1 // Copyright 2019 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 darwin && go1.13 |
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6 // +build darwin,go1.13 |
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7 |
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8 package unix |
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9 |
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10 import ( |
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11 "unsafe" |
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12 |
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13 "golang.org/x/sys/internal/unsafeheader" |
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14 ) |
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15 |
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16 //sys closedir(dir uintptr) (err error) |
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17 //sys readdir_r(dir uintptr, entry *Dirent, result **Dirent) (res Errno) |
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18 |
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19 func fdopendir(fd int) (dir uintptr, err error) { |
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20 r0, _, e1 := syscall_syscallPtr(libc_fdopendir_trampoline_addr, uintptr(fd), 0, 0) |
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21 dir = uintptr(r0) |
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22 if e1 != 0 { |
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23 err = errnoErr(e1) |
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24 } |
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25 return |
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26 } |
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27 |
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28 var libc_fdopendir_trampoline_addr uintptr |
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29 |
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30 //go:cgo_import_dynamic libc_fdopendir fdopendir "/usr/lib/libSystem.B.dylib" |
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31 |
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32 func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) { |
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33 // Simulate Getdirentries using fdopendir/readdir_r/closedir. |
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34 // We store the number of entries to skip in the seek |
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35 // offset of fd. See issue #31368. |
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36 // It's not the full required semantics, but should handle the case |
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37 // of calling Getdirentries or ReadDirent repeatedly. |
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38 // It won't handle assigning the results of lseek to *basep, or handle |
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39 // the directory being edited underfoot. |
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40 skip, err := Seek(fd, 0, 1 /* SEEK_CUR */) |
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41 if err != nil { |
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42 return 0, err |
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43 } |
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44 |
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45 // We need to duplicate the incoming file descriptor |
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46 // because the caller expects to retain control of it, but |
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47 // fdopendir expects to take control of its argument. |
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48 // Just Dup'ing the file descriptor is not enough, as the |
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49 // result shares underlying state. Use Openat to make a really |
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50 // new file descriptor referring to the same directory. |
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51 fd2, err := Openat(fd, ".", O_RDONLY, 0) |
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52 if err != nil { |
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53 return 0, err |
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54 } |
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55 d, err := fdopendir(fd2) |
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56 if err != nil { |
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57 Close(fd2) |
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58 return 0, err |
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59 } |
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60 defer closedir(d) |
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61 |
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62 var cnt int64 |
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63 for { |
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64 var entry Dirent |
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65 var entryp *Dirent |
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66 e := readdir_r(d, &entry, &entryp) |
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67 if e != 0 { |
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68 return n, errnoErr(e) |
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69 } |
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70 if entryp == nil { |
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71 break |
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72 } |
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73 if skip > 0 { |
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74 skip-- |
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75 cnt++ |
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76 continue |
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77 } |
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78 |
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79 reclen := int(entry.Reclen) |
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80 if reclen > len(buf) { |
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81 // Not enough room. Return for now. |
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82 // The counter will let us know where we should start up again. |
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83 // Note: this strategy for suspending in the middle and |
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84 // restarting is O(n^2) in the length of the directory. Oh well. |
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85 break |
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86 } |
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87 |
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88 // Copy entry into return buffer. |
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89 var s []byte |
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90 hdr := (*unsafeheader.Slice)(unsafe.Pointer(&s)) |
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91 hdr.Data = unsafe.Pointer(&entry) |
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92 hdr.Cap = reclen |
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93 hdr.Len = reclen |
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94 copy(buf, s) |
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95 |
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96 buf = buf[reclen:] |
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97 n += reclen |
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98 cnt++ |
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99 } |
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100 // Set the seek offset of the input fd to record |
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101 // how many files we've already returned. |
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102 _, err = Seek(fd, cnt, 0 /* SEEK_SET */) |
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103 if err != nil { |
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104 return n, err |
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105 } |
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106 |
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107 return n, nil |
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108 } |
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