| // Copyright 2011 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package os |
| |
| import ( |
| "io" |
| "runtime" |
| "syscall" |
| "time" |
| ) |
| |
| // File represents an open file descriptor. |
| type File struct { |
| *file |
| } |
| |
| // file is the real representation of *File. |
| // The extra level of indirection ensures that no clients of os |
| // can overwrite this data, which could cause the finalizer |
| // to close the wrong file descriptor. |
| type file struct { |
| fd int |
| name string |
| dirinfo *dirInfo // nil unless directory being read |
| } |
| |
| // Fd returns the integer Plan 9 file descriptor referencing the open file. |
| // The file descriptor is valid only until f.Close is called or f is garbage collected. |
| func (f *File) Fd() uintptr { |
| if f == nil { |
| return ^(uintptr(0)) |
| } |
| return uintptr(f.fd) |
| } |
| |
| // NewFile returns a new File with the given file descriptor and name. |
| func NewFile(fd uintptr, name string) *File { |
| fdi := int(fd) |
| if fdi < 0 { |
| return nil |
| } |
| f := &File{&file{fd: fdi, name: name}} |
| runtime.SetFinalizer(f.file, (*file).close) |
| return f |
| } |
| |
| // Auxiliary information if the File describes a directory |
| type dirInfo struct { |
| buf [syscall.STATMAX]byte // buffer for directory I/O |
| nbuf int // length of buf; return value from Read |
| bufp int // location of next record in buf. |
| } |
| |
| func epipecheck(file *File, e error) { |
| } |
| |
| // DevNull is the name of the operating system's ``null device.'' |
| // On Unix-like systems, it is "/dev/null"; on Windows, "NUL". |
| const DevNull = "/dev/null" |
| |
| // syscallMode returns the syscall-specific mode bits from Go's portable mode bits. |
| func syscallMode(i FileMode) (o uint32) { |
| o |= uint32(i.Perm()) |
| if i&ModeAppend != 0 { |
| o |= syscall.DMAPPEND |
| } |
| if i&ModeExclusive != 0 { |
| o |= syscall.DMEXCL |
| } |
| if i&ModeTemporary != 0 { |
| o |= syscall.DMTMP |
| } |
| return |
| } |
| |
| // OpenFile is the generalized open call; most users will use Open |
| // or Create instead. It opens the named file with specified flag |
| // (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful, |
| // methods on the returned File can be used for I/O. |
| // If there is an error, it will be of type *PathError. |
| func OpenFile(name string, flag int, perm FileMode) (*File, error) { |
| var ( |
| fd int |
| e error |
| create bool |
| excl bool |
| trunc bool |
| append bool |
| ) |
| |
| if flag&O_CREATE == O_CREATE { |
| flag = flag & ^O_CREATE |
| create = true |
| } |
| if flag&O_EXCL == O_EXCL { |
| excl = true |
| } |
| if flag&O_TRUNC == O_TRUNC { |
| trunc = true |
| } |
| // O_APPEND is emulated on Plan 9 |
| if flag&O_APPEND == O_APPEND { |
| flag = flag &^ O_APPEND |
| append = true |
| } |
| |
| if (create && trunc) || excl { |
| fd, e = syscall.Create(name, flag, syscallMode(perm)) |
| } else { |
| fd, e = syscall.Open(name, flag) |
| if e != nil && create { |
| var e1 error |
| fd, e1 = syscall.Create(name, flag, syscallMode(perm)) |
| if e1 == nil { |
| e = nil |
| } |
| } |
| } |
| |
| if e != nil { |
| return nil, &PathError{"open", name, e} |
| } |
| |
| if append { |
| if _, e = syscall.Seek(fd, 0, io.SeekEnd); e != nil { |
| return nil, &PathError{"seek", name, e} |
| } |
| } |
| |
| return NewFile(uintptr(fd), name), nil |
| } |
| |
| // Close closes the File, rendering it unusable for I/O. |
| // It returns an error, if any. |
| func (f *File) Close() error { |
| if f == nil { |
| return ErrInvalid |
| } |
| return f.file.close() |
| } |
| |
| func (file *file) close() error { |
| if file == nil || file.fd < 0 { |
| return ErrInvalid |
| } |
| var err error |
| if e := syscall.Close(file.fd); e != nil { |
| err = &PathError{"close", file.name, e} |
| } |
| file.fd = -1 // so it can't be closed again |
| |
| // no need for a finalizer anymore |
| runtime.SetFinalizer(file, nil) |
| return err |
| } |
| |
| // Stat returns the FileInfo structure describing file. |
| // If there is an error, it will be of type *PathError. |
| func (f *File) Stat() (FileInfo, error) { |
| if f == nil { |
| return nil, ErrInvalid |
| } |
| d, err := dirstat(f) |
| if err != nil { |
| return nil, err |
| } |
| return fileInfoFromStat(d), nil |
| } |
| |
| // Truncate changes the size of the file. |
| // It does not change the I/O offset. |
| // If there is an error, it will be of type *PathError. |
| func (f *File) Truncate(size int64) error { |
| if f == nil { |
