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 func clen(n []byte) int {
  20         for i := 0; i < len(n); i++ {
  21                 if n[i] == 0 {
  22                         return i
  23                 }
  24         }
  25         return len(n)
  26 }
  27
  28 var nameMax int32
  29
  30 func (file *File) readdirnames(n int) (names []string, err error) {
  31         if file.dirinfo == nil {
  32                 p, err := syscall.BytePtrFromString(file.name)
  33                 if err != nil {
  34                         return nil, err
  35                 }
  36
  37                 elen := int(atomic.LoadInt32(&nameMax))
  38                 if elen == 0 {
  39                         syscall.Entersyscall()
  40                         plen := libc_pathconf(p, syscall.PC_NAME_MAX)
  41                         syscall.Exitsyscall()
  42                         if plen < 1024 {
  43                                 plen = 1024
  44                         }
  45                         var dummy syscall.Dirent
  46                         elen = int(unsafe.Offsetof(dummy.Name)) + plen + 1
  47                         atomic.StoreInt32(&nameMax, int32(elen))
  48                 }
  49
  50                 syscall.Entersyscall()
  51                 r := libc_opendir(p)
  52                 errno := syscall.GetErrno()
  53                 syscall.Exitsyscall()
  54                 if r == nil {
  55                         return nil, &PathError{"opendir", file.name, errno}
  56                 }
  57
  58                 file.dirinfo = new(dirInfo)
  59                 file.dirinfo.buf = make([]byte, elen)
  60                 file.dirinfo.dir = r
  61         }
  62
  63         entryDirent := (*syscall.Dirent)(unsafe.Pointer(&file.dirinfo.buf[0]))
  64
  65         size := n
  66         if size <= 0 {
  67                 size = 100
  68                 n = -1
  69         }
  70
  71         names = make([]string, 0, size) // Empty with room to grow.
  72
  73         for n != 0 {
  74                 var dirent *syscall.Dirent
  75                 pr := &dirent
  76                 syscall.Entersyscall()
  77                 i := libc_readdir_r(file.dirinfo.dir, entryDirent, pr)
  78                 syscall.Exitsyscall()
  79                 // On AIX when readdir_r hits EOF it sets dirent to nil and returns 9.
  80                 //  https://www.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.basetrf2/readdir_r.htm
  81                 if runtime.GOOS == "aix" && i == 9 && dirent == nil {
  82                         break
  83                 }
  84                 if i != 0 {
  85                         return names, NewSyscallError("readdir_r", i)
  86                 }
  87                 if dirent == nil {
  88                         break // EOF
  89                 }
  90                 bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
  91                 var name = string(bytes[0:clen(bytes[:])])
  92                 if name == "." || name == ".." { // Useless names
  93                         continue
  94                 }
  95                 names = append(names, name)
  96                 n--
  97         }
  98         if n >= 0 && len(names) == 0 {
  99                 return names, io.EOF
 100         }
 101         return names, nil
 102 }