os: RemoveAll doesn't remove nested un-readable directories

[cespare]

What version of Go are you using (go version)?

$ go version
go version go1.12 linux/amd64

Does this issue reproduce with the latest release?

Yes. It is a new regression in Go 1.12.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/caleb/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/caleb/p/go:/home/caleb"
GOPROXY=""
GORACE=""
GOROOT="/home/caleb/apps/go"
GOTMPDIR=""
GOTOOLDIR="/home/caleb/apps/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0
-fdebug-prefix-map=/tmp/go-build954814215=/tmp/go-build
-gno-record-gcc-switches"

What did you do?

os.RemoveAll doesn't remove nested directories if they are read-only. It does work if the top directory (i.e., the argument provided to RemoveAll) is read-only.

Demo:

package main

import (
	"log"
	"os"
	"path/filepath"
)

func main() {
	target := filepath.Join("d0", "d1")
	if err := os.MkdirAll(target, 0755); err != nil {
		log.Fatal(err)
	}
	if err := os.Chmod(target, 0300); err != nil {
		log.Fatal(err)
	}
	if err := os.RemoveAll("d0"); err != nil {
		log.Fatal(err)
	}
}

What did you expect to see?

No output; successful execution.

What did you see instead?

2019/03/03 18:36:49 openat d1: permission denied

Notes

This is a regression in Go 1.12. The bug is not present in Go 1.11.5.

The bug was introduced in https://golang.org/cl/146020, which was the fix for #27029.

Before that CL, RemoveAll would unconditionally attempt to call Remove on nested directories.

After that CL, it calls openat first and fails.

This regression is similar to (but distinct from) #29983, which was also caused by CL 146020.

cc @ianlancetaylor

[mvdan]

I presume this will need a backport into 1.12.1 as well.

/cc @ostenbom

[gopherbot]

Change https://golang.org/cl/165057 mentions this issue: os: fix RemoveAll can't remove unreadable directories

[ianlancetaylor]

@gopherbot please open backport to 1.12

[gopherbot]

Backport issue(s) opened: #30579 (for 1.12).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

[gopherbot]

Change https://golang.org/cl/165058 mentions this issue: [release-branch.go1.12] os: remove unreadable directories in RemoveAll