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	func epipecheck(file *File, e error) {
    17		if e == syscall.EPIPE {
    18			file.nepipe++
    19			if file.nepipe >= 10 {
    20				sigpipe()
    21			}
    22		} else {
    23			file.nepipe = 0
    24		}
    25	}
    26	
    27	// Link creates newname as a hard link to the oldname file.
    28	// If there is an error, it will be of type *LinkError.
    29	func Link(oldname, newname string) error {
    30		e := syscall.Link(oldname, newname)
    31		if e != nil {
    32			return &LinkError{"link", oldname, newname, e}
    33		}
    34		return nil
    35	}
    36	
    37	// Symlink creates newname as a symbolic link to oldname.
    38	// If there is an error, it will be of type *LinkError.
    39	func Symlink(oldname, newname string) error {
    40		e := syscall.Symlink(oldname, newname)
    41		if e != nil {
    42			return &LinkError{"symlink", oldname, newname, e}
    43		}
    44		return nil
    45	}
    46	
    47	// Readlink returns the destination of the named symbolic link.
    48	// If there is an error, it will be of type *PathError.
    49	func Readlink(name string) (string, error) {
    50		for len := 128; ; len *= 2 {
    51			b := make([]byte, len)
    52			n, e := syscall.Readlink(name, b)
    53			if e != nil {
    54				return "", &PathError{"readlink", name, e}
    55			}
    56			if n < len {
    57				return string(b[0:n]), nil
    58			}
    59		}
    60		// Silence 6g.
    61		return "", nil
    62	}
    63	
    64	// Rename renames a file.
    65	func Rename(oldname, newname string) error {
    66		e := syscall.Rename(oldname, newname)
    67		if e != nil {
    68			return &LinkError{"rename", oldname, newname, e}
    69		}
    70		return nil
    71	}
    72	
    73	// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
    74	func syscallMode(i FileMode) (o uint32) {
    75		o |= uint32(i.Perm())
    76		if i&ModeSetuid != 0 {
    77			o |= syscall.S_ISUID
    78		}
    79		if i&ModeSetgid != 0 {
    80			o |= syscall.S_ISGID
    81		}
    82		if i&ModeSticky != 0 {
    83			o |= syscall.S_ISVTX
    84		}
    85		// No mapping for Go's ModeTemporary (plan9 only).
    86		return
    87	}
    88	
    89	// Chmod changes the mode of the named file to mode.
    90	// If the file is a symbolic link, it changes the mode of the link's target.
    91	// If there is an error, it will be of type *PathError.
    92	func Chmod(name string, mode FileMode) error {
    93		if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
    94			return &PathError{"chmod", name, e}
    95		}
    96		return nil
    97	}
    98	
    99	// Chmod changes the mode of the file to mode.
   100	// If there is an error, it will be of type *PathError.
   101	func (f *File) Chmod(mode FileMode) error {
   102		if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
   103			return &PathError{"chmod", f.name, e}
   104		}
   105		return nil
   106	}
   107	
   108	// Chown changes the numeric uid and gid of the named file.
   109	// If the file is a symbolic link, it changes the uid and gid of the link's target.
   110	// If there is an error, it will be of type *PathError.
   111	func Chown(name string, uid, gid int) error {
   112		if e := syscall.Chown(name, uid, gid); e != nil {
   113			return &PathError{"chown", name, e}
   114		}
   115		return nil
   116	}
   117	
   118	// Lchown changes the numeric uid and gid of the named file.
   119	// If the file is a symbolic link, it changes the uid and gid of the link itself.
   120	// If there is an error, it will be of type *PathError.
   121	func Lchown(name string, uid, gid int) error {
   122		if e := syscall.Lchown(name, uid, gid); e != nil {
   123			return &PathError{"lchown", name, e}
   124		}
   125		return nil
   126	}
   127	
   128	// Chown changes the numeric uid and gid of the named file.
   129	// If there is an error, it will be of type *PathError.
   130	func (f *File) Chown(uid, gid int) error {
   131		if e := syscall.Fchown(f.fd, uid, gid); e != nil {
   132			return &PathError{"chown", f.name, e}
   133		}
   134		return nil
   135	}
   136	
   137	// Truncate changes the size of the file.
   138	// It does not change the I/O offset.
   139	// If there is an error, it will be of type *PathError.
   140	func (f *File) Truncate(size int64) error {
   141		if e := syscall.Ftruncate(f.fd, size); e != nil {
   142			return &PathError{"truncate", f.name, e}
   143		}
   144		return nil
   145	}
   146	
   147	// Sync commits the current contents of the file to stable storage.
   148	// Typically, this means flushing the file system's in-memory copy
   149	// of recently written data to disk.
   150	func (f *File) Sync() (err error) {
   151		if f == nil {
   152			return syscall.EINVAL
   153		}
   154		if e := syscall.Fsync(f.fd); e != nil {
   155			return NewSyscallError("fsync", e)
   156		}
   157		return nil
   158	}
   159	
   160	// Chtimes changes the access and modification times of the named
   161	// file, similar to the Unix utime() or utimes() functions.
   162	//
   163	// The underlying filesystem may truncate or round the values to a
   164	// less precise time unit.
   165	// If there is an error, it will be of type *PathError.
   166	func Chtimes(name string, atime time.Time, mtime time.Time) error {
   167		var utimes [2]syscall.Timeval
   168		atime_ns := atime.Unix()*1e9 + int64(atime.Nanosecond())
   169		mtime_ns := mtime.Unix()*1e9 + int64(mtime.Nanosecond())
   170		utimes[0] = syscall.NsecToTimeval(atime_ns)
   171		utimes[1] = syscall.NsecToTimeval(mtime_ns)
   172		if e := syscall.Utimes(name, utimes[0:]); e != nil {
   173			return &PathError{"chtimes", name, e}
   174		}
   175		return nil
   176	}