Home | History | Annotate | Download | only in os 
      1 // Copyright 2011 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 	"syscall"
      9 	"time"
     10 )
     11 
     12 const _BIT16SZ = 2
     13 
     14 func sameFile(fs1, fs2 *fileStat) bool {
     15 	a := fs1.sys.(*syscall.Dir)
     16 	b := fs2.sys.(*syscall.Dir)
     17 	return a.Qid.Path == b.Qid.Path && a.Type == b.Type && a.Dev == b.Dev
     18 }
     19 
     20 func fileInfoFromStat(d *syscall.Dir) FileInfo {
     21 	fs := &fileStat{
     22 		name:    d.Name,
     23 		size:    int64(d.Length),
     24 		modTime: time.Unix(int64(d.Mtime), 0),
     25 		sys:     d,
     26 	}
     27 	fs.mode = FileMode(d.Mode & 0777)
     28 	if d.Mode&syscall.DMDIR != 0 {
     29 		fs.mode |= ModeDir
     30 	}
     31 	if d.Mode&syscall.DMAPPEND != 0 {
     32 		fs.mode |= ModeAppend
     33 	}
     34 	if d.Mode&syscall.DMEXCL != 0 {
     35 		fs.mode |= ModeExclusive
     36 	}
     37 	if d.Mode&syscall.DMTMP != 0 {
     38 		fs.mode |= ModeTemporary
     39 	}
     40 	return fs
     41 }
     42 
     43 // arg is an open *File or a path string.
     44 func dirstat(arg interface{}) (*syscall.Dir, error) {
     45 	var name string
     46 	var err error
     47 
     48 	size := syscall.STATFIXLEN + 16*4
     49 
     50 	for i := 0; i < 2; i++ {
     51 		buf := make([]byte, _BIT16SZ+size)
     52 
     53 		var n int
     54 		switch a := arg.(type) {
     55 		case *File:
     56 			name = a.name
     57 			n, err = syscall.Fstat(a.fd, buf)
     58 		case string:
     59 			name = a
     60 			n, err = syscall.Stat(a, buf)
     61 		default:
     62 			panic("phase error in dirstat")
     63 		}
     64 
     65 		if n < _BIT16SZ {
     66 			return nil, &PathError{"stat", name, err}
     67 		}
     68 
     69 		// Pull the real size out of the stat message.
     70 		size = int(uint16(buf[0]) | uint16(buf[1])<<8)
     71 
     72 		// If the stat message is larger than our buffer we will
     73 		// go around the loop and allocate one that is big enough.
     74 		if size <= n {
     75 			d, err := syscall.UnmarshalDir(buf[:n])
     76 			if err != nil {
     77 				return nil, &PathError{"stat", name, err}
     78 			}
     79 			return d, nil
     80 		}
     81 
     82 	}
     83 
     84 	if err == nil {
     85 		err = syscall.ErrBadStat
     86 	}
     87 
     88 	return nil, &PathError{"stat", name, err}
     89 }
     90 
     91 // Stat returns a FileInfo describing the named file.
     92 // If there is an error, it will be of type *PathError.
     93 func Stat(name string) (FileInfo, error) {
     94 	d, err := dirstat(name)
     95 	if err != nil {
     96 		return nil, err
     97 	}
     98 	return fileInfoFromStat(d), nil
     99 }
    100 
    101 // Lstat returns a FileInfo describing the named file.
    102 // If the file is a symbolic link, the returned FileInfo
    103 // describes the symbolic link.  Lstat makes no attempt to follow the link.
    104 // If there is an error, it will be of type *PathError.
    105 func Lstat(name string) (FileInfo, error) {
    106 	return Stat(name)
    107 }
    108 
    109 // For testing.
    110 func atime(fi FileInfo) time.Time {
    111 	return time.Unix(int64(fi.Sys().(*syscall.Dir).Atime), 0)
    112 }
    113