1 files changed, 383 insertions, 0 deletions
diff --git a/src/pkg/os/file.go b/src/pkg/os/file.go
new file mode 100644
index 000000000..1562b1b0e
--- /dev/null
+++ b/src/pkg/os/file.go
@@ -0,0 +1,383 @@
+// Copyright 2009 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.
+
+// The os package provides a platform-independent interface to operating
+// system functionality.  The design is Unix-like.
+package os
+
+import (
+	"os";
+	"syscall";
+)
+
+// Auxiliary information if the File describes a directory
+type dirInfo struct {
+	buf	[]byte;	// buffer for directory I/O
+	nbuf	int;	// length of buf; return value from Getdirentries
+	bufp	int;	// location of next record in buf.
+}
+
+// File represents an open file descriptor.
+type File struct {
+	fd int;
+	name	string;
+	dirinfo	*dirInfo;	// nil unless directory being read
+	nepipe	int;	// number of consecutive EPIPE in Write
+}
+
+// Fd returns the integer Unix file descriptor referencing the open file.
+func (file *File) Fd() int {
+	return file.fd
+}
+
+// Name returns the name of the file as presented to Open.
+func (file *File) Name() string {
+	return file.name
+}
+
+// NewFile returns a new File with the given file descriptor and name.
+func NewFile(file int, name string) *File {
+	if file < 0 {
+		return nil
+	}
+	return &File{file, name, nil, 0}
+}
+
+// Stdin, Stdout, and Stderr are open Files pointing to the standard input,
+// standard output, and standard error file descriptors.
+var (
+	Stdin  = NewFile(0, "/dev/stdin");
+	Stdout = NewFile(1, "/dev/stdout");
+	Stderr = NewFile(2, "/dev/stderr");
+)
+
+// Flags to Open wrapping those of the underlying system. Not all flags
+// may be implemented on a given system.
+const (
+	O_RDONLY = syscall.O_RDONLY;	// open the file read-only.
+	O_WRONLY = syscall.O_WRONLY;	// open the file write-only.
+	O_RDWR = syscall.O_RDWR;	// open the file read-write.
+	O_APPEND = syscall.O_APPEND;	// open the file append-only.
+	O_ASYNC = syscall.O_ASYNC;	// generate a signal when I/O is available.
+	O_CREAT = syscall.O_CREAT;	// create a new file if none exists.
+	O_NOCTTY = syscall.O_NOCTTY;	// do not make file the controlling tty.
+	O_NONBLOCK = syscall.O_NONBLOCK;	// open in non-blocking mode.
+	O_NDELAY = O_NONBLOCK;		// synonym for O_NONBLOCK
+	O_SYNC = syscall.O_SYNC;	// open for synchronous I/O.
+	O_TRUNC = syscall.O_TRUNC;	// if possible, truncate file when opened.
+)
+
+// Open 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.
+// It returns the File and an Error, if any.
+func Open(name string, flag int, perm int) (file *File, err Error) {
+	r, e := syscall.Open(name, flag | syscall.O_CLOEXEC, perm);
+	if e != 0 {
+		return nil, ErrnoToError(e);
+	}
+
+	// There's a race here with fork/exec, which we are
+	// content to live with.  See ../syscall/exec.go
+	if syscall.O_CLOEXEC == 0 {	// O_CLOEXEC not supported
+		syscall.CloseOnExec(r);
+	}
+
+	return NewFile(r, name), ErrnoToError(e)
+}
+
+// Close closes the File, rendering it unusable for I/O.
+// It returns an Error, if any.
+func (file *File) Close() Error {
+	if file == nil {
+		return EINVAL
+	}
+	err := ErrnoToError(syscall.Close(file.fd));
+	file.fd = -1;  // so it can't be closed again
+	return err;
+}
+
+// Read reads up to len(b) bytes from the File.
+// It returns the number of bytes read and an Error, if any.
+// EOF is signaled by a zero count with a nil Error.
+// TODO(r): Add Pread, Pwrite (maybe ReadAt, WriteAt).
+func (file *File) Read(b []byte) (ret int, err Error) {
+	if file == nil {
+		return 0, EINVAL
+	}
+	n, e := syscall.Read(file.fd, b);
+	if n < 0 {
+		n = 0;
+	}
+	return n, ErrnoToError(e);
+}
+
+// Write writes len(b) bytes to the File.
+// It returns the number of bytes written and an Error, if any.
+// If the byte count differs from len(b), it usually implies an error occurred.
