filepath: new Abs function

R=golang-dev, rsc1, peterGo, bsiegert, r, mattn
CC=golang-dev
https://golang.org/cl/4271057

src/pkg/path/filepath/path.go

@@ -231,6 +231,21 @@ func EvalSymlinks(path string) (string, os.Error) {
 	return Clean(b.String()), nil
 }
 
+// Abs returns an absolute representation of path.
+// If the path is not absolute it will be joined with the current
+// working directory to turn it into an absolute path.  The absolute
+// path name for a given file is not guaranteed to be unique.
+func Abs(path string) (string, os.Error) {
+	if IsAbs(path) {
+		return path, nil
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	return Join(wd, path), nil
+}
+
 // Visitor methods are invoked for corresponding file tree entries
 // visited by Walk. The parameter path is the full path of f relative
 // to root.

src/pkg/path/filepath/path_test.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"runtime"
+	"strings"
 	"testing"
 )
 
@@ -459,9 +460,9 @@ func TestEvalSymlinks(t *testing.T) {
 	// relative
 	for _, d := range EvalSymlinksTests {
 		if p, err := filepath.EvalSymlinks(d.path); err != nil {
-			t.Errorf("EvalSymlinks(%v) error: %v", d.path, err)
+			t.Errorf("EvalSymlinks(%q) error: %v", d.path, err)
 		} else if p != d.dest {
-			t.Errorf("EvalSymlinks(%v)=%v, want %v", d.path, p, d.dest)
+			t.Errorf("EvalSymlinks(%q)=%q, want %q", d.path, p, d.dest)
 		}
 	}
 	// absolute
@@ -476,9 +477,49 @@ func TestEvalSymlinks(t *testing.T) {
 			filepath.Join(testroot, d.dest),
 		}
 		if p, err := filepath.EvalSymlinks(a.path); err != nil {
-			t.Errorf("EvalSymlinks(%v) error: %v", a.path, err)
+			t.Errorf("EvalSymlinks(%q) error: %v", a.path, err)
 		} else if p != a.dest {
-			t.Errorf("EvalSymlinks(%v)=%v, want %v", a.path, p, a.dest)
+			t.Errorf("EvalSymlinks(%q)=%q, want %q", a.path, p, a.dest)
+		}
+	}
+}
+
+// Test paths relative to $GOROOT/src
+var abstests = []string{
+	"../AUTHORS",
+	"pkg/../../AUTHORS",
+	"Make.pkg",
+	"pkg/Makefile",
+
+	// Already absolute
+	"$GOROOT/src/Make.pkg",
+}
+
+func TestAbs(t *testing.T) {
+	oldwd, err := os.Getwd()
+	if err != nil {
+		t.Fatal("Getwd failed: " + err.String())
+	}
+	defer os.Chdir(oldwd)
+	goroot := os.Getenv("GOROOT")
+	cwd := filepath.Join(goroot, "src")
+	os.Chdir(cwd)
+	for _, path := range abstests {
+		path = strings.Replace(path, "$GOROOT", goroot, -1)
+		abspath, err := filepath.Abs(path)
+		if err != nil {
+			t.Errorf("Abs(%q) error: %v", path, err)
+		}
+		info, err := os.Stat(path)
+		if err != nil {
+			t.Errorf("%s: %s", path, err)
+		}
+		absinfo, err := os.Stat(abspath)
+		if err != nil || absinfo.Ino != info.Ino {
+			t.Errorf("Abs(%q)=%q, not the same file", path, abspath)
+		}
+		if !filepath.IsAbs(abspath) {
+			t.Errorf("Abs(%q)=%q, not an absolute path", path, abspath)
 		}
 	}
 }