libgo/go/os/dir.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         "syscall"
  10         "unsafe"
  11 )
  12
  13 //extern opendir
  14 func libc_opendir(*byte) *syscall.DIR
  15
  16 //extern closedir
  17 func libc_closedir(*syscall.DIR) int
  18
  19 // FIXME: pathconf returns long, not int.
  20 //extern pathconf
  21 func libc_pathconf(*byte, int) int
  22
  23 func clen(n []byte) int {
  24         for i := 0; i < len(n); i++ {
  25                 if n[i] == 0 {
  26                         return i
  27                 }
  28         }
  29         return len(n)
  30 }
  31
  32 var elen int
  33
  34 func (file *File) readdirnames(n int) (names []string, err error) {
  35         if elen == 0 {
  36                 var dummy syscall.Dirent
  37                 elen = (int(unsafe.Offsetof(dummy.Name)) +
  38                         libc_pathconf(syscall.StringBytePtr(file.name), syscall.PC_NAME_MAX) +
  39                         1)
  40         }
  41
  42         if file.dirinfo == nil {
  43                 file.dirinfo = new(dirInfo)
  44                 file.dirinfo.buf = make([]byte, elen)
  45                 p := syscall.StringBytePtr(file.name)
  46                 syscall.Entersyscall()
  47                 r := libc_opendir(p)
  48                 syscall.Exitsyscall()
  49                 file.dirinfo.dir = r
  50         }
  51
  52         entry_dirent := (*syscall.Dirent)(unsafe.Pointer(&file.dirinfo.buf[0]))
  53
  54         size := n
  55         if size < 0 {
  56                 size = 100
  57                 n = -1
  58         }
  59
  60         names = make([]string, 0, size) // Empty with room to grow.
  61
  62         dir := file.dirinfo.dir
  63         if dir == nil {
  64                 return names, NewSyscallError("opendir", syscall.GetErrno())
  65         }
  66
  67         for n != 0 {
  68                 var result *syscall.Dirent
  69                 pr := &result
  70                 syscall.Entersyscall()
  71                 i := libc_readdir_r(dir, entry_dirent, pr)
  72                 syscall.Exitsyscall()
  73                 if i != 0 {
  74                         return names, NewSyscallError("readdir_r", i)
  75                 }
  76                 if result == nil {
  77                         break // EOF
  78                 }
  79                 var name = string(result.Name[0:clen(result.Name[0:])])
  80                 if name == "." || name == ".." { // Useless names
  81                         continue
  82                 }
  83                 names = append(names, name)
  84                 n--
  85         }
  86         if n >= 0 && len(names) == 0 {
  87                 return names, io.EOF
  88         }
  89         return names, nil
  90 }