+func (file *File) Write(b []byte) (ret int, err Error) {
+	if file == nil {
+		return 0, EINVAL
+	}
+	n, e := syscall.Write(file.fd, b);
+	if n < 0 {
+		n = 0
+	}
+	if e == syscall.EPIPE {
+		file.nepipe++;
+		if file.nepipe >= 10 {
+			os.Exit(syscall.EPIPE);
+		}
+	} else {
+		file.nepipe = 0;
+	}
+	return n, ErrnoToError(e)
+}
+
+// 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 (file *File) Seek(offset int64, whence int) (ret int64, err Error) {
+	r, e := syscall.Seek(file.fd, offset, whence);
+	if e != 0 {
+		return -1, ErrnoToError(e)
+	}
+	if file.dirinfo != nil && r != 0 {
+		return -1, ErrnoToError(syscall.EISDIR)
+	}
+	return r, nil
+}
+
+// WriteString is like Write, but writes the contents of string s rather than
+// an array of bytes.
+func (file *File) WriteString(s string) (ret int, err Error) {
+	if file == nil {
+		return 0, EINVAL
+	}
+	b := syscall.StringByteSlice(s);
+	b = b[0:len(b)-1];
+	r, e := syscall.Write(file.fd, b);
+	if r < 0 {
+		r = 0
+	}
+	return int(r), ErrnoToError(e)
+}
+
+// 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;
+
+	// See ../syscall/exec.go for description of lock.
+	syscall.ForkLock.RLock();
+	e := syscall.Pipe(&p);
+	if e != 0 {
+		syscall.ForkLock.RUnlock();
+		return nil, nil, ErrnoToError(e)
+	}
+	syscall.CloseOnExec(p[0]);
+	syscall.CloseOnExec(p[1]);
+	syscall.ForkLock.RUnlock();
+
+	return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
+}
+
+// Mkdir creates a new directory with the specified name and permission bits.
+// It returns an error, if any.
+func Mkdir(name string, perm int) Error {
+	return ErrnoToError(syscall.Mkdir(name, perm));
+}
+
+// Stat returns a Dir structure describing the named file and an error, if any.
+// If name names a valid symbolic link, the returned Dir describes
+// the file pointed at by the link and has dir.FollowedSymlink set to true.
+// If name names an invalid symbolic link, the returned Dir describes
+// the link itself and has dir.FollowedSymlink set to false.
+func Stat(name string) (dir *Dir, err Error) {
+	var lstat, stat syscall.Stat_t;
+	e := syscall.Lstat(name, &lstat);
+	if e != 0 {
+		return nil, ErrnoToError(e);
+	}
+	statp := &lstat;
+	if lstat.Mode & syscall.S_IFMT == syscall.S_IFLNK {
+		e := syscall.Stat(name, &stat);
+		if e == 0 {
+			statp = &stat;
+		}
+	}
+	return dirFromStat(name, new(Dir), &lstat, statp), nil
+}
+
+// Stat returns the Dir structure describing file.
+// It returns the Dir and an error, if any.
+func (file *File) Stat() (dir *Dir, err Error) {
+	var stat syscall.Stat_t;
+	e := syscall.Fstat(file.fd, &stat);
+	if e != 0 {
+		return nil, ErrnoToError(e)
+	}
+	return dirFromStat(file.name, new(Dir), &stat, &stat), nil
+}
+
+// Lstat returns the Dir structure describing the named file and an error, if any.
+// If the file is a symbolic link, the returned Dir describes the
+// symbolic link.  Lstat makes no attempt to follow the link.
+func Lstat(name string) (dir *Dir, err Error) {
+	var stat syscall.Stat_t;
+	e := syscall.Lstat(name, &stat);
+	if e != 0 {
+		return nil, ErrnoToError(e)
+	}
+	return dirFromStat(name, new(Dir), &stat, &stat), nil
+}
+
+// Readdirnames has a non-portable implemenation so its code is separated into an
+// operating-system-dependent file.
+func readdirnames(file *File, count int) (names []string, err Error)
+
+// Readdirnames reads the contents of the directory associated with file and
+// returns an array of up to count names, in directory order.  Subsequent
+// calls on the same file will yield further names.
+// A negative count means to read until EOF.
+// Readdirnames returns the array and an Error, if any.
