Holger Hildebrandt | fa07499 | 2020-03-27 15:42:06 +0000 | [diff] [blame^] | 1 | // Copyright 2019 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,go1.13 |
| 6 | |
| 7 | package unix |
| 8 | |
| 9 | import "unsafe" |
| 10 | |
| 11 | //sys closedir(dir uintptr) (err error) |
| 12 | //sys readdir_r(dir uintptr, entry *Dirent, result **Dirent) (res Errno) |
| 13 | |
| 14 | func fdopendir(fd int) (dir uintptr, err error) { |
| 15 | r0, _, e1 := syscall_syscallPtr(funcPC(libc_fdopendir_trampoline), uintptr(fd), 0, 0) |
| 16 | dir = uintptr(r0) |
| 17 | if e1 != 0 { |
| 18 | err = errnoErr(e1) |
| 19 | } |
| 20 | return |
| 21 | } |
| 22 | |
| 23 | func libc_fdopendir_trampoline() |
| 24 | |
| 25 | //go:linkname libc_fdopendir libc_fdopendir |
| 26 | //go:cgo_import_dynamic libc_fdopendir fdopendir "/usr/lib/libSystem.B.dylib" |
| 27 | |
| 28 | func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) { |
| 29 | // Simulate Getdirentries using fdopendir/readdir_r/closedir. |
| 30 | // We store the number of entries to skip in the seek |
| 31 | // offset of fd. See issue #31368. |
| 32 | // It's not the full required semantics, but should handle the case |
| 33 | // of calling Getdirentries or ReadDirent repeatedly. |
| 34 | // It won't handle assigning the results of lseek to *basep, or handle |
| 35 | // the directory being edited underfoot. |
| 36 | skip, err := Seek(fd, 0, 1 /* SEEK_CUR */) |
| 37 | if err != nil { |
| 38 | return 0, err |
| 39 | } |
| 40 | |
| 41 | // We need to duplicate the incoming file descriptor |
| 42 | // because the caller expects to retain control of it, but |
| 43 | // fdopendir expects to take control of its argument. |
| 44 | // Just Dup'ing the file descriptor is not enough, as the |
| 45 | // result shares underlying state. Use Openat to make a really |
| 46 | // new file descriptor referring to the same directory. |
| 47 | fd2, err := Openat(fd, ".", O_RDONLY, 0) |
| 48 | if err != nil { |
| 49 | return 0, err |
| 50 | } |
| 51 | d, err := fdopendir(fd2) |
| 52 | if err != nil { |
| 53 | Close(fd2) |
| 54 | return 0, err |
| 55 | } |
| 56 | defer closedir(d) |
| 57 | |
| 58 | var cnt int64 |
| 59 | for { |
| 60 | var entry Dirent |
| 61 | var entryp *Dirent |
| 62 | e := readdir_r(d, &entry, &entryp) |
| 63 | if e != 0 { |
| 64 | return n, errnoErr(e) |
| 65 | } |
| 66 | if entryp == nil { |
| 67 | break |
| 68 | } |
| 69 | if skip > 0 { |
| 70 | skip-- |
| 71 | cnt++ |
| 72 | continue |
| 73 | } |
| 74 | reclen := int(entry.Reclen) |
| 75 | if reclen > len(buf) { |
| 76 | // Not enough room. Return for now. |
| 77 | // The counter will let us know where we should start up again. |
| 78 | // Note: this strategy for suspending in the middle and |
| 79 | // restarting is O(n^2) in the length of the directory. Oh well. |
| 80 | break |
| 81 | } |
| 82 | // Copy entry into return buffer. |
| 83 | s := struct { |
| 84 | ptr unsafe.Pointer |
| 85 | siz int |
| 86 | cap int |
| 87 | }{ptr: unsafe.Pointer(&entry), siz: reclen, cap: reclen} |
| 88 | copy(buf, *(*[]byte)(unsafe.Pointer(&s))) |
| 89 | buf = buf[reclen:] |
| 90 | n += reclen |
| 91 | cnt++ |
| 92 | } |
| 93 | // Set the seek offset of the input fd to record |
| 94 | // how many files we've already returned. |
| 95 | _, err = Seek(fd, cnt, 0 /* SEEK_SET */) |
| 96 | if err != nil { |
| 97 | return n, err |
| 98 | } |
| 99 | |
| 100 | return n, nil |
| 101 | } |