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1 // Copyright 2009 The Go Authors. All rights reserved.
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2 // Use of this source code is governed by a BSD-style
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3 // license that can be found in the LICENSE file.
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4
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5 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
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6 // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
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7
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8 package unix
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9
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10 import "unsafe"
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11
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12 // readInt returns the size-bytes unsigned integer in native byte order at offset off.
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13 func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
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14 if len(b) < int(off+size) {
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15 return 0, false
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16 }
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17 if isBigEndian {
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18 return readIntBE(b[off:], size), true
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19 }
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20 return readIntLE(b[off:], size), true
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21 }
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22
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23 func readIntBE(b []byte, size uintptr) uint64 {
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24 switch size {
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25 case 1:
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26 return uint64(b[0])
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27 case 2:
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28 _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
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29 return uint64(b[1]) | uint64(b[0])<<8
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30 case 4:
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31 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
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32 return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24
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33 case 8:
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34 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
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35 return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
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36 uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
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37 default:
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38 panic("syscall: readInt with unsupported size")
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39 }
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40 }
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41
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42 func readIntLE(b []byte, size uintptr) uint64 {
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43 switch size {
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44 case 1:
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45 return uint64(b[0])
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46 case 2:
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47 _ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
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48 return uint64(b[0]) | uint64(b[1])<<8
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49 case 4:
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50 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
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51 return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
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52 case 8:
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53 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
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54 return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
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55 uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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56 default:
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57 panic("syscall: readInt with unsupported size")
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58 }
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59 }
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60
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61 // ParseDirent parses up to max directory entries in buf,
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62 // appending the names to names. It returns the number of
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63 // bytes consumed from buf, the number of entries added
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64 // to names, and the new names slice.
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65 func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) {
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66 origlen := len(buf)
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67 count = 0
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68 for max != 0 && len(buf) > 0 {
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69 reclen, ok := direntReclen(buf)
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70 if !ok || reclen > uint64(len(buf)) {
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71 return origlen, count, names
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72 }
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73 rec := buf[:reclen]
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74 buf = buf[reclen:]
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75 ino, ok := direntIno(rec)
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76 if !ok {
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77 break
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78 }
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79 if ino == 0 { // File absent in directory.
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80 continue
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81 }
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82 const namoff = uint64(unsafe.Offsetof(Dirent{}.Name))
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83 namlen, ok := direntNamlen(rec)
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84 if !ok || namoff+namlen > uint64(len(rec)) {
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85 break
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86 }
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87 name := rec[namoff : namoff+namlen]
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88 for i, c := range name {
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89 if c == 0 {
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90 name = name[:i]
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91 break
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92 }
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93 }
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94 // Check for useless names before allocating a string.
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95 if string(name) == "." || string(name) == ".." {
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96 continue
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97 }
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98 max--
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99 count++
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100 names = append(names, string(name))
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101 }
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102 return origlen - len(buf), count, names
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103 }
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