1 files changed, 71 insertions, 0 deletions
diff --git a/src/cmd/go/internal/base/path.go b/src/cmd/go/internal/base/path.go
new file mode 100644
index 0000000..ebe4f15
--- /dev/null
+++ b/src/cmd/go/internal/base/path.go
@@ -0,0 +1,71 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package base
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"sync"
+)
+
+var cwd string
+var cwdOnce sync.Once
+
+// Cwd returns the current working directory at the time of the first call.
+func Cwd() string {
+	cwdOnce.Do(func() {
+		var err error
+		cwd, err = os.Getwd()
+		if err != nil {
+			Fatalf("cannot determine current directory: %v", err)
+		}
+	})
+	return cwd
+}
+
+// ShortPath returns an absolute or relative name for path, whatever is shorter.
+func ShortPath(path string) string {
+	if rel, err := filepath.Rel(Cwd(), path); err == nil && len(rel) < len(path) {
+		return rel
+	}
+	return path
+}
+
+// RelPaths returns a copy of paths with absolute paths
+// made relative to the current directory if they would be shorter.
+func RelPaths(paths []string) []string {
+	var out []string
+	for _, p := range paths {
+		rel, err := filepath.Rel(Cwd(), p)
+		if err == nil && len(rel) < len(p) {
+			p = rel
+		}
+		out = append(out, p)
+	}
+	return out
+}
+
+// IsTestFile reports whether the source file is a set of tests and should therefore
+// be excluded from coverage analysis.
+func IsTestFile(file string) bool {
+	// We don't cover tests, only the code they test.
+	return strings.HasSuffix(file, "_test.go")
+}
+
+// IsNull reports whether the path is a common name for the null device.
+// It returns true for /dev/null on Unix, or NUL (case-insensitive) on Windows.
+func IsNull(path string) bool {
+	if path == os.DevNull {
+		return true
+	}
+	if runtime.GOOS == "windows" {
+		if strings.EqualFold(path, "NUL") {
+			return true
+		}
+	}
+	return false
+}