external repos: add a Skylark library for common tasks

...thus avoiding having them several times for the various repository
rules, each with slightly different behavior and bugs.

Change-Id: I6cec0c0dd0901453458903e226ceb2098a93cdd8
PiperOrigin-RevId: 187306904

src/test/shell/bazel/BUILD

@@ -246,6 +246,7 @@ sh_test(
  size = "medium",
  srcs = ["external_patching_test.sh"],
  data = [":test-deps"],
+ shard_count = 3,
 )
 
 sh_test(

src/test/shell/bazel/external_patching_test.sh

@@ -223,6 +223,129 @@ EOF
  expect_not_log "BAD"
 }
 
+test_override_buildfile_git() {
+ ## Verify that the BUILD file of an external repository can be overriden
+ ## via the git_repository rule.
+ EXTREPODIR=`pwd`
+ export GIT_CONFIG_NOSYSTEM=YES
+
+ mkdir withbuild
+ (cd withbuild && git init)
+ cat > withbuild/BUILD.bazel <<'EOF'
+genrule(
+ name="target",
+ srcs=["file.txt"],
+ outs=["target.txt"],
+ cmd="cp $< $@ && echo BAD >> $@",
+ visibility=["//visibility:public"],
+)
+EOF
+ cat > withbuild/file.txt <<'EOF'
+from external repo
+EOF
+ (cd withbuild
+ git add .
+ git commit --author="A U Thor <author@example.com>" -m 'initial commit'
+ git tag mytag)
+
+ mkdir main
+ cd main
+ cat > WORKSPACE <<EOF
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
+new_git_repository(
+ name="withbuild",
+ remote="file://${EXTREPODIR}/withbuild/.git",
+ tag="mytag",
+ build_file="@//:ext.BUILD",
+)
+EOF
+ cat > BUILD <<'EOF'
+genrule(
+ name = "local",
+ outs = ["local.txt"],
+ srcs = ["@withbuild//:target"],
+ cmd = "cp $< $@",
+)
+EOF
+ cat > ext.BUILD <<'EOF'
+genrule(
+ name="target",
+ srcs=["file.txt"],
+ outs=["target.txt"],
+ cmd="cp $< $@ && echo GOOD >> $@",
+ visibility=["//visibility:public"],
+)
+EOF
+
+ bazel build //:local || fail "Expected success"
+
+ cat `bazel info bazel-genfiles`/local.txt > "${TEST_log}"
+ expect_log "from external repo"
+ expect_log "GOOD"
+ expect_not_log "BAD"
+}
+
+test_override_buildfilecontents_git() {
+ ## Verify that the BUILD file of an external repository can be overriden
+ ## via specified content in the git_repository rule.
+ EXTREPODIR=`pwd`
+ export GIT_CONFIG_NOSYSTEM=YES
+
+ mkdir withbuild
+ (cd withbuild && git init)
+ cat > withbuild/BUILD.bazel <<'EOF'
+genrule(
+ name="target",
+ srcs=["file.txt"],
+ outs=["target.txt"],
+ cmd="cp $< $@ && echo BAD >> $@",
+ visibility=["//visibility:public"],
+)
+EOF
+ cat > withbuild/file.txt <<'EOF'
+from external repo
+EOF
+ (cd withbuild
+ git add .
+ git commit --author="A U Thor <author@example.com>" -m 'initial commit'
+ git tag mytag)
+
+ mkdir main
+ cd main
+ cat > WORKSPACE <<EOF
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
+new_git_repository(
+ name="withbuild",
+ remote="file://${EXTREPODIR}/withbuild/.git",
+ tag="mytag",
+ build_file_content="""
+genrule(
+ name="target",
+ srcs=["file.txt"],
+ outs=["target.txt"],
+ cmd="cp \$< \$@ && echo GOOD >> \$@",
+ visibility=["//visibility:public"],
+)
+ """,
+)
+EOF
+ cat > BUILD <<'EOF'
+genrule(
+ name = "local",
+ outs = ["local.txt"],
+ srcs = ["@withbuild//:target"],
+ cmd = "cp $< $@",
+)
+EOF
+
+ bazel build //:local || fail "Expected success"
+
+ cat `bazel info bazel-genfiles`/local.txt > "${TEST_log}"
+ expect_log "from external repo"
+ expect_log "GOOD"
+ expect_not_log "BAD"
+}
+
 test_build_file_build_bazel() {
  ## Verify that the BUILD file of an external repository can be overriden
  ## via the http_archive rule.

tools/build_defs/repo/git.bzl

@@ -13,6 +13,8 @@
 # limitations under the License.
 """Rules for cloning external git repositories."""
 
