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