diff -r 000000000000 -r 6474c204b198 python/mozbuild/mozpack/manifests.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/mozbuild/mozpack/manifests.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,347 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import unicode_literals
+
+from contextlib import contextmanager
+import json
+
+from .files import (
+    AbsoluteSymlinkFile,
+    ExistingFile,
+    File,
+    FileFinder,
+    PreprocessedFile,
+)
+import mozpack.path as mozpath
+
+
+# This probably belongs in a more generic module. Where?
+@contextmanager
+def _auto_fileobj(path, fileobj, mode='r'):
+    if path and fileobj:
+        raise AssertionError('Only 1 of path or fileobj may be defined.')
+
+    if not path and not fileobj:
+        raise AssertionError('Must specified 1 of path or fileobj.')
+
+    if path:
+        fileobj = open(path, mode)
+
+    try:
+        yield fileobj
+    finally:
+        if path:
+            fileobj.close()
+
+
+class UnreadableInstallManifest(Exception):
+    """Raised when an invalid install manifest is parsed."""
+
+
+class InstallManifest(object):
+    """Describes actions to be used with a copier.FileCopier instance.
+
+    This class facilitates serialization and deserialization of data used to
+    construct a copier.FileCopier and to perform copy operations.
+
+    The manifest defines source paths, destination paths, and a mechanism by
+    which the destination file should come into existence.
+
+    Entries in the manifest correspond to the following types:
+
+      copy -- The file specified as the source path will be copied to the
+          destination path.
+
+      symlink -- The destination path will be a symlink to the source path.
+          If symlinks are not supported, a copy will be performed.
+
+      exists -- The destination path is accounted for and won't be deleted by
+          the FileCopier. If the destination path doesn't exist, an error is
+          raised.
+
+      optional -- The destination path is accounted for and won't be deleted by
+          the FileCopier. No error is raised if the destination path does not
+          exist.
+
+      patternsymlink -- Paths matched by the expression in the source path
+          will be symlinked to the destination directory.
+
+      patterncopy -- Similar to patternsymlink except files are copied, not
+          symlinked.
+
+      preprocess -- The file specified at the source path will be run through
+          the preprocessor, and the output will be written to the destination
+          path.
+
+    Version 1 of the manifest was the initial version.
+    Version 2 added optional path support
+    Version 3 added support for pattern entries.
+    Version 4 added preprocessed file support.
+    """
+
+    CURRENT_VERSION = 4
+
+    FIELD_SEPARATOR = '\x1f'
+
+    SYMLINK = 1
+    COPY = 2
+    REQUIRED_EXISTS = 3
+    OPTIONAL_EXISTS = 4
+    PATTERN_SYMLINK = 5
+    PATTERN_COPY = 6
+    PREPROCESS = 7
+
+    def __init__(self, path=None, fileobj=None):
+        """Create a new InstallManifest entry.
+
+        If path is defined, the manifest will be populated with data from the
+        file path.
+
+        If fileobj is defined, the manifest will be populated with data read
+        from the specified file object.
+
+        Both path and fileobj cannot be defined.
+        """
+        self._dests = {}
+        self._source_file = None
+
+        if path or fileobj:
+            with _auto_fileobj(path, fileobj, 'rb') as fh:
+                self._source_file = fh.name
+                self._load_from_fileobj(fh)
+
+    def _load_from_fileobj(self, fileobj):
+        version = fileobj.readline().rstrip()
+        if version not in ('1', '2', '3', '4'):
+            raise UnreadableInstallManifest('Unknown manifest version: ' %
+                version)
+
+        for line in fileobj:
+            line = line.rstrip()
+
+            fields = line.split(self.FIELD_SEPARATOR)
+
+            record_type = int(fields[0])
+
+            if record_type == self.SYMLINK:
+                dest, source = fields[1:]
+                self.add_symlink(source, dest)
+                continue
+
+            if record_type == self.COPY:
+                dest, source = fields[1:]
+                self.add_copy(source, dest)
+                continue
+
+            if record_type == self.REQUIRED_EXISTS:
+                _, path = fields
+                self.add_required_exists(path)
+                continue
+
+            if record_type == self.OPTIONAL_EXISTS:
+                _, path = fields
+                self.add_optional_exists(path)
+                continue
+
+            if record_type == self.PATTERN_SYMLINK:
+                _, base, pattern, dest = fields[1:]
+                self.add_pattern_symlink(base, pattern, dest)
+                continue
+
+            if record_type == self.PATTERN_COPY:
+                _, base, pattern, dest = fields[1:]
+                self.add_pattern_copy(base, pattern, dest)
+                continue
+
+            if record_type == self.PREPROCESS:
+                dest, source, deps, marker, defines = fields[1:]
+                self.add_preprocess(source, dest, deps, marker,
+                    self._decode_field_entry(defines))
+                continue
+
+            raise UnreadableInstallManifest('Unknown record type: %d' %
+                record_type)
+
+    def __len__(self):
+        return len(self._dests)
+
+    def __contains__(self, item):
+        return item in self._dests
+
+    def __eq__(self, other):
+        return isinstance(other, InstallManifest) and self._dests == other._dests
+
+    def __neq__(self, other):
+        return not self.__eq__(other)
+
+    def __ior__(self, other):
+        if not isinstance(other, InstallManifest):
+            raise ValueError('Can only | with another instance of InstallManifest.')
+
+        for dest in sorted(other._dests):
+            self._add_entry(dest, other._dests[dest])
+
+        return self
+
+    def _encode_field_entry(self, data):
+        """Converts an object into a format that can be stored in the manifest file.
