @executable_path/../+..."
+        # assume that we start in X.app/Contents/, since we know neccessarily that @executable_path/../ gives us that
+        # so then we only need
+        base = os.path.abspath(str(installed_bin))
+        emb = os.path.abspath(emb) #XXX is abspath really necessary?
+        down = emb[len(os.path.commonprefix([base, emb])):] #the path from Contents/ down to the file. Since we are taking away the length of the common prefix we are left with only what is unique to the embedded library's path
+        return os.path.join("@executable_path/../", down)
+
+    #todo: precache all this shit, in case we have to change the install names of a lot of libraries
+
+    def automagic_references(embedded): #XXX bad name
+        "modify a binary file to patch up all it's references"
+
+        for ref in otool.dependencies(embedded):
+            if ref in locals:
+                embd = locals[ref][1] #the path that this reference is getting embedded at
+                otool.change_ref(str(embedded), ref, relative(embd))
+
+
+    def patch_lib(embedded):
+        otool.change_id(embedded, relative(embedded)) #change the name the library knows itself as
+        automagic_references(embedded)
+        if strip: #XXX stripping seems to only work on libs compiled a certain way, todo: try out ALL the options, see if can adapt it to work on every sort of lib
+            system("strip -S '%s' 2>/dev/null" % embedded), #(the stripping fails with ""symbols referenced by relocation entries that can't be stripped"" for some obscure Apple-only reason sometimes, related to their hacks to gcc---it depends on how the file was compiled; since we don't /really/ care about this we just let it silently fail)
+
+
+
+    #Workarounds for a bug/feature in SCons such that it doesn't neccessarily run the source builders before the target builders (wtf scons??)
+    Execute(Mkdir(contents))
+    Execute(Mkdir(MacOS))
+    Execute(Mkdir(frameworks))
+    Execute(Mkdir(plugins))
+
+
+    #XXX locals should be keyed by absolute path to the lib, not by reference; that way it's easy to tell when a lib referenced in two different ways is actually the same
+    #XXX rename locals => embeds
+    #precache the list of names of libs we are using so we can figure out if a lib is local or not (and therefore a ref to it needs to be updated) #XXX it seems kind of wrong to only look at the basename (even if, by the nature of libraries, that must be enough) but there is no easy way to compute the abspath
+    locals = {} # [ref] => (absolute_path, embedded_path) (ref is the original reference from looking at otool -L; we use this to decide if two libs are the same)
+
+    #XXX it would be handy if embed_dependencies returned the otool list for each ref it reads..
+    for ref, path in otool.embed_dependencies(str(binary), LOCAL=otool_local_paths, SYSTEM=otool_system_paths):
+        locals[ref] = (path, embed_lib(path))
+
+    plugins_l = [] #XXX bad name #list of tuples (source, embed) of plugins to stick under the plugins/ dir
+    for p in env['PLUGINS']: #build any neccessary dirs for plugins (siiiigh)
+        embedded_p = os.path.join(str(plugins), os.path.basename(str(p)))
+        plugins_l.append(  (str(p), embedded_p)  )
+
+    for subdir, p in env['QT_HACK']:
+            Execute(Mkdir(os.path.join(str(plugins), subdir)))
+            embedded_p = os.path.join(str(plugins), subdir, os.path.basename(str(p)))
+            plugins_l.append( (p, embedded_p) )
+
+    print "Scanning plugins for new dependencies:"
+    for p, ep in plugins_l:
+        print "Scanning plugin", p
+        for ref, path in otool.embed_dependencies(p, LOCAL=otool_local_paths, SYSTEM=otool_system_paths):
+            if ref not in locals:
+                locals[ref] = path, embed_lib(path)
+            else:
