libgo/go/os/dir_gccgo.go

   1 // Copyright 2009 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 package os
   6
   7 import (
   8         "io"
   9         "runtime"
  10         "sync/atomic"
  11         "syscall"
  12         "unsafe"
  13 )
  14
  15 // FIXME: pathconf returns long, not int.
  16 //extern pathconf
  17 func libc_pathconf(*byte, int) int
  18
  19 //extern fdopendir
  20 func libc_fdopendir(int32) *syscall.DIR
  21
  22 func clen(n []byte) int {
  23         for i := 0; i < len(n); i++ {
  24                 if n[i] == 0 {
  25                         return i
  26                 }
  27         }
  28         return len(n)
  29 }
  30
  31 var nameMax int32
  32
  33 func (file *File) readdirnames(n int) (names []string, err error) {
  34         if file.dirinfo == nil {
  35                 p, err := syscall.BytePtrFromString(file.name)
  36                 if err != nil {
  37                         return nil, err
  38                 }
  39
  40                 elen := int(atomic.LoadInt32(&nameMax))
  41                 if elen == 0 {
  42                         syscall.Entersyscall()
  43                         plen := libc_pathconf(p, syscall.PC_NAME_MAX)
  44                         syscall.Exitsyscall()
  45                         if plen < 1024 {
  46                                 plen = 1024
  47                         }
  48                         var dummy syscall.Dirent
  49                         elen = int(unsafe.Offsetof(dummy.Name)) + plen + 1
  50                         atomic.StoreInt32(&nameMax, int32(elen))
  51                 }
  52
  53                 syscall.Entersyscall()
  54                 r := libc_fdopendir(int32(file.pfd.Sysfd))
  55                 errno := syscall.GetErrno()
  56                 syscall.Exitsyscall()
  57                 if r == nil {
  58                         return nil, &PathError{"fdopendir", file.name, errno}
  59                 }
  60
  61                 file.dirinfo = new(dirInfo)
  62                 file.dirinfo.buf = make([]byte, elen)
  63                 file.dirinfo.dir = r
  64         }
  65
  66         entryDirent := (*syscall.Dirent)(unsafe.Pointer(&file.dirinfo.buf[0]))
  67
  68         size := n
  69         if size <= 0 {
  70                 size = 100
  71                 n = -1
  72         }
  73
  74         names = make([]string, 0, size) // Empty with room to grow.
  75
  76         for n != 0 {
  77                 var dirent *syscall.Dirent
  78                 pr := &dirent
  79                 syscall.Entersyscall()
  80                 i := libc_readdir_r(file.dirinfo.dir, entryDirent, pr)
  81                 syscall.Exitsyscall()
  82                 // On AIX when readdir_r hits EOF it sets dirent to nil and returns 9.
  83                 //  https://www.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.basetrf2/readdir_r.htm
  84                 if runtime.GOOS == "aix" && i == 9 && dirent == nil {
  85                         break
  86                 }
  87                 if i != 0 {
  88                         return names, NewSyscallError("readdir_r", i)
  89                 }
  90                 if dirent == nil {
  91                         break // EOF
  92                 }
  93                 bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
  94                 var name = string(bytes[0:clen(bytes[:])])
  95                 if name == "." || name == ".." { // Useless names
  96                         continue
  97                 }
  98                 names = append(names, name)
  99                 n--
 100         }
 101         if n >= 0 && len(names) == 0 {
 102                 return names, io.EOF
 103         }
 104         return names, nil
 105 }