Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 770 insertions, 0 deletions

diff --git a/src/os/file.go b/src/os/file.go
new file mode 100644
index 0000000..7fd2f5d
--- /dev/null
+++ b/src/os/file.go
@@ -0,0 +1,770 @@
+// 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])
+//
+// Note: The maximum number of concurrent operations on a File may be limited by
+// the OS or the system. The number should be high, but exceeding it may degrade
+// performance or cause other issues.
+package os
+
+import (
+	"errors"
+	"internal/poll"
+	"internal/safefilepath"
+	"internal/testlog"
+	"io"
+	"io/fs"
+	"runtime"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+// 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.
+//
+// Note that the Go runtime writes to standard error for panics and crashes;
+// closing Stderr may cause those messages to go elsewhere, perhaps
+// to a file opened later.
+var (
+	Stdin  = NewFile(uintptr(syscall.Stdin), "/dev/stdin")
+	Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")
+	Stderr = NewFile(uintptr(syscall.Stderr), "/dev/stderr")
+)
+
+// Flags to OpenFile wrapping those of the underlying system. Not all
+// flags may be implemented on a given system.
+const (
+	// Exactly one of O_RDONLY, O_WRONLY, or O_RDWR must be specified.
+	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.
+	// The remaining values may be or'ed in to control behavior.
+	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  // truncate regular writable file when opened.
+)
+
+// Seek whence values.
+//
+// Deprecated: Use io.SeekStart, io.SeekCurrent, and io.SeekEnd.
+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()
+}
+
+func (e *LinkError) Unwrap() error {
+	return e.Err
+}
+
+// Read reads up to len(b) bytes from the File and stores them in b.
+// It returns the number of bytes read and any error encountered.
+// At end of file, Read returns 0, io.EOF.
+func (f *File) Read(b []byte) (n int, err error) {
+	if err := f.checkValid("read"); err != nil {
+		return 0, err
+	}
+	n, e := f.read(b)
+	return n, f.wrapErr("read", e)
+}
+
+// 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 err := f.checkValid("read"); err != nil {
+		return 0, err
+	}
+
+	if off < 0 {
+		return 0, &PathError{Op: "readat", Path: f.name, Err: errors.New("negative offset")}
+	}
+
+	for len(b) > 0 {
+		m, e := f.pread(b, off)
+		if e != nil {
+			err = f.wrapErr("read", e)
+			break
+		}
+		n += m
+		b = b[m:]
+		off += int64(m)
+	}
+	return
+}
+
+// ReadFrom implements io.ReaderFrom.
+func (f *File) ReadFrom(r io.Reader) (n int64, err error) {
+	if err := f.checkValid("write"); err != nil {
+		return 0, err
+	}
+	n, handled, e := f.readFrom(r)
+	if !handled {
+		return genericReadFrom(f, r) // without wrapping
+	}
+	return n, f.wrapErr("write", e)
+}
+
+func genericReadFrom(f *File, r io.Reader) (int64, error) {
+	return io.Copy(fileWithoutReadFrom{f}, r)
+}
+
+// fileWithoutReadFrom implements all the methods of *File other
+// than ReadFrom. This is used to permit ReadFrom to call io.Copy
+// without leading to a recursive call to ReadFrom.
+type fileWithoutReadFrom struct {
+	*File
+}
+
+// This ReadFrom method hides the *File ReadFrom method.
+func (fileWithoutReadFrom) ReadFrom(fileWithoutReadFrom) {
+	panic("unreachable")
+}
+
+// Write writes len(b) bytes from b 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 err := f.checkValid("write"); err != nil {
+		return 0, err
+	}
+	n, e := f.write(b)
+	if n < 0 {
+		n = 0
+	}
+	if n != len(b) {
+		err = io.ErrShortWrite
+	}
+
+	epipecheck(f, e)
+
+	if e != nil {
+		err = f.wrapErr("write", e)
+	}
+
+	return n, err
+}
+
+var errWriteAtInAppendMode = errors.New("os: invalid use of WriteAt on file opened with O_APPEND")
+
+// 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).
+//
+// If file was opened with the O_APPEND flag, WriteAt returns an error.
