src/libstd/sys/wasm/stdio.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use io;
  12 use sys::{ReadSysCall, WriteSysCall};
  13
  14 pub struct Stdin;
  15 pub struct Stdout;
  16 pub struct Stderr;
  17
  18 impl Stdin {
  19     pub fn new() -> io::Result<Stdin> {
  20         Ok(Stdin)
  21     }
  22
  23     pub fn read(&self, data: &mut [u8]) -> io::Result<usize> {
  24         Ok(ReadSysCall::perform(0, data))
  25     }
  26 }
  27
  28 impl Stdout {
  29     pub fn new() -> io::Result<Stdout> {
  30         Ok(Stdout)
  31     }
  32
  33     pub fn write(&self, data: &[u8]) -> io::Result<usize> {
  34         WriteSysCall::perform(1, data);
  35         Ok(data.len())
  36     }
  37
  38     pub fn flush(&self) -> io::Result<()> {
  39         Ok(())
  40     }
  41 }
  42
  43 impl Stderr {
  44     pub fn new() -> io::Result<Stderr> {
  45         Ok(Stderr)
  46     }
  47
  48     pub fn write(&self, data: &[u8]) -> io::Result<usize> {
  49         WriteSysCall::perform(2, data);
  50         Ok(data.len())
  51     }
  52
  53     pub fn flush(&self) -> io::Result<()> {
  54         Ok(())
  55     }
  56 }
  57
  58 impl io::Write for Stderr {
  59     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
  60         (&*self).write(data)
  61     }
  62     fn flush(&mut self) -> io::Result<()> {
  63         (&*self).flush()
  64     }
  65 }
  66
  67 pub const STDIN_BUF_SIZE: usize = 0;
  68
  69 pub fn is_ebadf(_err: &io::Error) -> bool {
  70     true
  71 }
  72
  73 pub fn stderr_prints_nothing() -> bool {
  74     !cfg!(feature = "wasm_syscall")
  75 }