+                assert path == locals[ref][0], "Path '%s' is not '%s'" % (path, locals[ref][0])
+
+    #we really should have a libref-to-abspath function somewhere... right now it's inline in embed_dependencies()
+    #better yet, make a Frameworks type that you say Framework("QtCore") and then can use that as a dependency
+
+
+    print "Installing main binary:"
+    Execute(Copy(installed_bin, binary)) #e.g. this SHOULD be an env.Install() call, but if scons decides to run build_app before that env.Install then build_app fails and brings the rest of the build with it, of course
+    for ref in otool.dependencies(str(installed_bin)):
+        if ref in locals:
+            embedded = locals[ref][1]
+            otool.change_ref(str(installed_bin), ref, relative(embedded)) #change the reference to the library in the program binary
+    if strip:
+        system("strip '%s'" % installed_bin)
+
+
+    print "Installing embedded libs:"
+    for ref, (abs, embedded) in locals.iteritems():
+        Execute(Copy(embedded, abs))
+        if not os.access(embedded, os.W_OK):
+            print "Adding write permissions to %s" % embedded_p
+            mode = os.stat(embedded).st_mode
+            os.chmod(embedded, mode | stat.S_IWUSR)
+        patch_lib(embedded)
+
+
+    print "Installing plugins:"
+    for p, embedded_p in plugins_l:
+        print "installing", p,"to",embedded_p
+        Execute(Copy(embedded_p, p)) #:/
+        patch_lib(str(embedded_p))
+
+
+def emit_app(target, source, env):
+    """The first source is the binary program file, the rest are files/folders to include in the App's Resources directory.
+
+    extra variables available:
+    ICON - the filename of the icon file to use, used in package metadata. If not specified defaults to 'application.icns' (which should be in your sources list, but if you spec a file not in there it'll actually add it for you)
+    SIGNATURE - the bundle signature, a four byte code. If not specified uses the first four characters of the bundle name.
+    PLUGINS - a list of files/folders to place in Contents/PlugIns (Adium uses Contents/PlugIns, Audacity uses plug-ins AND Contents/plug-ins..., Apple Mail uses Contents/PlugIns, so that's what we should stick with)
+    IDENTIFIER - An identifier string that specifies the application type of the bundle in reverse DNS format.
+    DISPLAY_NAME - The application name to be encoded in the Plist and menu bar.
+    SHORT_VERSION - Specifies the release version number of the bundle, which identifies a released iteration of the application. The release version number is a string comprised of three period-separated integers
+    COPYRIGHT - Human readable copyright (NSHumanReadableCopyright)
+    CATEGORY - Your application's category.
+    """
+
+
+    #TODO: implement a FRAMEWORKS= arg, or maybe a Framework() builder so that we can declare "this app depends on these frameworks"; then look in env['FRAMEWORKS'] and env['LIBS'] and figure out the library dependencies *ahead of time* so that we can get scons to copy them (and so that we needn't redo their install_name's &c all the time)
+
+    #bah, unless we decide to change the interface so you pass the app icon in as a separate param, then we *have* to change Mixxx to work properly with the Resources/ dir
+
+
+    assert len(target) == 1
+    bundle = target[0]
+    #pull the binary off the front since it's a special case
+    binary, resources = source[0], source[1:]
+    try:
+        icon = env['ICON']
+    except KeyError:
+        icon = "application.icns"
+
+    try:
+        plugins = env['PLUGINS']
+    except KeyError:
+        plugins = env['PLUGINS'] = []
+
+    #so, this doesn't work realistically because if the passed in icon is a remote path then shit clashes
+    #but still it might be useful. XXX think this through.