+func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
+	if err := f.checkValid("write"); err != nil {
+		return 0, err
+	}
+	if f.appendMode {
+		return 0, errWriteAtInAppendMode
+	}
+
+	if off < 0 {
+		return 0, &PathError{Op: "writeat", Path: f.name, Err: errors.New("negative offset")}
+	}
+
+	for len(b) > 0 {
+		m, e := f.pwrite(b, off)
+		if e != nil {
+			err = f.wrapErr("write", 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.
+// The behavior of Seek on a file opened with O_APPEND is not specified.
+func (f *File) Seek(offset int64, whence int) (ret int64, err error) {
+	if err := f.checkValid("seek"); err != nil {
+		return 0, err
+	}
+	r, e := f.seek(offset, whence)
+	if e == nil && f.dirinfo != nil && r != 0 {
+		e = syscall.EISDIR
+	}
+	if e != nil {
+		return 0, f.wrapErr("seek", 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) (n int, err error) {
+	b := unsafe.Slice(unsafe.StringData(s), len(s))
+	return f.Write(b)
+}
+
+// Mkdir creates a new directory with the specified name and permission
+// bits (before umask).
+// If there is an error, it will be of type *PathError.
+func Mkdir(name string, perm FileMode) error {
+	longName := fixLongPath(name)
+	e := ignoringEINTR(func() error {
+		return syscall.Mkdir(longName, syscallMode(perm))
+	})
+
+	if e != nil {
+		return &PathError{Op: "mkdir", Path: name, Err: e}
+	}
+
+	// mkdir(2) itself won't handle the sticky bit on *BSD and Solaris
+	if !supportsCreateWithStickyBit && perm&ModeSticky != 0 {
+		e = setStickyBit(name)
+
+		if e != nil {
+			Remove(name)
+			return e
+		}
+	}
+
+	return nil
+}
+
+// setStickyBit adds ModeSticky to the permission bits of path, non atomic.
+func setStickyBit(name string) error {
+	fi, err := Stat(name)
+	if err != nil {
+		return err
+	}
+	return Chmod(name, fi.Mode()|ModeSticky)
+}
+
+// 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 {
+		testlog.Open(dir) // observe likely non-existent directory
+		return &PathError{Op: "chdir", Path: dir, Err: e}
+	}
+	if log := testlog.Logger(); log != nil {
+		wd, err := Getwd()
+		if err == nil {
+			log.Chdir(wd)
+		}
+	}
+	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, error) {
+	return OpenFile(name, O_RDONLY, 0)
+}
+
+// Create creates or truncates the named file. If the file already exists,
+// it is truncated. If the file does not exist, it is created with mode 0666
+// (before umask). 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, error) {
+	return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
+}
+
+// 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.). If the file does not exist, and the O_CREATE flag
+// is passed, it is created with mode perm (before umask). 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) {
+	testlog.Open(name)
+	f, err := openFileNolog(name, flag, perm)
+	if err != nil {
+		return nil, err
+	}
+	f.appendMode = flag&O_APPEND != 0
+
+	return f, nil
+}
+
+// lstat is overridden in tests.
+var lstat = Lstat
+
+// Rename renames (moves) oldpath to newpath.
+// If newpath already exists and is not a directory, Rename replaces it.
+// OS-specific restrictions may apply when oldpath and newpath are in different directories.
+// Even within the same directory, on non-Unix platforms Rename is not an atomic operation.
+// If there is an error, it will be of type *LinkError.
+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
+}
+
+// checkWrapErr is the test hook to enable checking unexpected wrapped errors of poll.ErrFileClosing.
+// It is set to true in the export_test.go for tests (including fuzz tests).
+var checkWrapErr = false
+
+// wrapErr wraps an error that occurred during an operation on an open file.
+// It passes io.EOF through unchanged, otherwise converts
+// poll.ErrFileClosing to ErrClosed and wraps the error in a PathError.
+func (f *File) wrapErr(op string, err error) error {
+	if err == nil || err == io.EOF {
+		return err
+	}
+	if err == poll.ErrFileClosing {
+		err = ErrClosed
+	} else if checkWrapErr && errors.Is(err, poll.ErrFileClosing) {
+		panic("unexpected error wrapping poll.ErrFileClosing: " + err.Error())
+	}
+	return &PathError{Op: op, Path: f.name, Err: err}
+}
+
+// TempDir returns the default directory to use for temporary files.
+//
+// On Unix systems, it returns $TMPDIR if non-empty, else /tmp.
