David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame^] | 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 | |
| 5 | // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris |
| 6 | |
| 7 | package unix |
| 8 | |
| 9 | import "unsafe" |
| 10 | |
| 11 | // readInt returns the size-bytes unsigned integer in native byte order at offset off. |
| 12 | func readInt(b []byte, off, size uintptr) (u uint64, ok bool) { |
| 13 | if len(b) < int(off+size) { |
| 14 | return 0, false |
| 15 | } |
| 16 | if isBigEndian { |
| 17 | return readIntBE(b[off:], size), true |
| 18 | } |
| 19 | return readIntLE(b[off:], size), true |
| 20 | } |
| 21 | |
| 22 | func readIntBE(b []byte, size uintptr) uint64 { |
| 23 | switch size { |
| 24 | case 1: |
| 25 | return uint64(b[0]) |
| 26 | case 2: |
| 27 | _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808 |
| 28 | return uint64(b[1]) | uint64(b[0])<<8 |
| 29 | case 4: |
| 30 | _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 |
| 31 | return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24 |
| 32 | case 8: |
| 33 | _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 |
| 34 | return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 | |
| 35 | uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56 |
| 36 | default: |
| 37 | panic("syscall: readInt with unsupported size") |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | func readIntLE(b []byte, size uintptr) uint64 { |
| 42 | switch size { |
| 43 | case 1: |
| 44 | return uint64(b[0]) |
| 45 | case 2: |
| 46 | _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808 |
| 47 | return uint64(b[0]) | uint64(b[1])<<8 |
| 48 | case 4: |
| 49 | _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 |
| 50 | return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
| 51 | case 8: |
| 52 | _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 |
| 53 | return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | |
| 54 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56 |
| 55 | default: |
| 56 | panic("syscall: readInt with unsupported size") |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | // ParseDirent parses up to max directory entries in buf, |
| 61 | // appending the names to names. It returns the number of |
| 62 | // bytes consumed from buf, the number of entries added |
| 63 | // to names, and the new names slice. |
| 64 | func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) { |
| 65 | origlen := len(buf) |
| 66 | count = 0 |
| 67 | for max != 0 && len(buf) > 0 { |
| 68 | reclen, ok := direntReclen(buf) |
| 69 | if !ok || reclen > uint64(len(buf)) { |
| 70 | return origlen, count, names |
| 71 | } |
| 72 | rec := buf[:reclen] |
| 73 | buf = buf[reclen:] |
| 74 | ino, ok := direntIno(rec) |
| 75 | if !ok { |
| 76 | break |
| 77 | } |
| 78 | if ino == 0 { // File absent in directory. |
| 79 | continue |
| 80 | } |
| 81 | const namoff = uint64(unsafe.Offsetof(Dirent{}.Name)) |
| 82 | namlen, ok := direntNamlen(rec) |
| 83 | if !ok || namoff+namlen > uint64(len(rec)) { |
| 84 | break |
| 85 | } |
| 86 | name := rec[namoff : namoff+namlen] |
| 87 | for i, c := range name { |
| 88 | if c == 0 { |
| 89 | name = name[:i] |
| 90 | break |
| 91 | } |
| 92 | } |
| 93 | // Check for useless names before allocating a string. |
| 94 | if string(name) == "." || string(name) == ".." { |
| 95 | continue |
| 96 | } |
| 97 | max-- |
| 98 | count++ |
| 99 | names = append(names, string(name)) |
| 100 | } |
| 101 | return origlen - len(buf), count, names |
| 102 | } |