1 files changed, 266 insertions, 0 deletions
diff --git a/src/os/file.go b/src/os/file.go
new file mode 100644
index 000000000..e12428cbe
--- /dev/null
+++ b/src/os/file.go
@@ -0,0 +1,266 @@
+// 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.
+
+// Package os provides a platform-independent interface to operating system
+// functionality. The design is Unix-like, although the error handling is
+// Go-like; failing calls return values of type error rather than error numbers.
+// Often, more information is available within the error. For example,
+// if a call that takes a file name fails, such as Open or Stat, the error
+// will include the failing file name when printed and will be of type
+// *PathError, which may be unpacked for more information.
+//
+// The os interface is intended to be uniform across all operating systems.
+// Features not generally available appear in the system-specific package syscall.
+//
+// Here is a simple example, opening a file and reading some of it.
+//
+//	file, err := os.Open("file.go") // For read access.
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//
+// If the open fails, the error string will be self-explanatory, like
+//
+//	open file.go: no such file or directory
+//
+// The file's data can then be read into a slice of bytes. Read and
+// Write take their byte counts from the length of the argument slice.
+//
+//	data := make([]byte, 100)
+//	count, err := file.Read(data)
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	fmt.Printf("read %d bytes: %q\n", count, data[:count])
+//
+package os
+
+import (
+	"io"
+	"syscall"
+)
+
+// Name returns the name of the file as presented to Open.
+func (f *File) Name() string { return f.name }
+
+// Stdin, Stdout, and Stderr are open Files pointing to the standard input,
+// standard output, and standard error file descriptors.
+var (
+	Stdin  = NewFile(uintptr(syscall.Stdin), "/dev/stdin")
+	Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")
+	Stderr = NewFile(uintptr(syscall.Stderr), "/dev/stderr")
+)
+
+// Flags to Open wrapping those of the underlying system. Not all flags
+// may be implemented on a given system.
+const (
+	O_RDONLY int = syscall.O_RDONLY // open the file read-only.
+	O_WRONLY int = syscall.O_WRONLY // open the file write-only.
+	O_RDWR   int = syscall.O_RDWR   // open the file read-write.
+	O_APPEND int = syscall.O_APPEND // append data to the file when writing.
+	O_CREATE int = syscall.O_CREAT  // create a new file if none exists.
+	O_EXCL   int = syscall.O_EXCL   // used with O_CREATE, file must not exist
+	O_SYNC   int = syscall.O_SYNC   // open for synchronous I/O.
+	O_TRUNC  int = syscall.O_TRUNC  // if possible, truncate file when opened.
+)
+
+// Seek whence values.
+const (
+	SEEK_SET int = 0 // seek relative to the origin of the file
+	SEEK_CUR int = 1 // seek relative to the current offset
+	SEEK_END int = 2 // seek relative to the end
+)
+
+// LinkError records an error during a link or symlink or rename
+// system call and the paths that caused it.
+type LinkError struct {
+	Op  string
+	Old string
+	New string
+	Err error
+}
+
+func (e *LinkError) Error() string {
+	return e.Op + " " + e.Old + " " + e.New + ": " + e.Err.Error()
+}
+
+// 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 err set to io.EOF.
+func (f *File) Read(b []byte) (n int, err error) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	n, e := f.read(b)
+	if n < 0 {
+		n = 0
+	}
+	if n == 0 && len(b) > 0 && e == nil {
+		return 0, io.EOF
+	}
+	if e != nil {
+		err = &PathError{"read", f.name, e}
+	}
+	return n, err
+}
+
+// ReadAt reads len(b) bytes from the File starting at byte offset off.
+// It returns the number of bytes read and the error, if any.
+// ReadAt always returns a non-nil error when n < len(b).
+// At end of file, that error is io.EOF.