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "workspace_and_buildfile")
+
 def _clone_or_update(ctx):
  if ((not ctx.attr.tag and not ctx.attr.commit) or
  (ctx.attr.tag and ctx.attr.commit)):
@@ -83,11 +85,7 @@ def _new_git_repository_implementation(ctx):
  (ctx.attr.build_file and ctx.attr.build_file_content)):
  fail('Exactly one of build_file and build_file_content must be provided.')
  _clone_or_update(ctx)
- ctx.file('WORKSPACE', 'workspace(name = \'{name}\')\n'.format(name=ctx.name))
- if ctx.attr.build_file:
- ctx.symlink(ctx.attr.build_file, 'BUILD.bazel')
- else:
- ctx.file('BUILD.bazel', ctx.attr.build_file_content)
+ workspace_and_buildfile(ctx)
 
 def _git_repository_implementation(ctx):
  _clone_or_update(ctx)

tools/build_defs/repo/http.bzl

@@ -29,6 +29,8 @@ These rules are improved versions of the native http rules and will eventually
 replace the native rules.
 """
 
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "workspace_and_buildfile")
+
 def _patch(ctx):
  """Implementation of patching an already extracted repository"""
  bash_exe = ctx.os.environ["BAZEL_SH"] if "BAZEL_SH" in ctx.os.environ else "bash"
@@ -73,16 +75,7 @@ def _http_archive_impl(ctx):
  ctx.download_and_extract(all_urls, "", ctx.attr.sha256, ctx.attr.type,
  ctx.attr.strip_prefix)
  _patch(ctx)
- ctx.file("WORKSPACE", "workspace(name = \"{name}\")\n".format(name=ctx.name))
- if ctx.attr.build_file:
- bash_exe = ctx.os.environ["BAZEL_SH"] if "BAZEL_SH" in ctx.os.environ else "bash"
- ctx.execute([bash_exe, "-c", "rm -f BUILD BUILD.bazel"])
- ctx.symlink(ctx.attr.build_file, "BUILD")
- elif ctx.attr.build_file_content:
- bash_exe = ctx.os.environ["BAZEL_SH"] if "BAZEL_SH" in ctx.os.environ else "bash"
- ctx.execute([bash_exe, "-c", "rm -f BUILD.bazel"])
- ctx.file("BUILD", ctx.attr.build_file_content)
-
+ workspace_and_buildfile(ctx)
 
 _HTTP_FILE_BUILD = """
 package(default_visibility = ["//visibility:public"])

tools/build_defs/repo/utils.bzl

@@ -0,0 +1,53 @@
+# Copyright 2018 The Bazel 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.
+"""Utils for manipulating external repositories, once fetched.
+
+### Setup
+
+These utility are intended to be used by other repository rules. They
+can be loaded as follows.
+
+```python
+load(
+ "@bazel_tools//tools/build_defs/repo:utils.bzl",
+ "workspace_and_buildfile",
+)
+```
+"""
+
+def workspace_and_buildfile(ctx):
+ """Utility function for writing WORKSPACE and, if requested, a BUILD file.
+
+ It assumes the paramters name, build_file, and build_file_contents to be
+ present in ctx.attr, the latter two possibly with value None.
+
+ Args:
+ ctx: The repository context of the repository rule calling this utility
+ function.
+ """
+ if ctx.attr.build_file and ctx.attr.build_file_content:
+ ctx.fail("Only one of build_file and build_file_content can be provided.")
+
+ ctx.file("WORKSPACE", "workspace(name = \"{name}\")\n".format(name=ctx.name))
+
+ if ctx.attr.build_file:
+ bash_exe = ctx.os.environ["BAZEL_SH"] if "BAZEL_SH" in ctx.os.environ else "bash"
+ ctx.execute([bash_exe, "-c", "rm -f BUILD BUILD.bazel"])
+ ctx.symlink(ctx.attr.build_file, "BUILD")
+ elif ctx.attr.build_file_content:
+ bash_exe = ctx.os.environ["BAZEL_SH"] if "BAZEL_SH" in ctx.os.environ else "bash"
+ ctx.execute([bash_exe, "-c", "rm -f BUILD.bazel"])
+ ctx.file("BUILD", ctx.attr.build_file_content)
+
+