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	"syscall"
9	"time"
10)
11
12// Getpagesize returns the underlying system's memory page size.
13func Getpagesize() int { return syscall.Getpagesize() }
14
15// File represents an open file descriptor.
16type File struct {
17	*file // os specific
18}
19
20// A FileInfo describes a file and is returned by Stat and Lstat.
21type FileInfo interface {
22	Name() string       // base name of the file
23	Size() int64        // length in bytes for regular files; system-dependent for others
24	Mode() FileMode     // file mode bits
25	ModTime() time.Time // modification time
26	IsDir() bool        // abbreviation for Mode().IsDir()
27	Sys() interface{}   // underlying data source (can return nil)
28}
29
30// A FileMode represents a file's mode and permission bits.
31// The bits have the same definition on all systems, so that
32// information about files can be moved from one system
33// to another portably. Not all bits apply to all systems.
34// The only required bit is ModeDir for directories.
35type FileMode uint32
36
37// The defined file mode bits are the most significant bits of the FileMode.
38// The nine least-significant bits are the standard Unix rwxrwxrwx permissions.
39// The values of these bits should be considered part of the public API and
40// may be used in wire protocols or disk representations: they must not be
41// changed, although new bits might be added.
42const (
43	// The single letters are the abbreviations
44	// used by the String method's formatting.
45	ModeDir        FileMode = 1 << (32 - 1 - iota) // d: is a directory
46	ModeAppend                                     // a: append-only
47	ModeExclusive                                  // l: exclusive use
48	ModeTemporary                                  // T: temporary file; Plan 9 only
49	ModeSymlink                                    // L: symbolic link
50	ModeDevice                                     // D: device file
51	ModeNamedPipe                                  // p: named pipe (FIFO)
52	ModeSocket                                     // S: Unix domain socket
53	ModeSetuid                                     // u: setuid
54	ModeSetgid                                     // g: setgid
55	ModeCharDevice                                 // c: Unix character device, when ModeDevice is set
56	ModeSticky                                     // t: sticky
57
58	// Mask for the type bits. For regular files, none will be set.
59	ModeType = ModeDir | ModeSymlink | ModeNamedPipe | ModeSocket | ModeDevice
60
61	ModePerm FileMode = 0777 // Unix permission bits
62)
63
64func (m FileMode) String() string {
65	const str = "dalTLDpSugct"
66	var buf [32]byte // Mode is uint32.
67	w := 0
68	for i, c := range str {
69		if m&(1<<uint(32-1-i)) != 0 {
70			buf[w] = byte(c)
71			w++
72		}
73	}
74	if w == 0 {
75		buf[w] = '-'
76		w++
77	}
78	const rwx = "rwxrwxrwx"
79	for i, c := range rwx {
80		if m&(1<<uint(9-1-i)) != 0 {
81			buf[w] = byte(c)
82		} else {
83			buf[w] = '-'
84		}
85		w++
86	}
87	return string(buf[:w])
88}
89
90// IsDir reports whether m describes a directory.
91// That is, it tests for the ModeDir bit being set in m.
92func (m FileMode) IsDir() bool {
93	return m&ModeDir != 0
94}
95
96// IsRegular reports whether m describes a regular file.
97// That is, it tests that no mode type bits are set.
98func (m FileMode) IsRegular() bool {
99	return m&ModeType == 0
100}
101
102// Perm returns the Unix permission bits in m.
103func (m FileMode) Perm() FileMode {
104	return m & ModePerm
105}
106
107func (fs *fileStat) Name() string { return fs.name }
108func (fs *fileStat) IsDir() bool  { return fs.Mode().IsDir() }
109
110// SameFile reports whether fi1 and fi2 describe the same file.
111// For example, on Unix this means that the device and inode fields
112// of the two underlying structures are identical; on other systems
113// the decision may be based on the path names.
114// SameFile only applies to results returned by this package's Stat.
115// It returns false in other cases.
116func SameFile(fi1, fi2 FileInfo) bool {
117	fs1, ok1 := fi1.(*fileStat)
118	fs2, ok2 := fi2.(*fileStat)
119	if !ok1 || !ok2 {
120		return false
121	}
122	return sameFile(fs1, fs2)
123}
124