| return ErrInvalid |
| } |
| |
| var d syscall.Dir |
| d.Null() |
| d.Length = size |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &PathError{"truncate", f.name, err} |
| } |
| if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { |
| return &PathError{"truncate", f.name, err} |
| } |
| return nil |
| } |
| |
| const chmodMask = uint32(syscall.DMAPPEND | syscall.DMEXCL | syscall.DMTMP | ModePerm) |
| |
| // Chmod changes the mode of the file to mode. |
| // If there is an error, it will be of type *PathError. |
| func (f *File) Chmod(mode FileMode) error { |
| if f == nil { |
| return ErrInvalid |
| } |
| var d syscall.Dir |
| |
| odir, e := dirstat(f) |
| if e != nil { |
| return &PathError{"chmod", f.name, e} |
| } |
| d.Null() |
| d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &PathError{"chmod", f.name, err} |
| } |
| if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { |
| return &PathError{"chmod", f.name, err} |
| } |
| return nil |
| } |
| |
| // Sync commits the current contents of the file to stable storage. |
| // Typically, this means flushing the file system's in-memory copy |
| // of recently written data to disk. |
| func (f *File) Sync() error { |
| if f == nil { |
| return ErrInvalid |
| } |
| var d syscall.Dir |
| d.Null() |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return NewSyscallError("fsync", err) |
| } |
| if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { |
| return NewSyscallError("fsync", err) |
| } |
| return nil |
| } |
| |
| // read reads up to len(b) bytes from the File. |
| // It returns the number of bytes read and an error, if any. |
| func (f *File) read(b []byte) (n int, err error) { |
| return fixCount(syscall.Read(f.fd, b)) |
| } |
| |
| // pread reads len(b) bytes from the File starting at byte offset off. |
| // It returns the number of bytes read and the error, if any. |
| // EOF is signaled by a zero count with err set to nil. |
| func (f *File) pread(b []byte, off int64) (n int, err error) { |
| return fixCount(syscall.Pread(f.fd, b, off)) |
| } |
| |
| // write writes len(b) bytes to the File. |
| // It returns the number of bytes written and an error, if any. |
| // Since Plan 9 preserves message boundaries, never allow |
| // a zero-byte write. |
| func (f *File) write(b []byte) (n int, err error) { |
| if len(b) == 0 { |
| return 0, nil |
| } |
| return fixCount(syscall.Write(f.fd, b)) |
| } |
| |
| // pwrite writes len(b) bytes to the File starting at byte offset off. |
| // It returns the number of bytes written and an error, if any. |
| // Since Plan 9 preserves message boundaries, never allow |
| // a zero-byte write. |
| func (f *File) pwrite(b []byte, off int64) (n int, err error) { |
| if len(b) == 0 { |
| return 0, nil |
| } |
| return fixCount(syscall.Pwrite(f.fd, b, off)) |
| } |
| |
| // seek sets the offset for the next Read or Write on file to offset, interpreted |
| // according to whence: 0 means relative to the origin of the file, 1 means |
| // relative to the current offset, and 2 means relative to the end. |
| // It returns the new offset and an error, if any. |
| func (f *File) seek(offset int64, whence int) (ret int64, err error) { |
| return syscall.Seek(f.fd, offset, whence) |
| } |
| |
| // Truncate changes the size of the named file. |
| // If the file is a symbolic link, it changes the size of the link's target. |
| // If there is an error, it will be of type *PathError. |
| func Truncate(name string, size int64) error { |
| var d syscall.Dir |
| |
| d.Null() |
| d.Length = size |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &PathError{"truncate", name, err} |
| } |
| if err = syscall.Wstat(name, buf[:n]); err != nil { |
| return &PathError{"truncate", name, err} |
| } |
| return nil |
| } |
| |
| // Remove removes the named file or directory. |
| // If there is an error, it will be of type *PathError. |
| func Remove(name string) error { |
| if e := syscall.Remove(name); e != nil { |
| return &PathError{"remove", name, e} |
| } |
| return nil |
| } |
| |
| // HasPrefix from the strings package. |
| func hasPrefix(s, prefix string) bool { |
| return len(s) >= len(prefix) && s[0:len(prefix)] == prefix |
| } |
| |
| // LastIndexByte from the strings package. |
| func lastIndex(s string, sep byte) int { |
| for i := len(s) - 1; i >= 0; i-- { |
| if s[i] == sep { |
| return i |
| } |
| } |
| return -1 |
| } |
| |
| func rename(oldname, newname string) error { |
| dirname := oldname[:lastIndex(oldname, '/')+1] |
