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Add CurrentRepository() to Python runfiles library
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`runfiles.CurrentRepository()` can be used to get the canonical name of
the Bazel repository containing the caller at runtime. This information
is required to look up runfiles while taking repository mappings into
account.

Work towards bazelbuild#16124

Closes bazelbuild#16341.

PiperOrigin-RevId: 483400557
Change-Id: Ia906c42bad6ca0935b86b958e4401c6745789dff
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fmeum authored and copybara-github committed Oct 24, 2022
1 parent 6578b5b commit d60ce2c
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112 changes: 111 additions & 1 deletion src/test/py/bazel/py_test.py
Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@ def testSmoke(self):
self.createSimpleFiles()
exit_code, stdout, stderr = self.RunBazel(['run', '//a:a'])
self.AssertExitCode(exit_code, 0, stderr)
self.assertTrue('Hello, World' in stdout)
self.assertIn('Hello, World', stdout)

def testRunfilesSymlinks(self):
if test_base.TestBase.IsWindows():
Expand Down Expand Up @@ -208,5 +208,115 @@ def testPyTestWithStdlibCollisionRunsRemotely(self):
self.assertIn('Test ran', stdout)


class PyRunfilesLibraryTest(test_base.TestBase):

def testPyRunfilesLibraryCurrentRepository(self):
self.CreateWorkspaceWithDefaultRepos('WORKSPACE', [
'local_repository(', ' name = "other_repo",',
' path = "other_repo_path",', ')'
])

self.ScratchFile('pkg/BUILD.bazel', [
'py_library(',
' name = "library",',
' srcs = ["library.py"],',
' visibility = ["//visibility:public"],',
' deps = ["@bazel_tools//tools/python/runfiles"],',
')',
'',
'py_binary(',
' name = "binary",',
' srcs = ["binary.py"],',
' deps = [',
' ":library",',
' "@bazel_tools//tools/python/runfiles",',
' ],',
')',
'',
'py_test(',
' name = "test",',
' srcs = ["test.py"],',
' deps = [',
' ":library",',
' "@bazel_tools//tools/python/runfiles",',
' ],',
')',
])
self.ScratchFile('pkg/library.py', [
'from bazel_tools.tools.python.runfiles import runfiles',
'def print_repo_name():',
' print("in pkg/library.py: \'%s\'" % runfiles.Create().CurrentRepository())',
])
self.ScratchFile('pkg/binary.py', [
'from bazel_tools.tools.python.runfiles import runfiles',
'from pkg import library',
'library.print_repo_name()',
'print("in pkg/binary.py: \'%s\'" % runfiles.Create().CurrentRepository())',
])
self.ScratchFile('pkg/test.py', [
'from bazel_tools.tools.python.runfiles import runfiles',
'from pkg import library',
'library.print_repo_name()',
'print("in pkg/test.py: \'%s\'" % runfiles.Create().CurrentRepository())',
])

self.ScratchFile('other_repo_path/WORKSPACE')
self.ScratchFile('other_repo_path/pkg/BUILD.bazel', [
'py_binary(',
' name = "binary",',
' srcs = ["binary.py"],',
' deps = [',
' "@//pkg:library",',
' "@bazel_tools//tools/python/runfiles",',
' ],',
')',
'',
'py_test(',
' name = "test",',
' srcs = ["test.py"],',
' deps = [',
' "@//pkg:library",',
' "@bazel_tools//tools/python/runfiles",',
' ],',
')',
])
self.ScratchFile('other_repo_path/pkg/binary.py', [
'from bazel_tools.tools.python.runfiles import runfiles',
'from pkg import library',
'library.print_repo_name()',
'print("in external/other_repo/pkg/binary.py: \'%s\'" % runfiles.Create().CurrentRepository())',
])
self.ScratchFile('other_repo_path/pkg/test.py', [
'from bazel_tools.tools.python.runfiles import runfiles',
'from pkg import library',
'library.print_repo_name()',
'print("in external/other_repo/pkg/test.py: \'%s\'" % runfiles.Create().CurrentRepository())',
])

exit_code, stdout, stderr = self.RunBazel(['run', '//pkg:binary'])
self.AssertExitCode(exit_code, 0, stderr, stdout)
self.assertIn('in pkg/binary.py: \'\'', stdout)
self.assertIn('in pkg/library.py: \'\'', stdout)

exit_code, stdout, stderr = self.RunBazel(
['test', '//pkg:test', '--test_output=streamed'])
self.AssertExitCode(exit_code, 0, stderr, stdout)
self.assertIn('in pkg/test.py: \'\'', stdout)
self.assertIn('in pkg/library.py: \'\'', stdout)

exit_code, stdout, stderr = self.RunBazel(
['run', '@other_repo//pkg:binary'])
self.AssertExitCode(exit_code, 0, stderr, stdout)
self.assertIn('in external/other_repo/pkg/binary.py: \'other_repo\'',
stdout)
self.assertIn('in pkg/library.py: \'\'', stdout)

exit_code, stdout, stderr = self.RunBazel(
['test', '@other_repo//pkg:test', '--test_output=streamed'])
self.AssertExitCode(exit_code, 0, stderr, stdout)
self.assertIn('in external/other_repo/pkg/test.py: \'other_repo\'', stdout)
self.assertIn('in pkg/library.py: \'\'', stdout)


if __name__ == '__main__':
unittest.main()
35 changes: 35 additions & 0 deletions tools/python/gen_runfiles_constants.bzl
Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
# Copyright 2022 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.

"""A rule to generate a Python source file containing the main repo's
runfiles directory name."""

