Source file src/pkg/os/file_posix.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	// +build darwin freebsd linux netbsd openbsd windows
     6	
     7	package os
     8	
     9	import (
    10		"syscall"
    11		"time"
    12	)
    13	
    14	func sigpipe() // implemented in package runtime
    15	
    16	// Link creates newname as a hard link to the oldname file.
    17	// If there is an error, it will be of type *LinkError.
    18	func Link(oldname, newname string) error {
    19		e := syscall.Link(oldname, newname)
    20		if e != nil {
    21			return &LinkError{"link", oldname, newname, e}
    22		}
    23		return nil
    24	}
    25	
    26	// Symlink creates newname as a symbolic link to oldname.
    27	// If there is an error, it will be of type *LinkError.
    28	func Symlink(oldname, newname string) error {
    29		e := syscall.Symlink(oldname, newname)
    30		if e != nil {
    31			return &LinkError{"symlink", oldname, newname, e}
    32		}
    33		return nil
    34	}
    35	
    36	// Readlink returns the destination of the named symbolic link.
    37	// If there is an error, it will be of type *PathError.
    38	func Readlink(name string) (string, error) {
    39		for len := 128; ; len *= 2 {
    40			b := make([]byte, len)
    41			n, e := syscall.Readlink(name, b)
    42			if e != nil {
    43				return "", &PathError{"readlink", name, e}
    44			}
    45			if n < len {
    46				return string(b[0:n]), nil
    47			}
    48		}
    49	}
    50	
    51	// Rename renames a file.
    52	func Rename(oldname, newname string) error {
    53		e := syscall.Rename(oldname, newname)
    54		if e != nil {
    55			return &LinkError{"rename", oldname, newname, e}
    56		}
    57		return nil
    58	}
    59	
    60	// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
    61	func syscallMode(i FileMode) (o uint32) {
    62		o |= uint32(i.Perm())
    63		if i&ModeSetuid != 0 {
    64			o |= syscall.S_ISUID
    65		}
    66		if i&ModeSetgid != 0 {
    67			o |= syscall.S_ISGID
    68		}
    69		if i&ModeSticky != 0 {
    70			o |= syscall.S_ISVTX
    71		}
    72		// No mapping for Go's ModeTemporary (plan9 only).
    73		return
    74	}
    75	
    76	// Chmod changes the mode of the named file to mode.
    77	// If the file is a symbolic link, it changes the mode of the link's target.
    78	// If there is an error, it will be of type *PathError.
    79	func Chmod(name string, mode FileMode) error {
    80		if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
    81			return &PathError{"chmod", name, e}
    82		}
    83		return nil
    84	}
    85	
    86	// Chmod changes the mode of the file to mode.
    87	// If there is an error, it will be of type *PathError.
    88	func (f *File) Chmod(mode FileMode) error {
    89		if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
    90			return &PathError{"chmod", f.name, e}
    91		}
    92		return nil
    93	}
    94	
    95	// Chown changes the numeric uid and gid of the named file.
    96	// If the file is a symbolic link, it changes the uid and gid of the link's target.
    97	// If there is an error, it will be of type *PathError.
    98	func Chown(name string, uid, gid int) error {
    99		if e := syscall.Chown(name, uid, gid); e != nil {
   100			return &PathError{"chown", name, e}
   101		}
   102		return nil
   103	}
   104	
   105	// Lchown changes the numeric uid and gid of the named file.
   106	// If the file is a symbolic link, it changes the uid and gid of the link itself.
   107	// If there is an error, it will be of type *PathError.
   108	func Lchown(name string, uid, gid int) error {
   109		if e := syscall.Lchown(name, uid, gid); e != nil {
   110			return &PathError{"lchown", name, e}
   111		}
   112		return nil
   113	}
   114	
   115	// Chown changes the numeric uid and gid of the named file.
   116	// If there is an error, it will be of type *PathError.
   117	func (f *File) Chown(uid, gid int) error {
   118		if e := syscall.Fchown(f.fd, uid, gid); e != nil {
   119			return &PathError{"chown", f.name, e}
   120		}
   121		return nil
   122	}
   123	
   124	// Truncate changes the size of the file.
   125	// It does not change the I/O offset.
   126	// If there is an error, it will be of type *PathError.
   127	func (f *File) Truncate(size int64) error {
   128		if e := syscall.Ftruncate(f.fd, size); e != nil {
   129			return &PathError{"truncate", f.name, e}
   130		}
   131		return nil
   132	}
   133	
   134	// Sync commits the current contents of the file to stable storage.
   135	// Typically, this means flushing the file system's in-memory copy
   136	// of recently written data to disk.
   137	func (f *File) Sync() (err error) {
   138		if f == nil {
   139			return syscall.EINVAL
   140		}
   141		if e := syscall.Fsync(f.fd); e != nil {
   142			return NewSyscallError("fsync", e)
   143		}
   144		return nil
   145	}
   146	
   147	// Chtimes changes the access and modification times of the named
   148	// file, similar to the Unix utime() or utimes() functions.
   149	//
   150	// The underlying filesystem may truncate or round the values to a
   151	// less precise time unit.
   152	// If there is an error, it will be of type *PathError.
   153	func Chtimes(name string, atime time.Time, mtime time.Time) error {
   154		var utimes [2]syscall.Timespec
   155		utimes[0] = syscall.NsecToTimespec(atime.UnixNano())
   156		utimes[1] = syscall.NsecToTimespec(mtime.UnixNano())
   157		if e := syscall.UtimesNano(name, utimes[0:]); e != nil {
   158			return &PathError{"chtimes", name, e}
   159		}
   160		return nil
   161	}

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