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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 dragonfly freebsd linux nacl netbsd openbsd solaris 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	func rename(oldname, newname string) error {
    52		e := syscall.Rename(oldname, newname)
    53		if e != nil {
    54			return &LinkError{"rename", oldname, newname, e}
    55		}
    56		return nil
    57	}
    58	
    59	// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
    60	func syscallMode(i FileMode) (o uint32) {
    61		o |= uint32(i.Perm())
    62		if i&ModeSetuid != 0 {
    63			o |= syscall.S_ISUID
    64		}
    65		if i&ModeSetgid != 0 {
    66			o |= syscall.S_ISGID
    67		}
    68		if i&ModeSticky != 0 {
    69			o |= syscall.S_ISVTX
    70		}
    71		// No mapping for Go's ModeTemporary (plan9 only).
    72		return
    73	}
    74	
    75	// Chmod changes the mode of the named file to mode.
    76	// If the file is a symbolic link, it changes the mode of the link's target.
    77	// If there is an error, it will be of type *PathError.
    78	func Chmod(name string, mode FileMode) error {
    79		if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
    80			return &PathError{"chmod", name, e}
    81		}
    82		return nil
    83	}
    84	
    85	// Chmod changes the mode of the file to mode.
    86	// If there is an error, it will be of type *PathError.
    87	func (f *File) Chmod(mode FileMode) error {
    88		if f == nil {
    89			return ErrInvalid
    90		}
    91		if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
    92			return &PathError{"chmod", f.name, e}
    93		}
    94		return nil
    95	}
    96	
    97	// Chown changes the numeric uid and gid of the named file.
    98	// If the file is a symbolic link, it changes the uid and gid of the link's target.
    99	// If there is an error, it will be of type *PathError.
   100	func Chown(name string, uid, gid int) error {
   101		if e := syscall.Chown(name, uid, gid); e != nil {
   102			return &PathError{"chown", name, e}
   103		}
   104		return nil
   105	}
   106	
   107	// Lchown changes the numeric uid and gid of the named file.
   108	// If the file is a symbolic link, it changes the uid and gid of the link itself.
   109	// If there is an error, it will be of type *PathError.
   110	func Lchown(name string, uid, gid int) error {
   111		if e := syscall.Lchown(name, uid, gid); e != nil {
   112			return &PathError{"lchown", name, e}
   113		}
   114		return nil
   115	}
   116	
   117	// Chown changes the numeric uid and gid of the named file.
   118	// If there is an error, it will be of type *PathError.
   119	func (f *File) Chown(uid, gid int) error {
   120		if f == nil {
   121			return ErrInvalid
   122		}
   123		if e := syscall.Fchown(f.fd, uid, gid); e != nil {
   124			return &PathError{"chown", f.name, e}
   125		}
   126		return nil
   127	}
   128	
   129	// Truncate changes the size of the file.
   130	// It does not change the I/O offset.
   131	// If there is an error, it will be of type *PathError.
   132	func (f *File) Truncate(size int64) error {
   133		if f == nil {
   134			return ErrInvalid
   135		}
   136		if e := syscall.Ftruncate(f.fd, size); e != nil {
   137			return &PathError{"truncate", f.name, e}
   138		}
   139		return nil
   140	}
   141	
   142	// Sync commits the current contents of the file to stable storage.
   143	// Typically, this means flushing the file system's in-memory copy
   144	// of recently written data to disk.
   145	func (f *File) Sync() (err error) {
   146		if f == nil {
   147			return ErrInvalid
   148		}
   149		if e := syscall.Fsync(f.fd); e != nil {
   150			return NewSyscallError("fsync", e)
   151		}
   152		return nil
   153	}
   154	
   155	// Chtimes changes the access and modification times of the named
   156	// file, similar to the Unix utime() or utimes() functions.
   157	//
   158	// The underlying filesystem may truncate or round the values to a
   159	// less precise time unit.
   160	// If there is an error, it will be of type *PathError.
   161	func Chtimes(name string, atime time.Time, mtime time.Time) error {
   162		var utimes [2]syscall.Timespec
   163		utimes[0] = syscall.NsecToTimespec(atime.UnixNano())
   164		utimes[1] = syscall.NsecToTimespec(mtime.UnixNano())
   165		if e := syscall.UtimesNano(name, utimes[0:]); e != nil {
   166			return &PathError{"chtimes", name, e}
   167		}
   168		return nil
   169	}
   170	

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