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minio/cmd/os-readdir_unix.go

211 lines
5.4 KiB

// +build linux,!appengine darwin freebsd netbsd openbsd
/*
* MinIO Cloud Storage, (C) 2016-2020 MinIO, Inc.
*
* 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 cmd
import (
"fmt"
"os"
"sync"
"syscall"
"unsafe"
)
// The buffer must be at least a block long.
// refer https://github.com/golang/go/issues/24015
const blockSize = 8 << 10 // 8192
// By default atleast 1000 entries in single getdents call
var direntPool = sync.Pool{
New: func() interface{} {
buf := make([]byte, blockSize*1000)
return &buf
},
}
// unexpectedFileMode is a sentinel (and bogus) os.FileMode
// value used to represent a syscall.DT_UNKNOWN Dirent.Type.
const unexpectedFileMode os.FileMode = os.ModeNamedPipe | os.ModeSocket | os.ModeDevice
func parseDirEnt(buf []byte) (consumed int, name string, typ os.FileMode, err error) {
// golang.org/issue/15653
dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[0]))
if v := unsafe.Offsetof(dirent.Reclen) + unsafe.Sizeof(dirent.Reclen); uintptr(len(buf)) < v {
return consumed, name, typ, fmt.Errorf("buf size of %d smaller than dirent header size %d", len(buf), v)
}
if len(buf) < int(dirent.Reclen) {
return consumed, name, typ, fmt.Errorf("buf size %d < record length %d", len(buf), dirent.Reclen)
}
consumed = int(dirent.Reclen)
if direntInode(dirent) == 0 { // File absent in directory.
return
}
switch dirent.Type {
case syscall.DT_REG:
typ = 0
case syscall.DT_DIR:
typ = os.ModeDir
case syscall.DT_LNK:
typ = os.ModeSymlink
default:
// Skip all other file types. Revisit if/when this code needs
// to handle such files, MinIO is only interested in
// files and directories.
typ = unexpectedFileMode
}
nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))
nameLen, err := direntNamlen(dirent)
if err != nil {
return consumed, name, typ, err
}
name = string(nameBuf[:nameLen])
return consumed, name, typ, nil
}
// Return all the entries at the directory dirPath.
func readDir(dirPath string) (entries []string, err error) {
return readDirN(dirPath, -1)
}
// readDir applies the filter function on each entries at dirPath, doesn't recurse into
// the directory itself.
func readDirFilterFn(dirPath string, filter func(name string, typ os.FileMode) error) error {
fd, err := syscall.Open(dirPath, 0, 0)
if err != nil {
if os.IsNotExist(err) || isSysErrNotDir(err) {
return errFileNotFound
}
if os.IsPermission(err) {
return errFileAccessDenied
}
return err
}
defer syscall.Close(fd)
buf := make([]byte, blockSize)
boff := 0 // starting read position in buf
nbuf := 0 // end valid data in buf
for {
if boff >= nbuf {
boff = 0
nbuf, err = syscall.ReadDirent(fd, buf)
if err != nil {
if isSysErrNotDir(err) {
return errFileNotFound
}
return err
}
if nbuf <= 0 {
break // EOF
}
}
consumed, name, typ, err := parseDirEnt(buf[boff:nbuf])
if err != nil {
return err
}
boff += consumed
if name == "" || name == "." || name == ".." {
continue
}
if typ&os.ModeSymlink == os.ModeSymlink {
continue
}
if err = filter(name, typ); err == errDoneForNow {
// filtering requested to return by caller.
return nil
}
}
return err
}
// Return count entries at the directory dirPath and all entries
// if count is set to -1
func readDirN(dirPath string, count int) (entries []string, err error) {
fd, err := syscall.Open(dirPath, 0, 0)
if err != nil {
if os.IsNotExist(err) || isSysErrNotDir(err) {
return nil, errFileNotFound
}
if os.IsPermission(err) {
return nil, errFileAccessDenied
}
return nil, err
}
defer syscall.Close(fd)
bufp := direntPool.Get().(*[]byte)
defer direntPool.Put(bufp)
boff := 0 // starting read position in buf
nbuf := 0 // end valid data in buf
for count != 0 {
if boff >= nbuf {
boff = 0
nbuf, err = syscall.ReadDirent(fd, *bufp)
if err != nil {
if isSysErrNotDir(err) {
return nil, errFileNotFound
}
return nil, err
}
if nbuf <= 0 {
break
}
}
consumed, name, typ, err := parseDirEnt((*bufp)[boff:nbuf])
if err != nil {
return nil, err
}
boff += consumed
if name == "" || name == "." || name == ".." {
continue
}
// Fallback for filesystems (like old XFS) that don't
// support Dirent.Type and have DT_UNKNOWN (0) there
// instead.
if typ == unexpectedFileMode {
fi, err := os.Lstat(pathJoin(dirPath, name))
if err != nil {
// It got deleted in the meantime, not found
// or returns too many symlinks ignore this
// file/directory.
if os.IsNotExist(err) || isSysErrPathNotFound(err) ||
isSysErrTooManySymlinks(err) {
continue
}
return nil, err
}
typ = fi.Mode() & os.ModeType
}
if typ&os.ModeSymlink == os.ModeSymlink {
continue
}
if typ.IsRegular() {
entries = append(entries, name)
} else if typ.IsDir() {
entries = append(entries, name+SlashSeparator)
}
count--
}
return
}