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minio/posix-dir-nix.go

146 lines
3.7 KiB

// +build linux darwin dragonfly freebsd netbsd openbsd
/*
* Minio Cloud Storage, (C) 2016 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 main
import (
"os"
"path"
"runtime"
"sort"
"syscall"
"unsafe"
)
const (
// readDirentBufSize for syscall.ReadDirent() to hold multiple
// directory entries in one buffer. golang source uses 4096 as
// buffer size whereas we want 25 times larger to save lots of
// entries to avoid multiple syscall.ReadDirent() call.
readDirentBufSize = 4096 * 25
)
// actual length of the byte array from the c - world.
func clen(n []byte) int {
for i := 0; i < len(n); i++ {
if n[i] == 0 {
return i
}
}
return len(n)
}
// parseDirents - inspired from
// https://golang.org/src/syscall/syscall_<os>.go
func parseDirents(dirPath string, buf []byte) []fsDirent {
bufidx := 0
dirents := []fsDirent{}
for bufidx < len(buf) {
dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[bufidx]))
// On non-Linux operating systems for rec length of zero means
// we have reached EOF break out.
if runtime.GOOS != "linux" && dirent.Reclen == 0 {
break
}
bufidx += int(dirent.Reclen)
// Skip dirents if they are absent in directory.
if isEmptyDirent(dirent) {
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:clen(bytes[:])])
// Reserved names skip them.
if name == "." || name == ".." {
continue
}
var mode os.FileMode
switch dirent.Type {
case syscall.DT_BLK, syscall.DT_WHT:
mode = os.ModeDevice
case syscall.DT_CHR:
mode = os.ModeDevice | os.ModeCharDevice
case syscall.DT_DIR:
mode = os.ModeDir
case syscall.DT_FIFO:
mode = os.ModeNamedPipe
case syscall.DT_LNK:
mode = os.ModeSymlink
case syscall.DT_REG:
mode = 0
case syscall.DT_SOCK:
mode = os.ModeSocket
case syscall.DT_UNKNOWN:
// On Linux XFS does not implement d_type for on disk
// format << v5. Fall back to Stat().
if fi, err := os.Stat(path.Join(dirPath, name)); err == nil {
mode = fi.Mode()
} else {
// Caller listing would fail, if Stat failed but we
// won't crash the server.
mode = 0xffffffff
}
}
dirents = append(dirents, fsDirent{
name: name,
mode: mode,
})
}
return dirents
}
// scans the directory dirPath, calling filter() on each directory
// entry. Entries for which filter() returns true are stored, lexically
// sorted using sort.Sort(). If filter is NULL, all entries are selected.
// If namesOnly is true, dirPath is not appended into entry name.
func scandir(dirPath string, filter func(fsDirent) bool, namesOnly bool) ([]fsDirent, error) {
buf := make([]byte, readDirentBufSize)
d, err := os.Open(dirPath)
if err != nil {
return nil, err
}
defer d.Close()
fd := int(d.Fd())
dirents := []fsDirent{}
for {
nbuf, err := syscall.ReadDirent(fd, buf)
if err != nil {
return nil, err
}
if nbuf <= 0 {
break
}
for _, dirent := range parseDirents(dirPath, buf[:nbuf]) {
if !namesOnly {
dirent.name = path.Join(dirPath, dirent.name)
}
if dirent.IsDir() {
dirent.name += "/"
dirent.size = 0
}
if filter == nil || filter(dirent) {
dirents = append(dirents, dirent)
}
}
}
sort.Sort(byDirentName(dirents))
return dirents, nil
}