1 files changed, 97 insertions, 0 deletions
diff --git a/go/runfiles/global.go b/go/runfiles/global.go
new file mode 100644
index 00000000..52ec3569
--- /dev/null
+++ b/go/runfiles/global.go
@@ -0,0 +1,97 @@
+// Copyright 2020, 2021 Google LLC
+//
+// 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
+//
+//     https://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.
+
+package runfiles
+
+import (
+	"regexp"
+	"runtime"
+	"sync"
+)
+
+// Rlocation returns the absolute path name of a runfile.  The runfile name must be
+// a relative path, using the slash (not backslash) as directory separator.  If
+// the runfiles manifest maps s to an empty name (indicating an empty runfile
+// not present in the filesystem), Rlocation returns an error that wraps ErrEmpty.
+func Rlocation(path string) (string, error) {
+	return RlocationFrom(path, CallerRepository())
+}
+
+func RlocationFrom(path string, sourceRepo string) (string, error) {
+	r, err := g.get()
+	if err != nil {
+		return "", err
+	}
+	return r.WithSourceRepo(sourceRepo).Rlocation(path)
+}
+
+// Env returns additional environmental variables to pass to subprocesses.
+// Each element is of the form “key=value”.  Pass these variables to
+// Bazel-built binaries so they can find their runfiles as well.  See the
+// Runfiles example for an illustration of this.
+//
+// The return value is a newly-allocated slice; you can modify it at will.
+func Env() ([]string, error) {
+	r, err := g.get()
+	if err != nil {
+		return nil, err
+	}
+	return r.Env(), nil
+}
+
+var legacyExternalGeneratedFile = regexp.MustCompile(`^bazel-out[/][^/]+/bin/external/([^/]+)/`)
+var legacyExternalFile = regexp.MustCompile(`^external/([^/]+)/`)
+
+// CurrentRepository returns the canonical name of the Bazel repository that
+// contains the source file of the caller of CurrentRepository.
+func CurrentRepository() string {
+	return callerRepository(1)
+}
+
+// CallerRepository returns the canonical name of the Bazel repository that
+// contains the source file of the caller of the function that itself calls
+// CallerRepository.
+func CallerRepository() string {
+	return callerRepository(2)
+}
+
+func callerRepository(skip int) string {
+	_, file, _, _ := runtime.Caller(skip + 1)
+	if match := legacyExternalGeneratedFile.FindStringSubmatch(file); match != nil {
+		return match[1]
+	}
+	if match := legacyExternalFile.FindStringSubmatch(file); match != nil {
+		return match[1]
+	}
+	// If a file is not in an external repository, it is in the main repository,
+	// which has the empty string as its canonical name.
+	return ""
+}
+
+type global struct {
+	once     sync.Once
+	runfiles *Runfiles
+	err      error
+}
+
+func (g *global) get() (*Runfiles, error) {
+	g.once.Do(g.init)
+	return g.runfiles, g.err
+}
+
+func (g *global) init() {
+	g.runfiles, g.err = New()
+}
+
+var g global