mirror of
https://github.com/minio/minio.git
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332 lines
8.4 KiB
Go
332 lines
8.4 KiB
Go
//go:build (linux && !appengine) || darwin || freebsd || netbsd || openbsd
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// +build linux,!appengine darwin freebsd netbsd openbsd
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// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package cmd
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import (
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"bytes"
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"fmt"
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"os"
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"sync"
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"syscall"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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func access(name string) error {
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if err := unix.Access(name, unix.R_OK|unix.W_OK); err != nil {
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return &os.PathError{Op: "lstat", Path: name, Err: err}
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}
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return nil
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}
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// Forked from Golang but chooses fast path upon os.Mkdir()
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// error to avoid os.Lstat() call.
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//
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// osMkdirAll creates a directory named path,
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// along with any necessary parents, and returns nil,
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// or else returns an error.
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// The permission bits perm (before umask) are used for all
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// directories that MkdirAll creates.
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// If path is already a directory, MkdirAll does nothing
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// and returns nil.
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func osMkdirAll(dirPath string, perm os.FileMode) error {
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// Fast path: if we can tell whether path is a directory or file, stop with success or error.
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err := Access(dirPath)
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if err == nil {
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return nil
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}
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if !osIsNotExist(err) {
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return &os.PathError{Op: "mkdir", Path: dirPath, Err: err}
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}
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// Slow path: make sure parent exists and then call Mkdir for path.
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i := len(dirPath)
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for i > 0 && os.IsPathSeparator(dirPath[i-1]) { // Skip trailing path separator.
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i--
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}
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j := i
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for j > 0 && !os.IsPathSeparator(dirPath[j-1]) { // Scan backward over element.
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j--
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}
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if j > 1 {
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// Create parent.
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if err = osMkdirAll(dirPath[:j-1], perm); err != nil {
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return err
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}
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}
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// Parent now exists; invoke Mkdir and use its result.
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if err = Mkdir(dirPath, perm); err != nil {
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if osIsExist(err) {
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return nil
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}
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return err
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}
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return nil
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}
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// The buffer must be at least a block long.
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// refer https://github.com/golang/go/issues/24015
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const blockSize = 8 << 10 // 8192
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// By default atleast 128 entries in single getdents call (1MiB buffer)
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var (
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direntPool = sync.Pool{
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New: func() interface{} {
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buf := make([]byte, blockSize*128)
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return &buf
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},
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}
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direntNamePool = sync.Pool{
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New: func() interface{} {
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buf := make([]byte, blockSize)
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return &buf
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},
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}
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)
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// unexpectedFileMode is a sentinel (and bogus) os.FileMode
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// value used to represent a syscall.DT_UNKNOWN Dirent.Type.
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const unexpectedFileMode os.FileMode = os.ModeNamedPipe | os.ModeSocket | os.ModeDevice
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func parseDirEnt(buf []byte) (consumed int, name []byte, typ os.FileMode, err error) {
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// golang.org/issue/15653
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dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[0]))
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if v := unsafe.Offsetof(dirent.Reclen) + unsafe.Sizeof(dirent.Reclen); uintptr(len(buf)) < v {
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return consumed, nil, typ, fmt.Errorf("buf size of %d smaller than dirent header size %d", len(buf), v)
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}
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if len(buf) < int(dirent.Reclen) {
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return consumed, nil, typ, fmt.Errorf("buf size %d < record length %d", len(buf), dirent.Reclen)
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}
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consumed = int(dirent.Reclen)
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if direntInode(dirent) == 0 { // File absent in directory.
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return
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}
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switch dirent.Type {
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case syscall.DT_REG:
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typ = 0
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case syscall.DT_DIR:
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typ = os.ModeDir
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case syscall.DT_LNK:
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typ = os.ModeSymlink
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default:
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// Skip all other file types. Revisit if/when this code needs
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// to handle such files, MinIO is only interested in
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// files and directories.
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typ = unexpectedFileMode
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}
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nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))
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nameLen, err := direntNamlen(dirent)
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if err != nil {
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return consumed, nil, typ, err
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}
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return consumed, nameBuf[:nameLen], typ, nil
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}
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// readDirFn applies the fn() function on each entries at dirPath, doesn't recurse into
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// the directory itself, if the dirPath doesn't exist this function doesn't return
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// an error.