+// On Windows, it uses GetTempPath, returning the first non-empty
+// value from %TMP%, %TEMP%, %USERPROFILE%, or the Windows directory.
+// On Plan 9, it returns /tmp.
+//
+// The directory is neither guaranteed to exist nor have accessible
+// permissions.
+func TempDir() string {
+	return tempDir()
+}
+
+// UserCacheDir returns the default root directory to use for user-specific
+// cached data. Users should create their own application-specific subdirectory
+// within this one and use that.
+//
+// On Unix systems, it returns $XDG_CACHE_HOME as specified by
+// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html if
+// non-empty, else $HOME/.cache.
+// On Darwin, it returns $HOME/Library/Caches.
+// On Windows, it returns %LocalAppData%.
+// On Plan 9, it returns $home/lib/cache.
+//
+// If the location cannot be determined (for example, $HOME is not defined),
+// then it will return an error.
+func UserCacheDir() (string, error) {
+	var dir string
+
+	switch runtime.GOOS {
+	case "windows":
+		dir = Getenv("LocalAppData")
+		if dir == "" {
+			return "", errors.New("%LocalAppData% is not defined")
+		}
+
+	case "darwin", "ios":
+		dir = Getenv("HOME")
+		if dir == "" {
+			return "", errors.New("$HOME is not defined")
+		}
+		dir += "/Library/Caches"
+
+	case "plan9":
+		dir = Getenv("home")
+		if dir == "" {
+			return "", errors.New("$home is not defined")
+		}
+		dir += "/lib/cache"
+
+	default: // Unix
+		dir = Getenv("XDG_CACHE_HOME")
+		if dir == "" {
+			dir = Getenv("HOME")
+			if dir == "" {
+				return "", errors.New("neither $XDG_CACHE_HOME nor $HOME are defined")
+			}
+			dir += "/.cache"
+		}
+	}
+
+	return dir, nil
+}
+
+// UserConfigDir returns the default root directory to use for user-specific
+// configuration data. Users should create their own application-specific
+// subdirectory within this one and use that.
+//
+// On Unix systems, it returns $XDG_CONFIG_HOME as specified by
+// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html if
+// non-empty, else $HOME/.config.
+// On Darwin, it returns $HOME/Library/Application Support.
+// On Windows, it returns %AppData%.
+// On Plan 9, it returns $home/lib.
+//
+// If the location cannot be determined (for example, $HOME is not defined),
+// then it will return an error.
+func UserConfigDir() (string, error) {
+	var dir string
+
+	switch runtime.GOOS {
+	case "windows":
+		dir = Getenv("AppData")
+		if dir == "" {
+			return "", errors.New("%AppData% is not defined")
+		}
+
+	case "darwin", "ios":
+		dir = Getenv("HOME")
+		if dir == "" {
+			return "", errors.New("$HOME is not defined")
+		}
+		dir += "/Library/Application Support"
+
+	case "plan9":
+		dir = Getenv("home")
+		if dir == "" {
+			return "", errors.New("$home is not defined")
+		}
+		dir += "/lib"
+
+	default: // Unix
+		dir = Getenv("XDG_CONFIG_HOME")
+		if dir == "" {
+			dir = Getenv("HOME")
+			if dir == "" {
+				return "", errors.New("neither $XDG_CONFIG_HOME nor $HOME are defined")
+			}
+			dir += "/.config"
+		}
+	}
+
+	return dir, nil
+}
+
+// UserHomeDir returns the current user's home directory.
+//
+// On Unix, including macOS, it returns the $HOME environment variable.
+// On Windows, it returns %USERPROFILE%.
+// On Plan 9, it returns the $home environment variable.
+//
+// If the expected variable is not set in the environment, UserHomeDir
+// returns either a platform-specific default value or a non-nil error.
+func UserHomeDir() (string, error) {
+	env, enverr := "HOME", "$HOME"
+	switch runtime.GOOS {
+	case "windows":
+		env, enverr = "USERPROFILE", "%userprofile%"
+	case "plan9":
+		env, enverr = "home", "$home"
+	}
+	if v := Getenv(env); v != "" {
+		return v, nil
+	}
+	// On some geese the home directory is not always defined.
