/
stdio.rs
410 lines (373 loc) · 14.1 KB
/
stdio.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*! Non-blocking access to stdin, stdout, and stderr.
This module provides bindings to the local event loop's TTY interface, using it
to offer synchronous but non-blocking versions of stdio. These handles can be
inspected for information about terminal dimensions or for related information
about the stream or terminal to which it is attached.
# Example
```rust
# #![allow(unused_must_use)]
use std::io;
let mut out = io::stdout();
out.write(b"Hello, world!");
```
*/
use failure::local_stderr;
use fmt;
use io::{Reader, Writer, IoResult, IoError, OtherIoError,
standard_error, EndOfFile, LineBufferedWriter, BufferedReader};
use iter::Iterator;
use kinds::Send;
use libc;
use option::{Option, Some, None};
use boxed::Box;
use result::{Ok, Err};
use rt;
use rt::local::Local;
use rt::task::Task;
use rt::rtio::{DontClose, IoFactory, LocalIo, RtioFileStream, RtioTTY};
use slice::ImmutableVector;
use str::StrSlice;
use uint;
// And so begins the tale of acquiring a uv handle to a stdio stream on all
// platforms in all situations. Our story begins by splitting the world into two
// categories, windows and unix. Then one day the creators of unix said let
// there be redirection! And henceforth there was redirection away from the
// console for standard I/O streams.
//
// After this day, the world split into four factions:
//
// 1. Unix with stdout on a terminal.
// 2. Unix with stdout redirected.
// 3. Windows with stdout on a terminal.
// 4. Windows with stdout redirected.
//
// Many years passed, and then one day the nation of libuv decided to unify this
// world. After months of toiling, uv created three ideas: TTY, Pipe, File.
// These three ideas propagated throughout the lands and the four great factions
// decided to settle among them.
//
// The groups of 1, 2, and 3 all worked very hard towards the idea of TTY. Upon
// doing so, they even enhanced themselves further then their Pipe/File
// brethren, becoming the dominant powers.
//
// The group of 4, however, decided to work independently. They abandoned the
// common TTY belief throughout, and even abandoned the fledgling Pipe belief.
// The members of the 4th faction decided to only align themselves with File.
//
// tl;dr; TTY works on everything but when windows stdout is redirected, in that
// case pipe also doesn't work, but magically file does!
enum StdSource {
TTY(Box<RtioTTY + Send>),
File(Box<RtioFileStream + Send>),
}
fn src<T>(fd: libc::c_int, readable: bool, f: |StdSource| -> T) -> T {
LocalIo::maybe_raise(|io| {
Ok(match io.tty_open(fd, readable) {
Ok(tty) => f(TTY(tty)),
Err(_) => f(File(io.fs_from_raw_fd(fd, DontClose))),
})
}).map_err(IoError::from_rtio_error).unwrap()
}
local_data_key!(local_stdout: Box<Writer + Send>)
/// Creates a new non-blocking handle to the stdin of the current process.
///
/// The returned handled is buffered by default with a `BufferedReader`. If
/// buffered access is not desired, the `stdin_raw` function is provided to
/// provided unbuffered access to stdin.
///
/// Care should be taken when creating multiple handles to the stdin of a
/// process. Because this is a buffered reader by default, it's possible for
/// pending input to be unconsumed in one reader and unavailable to other
/// readers. It is recommended that only one handle at a time is created for the
/// stdin of a process.
///
/// See `stdout()` for more notes about this function.
pub fn stdin() -> BufferedReader<StdReader> {
// The default buffer capacity is 64k, but apparently windows doesn't like
// 64k reads on stdin. See #13304 for details, but the idea is that on
// windows we use a slightly smaller buffer that's been seen to be
// acceptable.
if cfg!(windows) {
BufferedReader::with_capacity(8 * 1024, stdin_raw())
} else {
BufferedReader::new(stdin_raw())
}
}
/// Creates a new non-blocking handle to the stdin of the current process.
///
/// Unlike `stdin()`, the returned reader is *not* a buffered reader.
///
/// See `stdout()` for more notes about this function.
pub fn stdin_raw() -> StdReader {
src(libc::STDIN_FILENO, true, |src| StdReader { inner: src })
}
/// Creates a line-buffered handle to the stdout of the current process.
///
/// Note that this is a fairly expensive operation in that at least one memory
/// allocation is performed. Additionally, this must be called from a runtime
/// task context because the stream returned will be a non-blocking object using
/// the local scheduler to perform the I/O.
///
/// Care should be taken when creating multiple handles to an output stream for
/// a single process. While usage is still safe, the output may be surprising if
/// no synchronization is performed to ensure a sane output.
pub fn stdout() -> LineBufferedWriter<StdWriter> {
LineBufferedWriter::new(stdout_raw())
}
/// Creates an unbuffered handle to the stdout of the current process
///
/// See notes in `stdout()` for more information.
pub fn stdout_raw() -> StdWriter {
src(libc::STDOUT_FILENO, false, |src| StdWriter { inner: src })
}
/// Creates a line-buffered handle to the stderr of the current process.