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func readDirFn(dirPath string, fn func(name string, typ os.FileMode) error) error {
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f, err := Open(dirPath)
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if err != nil {
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if osErrToFileErr(err) == errFileNotFound {
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return nil
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}
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return osErrToFileErr(err)
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}
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defer f.Close()
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bufp := direntPool.Get().(*[]byte)
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defer direntPool.Put(bufp)
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buf := *bufp
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boff := 0 // starting read position in buf
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nbuf := 0 // end valid data in buf
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for {
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if boff >= nbuf {
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boff = 0
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stop := globalOSMetrics.time(osMetricReadDirent)
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nbuf, err = syscall.ReadDirent(int(f.Fd()), buf)
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stop()
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if err != nil {
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if isSysErrNotDir(err) {
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return nil
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}
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err = osErrToFileErr(err)
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if err == errFileNotFound {
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return nil
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}
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return err
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}
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if nbuf <= 0 {
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break // EOF
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}
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}
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consumed, name, typ, err := parseDirEnt(buf[boff:nbuf])
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if err != nil {
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return err
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}
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boff += consumed
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if len(name) == 0 || bytes.Equal(name, []byte{'.'}) || bytes.Equal(name, []byte{'.', '.'}) {
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continue
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}
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// Fallback for filesystems (like old XFS) that don't
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// support Dirent.Type and have DT_UNKNOWN (0) there
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// instead.
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if typ == unexpectedFileMode || typ&os.ModeSymlink == os.ModeSymlink {
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fi, err := Stat(pathJoin(dirPath, string(name)))
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if err != nil {
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// It got deleted in the meantime, not found
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// or returns too many symlinks ignore this
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// file/directory.
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if osIsNotExist(err) || isSysErrPathNotFound(err) ||
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isSysErrTooManySymlinks(err) {
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continue
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}
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return err
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}
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// Ignore symlinked directories.
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if typ&os.ModeSymlink == os.ModeSymlink && fi.IsDir() {
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continue
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}
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typ = fi.Mode() & os.ModeType
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}
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if err = fn(string(name), typ); err == errDoneForNow {
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// fn() requested to return by caller.
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return nil
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}
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}
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return err
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}
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// Return count entries at the directory dirPath and all entries
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// if count is set to -1
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func readDirWithOpts(dirPath string, opts readDirOpts) (entries []string, err error) {
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f, err := OpenFile(dirPath, readMode, 0o666)
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if err != nil {
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if osIsPermission(err) {
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f, err = Open(dirPath)
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if err != nil {
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return nil, osErrToFileErr(err)
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}
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} else {
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return nil, osErrToFileErr(err)
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}
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}
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defer f.Close()
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bufp := direntPool.Get().(*[]byte)
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defer direntPool.Put(bufp)
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buf := *bufp
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nameTmp := direntNamePool.Get().(*[]byte)
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defer direntNamePool.Put(nameTmp)
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tmp := *nameTmp
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boff := 0 // starting read position in buf
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nbuf := 0 // end valid data in buf
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count := opts.count
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for count != 0 {
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if boff >= nbuf {
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boff = 0
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stop := globalOSMetrics.time(osMetricReadDirent)
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nbuf, err = syscall.ReadDirent(int(f.Fd()), buf)
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stop()
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if err != nil {
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if isSysErrNotDir(err) {
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return nil, errFileNotFound
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}
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return nil, osErrToFileErr(err)
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}
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if nbuf <= 0 {
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break
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}
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}
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consumed, name, typ, err := parseDirEnt(buf[boff:nbuf])
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if err != nil {
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return nil, err
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}
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boff += consumed
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if len(name) == 0 || bytes.Equal(name, []byte{'.'}) || bytes.Equal(name, []byte{'.', '.'}) {
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continue
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}
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// Fallback for filesystems (like old XFS) that don't
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// support Dirent.Type and have DT_UNKNOWN (0) there
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// instead.
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if typ == unexpectedFileMode || typ&os.ModeSymlink == os.ModeSymlink {
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fi, err := Stat(pathJoin(dirPath, string(name)))
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if err != nil {
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// It got deleted in the meantime, not found
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// or returns too many symlinks ignore this
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// file/directory.
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if osIsNotExist(err) || isSysErrPathNotFound(err) ||
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isSysErrTooManySymlinks(err) {
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continue
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}
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return nil, err
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}
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// Ignore symlinked directories.
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if !opts.followDirSymlink && typ&os.ModeSymlink == os.ModeSymlink && fi.IsDir() {
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continue
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}
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typ = fi.Mode() & os.ModeType
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}
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var nameStr string
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if typ.IsRegular() {
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nameStr = string(name)
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} else if typ.IsDir() {
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// Use temp buffer to append a slash to avoid string concat.
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tmp = tmp[:len(name)+1]
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copy(tmp, name)
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tmp[len(tmp)-1] = '/' // SlashSeparator
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nameStr = string(tmp)
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}
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count--
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entries = append(entries, nameStr)
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}
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return
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}
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func globalSync() {
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defer globalOSMetrics.time(osMetricSync)
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syscall.Sync()
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}
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