+	switch runtime.GOOS {
+	case "android":
+		return "/sdcard", nil
+	case "ios":
+		return "/", nil
+	}
+	return "", errors.New(enverr + " is not defined")
+}
+
+// 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.
+//
+// A different subset of the mode bits are used, depending on the
+// operating system.
+//
+// On Unix, the mode's permission bits, ModeSetuid, ModeSetgid, and
+// ModeSticky are used.
+//
+// On Windows, only the 0200 bit (owner writable) of mode is used; it
+// controls whether the file's read-only attribute is set or cleared.
+// The other bits are currently unused. For compatibility with Go 1.12
+// and earlier, use a non-zero mode. Use mode 0400 for a read-only
+// file and 0600 for a readable+writable file.
+//
+// On Plan 9, the mode's permission bits, ModeAppend, ModeExclusive,
+// and ModeTemporary are used.
+func Chmod(name string, mode FileMode) error { return chmod(name, mode) }
+
+// 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 { return f.chmod(mode) }
+
+// SetDeadline sets the read and write deadlines for a File.
+// It is equivalent to calling both SetReadDeadline and SetWriteDeadline.
+//
+// Only some kinds of files support setting a deadline. Calls to SetDeadline
+// for files that do not support deadlines will return ErrNoDeadline.
+// On most systems ordinary files do not support deadlines, but pipes do.
+//
+// A deadline is an absolute time after which I/O operations fail with an
+// error instead of blocking. The deadline applies to all future and pending
+// I/O, not just the immediately following call to Read or Write.
+// After a deadline has been exceeded, the connection can be refreshed
+// by setting a deadline in the future.
+//
+// If the deadline is exceeded a call to Read or Write or to other I/O
+// methods will return an error that wraps ErrDeadlineExceeded.
+// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
+// That error implements the Timeout method, and calling the Timeout
+// method will return true, but there are other possible errors for which
+// the Timeout will return true even if the deadline has not been exceeded.
+//
+// An idle timeout can be implemented by repeatedly extending
+// the deadline after successful Read or Write calls.
+//
+// A zero value for t means I/O operations will not time out.
+func (f *File) SetDeadline(t time.Time) error {
+	return f.setDeadline(t)
+}
+
+// SetReadDeadline sets the deadline for future Read calls and any
+// currently-blocked Read call.
+// A zero value for t means Read will not time out.
+// Not all files support setting deadlines; see SetDeadline.
+func (f *File) SetReadDeadline(t time.Time) error {
+	return f.setReadDeadline(t)
+}
+
+// SetWriteDeadline sets the deadline for any future Write calls and any
+// currently-blocked Write call.
+// Even if Write times out, it may return n > 0, indicating that
+// some of the data was successfully written.
+// A zero value for t means Write will not time out.
+// Not all files support setting deadlines; see SetDeadline.
+func (f *File) SetWriteDeadline(t time.Time) error {
+	return f.setWriteDeadline(t)
+}
+
+// SyscallConn returns a raw file.
+// This implements the syscall.Conn interface.
+func (f *File) SyscallConn() (syscall.RawConn, error) {
+	if err := f.checkValid("SyscallConn"); err != nil {
+		return nil, err
+	}
+	return newRawConn(f)
+}
+
+// DirFS returns a file system (an fs.FS) for the tree of files rooted at the directory dir.
+//
+// Note that DirFS("/prefix") only guarantees that the Open calls it makes to the
+// operating system will begin with "/prefix": DirFS("/prefix").Open("file") is the
+// same as os.Open("/prefix/file"). So if /prefix/file is a symbolic link pointing outside
+// the /prefix tree, then using DirFS does not stop the access any more than using
+// os.Open does. Additionally, the root of the fs.FS returned for a relative path,
+// DirFS("prefix"), will be affected by later calls to Chdir. DirFS is therefore not
+// a general substitute for a chroot-style security mechanism when the directory tree
+// contains arbitrary content.
+//
+// The directory dir must not be "".
+//
+// The result implements [io/fs.StatFS], [io/fs.ReadFileFS] and
+// [io/fs.ReadDirFS].
+func DirFS(dir string) fs.FS {
+	return dirFS(dir)
+}
+
+// containsAny reports whether any bytes in chars are within s.
