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//go:build baremetal || (wasm && !wasi)
package os
import (
_ "unsafe"
)
// 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")
)
const DevNull = "/dev/null"
// isOS indicates whether we're running on a real operating system with
// filesystem support.
const isOS = false
// stdioFileHandle represents one of stdin, stdout, or stderr depending on the
// number. It implements the FileHandle interface.
type stdioFileHandle uint8
// 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 {
handle FileHandle
name string
}
func NewFile(fd uintptr, name string) *File {
return &File{&file{stdioFileHandle(fd), name}}
}
// Read reads up to len(b) bytes from machine.Serial.
// It returns the number of bytes read and any error encountered.
func (f stdioFileHandle) Read(b []byte) (n int, err error) {
if len(b) == 0 {
return 0, nil
}
size := buffered()
for size == 0 {
gosched()
size = buffered()
}
if size > len(b) {
size = len(b)
}
for i := 0; i < size; i++ {
b[i] = getchar()
}
return size, nil
}
func (f stdioFileHandle) ReadAt(b []byte, off int64) (n int, err error) {
return 0, ErrNotImplemented
}
// Write writes len(b) bytes to the output. It returns the number of bytes
// written or an error if this file is not stdout or stderr.
func (f stdioFileHandle) Write(b []byte) (n int, err error) {
switch f {
case 1, 2: // stdout, stderr
for _, c := range b {
putchar(c)
}
return len(b), nil
default:
return 0, ErrUnsupported
}
}
// Close is unsupported on this system.
func (f stdioFileHandle) Close() error {
return ErrUnsupported
}
// Seek wraps syscall.Seek.
func (f stdioFileHandle) Seek(offset int64, whence int) (int64, error) {
return -1, ErrUnsupported
}
func (f stdioFileHandle) Fd() uintptr {
return uintptr(f)
}
//go:linkname putchar runtime.putchar
func putchar(c byte)
//go:linkname getchar runtime.getchar
func getchar() byte
//go:linkname buffered runtime.buffered
func buffered() int
//go:linkname gosched runtime.Gosched
func gosched() int
func Pipe() (r *File, w *File, err error) {
return nil, nil, ErrNotImplemented
}
func Readlink(name string) (string, error) {
return "", ErrNotImplemented
}
func tempDir() string {
return "/tmp"
}
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