Create zip_file() rule

This doesn't work quite the same way as Fileset(). But it should be able
to serve as a decent replacement.

The important part of this design is that zips can depend on other zips.
Therefore definitions don't have to be monolithic. This will be
important when migrating the Domain Registry codebase, because our
Fileset() definitions are dispersed across many BUILD files. So we'll be
able to migrate to zip_file() with the least amount of intrusiveness.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129034885

java/google/registry/builddefs/BUILD

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+package(default_visibility = ["//java/google/registry:registry_project"])
+
+licenses(["notice"])  # Apache 2.0
+

java/google/registry/builddefs/defs.bzl

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+# Copyright 2016 The Domain Registry Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Common routines for Domain Registry build rules."""
+
+ZIPPER = "@bazel_tools//tools/zip:zipper"
+
+_OUTPUT_DIRS = ("bazel-out/", "bazel-genfiles/")
+
+def runpath(f):
+  """Figures out the proper runfiles path for a file."""
+  for prefix in _OUTPUT_DIRS:
+    if f.path.startswith(prefix):
+      return f.short_path
+  return f.path

java/google/registry/builddefs/zip_file.bzl

@@ -0,0 +1,113 @@
+# Copyright 2016 The Domain Registry Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+
+load('//java/google/registry/builddefs:defs.bzl', 'ZIPPER', 'runpath')
+
+def _impl(ctx):
+  """Implementation of zip_file() rule."""
+  for s, d in ctx.attr.mappings.items():
+    if (s.startswith('/') or s.endswith('/') or
+        d.startswith('/') or d.endswith('/')):
+      fail('mappings should not begin or end with slash')
+  mapped = _map_sources(ctx.files.srcs, ctx.attr.mappings)
+  cmd = [
+      'set -e',
+      'repo="$(pwd)"',
+      'zipper="${repo}/%s"' % ctx.file._zipper.path,
+      'archive="${repo}/%s"' % ctx.outputs.out.path,
+      'tmp="$(mktemp -d "${TMPDIR:-/tmp}/zip_file.XXXXXXXXXX")"',
+      'cd "${tmp}"',
+  ]
+  cmd += ['"${zipper}" x "${repo}/%s"' % dep.zip_file.path
+          for dep in ctx.attr.deps]
+  cmd += ['mkdir -p "${tmp}/%s"' % zip_path
+          for zip_path in set(
+              [zip_path[:zip_path.rindex('/')]
+               for _, zip_path in mapped if '/' in zip_path])]
+  cmd += ['ln -sf "${repo}/%s" "${tmp}/%s"' % (path, zip_path)
+          for path, zip_path in mapped]
+  cmd += [
+      ('find . | sed 1d | cut -c 3- | LC_ALL=C sort' +
+       ' | xargs "${zipper}" cC "${archive}"'),
+      'cd "${repo}"',
+      'rm -rf "${tmp}"',
+  ]
+  inputs = [ctx.file._zipper]
+  inputs += [dep.zip_file for dep in ctx.attr.deps]
+  inputs += ctx.files.srcs
+  ctx.action(
+      inputs=inputs,
+      outputs=[ctx.outputs.out],
+      command='\n'.join(cmd),
+      mnemonic='zip',
+      progress_message='Creating zip with %d inputs %s' % (
+          len(inputs), ctx.label))
+  return struct(files=set([ctx.outputs.out]),
+                zip_file=ctx.outputs.out)
+
+def _map_sources(srcs, mappings):
+  """Calculates paths in zip file for srcs."""
+  # order mappings with more path components first
+  mappings = sorted([(-len(source.split('/')), source, dest)
+                     for source, dest in mappings.items()])
+  # get rid of the integer part of tuple used for sorting
+  mappings = [(source, dest) for _, source, dest in mappings]
+  mappings_indexes = range(len(mappings))
+  used = {i: False for i in mappings_indexes}
+  mapped = []
+  for file_ in srcs:
+    short_path = runpath(file_)
+    zip_path = None
+    for i in mappings_indexes:
+      source = mappings[i][0]
+      dest = mappings[i][1]
+      if not source:
+        if dest:
+          zip_path = dest + '/' + short_path
+        else:
+          zip_path = short_path
+      elif source == short_path:
+        if dest:
+          zip_path = dest
+        else:
+          zip_path = short_path
+      elif short_path.startswith(source + '/'):
+        if dest:
+          zip_path = dest + short_path[len(source):]
+        else:
+          zip_path = short_path[len(source) + 1:]
+      else:
+        continue
+      used[i] = True
+      break
+    if not zip_path:
+      fail('no mapping matched: ' + short_path)
+    mapped += [(file_.path, zip_path)]
+  for i in mappings_indexes:
+    if not used[i]:
+      fail('superfluous mapping: "%s" -> "%s"' % mappings[i])
+  return mapped
+
+zip_file = rule(
+    implementation=_impl,
+    output_to_genfiles = True,
+    attrs={
+        'out': attr.output(mandatory=True),
+        'srcs': attr.label_list(allow_files=True),
+        'deps': attr.label_list(providers=['zip_file']),
+        'mappings': attr.string_dict(),
+        '_zipper': attr.label(default=Label(ZIPPER), single_file=True),
+    })