1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package os
6
7import (
8	"io"
9	"runtime"
10	"syscall"
11	"unsafe"
12)
13
14// Auxiliary information if the File describes a directory
15type dirInfo struct {
16	dir uintptr // Pointer to DIR structure from dirent.h
17}
18
19func (d *dirInfo) close() {
20	if d.dir == 0 {
21		return
22	}
23	closedir(d.dir)
24	d.dir = 0
25}
26
27func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
28	// If this file has no dirinfo, create one.
29	var d *dirInfo
30	for {
31		d = f.dirinfo.Load()
32		if d != nil {
33			break
34		}
35		dir, call, errno := f.pfd.OpenDir()
36		if errno != nil {
37			return nil, nil, nil, &PathError{Op: call, Path: f.name, Err: errno}
38		}
39		d = &dirInfo{dir: dir}
40		if f.dirinfo.CompareAndSwap(nil, d) {
41			break
42		}
43		// We lost the race: try again.
44		d.close()
45	}
46
47	size := n
48	if size <= 0 {
49		size = 100
50		n = -1
51	}
52
53	var dirent syscall.Dirent
54	var entptr *syscall.Dirent
55	for len(names)+len(dirents)+len(infos) < size || n == -1 {
56		if errno := readdir_r(d.dir, &dirent, &entptr); errno != 0 {
57			if errno == syscall.EINTR {
58				continue
59			}
60			return names, dirents, infos, &PathError{Op: "readdir", Path: f.name, Err: errno}
61		}
62		if entptr == nil { // EOF
63			break
64		}
65		// Darwin may return a zero inode when a directory entry has been
66		// deleted but not yet removed from the directory. The man page for
67		// getdirentries(2) states that programs are responsible for skipping
68		// those entries:
69		//
70		//   Users of getdirentries() should skip entries with d_fileno = 0,
71		//   as such entries represent files which have been deleted but not
72		//   yet removed from the directory entry.
73		//
74		if dirent.Ino == 0 {
75			continue
76		}
77		name := (*[len(syscall.Dirent{}.Name)]byte)(unsafe.Pointer(&dirent.Name))[:]
78		for i, c := range name {
79			if c == 0 {
80				name = name[:i]
81				break
82			}
83		}
84		// Check for useless names before allocating a string.
85		if string(name) == "." || string(name) == ".." {
86			continue
87		}
88		if mode == readdirName {
89			names = append(names, string(name))
90		} else if mode == readdirDirEntry {
91			de, err := newUnixDirent(f.name, string(name), dtToType(dirent.Type))
92			if IsNotExist(err) {
93				// File disappeared between readdir and stat.
94				// Treat as if it didn't exist.
95				continue
96			}
97			if err != nil {
98				return nil, dirents, nil, err
99			}
100			dirents = append(dirents, de)
101		} else {
102			info, err := lstat(f.name + "/" + string(name))
103			if IsNotExist(err) {
104				// File disappeared between readdir + stat.
105				// Treat as if it didn't exist.
106				continue
107			}
108			if err != nil {
109				return nil, nil, infos, err
110			}
111			infos = append(infos, info)
112		}
113		runtime.KeepAlive(f)
114	}
115
116	if n > 0 && len(names)+len(dirents)+len(infos) == 0 {
117		return nil, nil, nil, io.EOF
118	}
119	return names, dirents, infos, nil
120}
121
122func dtToType(typ uint8) FileMode {
123	switch typ {
124	case syscall.DT_BLK:
125		return ModeDevice
126	case syscall.DT_CHR:
127		return ModeDevice | ModeCharDevice
128	case syscall.DT_DIR:
129		return ModeDir
130	case syscall.DT_FIFO:
131		return ModeNamedPipe
132	case syscall.DT_LNK:
133		return ModeSymlink
134	case syscall.DT_REG:
135		return 0
136	case syscall.DT_SOCK:
137		return ModeSocket
138	}
139	return ^FileMode(0)
140}
141
142// Implemented in syscall/syscall_darwin.go.
143
144//go:linkname closedir syscall.closedir
145func closedir(dir uintptr) (err error)
146
147//go:linkname readdir_r syscall.readdir_r
148func readdir_r(dir uintptr, entry *syscall.Dirent, result **syscall.Dirent) (res syscall.Errno)
149