1//go:build aix || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris
2
3package dirent
4
5import (
6 "os"
7 "runtime"
8 "syscall"
9 "unsafe"
10)
11
12// readInt returns the size-bytes unsigned integer in native byte order at offset off.
13func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
14 if len(b) < int(off+size) {
15 return 0, false
16 }
17 if isBigEndian {
18 return readIntBE(b[off:], size), true
19 }
20 return readIntLE(b[off:], size), true
21}
22
23func readIntBE(b []byte, size uintptr) uint64 {
24 switch size {
25 case 1:
26 return uint64(b[0])
27 case 2:
28 _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
29 return uint64(b[1]) | uint64(b[0])<<8
30 case 4:
31 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
32 return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24
33 case 8:
34 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
35 return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
36 uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
37 default:
38 panic("syscall: readInt with unsupported size")
39 }
40}
41
42func readIntLE(b []byte, size uintptr) uint64 {
43 switch size {
44 case 1:
45 return uint64(b[0])
46 case 2:
47 _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
48 return uint64(b[0]) | uint64(b[1])<<8
49 case 4:
50 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
51 return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
52 case 8:
53 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
54 return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
55 uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
56 default:
57 panic("syscall: readInt with unsupported size")
58 }
59}
60
61const InvalidMode = os.FileMode(1<<32 - 1)
62
63func Parse(buf []byte) (consumed int, name string, typ os.FileMode) {
64
65 reclen, ok := direntReclen(buf)
66 if !ok || reclen > uint64(len(buf)) {
67 // WARN: this is a hard error because we consumed 0 bytes
68 // and not stopping here could lead to an infinite loop.
69 return 0, "", InvalidMode
70 }
71 consumed = int(reclen)
72 rec := buf[:reclen]
73
74 ino, ok := direntIno(rec)
75 if !ok {
76 return consumed, "", InvalidMode
77 }
78 // When building to wasip1, the host runtime might be running on Windows
79 // or might expose a remote file system which does not have the concept
80 // of inodes. Therefore, we cannot make the assumption that it is safe
81 // to skip entries with zero inodes.
82 if ino == 0 && runtime.GOOS != "wasip1" {
83 return consumed, "", InvalidMode
84 }
85
86 typ = direntType(buf)
87
88 const namoff = uint64(unsafe.Offsetof(syscall.Dirent{}.Name))
89 namlen, ok := direntNamlen(rec)
90 if !ok || namoff+namlen > uint64(len(rec)) {
91 return consumed, "", InvalidMode
92 }
93 namebuf := rec[namoff : namoff+namlen]
94 for i, c := range namebuf {
95 if c == 0 {
96 namebuf = namebuf[:i]
97 break
98 }
99 }
100 // Check for useless names before allocating a string.
101 if string(namebuf) == "." {
102 name = "."
103 } else if string(namebuf) == ".." {
104 name = ".."
105 } else {
106 name = string(namebuf)
107 }
108 return consumed, name, typ
109}