+func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	for len(b) > 0 {
+		m, e := f.pread(b, off)
+		if m == 0 && e == nil {
+			return n, io.EOF
+		}
+		if e != nil {
+			err = &PathError{"read", f.name, e}
+			break
+		}
+		n += m
+		b = b[m:]
+		off += int64(m)
+	}
+	return
+}
+
+// Write writes len(b) bytes to the File.
+// It returns the number of bytes written and an error, if any.
+// Write returns a non-nil error when n != len(b).
+func (f *File) Write(b []byte) (n int, err error) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	n, e := f.write(b)
+	if n < 0 {
+		n = 0
+	}
+	if n != len(b) {
+		err = io.ErrShortWrite
+	}
+
+	epipecheck(f, e)
+
+	if e != nil {
+		err = &PathError{"write", f.name, e}
+	}
+	return n, err
+}
+
+// WriteAt writes len(b) bytes to the File starting at byte offset off.
+// It returns the number of bytes written and an error, if any.
+// WriteAt returns a non-nil error when n != len(b).
+func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	for len(b) > 0 {
+		m, e := f.pwrite(b, off)
+		if e != nil {
+			err = &PathError{"write", f.name, e}
+			break
+		}
+		n += m
+		b = b[m:]
+		off += int64(m)
+	}
+	return
+}
+
+// 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) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	r, e := f.seek(offset, whence)
+	if e == nil && f.dirinfo != nil && r != 0 {
+		e = syscall.EISDIR
+	}
+	if e != nil {
+		return 0, &PathError{"seek", f.name, e}
+	}
+	return r, nil
+}
+
+// WriteString is like Write, but writes the contents of string s rather than
+// a slice of bytes.
+func (f *File) WriteString(s string) (ret int, err error) {
+	if f == nil {
+		return 0, ErrInvalid
+	}
+	return f.Write([]byte(s))
+}
+
+// Mkdir creates a new directory with the specified name and permission bits.
+// If there is an error, it will be of type *PathError.
+func Mkdir(name string, perm FileMode) error {
+	e := syscall.Mkdir(name, syscallMode(perm))
+	if e != nil {
+		return &PathError{"mkdir", name, e}
+	}
+	return nil
+}
+
+// Chdir changes the current working directory to the named directory.
+// If there is an error, it will be of type *PathError.
+func Chdir(dir string) error {
+	if e := syscall.Chdir(dir); e != nil {
+		return &PathError{"chdir", dir, e}
+	}
+	return nil
+}
+
+// Chdir changes the current working directory to the file,
+// which must be a directory.
+// If there is an error, it will be of type *PathError.
+func (f *File) Chdir() error {
+	if f == nil {
+		return ErrInvalid
+	}
+	if e := syscall.Fchdir(f.fd); e != nil {
+		return &PathError{"chdir", f.name, e}
+	}
+	return nil
+}
+
+// Open opens the named file for reading.  If successful, methods on
+// the returned file can be used for reading; the associated file
+// descriptor has mode O_RDONLY.
+// If there is an error, it will be of type *PathError.
+func Open(name string) (file *File, err error) {
+	return OpenFile(name, O_RDONLY, 0)
+}
+
+// Create creates the named file mode 0666 (before umask), truncating
+// it if it already exists.  If successful, methods on the returned
+// File can be used for I/O; the associated file descriptor has mode
+// O_RDWR.
+// If there is an error, it will be of type *PathError.
+func Create(name string) (file *File, err error) {
+	return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
+}
+
+// lstat is overridden in tests.
+var lstat = Lstat
+
+// Rename renames (moves) a file. OS-specific restrictions might apply.
+func Rename(oldpath, newpath string) error {
+	return rename(oldpath, newpath)
+}
+
+// Many functions in package syscall return a count of -1 instead of 0.
+// Using fixCount(call()) instead of call() corrects the count.
+func fixCount(n int, err error) (int, error) {
+	if n < 0 {
+		n = 0
+	}
+	return n, err
+}