os: add support for long path names on freebsd RemoveAll

Follow CL 146020 and enable RemoveAll based on Unlinkat and Openat on
freebsd.

Since the layout of syscall.Stat_t changes in FreeBSD 12, Fstatat needs
a compatibility wrapper akin to Fstatat in x/sys/unix. See CL 138595 and
CL 136816 for details.

Updates #27029

Change-Id: I8851a5b7fa658eaa6e69a1693150b16d9a68f36a
Reviewed-on: https://go-review.googlesource.com/c/146597
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Yuval Pavel Zholkover <paulzhol@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/internal/syscall/unix/at.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build linux darwin freebsd openbsd netbsd dragonfly
+// +build linux darwin openbsd netbsd dragonfly
 
 package unix
 

src/internal/syscall/unix/at_freebsd.go

@@ -0,0 +1,47 @@
+// Copyright 2018 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 unix
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+const (
+	AT_REMOVEDIR        = 0x800
+	AT_SYMLINK_NOFOLLOW = 0x200
+)
+
+func Unlinkat(dirfd int, path string, flags int) error {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return err
+	}
+
+	_, _, errno := syscall.Syscall(syscall.SYS_UNLINKAT, uintptr(dirfd), uintptr(unsafe.Pointer(p)), uintptr(flags))
+	if errno != 0 {
+		return errno
+	}
+
+	return nil
+}
+
+func Openat(dirfd int, path string, flags int, perm uint32) (int, error) {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return 0, err
+	}
+
+	fd, _, errno := syscall.Syscall6(syscall.SYS_OPENAT, uintptr(dirfd), uintptr(unsafe.Pointer(p)), uintptr(flags), uintptr(perm), 0, 0)
+	if errno != 0 {
+		return 0, errno
+	}
+
+	return int(fd), nil
+}
+
+func Fstatat(dirfd int, path string, stat *syscall.Stat_t, flags int) error {
+	return syscall.Fstatat(dirfd, path, stat, flags)
+}

src/internal/syscall/unix/at_sysnum_freebsd.go

@@ -1,14 +0,0 @@
-// Copyright 2018 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 unix
-
-import "syscall"
-
-const unlinkatTrap uintptr = syscall.SYS_UNLINKAT
-const openatTrap uintptr = syscall.SYS_OPENAT
-const fstatatTrap uintptr = syscall.SYS_FSTATAT
-
-const AT_REMOVEDIR = 0x800
-const AT_SYMLINK_NOFOLLOW = 0x200

src/os/removeall_at.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build linux darwin openbsd netbsd dragonfly solaris
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package os
 

src/os/removeall_noat.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !linux,!darwin,!openbsd,!netbsd,!dragonfly,!solaris
+// +build !linux,!darwin,!freebsd,!openbsd,!netbsd,!dragonfly,!solaris
 
 package os
 

src/os/removeall_test.go

@@ -162,7 +162,7 @@ func TestRemoveAllLarge(t *testing.T) {
 
 func TestRemoveAllLongPath(t *testing.T) {
 	switch runtime.GOOS {
-	case "linux", "darwin", "openbsd", "netbsd", "dragonfly", "solaris":
+	case "linux", "darwin", "freebsd", "openbsd", "netbsd", "dragonfly", "solaris":
 		break
 	default:
 		t.Skip("skipping for not implemented platforms")
@@ -212,7 +212,7 @@ func TestRemoveAllLongPath(t *testing.T) {
 
 func TestRemoveAllDot(t *testing.T) {
 	switch runtime.GOOS {
-	case "linux", "darwin", "openbsd", "netbsd", "dragonfly", "solaris":
+	case "linux", "darwin", "freebsd", "openbsd", "netbsd", "dragonfly", "solaris":
 		break
 	default:
 		t.Skip("skipping for not implemented platforms")

src/syscall/syscall_freebsd.go

@@ -223,6 +223,20 @@ func Fstat(fd int, st *Stat_t) (err error) {
 	return nil
 }
 
+func Fstatat(fd int, path string, st *Stat_t, flags int) (err error) {
+	var oldStat stat_freebsd11_t
+	if supportsABI(_ino64First) {
+		return fstatat_freebsd12(fd, path, st, flags)
+	}
+	err = fstatat(fd, path, &oldStat, flags)
+	if err != nil {
+		return err
+	}
+
+	st.convertFrom(&oldStat)
+	return nil
+}
+
 func Statfs(path string, st *Statfs_t) (err error) {
 	var oldStatfs statfs_freebsd11_t
 	if supportsABI(_ino64First) {
@@ -403,6 +417,7 @@ func convertFromDirents11(buf []byte, old []byte) int {
 //sys	Fpathconf(fd int, name int) (val int, err error)
 //sys	fstat(fd int, stat *stat_freebsd11_t) (err error)
 //sys	fstat_freebsd12(fd int, stat *Stat_t) (err error) = _SYS_FSTAT_FREEBSD12
+//sys	fstatat(fd int, path string, stat *stat_freebsd11_t, flags int) (err error)
 //sys	fstatat_freebsd12(fd int, path string, stat *Stat_t, flags int) (err error) = _SYS_FSTATAT_FREEBSD12
 //sys	fstatfs(fd int, stat *statfs_freebsd11_t) (err error)
 //sys	fstatfs_freebsd12(fd int, stat *Statfs_t) (err error) = _SYS_FSTATFS_FREEBSD12

src/syscall/zsyscall_freebsd_386.go

@@ -483,6 +483,21 @@ func fstat_freebsd12(fd int, stat *Stat_t) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func fstatat(fd int, path string, stat *stat_freebsd11_t, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := Syscall6(SYS_FSTATAT, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(stat)), uintptr(flags), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func fstatat_freebsd12(fd int, path string, stat *Stat_t, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)

src/syscall/zsyscall_freebsd_amd64.go

@@ -483,6 +483,21 @@ func fstat_freebsd12(fd int, stat *Stat_t) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func fstatat(fd int, path string, stat *stat_freebsd11_t, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := Syscall6(SYS_FSTATAT, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(stat)), uintptr(flags), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func fstatat_freebsd12(fd int, path string, stat *Stat_t, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)

src/syscall/zsyscall_freebsd_arm.go

@@ -483,6 +483,21 @@ func fstat_freebsd12(fd int, stat *Stat_t) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func fstatat(fd int, path string, stat *stat_freebsd11_t, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := Syscall6(SYS_FSTATAT, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(stat)), uintptr(flags), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func fstatat_freebsd12(fd int, path string, stat *Stat_t, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)