fix git.bzl error when outputRoot is in a git repo
`_clone_or_update()` should `git clone` external repositories only if repo is absent. Unfortunately, it may happen that the bazel outputRoot (~/.cache/bazel by default) is a subdirectory of some other git working copy. For example, user may track his whole home directory in git and add `.config` to .gitignore. In that case, it is not enough to check if the cache dir is a git repo. One must check that the cache dir holds a root of a git working copy. In other words, the `.git` folder must be in the repo dir, not on any level above.
* Steps to reproduce
```bash
cd ~/.cache
git init
cd /some/project/that/uses/bazel-git_repository
mv WORKSPACE WORKSPACE.orig
(echo "load('@bazel_tools//tools/build_defs/repo:git.bzl', 'git_repository')" ; cat WORKSPACE.orig) > WORKSPACE
bazel --batch build :all || echo "Ah, there is a bug"
```
Read on for definitive info.
* clone any project that uses `git_repository`
```bash
[arch@archlinux bazelbuild]$ git clone https://github.com/bazelbuild/bazel-watcher.git
[arch@archlinux bazelbuild]$ cd bazel-watcher
```
* enable Skylark implementation of `git_repository` as documented in https://github.com/bazelbuild/bazel/issues/1408#issuecomment-276815467
```bash
[arch@archlinux bazel-watcher]$ mv WORKSPACE WORKSPACE.orig
[arch@archlinux bazel-watcher]$ (echo "load('@bazel_tools//tools/build_defs/repo:git.bzl', 'git_repository')" ; cat WORKSPACE.orig) > WORKSPACE
[arch@archlinux bazel-watcher]$ grep -v ^# WORKSPACE |head -n4
load('@bazel_tools//tools/build_defs/repo:git.bzl', 'git_repository')
git_repository(
name = "com_github_bazelbuild_bazel_integration_testing",
```
* (optionally) define custom Bazel `outputRoot` directory (default is ~/.cache/bazel)
```bash
[arch@archlinux bazel-watcher]$ rm -rf /tmp/.cache/ ; mkdir /tmp/.cache/
[arch@archlinux bazel-watcher]$ export TEST_TMPDIR=/tmp/.cache/bazel
```
* try building the project to make sure everything works as expected
```bash
[arch@archlinux bazel-watcher]$ bazel --batch build :all
INFO: $TEST_TMPDIR defined: output root default is '/tmp/.cache/bazel' and max_idle_secs default is '15'.
Extracting Bazel installation...
WARNING: /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing/WORKSPACE:1: Workspace name in /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing/WORKSPACE (@build_bazel_integration_testing) does not match the name given in the repository's definition (@com_github_bazelbuild_bazel_integration_testing); this will cause a build error in future versions
INFO: Analysed target //:go_prefix (6 packages loaded).
INFO: Found 1 target...
Target //:go_prefix up-to-date (nothing to build)
INFO: Elapsed time: 15.088s, Critical Path: 0.05s
INFO: Build completed successfully, 1 total action
[arch@archlinux bazel-watcher]$ echo $?
0
```
* reproduce the issue by placing the `outputRoot` under a git working copy
```bash
[arch@archlinux bazel-watcher]$ rm -rf /tmp/.cache/ ; mkdir /tmp/.cache/
[arch@archlinux bazel-watcher]$ cd /tmp/.cache/ ; git init
Initialized empty Git repository in /tmp/.cache/.git/
[arch@archlinux .cache]$ cd -
[arch@archlinux bazel-watcher]$ bazel --batch build :all
INFO: $TEST_TMPDIR defined: output root default is '/tmp/.cache/bazel' and max_idle_secs default is '15'.
Extracting Bazel installation...
ERROR: error loading package '': Encountered error while reading extension file 'tools/repositories.bzl': no such package '@com_github_bazelbuild_bazel_integration_testing//tools': Traceback (most recent call last):
File "/tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl", line 69
_clone_or_update(ctx)
File "/tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl", line 44, in _clone_or_update
fail(("error cloning %s:\n%s" % (ctx....)))
error cloning com_github_bazelbuild_bazel_integration_testing:
+ cd /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external
+ cd /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing
+ git reset --hard 55a6a70dbcc2cc7699ee715746fb1452788f8d3c
fatal: Could not parse object '55a6a70dbcc2cc7699ee715746fb1452788f8d3c'.
