303 lines
7.7 KiB
Go
303 lines
7.7 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package os
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import (
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"errors"
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"io"
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"syscall"
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)
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// Readdir reads the contents of the directory associated with file and
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// returns an array of up to n FileInfo structures, as would be returned
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// by Lstat, in directory order. Subsequent calls on the same file will yield
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// further FileInfos.
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//
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// If n > 0, Readdir returns at most n FileInfo structures. In this case, if
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// Readdirnames returns an empty slice, it will return a non-nil error
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// explaining why. At the end of a directory, the error is io.EOF.
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//
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// If n <= 0, Readdir returns all the FileInfo from the directory in
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// a single slice. In this case, if Readdir succeeds (reads all
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// the way to the end of the directory), it returns the slice and a
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// nil error. If it encounters an error before the end of the
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// directory, Readdir returns the FileInfo read until that point
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// and a non-nil error.
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func (file *File) Readdir(n int) (fi []FileInfo, err error) {
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// If this file has no dirinfo, create one.
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if file.dirinfo == nil {
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file.dirinfo = new(dirInfo)
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}
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d := file.dirinfo
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size := n
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if size <= 0 {
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size = 100
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n = -1
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}
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result := make([]FileInfo, 0, size) // Empty with room to grow.
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for n != 0 {
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// Refill the buffer if necessary
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if d.bufp >= d.nbuf {
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d.bufp = 0
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var e error
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d.nbuf, e = file.Read(d.buf[:])
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if e != nil && e != io.EOF {
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return result, &PathError{"readdir", file.name, e}
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}
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if e == io.EOF {
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break
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}
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if d.nbuf < syscall.STATFIXLEN {
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return result, &PathError{"readdir", file.name, Eshortstat}
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}
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}
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// Get a record from buffer
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m, _ := gbit16(d.buf[d.bufp:])
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m += 2
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if m < syscall.STATFIXLEN {
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return result, &PathError{"readdir", file.name, Eshortstat}
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}
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dir, e := UnmarshalDir(d.buf[d.bufp : d.bufp+int(m)])
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if e != nil {
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return result, &PathError{"readdir", file.name, e}
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}
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var f FileInfo
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fileInfoFromStat(&f, dir)
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result = append(result, f)
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d.bufp += int(m)
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n--
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}
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if n >= 0 && len(result) == 0 {
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return result, io.EOF
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}
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return result, nil
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}
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// Readdirnames reads and returns a slice of names from the directory f.
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//
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// If n > 0, Readdirnames returns at most n names. In this case, if
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// Readdirnames returns an empty slice, it will return a non-nil error
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// explaining why. At the end of a directory, the error is io.EOF.
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//
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// If n <= 0, Readdirnames returns all the names from the directory in
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// a single slice. In this case, if Readdirnames succeeds (reads all
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// the way to the end of the directory), it returns the slice and a
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// nil error. If it encounters an error before the end of the
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// directory, Readdirnames returns the names read until that point and
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// a non-nil error.
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func (file *File) Readdirnames(n int) (names []string, err error) {
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fi, err := file.Readdir(n)
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names = make([]string, len(fi))
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for i := range fi {
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names[i] = fi[i].Name
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}
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return
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}
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type Dir struct {
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// system-modified data
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Type uint16 // server type
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Dev uint32 // server subtype
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// file data
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Qid Qid // unique id from server
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Mode uint32 // permissions
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Atime uint32 // last read time
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Mtime uint32 // last write time
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Length uint64 // file length
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Name string // last element of path
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Uid string // owner name
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Gid string // group name
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Muid string // last modifier name
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}
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type Qid struct {
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Path uint64 // the file server's unique identification for the file
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Vers uint32 // version number for given Path
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Type uint8 // the type of the file (syscall.QTDIR for example)
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}
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var nullDir = Dir{
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^uint16(0),
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^uint32(0),
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Qid{^uint64(0), ^uint32(0), ^uint8(0)},
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^uint32(0),
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^uint32(0),
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^uint32(0),
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^uint64(0),
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"",
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"",
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"",
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"",
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}
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// Null assigns members of d with special "don't care" values indicating
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// they should not be written by syscall.Wstat.
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func (d *Dir) Null() {
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*d = nullDir
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}
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// pdir appends a 9P Stat message based on the contents of Dir d to a byte slice b.
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func pdir(b []byte, d *Dir) []byte {
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n := len(b)
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b = pbit16(b, 0) // length, filled in later
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b = pbit16(b, d.Type)
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b = pbit32(b, d.Dev)
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b = pqid(b, d.Qid)
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b = pbit32(b, d.Mode)
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b = pbit32(b, d.Atime)
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b = pbit32(b, d.Mtime)
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b = pbit64(b, d.Length)
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b = pstring(b, d.Name)
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b = pstring(b, d.Uid)
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b = pstring(b, d.Gid)
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b = pstring(b, d.Muid)
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pbit16(b[0:n], uint16(len(b)-(n+2)))
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return b
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}
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// UnmarshalDir reads a 9P Stat message from a 9P protocol message stored in b,
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// returning the corresponding Dir struct.