+func (file *File) Readdirnames(count int) (names []string, err Error) {
+	return readdirnames(file, count);
+}
+
+// Readdir reads the contents of the directory associated with file and
+// returns an array of up to count Dir structures, as would be returned
+// by Stat, in directory order.  Subsequent calls on the same file will yield further Dirs.
+// A negative count means to read until EOF.
+// Readdir returns the array and an Error, if any.
+func (file *File) Readdir(count int) (dirs []Dir, err Error) {
+	dirname := file.name;
+	if dirname == "" {
+		dirname = ".";
+	}
+	dirname += "/";
+	names, err1 := file.Readdirnames(count);
+	if err1 != nil {
+		return nil, err1
+	}
+	dirs = make([]Dir, len(names));
+	for i, filename := range names {
+		dirp, err := Stat(dirname + filename);
+		if dirp ==  nil || err != nil {
+			dirs[i].Name = filename	// rest is already zeroed out
+		} else {
+			dirs[i] = *dirp
+		}
+	}
+	return
+}
+
+// Chdir changes the current working directory to the named directory.
+func Chdir(dir string) Error {
+	return ErrnoToError(syscall.Chdir(dir));
+}
+
+// Chdir changes the current working directory to the file,
+// which must be a directory.
+func (f *File) Chdir() Error {
+	return ErrnoToError(syscall.Fchdir(f.fd));
+}
+
+// Remove removes the named file or directory.
+func Remove(name string) Error {
+	// System call interface forces us to know
+	// whether name is a file or directory.
+	// Try both: it is cheaper on average than
+	// doing a Stat plus the right one.
+	e := syscall.Unlink(name);
+	if e == 0 {
+		return nil;
+	}
+	e1 := syscall.Rmdir(name);
+	if e1 == 0 {
+		return nil;
+	}
+
+	// Both failed: figure out which error to return.
+	// OS X and Linux differ on whether unlink(dir)
+	// returns EISDIR, so can't use that.  However,
+	// both agree that rmdir(file) returns ENOTDIR,
+	// so we can use that to decide which error is real.
+	// Rmdir might also return ENOTDIR if given a bad
+	// file path, like /etc/passwd/foo, but in that case,
+	// both errors will be ENOTDIR, so it's okay to
+	// use the error from unlink.
+	if e1 != syscall.ENOTDIR {
+		e = e1;
+	}
+	return ErrnoToError(e);
+}
+
+// Link creates a hard link.
+func Link(oldname, newname string) Error {
+	return ErrnoToError(syscall.Link(oldname, newname));
+}
+
+// Symlink creates a symbolic link.
+func Symlink(oldname, newname string) Error {
+	return ErrnoToError(syscall.Symlink(oldname, newname));
+}
+
+// Readlink reads the contents of a symbolic link: the destination of
+// the link.  It returns the contents and an Error, if any.
+func Readlink(name string) (string, Error) {
+	for len := 128; ; len *= 2 {
+		b := make([]byte, len);
+		n, e := syscall.Readlink(name, b);
+		if e != 0 {
+			return "", ErrnoToError(e);
+		}
+		if n < len {
+			return string(b[0:n]), nil;
+		}
+	}
+	// Silence 6g.
+	return "", nil;
+}
+
+// Chmod changes the mode of the named file to mode.
+// If the file is a symbolic link, it changes the uid and gid of the link's target.
+func Chmod(name string, mode int) Error {
+	return ErrnoToError(syscall.Chmod(name, mode));
+}
+
+// Chmod changes the mode of the file to mode.
+func (f *File) Chmod(mode int) Error {
+	return ErrnoToError(syscall.Fchmod(f.fd, mode));
+}
+
+// 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.
+func Chown(name string, uid, gid int) Error {
+	return ErrnoToError(syscall.Chown(name, uid, gid));
+}
+
+// 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.
+func Lchown(name string, uid, gid int) Error {
+	return ErrnoToError(syscall.Lchown(name, uid, gid));
+}
+
+// Chown changes the numeric uid and gid of the named file.
+func (f *File) Chown(uid, gid int) Error {
+	return ErrnoToError(syscall.Fchown(f.fd, uid, gid));
+}
+
+// Truncate changes the size of the named file.
+// If the file is a symbolic link, it changes the size of the link's target.
+func Truncate(name string, size int64) Error {
+	return ErrnoToError(syscall.Truncate(name, size));
+}
+
+// Truncate changes the size of the file.
+// It does not change the I/O offset.
+func (f *File) Truncate(size int64) Error {
+	return ErrnoToError(syscall.Ftruncate(f.fd, size));
+}
+