+
+        Complex data types, such as ``dict``, need to be converted into a text
+        representation before they can be written to a file.
+        """
+        return json.dumps(data, sort_keys=True)
+
+    def _decode_field_entry(self, data):
+        """Restores an object from a format that can be stored in the manifest file.
+
+        Complex data types, such as ``dict``, need to be converted into a text
+        representation before they can be written to a file.
+        """
+        return json.loads(data)
+
+    def write(self, path=None, fileobj=None):
+        """Serialize this manifest to a file or file object.
+
+        If path is specified, that file will be written to. If fileobj is specified,
+        the serialized content will be written to that file object.
+
+        It is an error if both are specified.
+        """
+        with _auto_fileobj(path, fileobj, 'wb') as fh:
+            fh.write('%d\n' % self.CURRENT_VERSION)
+
+            for dest in sorted(self._dests):
+                entry = self._dests[dest]
+
+                parts = ['%d' % entry[0], dest]
+                parts.extend(entry[1:])
+                fh.write('%s\n' % self.FIELD_SEPARATOR.join(
+                    p.encode('utf-8') for p in parts))
+
+    def add_symlink(self, source, dest):
+        """Add a symlink to this manifest.
+
+        dest will be a symlink to source.
+        """
+        self._add_entry(dest, (self.SYMLINK, source))
+
+    def add_copy(self, source, dest):
+        """Add a copy to this manifest.
+
+        source will be copied to dest.
+        """
+        self._add_entry(dest, (self.COPY, source))
+
+    def add_required_exists(self, dest):
+        """Record that a destination file must exist.
+
+        This effectively prevents the listed file from being deleted.
+        """
+        self._add_entry(dest, (self.REQUIRED_EXISTS,))
+
+    def add_optional_exists(self, dest):
+        """Record that a destination file may exist.
+
+        This effectively prevents the listed file from being deleted. Unlike a
+        "required exists" file, files of this type do not raise errors if the
+        destination file does not exist.
+        """
+        self._add_entry(dest, (self.OPTIONAL_EXISTS,))
+
+    def add_pattern_symlink(self, base, pattern, dest):
+        """Add a pattern match that results in symlinks being created.
+
+        A ``FileFinder`` will be created with its base set to ``base``
+        and ``FileFinder.find()`` will be called with ``pattern`` to discover
+        source files. Each source file will be symlinked under ``dest``.
+
+        Filenames under ``dest`` are constructed by taking the path fragment
+        after ``base`` and concatenating it with ``dest``. e.g.
+
+           <base>/foo/bar.h -> <dest>/foo/bar.h
+        """
+        self._add_entry(mozpath.join(base, pattern, dest),
+            (self.PATTERN_SYMLINK, base, pattern, dest))
+
+    def add_pattern_copy(self, base, pattern, dest):
+        """Add a pattern match that results in copies.
+
+        See ``add_pattern_symlink()`` for usage.
+        """
+        self._add_entry(mozpath.join(base, pattern, dest),
+            (self.PATTERN_COPY, base, pattern, dest))
+
+    def add_preprocess(self, source, dest, deps, marker='#', defines={}):
+        """Add a preprocessed file to this manifest.
+
+        ``source`` will be passed through preprocessor.py, and the output will be
+        written to ``dest``.
+        """
+        self._add_entry(dest,
+            (self.PREPROCESS, source, deps, marker, self._encode_field_entry(defines)))
+
+    def _add_entry(self, dest, entry):
+        if dest in self._dests:
+            raise ValueError('Item already in manifest: %s' % dest)
+
+        self._dests[dest] = entry
+
+    def _get_deps(self, dest):
+        return {self._source_file} if self._source_file else set()
+
+    def populate_registry(self, registry):
+        """Populate a mozpack.copier.FileRegistry instance with data from us.
+
+        The caller supplied a FileRegistry instance (or at least something that
+        conforms to its interface) and that instance is populated with data
+        from this manifest.
+        """
+        for dest in sorted(self._dests):
+            entry = self._dests[dest]
+            install_type = entry[0]
+
+            if install_type == self.SYMLINK:
+                registry.add(dest, AbsoluteSymlinkFile(entry[1]))
+                continue
+
+            if install_type == self.COPY:
+                registry.add(dest, File(entry[1]))
+                continue
+
+            if install_type == self.REQUIRED_EXISTS:
+                registry.add(dest, ExistingFile(required=True))
+                continue
+
+            if install_type == self.OPTIONAL_EXISTS:
+                registry.add(dest, ExistingFile(required=False))
+                continue
+
+            if install_type in (self.PATTERN_SYMLINK, self.PATTERN_COPY):
+                _, base, pattern, dest = entry
+                finder = FileFinder(base, find_executables=False)
+                paths = [f[0] for f in finder.find(pattern)]
+
+                if install_type == self.PATTERN_SYMLINK:
+                    cls = AbsoluteSymlinkFile
+                else:
+                    cls = File
+
+                for path in paths:
+                    source = mozpath.join(base, path)
+                    registry.add(mozpath.join(dest, path), cls(source))
+
+                continue
+
+            if install_type == self.PREPROCESS:
+                registry.add(dest, PreprocessedFile(entry[1],
+                    depfile_path=entry[2],
+                    marker=entry[3],
+                    defines=self._decode_field_entry(entry[4]),
+                    extra_depends=self._get_deps(dest)))
+
+                continue
+
+            raise Exception('Unknown install type defined in manifest: %d' %
+                install_type)