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readdir_unix.go
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readdir_unix.go
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// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
package godirwalk
import (
"os"
"path/filepath"
"syscall"
"unsafe"
"github.com/pkg/errors"
)
var defaultBufferSize, pageSize, maxNameLength int
func init() {
pageSize = os.Getpagesize()
defaultBufferSize = 2 * pageSize
}
func readdirents(osDirname string, scratchBuffer []byte) (Dirents, error) {
dh, err := os.Open(osDirname)
if err != nil {
return nil, errors.Wrap(err, "cannot Open")
}
var entries Dirents
fd := int(dh.Fd())
if len(scratchBuffer) < pageSize {
scratchBuffer = make([]byte, defaultBufferSize)
}
var de *syscall.Dirent
for {
n, err := syscall.ReadDirent(fd, scratchBuffer)
if err != nil {
_ = dh.Close() // ignore potential error returned by Close
return nil, errors.Wrap(err, "cannot ReadDirent")
}
if n <= 0 {
break // end of directory reached
}
// Loop over the bytes returned by reading the directory entries.
buf := scratchBuffer[:n]
for len(buf) > 0 {
de = (*syscall.Dirent)(unsafe.Pointer(&buf[0])) // point entry to first syscall.Dirent in buffer
buf = buf[de.Reclen:] // advance buffer
if de.Ino == 0 {
continue // this item has been deleted, but not yet removed from directory
}
nameSlice := nameFromDirent(de)
namlen := len(nameSlice)
if (namlen == 0) || (namlen == 1 && nameSlice[0] == '.') || (namlen == 2 && nameSlice[0] == '.' && nameSlice[1] == '.') {
continue // skip unimportant entries
}
osChildname := string(nameSlice)
// Convert syscall constant, which is in purview of OS, to a
// constant defined by Go, assumed by this project to be stable.
var mode os.FileMode
switch de.Type {
case syscall.DT_REG:
// regular file
case syscall.DT_DIR:
mode = os.ModeDir
case syscall.DT_LNK:
mode = os.ModeSymlink
case syscall.DT_CHR:
mode = os.ModeDevice | os.ModeCharDevice
case syscall.DT_BLK:
mode = os.ModeDevice
case syscall.DT_FIFO:
mode = os.ModeNamedPipe
case syscall.DT_SOCK:
mode = os.ModeSocket
default:
// If syscall returned unknown type (e.g., DT_UNKNOWN, DT_WHT),
// then resolve actual mode by getting stat.
fi, err := os.Stat(filepath.Join(osDirname, osChildname))
if err != nil {
_ = dh.Close() // ignore potential error returned by Close
return nil, errors.Wrap(err, "cannot Stat")
}
// We only care about the bits that identify the type of a file
// system node, and can ignore append, exclusive, temporary,
// setuid, setgid, permission bits, and sticky bits, which are
// coincident to the bits that declare type of the file system
// node.
mode = fi.Mode() & os.ModeType
}
entries = append(entries, &Dirent{name: osChildname, modeType: mode})
}
}
if err = dh.Close(); err != nil {
return nil, err
}
return entries, nil
}
func readdirnames(osDirname string, scratchBuffer []byte) ([]string, error) {
des, err := readdirents(osDirname, scratchBuffer)
if err != nil {
return nil, err
}
names := make([]string, len(des))
for i, v := range des {
names[i] = v.name
}
return names, nil
}