Merge pull request #1 from google/master

catch up

5 files changed, 40 insertions, 66 deletions

diff --git a/pkg/fspath/BUILD b/pkg/fspath/BUILD
index 0c5f50397..67dd1e225 100644
--- a/pkg/fspath/BUILD
+++ b/pkg/fspath/BUILD
@@ -1,20 +1,18 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 
-package(
-    default_visibility = ["//visibility:public"],
-    licenses = ["notice"],
-)
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
 
 go_library(
     name = "fspath",
     srcs = [
         "builder.go",
-        "builder_unsafe.go",
         "fspath.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/fspath",
-    deps = ["//pkg/syserror"],
+    deps = [
+        "//pkg/gohacks",
+    ],
 )
 
 go_test(
@@ -24,6 +22,5 @@ go_test(
         "builder_test.go",
         "fspath_test.go",
     ],
-    embed = [":fspath"],
-    deps = ["//pkg/syserror"],
+    library = ":fspath",
 )
diff --git a/pkg/fspath/builder.go b/pkg/fspath/builder.go
index 7ddb36826..6318d3874 100644
--- a/pkg/fspath/builder.go
+++ b/pkg/fspath/builder.go
@@ -16,6 +16,8 @@ package fspath
 
 import (
 	"fmt"
+
+	"gvisor.dev/gvisor/pkg/gohacks"
 )
 
 // Builder is similar to strings.Builder, but is used to produce pathnames
@@ -102,3 +104,9 @@ func (b *Builder) AppendString(str string) {
 	copy(b.buf[b.start:], b.buf[oldStart:])
 	copy(b.buf[len(b.buf)-len(str):], str)
 }
+
+// String returns the accumulated string. No other methods should be called
+// after String.
+func (b *Builder) String() string {
+	return gohacks.StringFromImmutableBytes(b.buf[b.start:])
+}
diff --git a/pkg/fspath/builder_unsafe.go b/pkg/fspath/builder_unsafe.go
deleted file mode 100644
index 75606808d..000000000
--- a/pkg/fspath/builder_unsafe.go
+++ /dev/null
@@ -1,27 +0,0 @@
-// Copyright 2019 The gVisor Authors.
-//
-// 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.
-
-package fspath
-
-import (
-	"unsafe"
-)
-
-// String returns the accumulated string. No other methods should be called
-// after String.
-func (b *Builder) String() string {
-	bs := b.buf[b.start:]
-	// Compare strings.Builder.String().
-	return *(*string)(unsafe.Pointer(&bs))
-}
diff --git a/pkg/fspath/fspath.go b/pkg/fspath/fspath.go
index f68752560..4c983d5fd 100644
--- a/pkg/fspath/fspath.go
+++ b/pkg/fspath/fspath.go
@@ -18,19 +18,17 @@ package fspath
 
 import (
 	"strings"
-
-	"gvisor.dev/gvisor/pkg/syserror"
 )
 
 const pathSep = '/'
 
-// Parse parses a pathname as described by path_resolution(7).
-func Parse(pathname string) (Path, error) {
+// Parse parses a pathname as described by path_resolution(7), except that
+// empty pathnames will be parsed successfully to a Path for which
+// Path.Absolute == Path.Dir == Path.HasComponents() == false. (This is
+// necessary to support AT_EMPTY_PATH.)
+func Parse(pathname string) Path {
 	if len(pathname) == 0 {
-		// "... POSIX decrees that an empty pathname must not be resolved
-		// successfully. Linux returns ENOENT in this case." -
-		// path_resolution(7)
-		return Path{}, syserror.ENOENT
+		return Path{}
 	}
 	// Skip leading path separators.
 	i := 0
@@ -41,7 +39,7 @@ func Parse(pathname string) (Path, error) {
 			return Path{
 				Absolute: true,
 				Dir:      true,
-			}, nil
+			}
 		}
 	}
 	// Skip trailing path separators. This is required by Iterator.Next. This
@@ -64,12 +62,13 @@ func Parse(pathname string) (Path, error) {
 		},
 		Absolute: i != 0,
 		Dir:      j != len(pathname)-1,
-	}, nil
+	}
 }
 
 // Path contains the information contained in a pathname string.
 //
-// Path is copyable by value.
+// Path is copyable by value. The zero value for Path is equivalent to
+// fspath.Parse(""), i.e. the empty path.
 type Path struct {
 	// Begin is an iterator to the first path component in the relative part of
 	// the path.
@@ -111,6 +110,12 @@ func (p Path) String() string {
 	return b.String()
 }
 
+// HasComponents returns true if p contains a non-zero number of path
+// components.
+func (p Path) HasComponents() bool {
+	return p.Begin.Ok()
+}
+
 // An Iterator represents either a path component in a Path or a terminal
 // iterator indicating that the end of the path has been reached.
 //
diff --git a/pkg/fspath/fspath_test.go b/pkg/fspath/fspath_test.go
index 215b35622..d5e9a549a 100644
--- a/pkg/fspath/fspath_test.go
+++ b/pkg/fspath/fspath_test.go
@@ -18,15 +18,10 @@ import (
 	"reflect"
 	"strings"
 	"testing"
-
-	"gvisor.dev/gvisor/pkg/syserror"
 )
 
 func TestParseIteratorPartialPathnames(t *testing.T) {
-	path, err := Parse("/foo//bar///baz////")
-	if err != nil {
-		t.Fatalf("Parse failed: %v", err)
-	}
+	path := Parse("/foo//bar///baz////")
 	// Parse strips leading slashes, and records their presence as
 	// Path.Absolute.
 	if !path.Absolute {
@@ -71,6 +66,12 @@ func TestParse(t *testing.T) {
 	}
 	tests := []testCase{
 		{
+			pathname: "",
+			relpath:  []string{},
+			abs:      false,
+			dir:      false,
+		},
+		{
 			pathname: "/",
 			relpath:  []string{},
 			abs:      true,
@@ -113,10 +114,7 @@ func TestParse(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.pathname, func(t *testing.T) {
-			p, err := Parse(test.pathname)
-			if err != nil {
-				t.Fatalf("failed to parse pathname %q: %v", test.pathname, err)
-			}
+			p := Parse(test.pathname)
 			t.Logf("pathname %q => path %q", test.pathname, p)
 			if p.Absolute != test.abs {
 				t.Errorf("path absoluteness: got %v, wanted %v", p.Absolute, test.abs)
@@ -134,10 +132,3 @@ func TestParse(t *testing.T) {
 		})
 	}
 }
-
-func TestParseEmptyPathname(t *testing.T) {
-	p, err := Parse("")
-	if err != syserror.ENOENT {
-		t.Errorf("parsing empty pathname: got (%v, %v), wanted (<unspecified>, ENOENT)", p, err)
-	}
-}