+    #if icon not in [str(ff) for ff in source]:
+    #    source.append(File(icon))
+
+    bundle_type = 'APPL'
+
+    try:
+        bundle_signature = env['SIGNATURE']
+    except KeyError:
+        bundle_signature = str(bundle)[:4].lower()
+    assert len(bundle_signature) == 4, "Bundle signature must be four bytes"
+
+
+    #coerce the target to a Bundle
+    #XXX huh, that's weird, it builds fine now... oh shit it's because it caches types in its database
+    #we don't need to tell it Bundle(), we just need to postpend the .app
+    #it seems that if we tell Builder "suffix = '.app'" then it _at that point_ assumes that $NAME.app is a file, which then causes "TypeError: Tried to lookup File 'Mixxx.app' as a Dir.:"
+    #so just work around that here
+    if type(bundle) != Bundle:
+        bundle = Bundle(str(bundle)+".app")
+
+    bundle_identifier = env['IDENTIFIER']
+    bundle_version = env['VERSION']
+    bundle_display_name = env['DISPLAY_NAME']
+    bundle_short_version_string = env['SHORT_VERSION']
+    human_readable_copyright = env['COPYRIGHT']
+    application_category_type = env['CATEGORY']
+    minimum_osx_version = env['MINIMUM_OSX_VERSION']
+
+
+    #BUG: if the icon file is changed but nothing else then the plist doesn't get rebuilt (but since it's a str() and not a Node() there's no clean way to hook this in)
+
+    #Precache some the important paths
+    #idea: hide these in the env[]?
+    bundle = Dir(str(bundle))    #coerce the bundle target into being a Dir
+    contents = Dir(os.path.join(str(bundle), "Contents"))
+    frameworks = Dir(os.path.join(str(contents), "Frameworks")) #we put both frameworks and standard unix sharedlibs in here
+
+    env['APP_RESOURCES'] = Dir(os.path.join(str(contents), "Resources"))
+
+
+    #env['APP_INSTALLED_BIN'] = installed_bin
+
+
+
+    #Generate the .plist and PkgInfo files
+
+    #"""The contents of the PkgInfo file are the 4-byte package type followed by the 4-byte signature of your application.
+    #Thus, for the TextEdit application, whose type is 'APPL' and whose signature is 'ttxt', the file would contain the ASCII string "APPLttxt"."""
+    #So, we use the first four characters of the app
+    env.Writer(File(os.path.join(str(contents),"PkgInfo")), [], DATA = "%s%s" % (bundle_type, bundle_signature))
+
+    #.title() in the next line is used to make sure the titlebar on OS X has the capitalized name of the app
+    plist_data = {'CFBundleExecutable': binary.name.title(),
+                  'CFBundleIconFile': icon,
+                  'CFBundlePackageType': bundle_type,
+                  'CFBundleSignature': bundle_signature,
+                  'CFBundleIdentifier': bundle_identifier,
+                  'CFBundleDisplayName': bundle_display_name,
+                  'CFBundleVersion': bundle_version,
+                  'CFBundleShortVersionString': bundle_short_version_string,
+                  'NSHumanReadableCopyright': human_readable_copyright,
+                  'LSApplicationCategoryType': application_category_type,
+                  'LSMinimumSystemVersion': minimum_osx_version}
+    if env['FOR_APP_STORE']:
+        plist_data['ForAppStore'] = 'yes'
+    env.Plist(os.path.join(str(contents), "Info"), PLIST=plist_data)
+
+    #NB: only need CFBundleExecutale if the binary name differs from the bundle name
+    #todo:
+    """Application Keys
+
+    At a minimum, all applications should contain the following keys in their information property list file:
+    CFBundleDisplayName
+      CFBundleIdentifier
+      CFBundleName
+      CFBundlePackageType
+      CFBundleShortVersionString
+      CFBundleSignature
+      CFBundleVersion
+      LSHasLocalizedDisplayName
+      NSHumanReadableCopyright
+      NSAppleScriptEnabled"""
+      #further: we should support generating document associations
+
+    resource_map = env.get('APP_RESOURCES_MAP', {})
+
+    for i in resources:
+        path = resource_map.get(str(i), '')
+        target = env['APP_RESOURCES']
+        if path != '':
+            target = Dir(os.path.join(str(target), path))
+        if isinstance(i, SCons.Node.FS.Dir):
+            InstallDir(target, i, env)
+        elif isinstance(i, SCons.Node.FS.File) or isinstance(i, basestring):
+            env.Install(target, i)
+
+    plugins = env['PLUGINS']
+
+    return bundle, source+plugins #+[installed_bin]
+
+App = Builder(action = build_app, emitter = emit_app)
+
+def codesign_path(identity, keychain, entitlements, path):
+    print "Codesigning: ", path
+    command = "codesign -f -s '%s'%s%s %s" % (
+        identity,
+        ' --keychain %s' % keychain if keychain else '',
+        ' --entitlements %s' % entitlements if entitlements else '',
+        path)
+    if system(command) != 0:
+        raise Exception('codesign failed: ' + command)
+
+def do_codesign(target, source, env):
+    # target[0] is a File object, coerce to string to get its path (usually
+    # something like osxXX_build/Mixxx)
+    bundle = str(target[0])
+
+    # HACK(XXX) SCons can't have a Dir which is a target so we append .app here
+    # since our actual target (the thing we want to codesign) is the bundle
+    # folder.
