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// Copyright 2019 The Go Authors. All rights reserved. |
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// Use of this source code is governed by a BSD-style |
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// license that can be found in the LICENSE file. |
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// +build darwin,go1.13 |
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package unix |
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import "unsafe" |
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//sys closedir(dir uintptr) (err error) |
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//sys readdir_r(dir uintptr, entry *Dirent, result **Dirent) (res Errno) |
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func fdopendir(fd int) (dir uintptr, err error) { |
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r0, _, e1 := syscall_syscallPtr(funcPC(libc_fdopendir_trampoline), uintptr(fd), 0, 0) |
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dir = uintptr(r0) |
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if e1 != 0 { |
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err = errnoErr(e1) |
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} |
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return |
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} |
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func libc_fdopendir_trampoline() |
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//go:linkname libc_fdopendir libc_fdopendir |
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//go:cgo_import_dynamic libc_fdopendir fdopendir "/usr/lib/libSystem.B.dylib" |
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func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) { |
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// Simulate Getdirentries using fdopendir/readdir_r/closedir. |
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// We store the number of entries to skip in the seek |
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// offset of fd. See issue #31368. |
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// It's not the full required semantics, but should handle the case |
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// of calling Getdirentries or ReadDirent repeatedly. |
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// It won't handle assigning the results of lseek to *basep, or handle |
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// the directory being edited underfoot. |
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skip, err := Seek(fd, 0, 1 /* SEEK_CUR */) |
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if err != nil { |
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return 0, err |
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} |
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// We need to duplicate the incoming file descriptor |
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// because the caller expects to retain control of it, but |
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// fdopendir expects to take control of its argument. |
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// Just Dup'ing the file descriptor is not enough, as the |
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// result shares underlying state. Use Openat to make a really |
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// new file descriptor referring to the same directory. |
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fd2, err := Openat(fd, ".", O_RDONLY, 0) |
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if err != nil { |
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return 0, err |
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} |
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d, err := fdopendir(fd2) |
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if err != nil { |
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Close(fd2) |
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return 0, err |
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} |
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defer closedir(d) |
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var cnt int64 |
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for { |
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var entry Dirent |
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var entryp *Dirent |
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e := readdir_r(d, &entry, &entryp) |
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if e != 0 { |
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return n, errnoErr(e) |
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} |
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if entryp == nil { |
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break |
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} |
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if skip > 0 { |
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skip-- |
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cnt++ |
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continue |
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} |
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reclen := int(entry.Reclen) |
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if reclen > len(buf) { |
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// Not enough room. Return for now. |
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// The counter will let us know where we should start up again. |
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// Note: this strategy for suspending in the middle and |
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// restarting is O(n^2) in the length of the directory. Oh well. |
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break |
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} |
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// Copy entry into return buffer. |
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s := struct { |
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ptr unsafe.Pointer |
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siz int |
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cap int |
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}{ptr: unsafe.Pointer(&entry), siz: reclen, cap: reclen} |
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copy(buf, *(*[]byte)(unsafe.Pointer(&s))) |
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buf = buf[reclen:] |
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n += reclen |
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cnt++ |
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} |
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// Set the seek offset of the input fd to record |
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// how many files we've already returned. |
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_, err = Seek(fd, cnt, 0 /* SEEK_SET */) |
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if err != nil { |
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return n, err |
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} |
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return n, nil |
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} |