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func UnmarshalDir(b []byte) (d *Dir, err error) {
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n := uint16(0)
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n, b = gbit16(b)
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if int(n) != len(b) {
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return nil, Ebadstat
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}
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d = new(Dir)
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d.Type, b = gbit16(b)
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d.Dev, b = gbit32(b)
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d.Qid, b = gqid(b)
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d.Mode, b = gbit32(b)
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d.Atime, b = gbit32(b)
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d.Mtime, b = gbit32(b)
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d.Length, b = gbit64(b)
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d.Name, b = gstring(b)
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d.Uid, b = gstring(b)
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d.Gid, b = gstring(b)
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d.Muid, b = gstring(b)
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if len(b) != 0 {
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return nil, Ebadstat
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}
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return d, nil
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}
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// gqid reads the qid part of a 9P Stat message from a 9P protocol message stored in b,
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// returning the corresponding Qid struct and the remaining slice of b.
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func gqid(b []byte) (Qid, []byte) {
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var q Qid
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q.Path, b = gbit64(b)
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q.Vers, b = gbit32(b)
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q.Type, b = gbit8(b)
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return q, b
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}
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// pqid appends a Qid struct q to a 9P message b.
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func pqid(b []byte, q Qid) []byte {
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b = pbit64(b, q.Path)
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b = pbit32(b, q.Vers)
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b = pbit8(b, q.Type)
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return b
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}
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// gbit8 reads a byte-sized numeric value from a 9P protocol message stored in b,
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// returning the value and the remaining slice of b.
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func gbit8(b []byte) (uint8, []byte) {
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return uint8(b[0]), b[1:]
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}
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// gbit16 reads a 16-bit numeric value from a 9P protocol message stored in b,
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// returning the value and the remaining slice of b.
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func gbit16(b []byte) (uint16, []byte) {
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return uint16(b[0]) | uint16(b[1])<<8, b[2:]
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}
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// gbit32 reads a 32-bit numeric value from a 9P protocol message stored in b,
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// returning the value and the remaining slice of b.
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func gbit32(b []byte) (uint32, []byte) {
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return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24, b[4:]
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}
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// gbit64 reads a 64-bit numeric value from a 9P protocol message stored in b,
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// returning the value and the remaining slice of b.
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func gbit64(b []byte) (uint64, []byte) {
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lo, b := gbit32(b)
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hi, b := gbit32(b)
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return uint64(hi)<<32 | uint64(lo), b
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}
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// gstring reads a string from a 9P protocol message stored in b,
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// returning the value as a Go string and the remaining slice of b.
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func gstring(b []byte) (string, []byte) {
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n, b := gbit16(b)
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return string(b[0:n]), b[n:]
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}
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// pbit8 appends a byte-sized numeric value x to a 9P message b.
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func pbit8(b []byte, x uint8) []byte {
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n := len(b)
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if n+1 > cap(b) {
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nb := make([]byte, n, 100+2*cap(b))
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copy(nb, b)
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b = nb
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}
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b = b[0 : n+1]
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b[n] = x
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return b
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}
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// pbit16 appends a 16-bit numeric value x to a 9P message b.
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func pbit16(b []byte, x uint16) []byte {
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n := len(b)
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if n+2 > cap(b) {
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nb := make([]byte, n, 100+2*cap(b))
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copy(nb, b)
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b = nb
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}
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b = b[0 : n+2]
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b[n] = byte(x)
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b[n+1] = byte(x >> 8)
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return b
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}
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// pbit32 appends a 32-bit numeric value x to a 9P message b.
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func pbit32(b []byte, x uint32) []byte {
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n := len(b)
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if n+4 > cap(b) {
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nb := make([]byte, n, 100+2*cap(b))
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copy(nb, b)
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b = nb
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}
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b = b[0 : n+4]
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b[n] = byte(x)
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b[n+1] = byte(x >> 8)
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b[n+2] = byte(x >> 16)
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b[n+3] = byte(x >> 24)
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return b
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}
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// pbit64 appends a 64-bit numeric value x to a 9P message b.
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func pbit64(b []byte, x uint64) []byte {
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b = pbit32(b, uint32(x))
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b = pbit32(b, uint32(x>>32))
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return b
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}
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// pstring appends a Go string s to a 9P message b.
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func pstring(b []byte, s string) []byte {
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if len(s) >= 1<<16 {
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panic(errors.New("string too long"))
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}
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b = pbit16(b, uint16(len(s)))
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b = append(b, s...)
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return b
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}
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