_RUNFILES_CONSTANTS_TEMPLATE = """# Generated by gen_runfiles_constants.bzl
# Internal-only; do no use.
# The name of the runfiles directory corresponding to the main repository.
MAIN_REPOSITORY_RUNFILES_DIRECTORY = '%s'
"""

def _gen_runfiles_constants_impl(ctx):
out = ctx.actions.declare_file(ctx.attr.name + ".py")
ctx.actions.write(out, _RUNFILES_CONSTANTS_TEMPLATE % ctx.workspace_name)

return DefaultInfo(
files = depset([out]),
runfiles = ctx.runfiles([out]),
)

gen_runfiles_constants = rule(
implementation = _gen_runfiles_constants_impl,
)
10 changes: 9 additions & 1 deletion tools/python/runfiles/BUILD
Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
load("//tools/python:gen_runfiles_constants.bzl", "gen_runfiles_constants")
load("//tools/python:private/defs.bzl", "py_library", "py_test")

package(default_visibility = ["//visibility:private"])
Expand All @@ -20,7 +21,14 @@ filegroup(
py_library(
name = "runfiles",
testonly = 1,
srcs = ["runfiles.py"],
srcs = [
"runfiles.py",
":_runfiles_constants",
],
)

gen_runfiles_constants(
name = "_runfiles_constants",
)

py_test(
Expand Down
10 changes: 9 additions & 1 deletion tools/python/runfiles/BUILD.tools
Original file line number Diff line number Diff line change
@@ -1,7 +1,15 @@
load("//tools/python:gen_runfiles_constants.bzl", "gen_runfiles_constants")
load("//tools/python:private/defs.bzl", "py_library")

py_library(
name = "runfiles",
srcs = ["runfiles.py"],
srcs = [
"runfiles.py",
":_runfiles_constants",
],
visibility = ["//visibility:public"],
)

gen_runfiles_constants(
name = "_runfiles_constants",
)
70 changes: 70 additions & 0 deletions tools/python/runfiles/runfiles.py
Original file line number Diff line number Diff line change
Expand Up @@ -58,8 +58,12 @@
p = subprocess.Popen([r.Rlocation("path/to/binary")], env, ...)
"""

import inspect
import os
import posixpath
import sys

from ._runfiles_constants import MAIN_REPOSITORY_RUNFILES_DIRECTORY


def CreateManifestBased(manifest_path):
Expand Down Expand Up @@ -114,6 +118,7 @@ class _Runfiles(object):

def __init__(self, strategy):
self._strategy = strategy
self._python_runfiles_root = _FindPythonRunfilesRoot()

def Rlocation(self, path):
"""Returns the runtime path of a runfile.
Expand Down Expand Up @@ -161,6 +166,71 @@ def EnvVars(self):
"""
return self._strategy.EnvVars()

def CurrentRepository(self, frame=1):
"""Returns the canonical name of the caller's Bazel repository.
For example, this function returns '' (the empty string) when called from
the main repository and a string of the form 'rules_python~0.13.0` when
called from code in the repository corresponding to the rules_python Bazel
module.
More information about the difference between canonical repository names and
the `@repo` part of labels is available at:
https://bazel.build/build/bzlmod#repository-names
NOTE: This function inspects the callstack to determine where in the
runfiles the caller is located to determine which repository it came from.
This may fail or produce incorrect results depending on who the caller is,
for example if it is not represented by a Python source file. Use the
`frame` argument to control the stack lookup.
Args:
frame: int; the stack frame to return the repository name for. Defaults to
1, the caller of the CurrentRepository function.
Returns:
The canonical name of the Bazel repository containing the file containing
the frame-th caller of this function
Raises:
ValueError: if the caller cannot be determined or the caller's file path
is not contained in the Python runfiles tree
"""
# pylint:disable=protected-access # for sys._getframe
# pylint:disable=raise-missing-from # we're still supporting Python 2...
try:
caller_path = inspect.getfile(sys._getframe(frame))
except (TypeError, ValueError):
raise ValueError("failed to determine caller's file path")
caller_runfiles_path = os.path.relpath(caller_path,
self._python_runfiles_root)
if caller_runfiles_path.startswith(".." + os.path.sep):
raise ValueError("{} does not lie under the runfiles root {}".format(
caller_path, self._python_runfiles_root))

caller_runfiles_directory = caller_runfiles_path[:caller_runfiles_path
.find(os.path.sep)]
if caller_runfiles_directory == MAIN_REPOSITORY_RUNFILES_DIRECTORY:
# The canonical name of the main repository (also known as the workspace)
# is the empty string.
return ""
# For all other repositories, the name of the runfiles directory is the
# canonical name.
return caller_runfiles_directory


def _FindPythonRunfilesRoot():
"""Finds the root of the Python runfiles tree."""
root = __file__
# Walk up our own runfiles path to the root of the runfiles tree from which
# the current file is being run. This path coincides with what the Bazel
# Python stub sets up as sys.path[0]. Since that entry can be changed at
# runtime, we rederive it here.
for _ in range(
"bazel_tools/tools/python/runfiles/runfiles.py".count("/") +
1):
root = os.path.dirname(root)
return root


class _ManifestBased(object):
"""`Runfiles` strategy that parses a runfiles-manifest to look up runfiles."""
Expand Down
4 changes: 4 additions & 0 deletions tools/python/runfiles/runfiles_test.py
Original file line number Diff line number Diff line change
Expand Up @@ -262,6 +262,10 @@ def testPathsFromEnvvars(self):
self.assertEqual(mf, "")
self.assertEqual(dr, "")

def testCurrentRepository(self):
self.assertEqual(
runfiles.Create({"RUNFILES_DIR": "whatever"}).CurrentRepository(), "")

@staticmethod
def IsWindows():
return os.name == "nt"
Expand Down

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