+ git fetch origin 55a6a70dbcc2cc7699ee715746fb1452788f8d3c:55a6a70dbcc2cc7699ee715746fb1452788f8d3c
fatal: 'origin' does not appear to be a git repository
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
ERROR: error loading package '': Encountered error while reading extension file 'tools/repositories.bzl': no such package '@com_github_bazelbuild_bazel_integration_testing//tools': Traceback (most recent call last):
File "/tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl", line 69
_clone_or_update(ctx)
File "/tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl", line 44, in _clone_or_update
fail(("error cloning %s:\n%s" % (ctx....)))
error cloning com_github_bazelbuild_bazel_integration_testing:
+ cd /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external
+ cd /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing
+ git reset --hard 55a6a70dbcc2cc7699ee715746fb1452788f8d3c
fatal: Could not parse object '55a6a70dbcc2cc7699ee715746fb1452788f8d3c'.
+ git fetch origin 55a6a70dbcc2cc7699ee715746fb1452788f8d3c:55a6a70dbcc2cc7699ee715746fb1452788f8d3c
fatal: 'origin' does not appear to be a git repository
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
INFO: Elapsed time: 4.974s
FAILED: Build did NOT complete successfully (0 packages loaded)
```
* let's find out why it failed
```bash
[arch@archlinux bazel-watcher]$ grep rev-parse /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl
if ! ( cd '{dir}' && git rev-parse --git-dir ) >/dev/null 2>&1; then
[arch@archlinux bazel-watcher]$ cd /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing
[arch@archlinux com_github_bazelbuild_bazel_integration_testing]$ git rev-parse --git-dir
/tmp/.cache/.git
[arch@archlinux com_github_bazelbuild_bazel_integration_testing]$ cd -
```
* let's fix git.bzl
```bash
[arch@archlinux bazel-watcher]$ sed -i -E 's/git rev-parse --git-dir/[[ "$(git rev-parse --git-dir)" == '.git' ]]/' /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl
[arch@archlinux bazel-watcher]$ grep rev-parse /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/bazel_tools/tools/build_defs/repo/git.bzl
if ! ( cd '{dir}' && [[ "$(git rev-parse --git-dir)" == .git ]] ) >/dev/null 2>&1; then
```
* make sure that Bazel works again
```bash
[arch@archlinux bazel-watcher]$ ls -a /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing
. ..
[arch@archlinux bazel-watcher]$ bazel --batch build :all
INFO: $TEST_TMPDIR defined: output root default is '/tmp/.cache/bazel' and max_idle_secs default is '15'.
Error: corrupt installation: file '/tmp/.cache/bazel/_bazel_arch/install/f20169627a8110e2cc3d005319e97c94/_embedded_binaries/embedded_tools/tools/build_defs/repo/git.bzl' modified. Please remove '/tmp/.cache/bazel/_bazel_arch/install/f20169627a8110e2cc3d005319e97c94' and try again.
[arch@archlinux bazel-watcher]$ touch -m -t 202712120101 /tmp/.cache/bazel/_bazel_arch/install/f20169627a8110e2cc3d005319e97c94/_embedded_binaries/embedded_tools/tools/build_defs/repo/git.bzl
[arch@archlinux bazel-watcher]$ bazel --batch build :all
INFO: $TEST_TMPDIR defined: output root default is '/tmp/.cache/bazel' and max_idle_secs default is '15'.
WARNING: /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing/WORKSPACE:1: Workspace name in /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing/WORKSPACE (@build_bazel_integration_testing) does not match the name given in the repository's definition (@com_github_bazelbuild_bazel_integration_testing); this will cause a build error in future versions
INFO: Analysed target //:go_prefix (6 packages loaded).
INFO: Found 1 target...
Target //:go_prefix up-to-date (nothing to build)
INFO: Elapsed time: 13.318s, Critical Path: 0.07s
INFO: Build completed successfully, 1 total action
[arch@archlinux bazel-watcher]$ ls -a /tmp/.cache/bazel/_bazel_arch/f2207b308c89ea5d32323052637210b1/external/com_github_bazelbuild_bazel_integration_testing
. .. AUTHORS bazel_integration_test bazel_integration_test.bzl bazel_version.bzl BUILD .ci CODEOWNERS CONTRIBUTING.md .git .gitignore go java javatests LICENSE README.md tools WORKSPACE
```
Closes #4358.
PiperOrigin-RevId: 181151078
diff --git a/tools/build_defs/repo/git.bzl b/tools/build_defs/repo/git.bzl
index 5147951..3e708df 100644
--- a/tools/build_defs/repo/git.bzl
+++ b/tools/build_defs/repo/git.bzl
@@ -27,7 +27,7 @@
st = ctx.execute(['bash', '-c', """
set -ex
( cd {working_dir} &&
- if ! ( cd '{dir}' && git rev-parse --git-dir ) >/dev/null 2>&1; then
+ if ! ( cd '{dir}' && [[ "$(git rev-parse --git-dir)" == '.git' ]] ) >/dev/null 2>&1; then
rm -rf '{dir}'
git clone '{remote}' '{dir}'
fi
