os: avoid error result when dir is removed out from under RemoveAll

Fixes #7776.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews, r
https://golang.org/cl/145860043

diff --git a/src/os/os_test.go b/src/os/os_test.go
index 0224c9b01d60f5592a8132949f9a8e5e1dee2e7b..7a28497414138383e953a05149f0049b5a95e722 100644 (file)
--- a/src/os/os_test.go
+++ b/src/os/os_test.go
@@ -18,6 +18,7 @@ import (
        "runtime"
        "sort"
        "strings"
+       "sync"
        "syscall"
        "testing"
        "text/template"
@@ -1403,3 +1404,44 @@ func TestNilFileMethods(t *testing.T) {
                }
        }
 }
+
+func mkdirTree(t *testing.T, root string, level, max int) {
+       if level >= max {
+               return
+       }
+       level++
+       for i := 'a'; i < 'c'; i++ {
+               dir := filepath.Join(root, string(i))
+               if err := Mkdir(dir, 0700); err != nil {
+                       t.Fatal(err)
+               }
+               mkdirTree(t, dir, level, max)
+       }
+}
+
+// Test that simultaneous RemoveAll do not report an error.
+// As long as it gets removed, we should be happy.
+func TestRemoveAllRace(t *testing.T) {
+       n := runtime.GOMAXPROCS(16)
+       defer runtime.GOMAXPROCS(n)
+       root, err := ioutil.TempDir("", "issue")
+       if err != nil {
+               t.Fatal(err)
+       }
+       mkdirTree(t, root, 1, 6)
+       hold := make(chan struct{})
+       var wg sync.WaitGroup
+       for i := 0; i < 4; i++ {
+               wg.Add(1)
+               go func() {
+                       defer wg.Done()
+                       <-hold
+                       err := RemoveAll(root)
+                       if err != nil {
+                               t.Errorf("unexpected error: %T, %q", err, err)
+                       }
+               }()
+       }
+       close(hold) // let workers race to remove root
+       wg.Wait()
+}

diff --git a/src/os/path.go b/src/os/path.go
index 02a77ec805171ff4eeef187664c7fb8a7e1f6ec7..6cc69403b612372f140af2ea15270c9de1e3faac 100644 (file)
--- a/src/os/path.go
+++ b/src/os/path.go
@@ -66,7 +66,7 @@ func MkdirAll(path string, perm FileMode) error {
 func RemoveAll(path string) error {
        // Simple case: if Remove works, we're done.
        err := Remove(path)
-       if err == nil {
+       if err == nil || IsNotExist(err) {
                return nil
        }
 
@@ -116,6 +116,9 @@ func RemoveAll(path string) error {
 
        // Remove directory.
        err1 := Remove(path)
+       if err1 == nil || IsNotExist(err1) {
+               return nil
+       }
        if err == nil {
                err = err1
        }