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https://github.com/rwinkhart/sys.git
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Tobias Klauser
3421d5a6bb
Getdirentries is implemented with the __getdirentries64 function
in libSystem.dylib on darwin/{386,amd64}. That function can't be used in
an app store application.
Implement Getdirentries using the underlying
fdopendir/readdir_r/closedir for Go 1.13. The simulation isn't faithful,
and could be slow, but it should handle common cases.
For Go 1.12, fall back to raw syscalls since syscall.syscallPtr needed
to use fdopendir from libSystem.dylib is not available.
Follow CL 168479 and CL 170892 which did the same for syscall in the
stdlib.
Tested on darwin/amd64 with Go 1.11, Go 1.12 and Go 1.13
Fixes golang/go#34400
Change-Id: I631382aaea9ee7e0c4ed09e06ad5427efc620769
Reviewed-on: https://go-review.googlesource.com/c/sys/+/196478
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
104 lines
2.7 KiB
Go
104 lines
2.7 KiB
Go
// 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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const ptrSize = unsafe.Sizeof(uintptr(0))
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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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}
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