+    if not bundle.endswith('.app'):
+        bundle += '.app'
+
+    binary_path = os.path.join(bundle, "Contents", "MacOS")
+    frameworks_path = os.path.join(bundle, 'Contents', 'Frameworks')
+    plugins_path = os.path.join(bundle, 'Contents', 'PlugIns')
+
+    keychain = env.get('CODESIGN_KEYCHAIN', None)
+    keychain_password = env.get('CODESIGN_KEYCHAIN_PASSWORD', None)
+    installer_identity = env.get('CODESIGN_INSTALLER_IDENTITY', None)
+    application_identity = env.get('CODESIGN_APPLICATION_IDENTITY', None)
+    entitlements = env.get('CODESIGN_ENTITLEMENTS', None)
+    if application_identity is not None:
+        if keychain and keychain_password is not None:
+            print "Unlocking keychain:"
+            if system("security unlock-keychain -p '%s' %s" % (keychain_password, keychain)) != 0:
+                raise Exception('Could not unlock keychain.')
+
+        # Codesign the frameworks.
+        for root, dirs, files in os.walk(frameworks_path):
+            for framework in dirs + files:
+                codesign_path(application_identity, keychain, entitlements, os.path.join(root, framework))
+            # Don't descend.
+            del dirs[:]
+
+        # Codesign binaries.
+        for root, dirs, files in os.walk(binary_path):
+            for filename in files:
+                codesign_path(application_identity, keychain, entitlements, os.path.join(root, filename))
+        # Codesign plugins.
+        for root, dirs, files in os.walk(plugins_path):
+            for filename in files:
+                codesign_path(application_identity, keychain, entitlements, os.path.join(root, filename))
+        # Codesign the bundle.
+        codesign_path(application_identity, keychain, entitlements, bundle)
+CodeSign = Builder(action = do_codesign)
+
+def build_plist(target, source, env):
+    d = env['PLIST']
+    assert len(target) == 1
+    target = target[0]
+
+    #XXX what happens if PLIST isn't passed in?
+    #todo: make this support more than just <string>. but to do that means more research and fuck that at this point
+
+    #this is a bad way to do this, should really use an XML writer... but fuck that
+    outer_template = """<?xml version="1.0" encoding="UTF-8"?>
+    <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+    <plist version="1.0">
+    <dict>
+    %s
+    </dict>
+    </plist>"""
+    inner_template = """<key>%s</key><string>%s</string>"""
+
+    inner = str.join('\n', [inner_template % (k,v) for k,v in d.iteritems()])
+    plist = outer_template % inner
+
+    f = open(str(target), "w")
+    f.write(plist)
+    f.close()
+
+
+Plist = Builder(action = build_plist, emitter = no_sources, suffix="plist")
+
+#TODO: want to be able to say env.Append(FRAMEWORKS=['QtCore']) and have it get translated properly... is there any way to do that here?
+
+
+def generate(env):
+    env['BUILDERS']['App'] = App
+    env['BUILDERS']['Dmg'] = Dmg
+    env['BUILDERS']['Plist'] = Plist
+    env['BUILDERS']['Writer'] = Writer #this should be in a different module, really
+    env['BUILDERS']['CodeSign'] = CodeSign
+
+
+def exists(env):
+    return os.platform == 'darwin'
+
+