| if hasPrefix(newname, dirname) { |
| newname = newname[len(dirname):] |
| } else { |
| return &LinkError{"rename", oldname, newname, ErrInvalid} |
| } |
| |
| // If newname still contains slashes after removing the oldname |
| // prefix, the rename is cross-directory and must be rejected. |
| if lastIndex(newname, '/') >= 0 { |
| return &LinkError{"rename", oldname, newname, ErrInvalid} |
| } |
| |
| var d syscall.Dir |
| |
| d.Null() |
| d.Name = newname |
| |
| buf := make([]byte, syscall.STATFIXLEN+len(d.Name)) |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &LinkError{"rename", oldname, newname, err} |
| } |
| |
| // If newname already exists and is not a directory, rename replaces it. |
| f, err := Stat(dirname + newname) |
| if err == nil && !f.IsDir() { |
| Remove(dirname + newname) |
| } |
| |
| if err = syscall.Wstat(oldname, buf[:n]); err != nil { |
| return &LinkError{"rename", oldname, newname, err} |
| } |
| return nil |
| } |
| |
| // Chmod changes the mode of the named file to mode. |
| // If the file is a symbolic link, it changes the mode of the link's target. |
| // If there is an error, it will be of type *PathError. |
| func Chmod(name string, mode FileMode) error { |
| var d syscall.Dir |
| |
| odir, e := dirstat(name) |
| if e != nil { |
| return &PathError{"chmod", name, e} |
| } |
| d.Null() |
| d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &PathError{"chmod", name, err} |
| } |
| if err = syscall.Wstat(name, buf[:n]); err != nil { |
| return &PathError{"chmod", name, err} |
| } |
| return nil |
| } |
| |
| // Chtimes changes the access and modification times of the named |
| // file, similar to the Unix utime() or utimes() functions. |
| // |
| // The underlying filesystem may truncate or round the values to a |
| // less precise time unit. |
| // If there is an error, it will be of type *PathError. |
| func Chtimes(name string, atime time.Time, mtime time.Time) error { |
| var d syscall.Dir |
| |
| d.Null() |
| d.Atime = uint32(atime.Unix()) |
| d.Mtime = uint32(mtime.Unix()) |
| |
| var buf [syscall.STATFIXLEN]byte |
| n, err := d.Marshal(buf[:]) |
| if err != nil { |
| return &PathError{"chtimes", name, err} |
| } |
| if err = syscall.Wstat(name, buf[:n]); err != nil { |
| return &PathError{"chtimes", name, err} |
| } |
| return nil |
| } |
| |
| // Pipe returns a connected pair of Files; reads from r return bytes |
| // written to w. It returns the files and an error, if any. |
| func Pipe() (r *File, w *File, err error) { |
| var p [2]int |
| |
| if e := syscall.Pipe(p[0:]); e != nil { |
| return nil, nil, NewSyscallError("pipe", e) |
| } |
| |
| return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil |
| } |
| |
| // not supported on Plan 9 |
| |
| // Link creates newname as a hard link to the oldname file. |
| // If there is an error, it will be of type *LinkError. |
| func Link(oldname, newname string) error { |
| return &LinkError{"link", oldname, newname, syscall.EPLAN9} |
| } |
| |
| // Symlink creates newname as a symbolic link to oldname. |
| // If there is an error, it will be of type *LinkError. |
| func Symlink(oldname, newname string) error { |
| return &LinkError{"symlink", oldname, newname, syscall.EPLAN9} |
| } |
| |
| // Readlink returns the destination of the named symbolic link. |
| // If there is an error, it will be of type *PathError. |
| func Readlink(name string) (string, error) { |
| return "", &PathError{"readlink", name, syscall.EPLAN9} |
| } |
| |
| // Chown changes the numeric uid and gid of the named file. |
| // If the file is a symbolic link, it changes the uid and gid of the link's target. |
| // If there is an error, it will be of type *PathError. |
| func Chown(name string, uid, gid int) error { |
| return &PathError{"chown", name, syscall.EPLAN9} |
| } |
| |
| // Lchown changes the numeric uid and gid of the named file. |
| // If the file is a symbolic link, it changes the uid and gid of the link itself. |
| // If there is an error, it will be of type *PathError. |
| func Lchown(name string, uid, gid int) error { |
| return &PathError{"lchown", name, syscall.EPLAN9} |
| } |
| |
| // Chown changes the numeric uid and gid of the named file. |
| // If there is an error, it will be of type *PathError. |
| func (f *File) Chown(uid, gid int) error { |
| if f == nil { |
| return ErrInvalid |
| } |
| return &PathError{"chown", f.name, syscall.EPLAN9} |
| } |
| |
| // TempDir returns the default directory to use for temporary files. |
| func TempDir() string { |
| return "/tmp" |
| } |