+func containsAny(s, chars string) bool {
+	for i := 0; i < len(s); i++ {
+		for j := 0; j < len(chars); j++ {
+			if s[i] == chars[j] {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+type dirFS string
+
+func (dir dirFS) Open(name string) (fs.File, error) {
+	fullname, err := dir.join(name)
+	if err != nil {
+		return nil, &PathError{Op: "stat", Path: name, Err: err}
+	}
+	f, err := Open(fullname)
+	if err != nil {
+		// DirFS takes a string appropriate for GOOS,
+		// while the name argument here is always slash separated.
+		// dir.join will have mixed the two; undo that for
+		// error reporting.
+		err.(*PathError).Path = name
+		return nil, err
+	}
+	return f, nil
+}
+
+// The ReadFile method calls the [ReadFile] function for the file
+// with the given name in the directory. The function provides
+// robust handling for small files and special file systems.
+// Through this method, dirFS implements [io/fs.ReadFileFS].
+func (dir dirFS) ReadFile(name string) ([]byte, error) {
+	fullname, err := dir.join(name)
+	if err != nil {
+		return nil, &PathError{Op: "readfile", Path: name, Err: err}
+	}
+	return ReadFile(fullname)
+}
+
+// ReadDir reads the named directory, returning all its directory entries sorted
+// by filename. Through this method, dirFS implements [io/fs.ReadDirFS].
+func (dir dirFS) ReadDir(name string) ([]DirEntry, error) {
+	fullname, err := dir.join(name)
+	if err != nil {
+		return nil, &PathError{Op: "readdir", Path: name, Err: err}
+	}
+	return ReadDir(fullname)
+}
+
+func (dir dirFS) Stat(name string) (fs.FileInfo, error) {
+	fullname, err := dir.join(name)
+	if err != nil {
+		return nil, &PathError{Op: "stat", Path: name, Err: err}
+	}
+	f, err := Stat(fullname)
+	if err != nil {
+		// See comment in dirFS.Open.
+		err.(*PathError).Path = name
+		return nil, err
+	}
+	return f, nil
+}
+
+// join returns the path for name in dir.
+func (dir dirFS) join(name string) (string, error) {
+	if dir == "" {
+		return "", errors.New("os: DirFS with empty root")
+	}
+	if !fs.ValidPath(name) {
+		return "", ErrInvalid
+	}
+	name, err := safefilepath.FromFS(name)
+	if err != nil {
+		return "", ErrInvalid
+	}
+	if IsPathSeparator(dir[len(dir)-1]) {
+		return string(dir) + name, nil
+	}
+	return string(dir) + string(PathSeparator) + name, nil
+}
+
+// ReadFile reads the named file and returns the contents.
+// A successful call returns err == nil, not err == EOF.
+// Because ReadFile reads the whole file, it does not treat an EOF from Read
+// as an error to be reported.
+func ReadFile(name string) ([]byte, error) {
+	f, err := Open(name)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var size int
+	if info, err := f.Stat(); err == nil {
+		size64 := info.Size()
+		if int64(int(size64)) == size64 {
+			size = int(size64)
+		}
+	}
+	size++ // one byte for final read at EOF
+
+	// If a file claims a small size, read at least 512 bytes.
+	// In particular, files in Linux's /proc claim size 0 but
+	// then do not work right if read in small pieces,
+	// so an initial read of 1 byte would not work correctly.
+	if size < 512 {
+		size = 512
+	}
+
+	data := make([]byte, 0, size)
+	for {
+		if len(data) >= cap(data) {
+			d := append(data[:cap(data)], 0)
+			data = d[:len(data)]
+		}
+		n, err := f.Read(data[len(data):cap(data)])
+		data = data[:len(data)+n]
+		if err != nil {
+			if err == io.EOF {
+				err = nil
+			}
+			return data, err
+		}
+	}
+}
+
+// WriteFile writes data to the named file, creating it if necessary.
+// If the file does not exist, WriteFile creates it with permissions perm (before umask);
+// otherwise WriteFile truncates it before writing, without changing permissions.
+// Since WriteFile requires multiple system calls to complete, a failure mid-operation
+// can leave the file in a partially written state.
+func WriteFile(name string, data []byte, perm FileMode) error {
+	f, err := OpenFile(name, O_WRONLY|O_CREATE|O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	_, err = f.Write(data)
+	if err1 := f.Close(); err1 != nil && err == nil {
+		err = err1
+	}
+	return err
+}