///
/// See `stdout()` for notes about this function.
pub fn stderr() -> LineBufferedWriter<StdWriter> {
LineBufferedWriter::new(stderr_raw())
}
/// Creates an unbuffered handle to the stderr of the current process
///
/// See notes in `stdout()` for more information.
pub fn stderr_raw() -> StdWriter {
src(libc::STDERR_FILENO, false, |src| StdWriter { inner: src })
}
/// Resets the task-local stdout handle to the specified writer
///
/// This will replace the current task's stdout handle, returning the old
/// handle. All future calls to `print` and friends will emit their output to
/// this specified handle.
///
/// Note that this does not need to be called for all new tasks; the default
/// output handle is to the process's stdout stream.
pub fn set_stdout(stdout: Box<Writer + Send>) -> Option<Box<Writer + Send>> {
local_stdout.replace(Some(stdout)).and_then(|mut s| {
let _ = s.flush();
Some(s)
})
}
/// Resets the task-local stderr handle to the specified writer
///
/// This will replace the current task's stderr handle, returning the old
/// handle. Currently, the stderr handle is used for printing failure messages
/// during task failure.
///
/// Note that this does not need to be called for all new tasks; the default
/// output handle is to the process's stderr stream.
pub fn set_stderr(stderr: Box<Writer + Send>) -> Option<Box<Writer + Send>> {
local_stderr.replace(Some(stderr)).and_then(|mut s| {
let _ = s.flush();
Some(s)
})
}
// Helper to access the local task's stdout handle
//
// Note that this is not a safe function to expose because you can create an
// aliased pointer very easily:
//
// with_task_stdout(|io1| {
// with_task_stdout(|io2| {
// // io1 aliases io2
// })
// })
fn with_task_stdout(f: |&mut Writer| -> IoResult<()>) {
let result = if Local::exists(None::<Task>) {
let mut my_stdout = local_stdout.replace(None).unwrap_or_else(|| {
box stdout() as Box<Writer + Send>
});
let result = f(my_stdout);
local_stdout.replace(Some(my_stdout));
result
} else {
let mut io = rt::Stdout;
f(&mut io as &mut Writer)
};
match result {
Ok(()) => {}
Err(e) => fail!("failed printing to stdout: {}", e),
}
}
/// Flushes the local task's stdout handle.
///
/// By default, this stream is a line-buffering stream, so flushing may be
/// necessary to ensure that all output is printed to the screen (if there are
/// no newlines printed).
///
/// Note that logging macros do not use this stream. Using the logging macros
/// will emit output to stderr, and while they are line buffered the log
/// messages are always terminated in a newline (no need to flush).
pub fn flush() {
with_task_stdout(|io| io.flush())
}
/// Prints a string to the stdout of the current process. No newline is emitted
/// after the string is printed.
pub fn print(s: &str) {
with_task_stdout(|io| io.write(s.as_bytes()))
}
/// Prints a string to the stdout of the current process. A literal
/// `\n` character is printed to the console after the string.
pub fn println(s: &str) {
with_task_stdout(|io| {
io.write(s.as_bytes()).and_then(|()| io.write(['\n' as u8]))
})
}
/// Similar to `print`, but takes a `fmt::Arguments` structure to be compatible
/// with the `format_args!` macro.
pub fn print_args(fmt: &fmt::Arguments) {
with_task_stdout(|io| write!(io, "{}", fmt))
}
/// Similar to `println`, but takes a `fmt::Arguments` structure to be
/// compatible with the `format_args!` macro.
pub fn println_args(fmt: &fmt::Arguments) {
with_task_stdout(|io| writeln!(io, "{}", fmt))
}
/// Representation of a reader of a standard input stream
pub struct StdReader {
inner: StdSource
}
impl StdReader {
/// Returns whether this stream is attached to a TTY instance or not.
pub fn isatty(&self) -> bool {
match self.inner {
TTY(..) => true,
File(..) => false,
}
}
}
impl Reader for StdReader {
fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
let ret = match self.inner {
TTY(ref mut tty) => {
// Flush the task-local stdout so that weird issues like a
// print!'d prompt not being shown until after the user hits
// enter.
flush();
tty.read(buf)
},
File(ref mut file) => file.read(buf).map(|i| i as uint),
}.map_err(IoError::from_rtio_error);
match ret {
// When reading a piped stdin, libuv will return 0-length reads when
// stdin reaches EOF. For pretty much all other streams it will
// return an actual EOF error, but apparently for stdin it's a
// little different. Hence, here we convert a 0 length read to an
// end-of-file indicator so the caller knows to stop reading.
Ok(0) => { Err(standard_error(EndOfFile)) }
ret @ Ok(..) | ret @ Err(..) => ret,
}
}
}
/// Representation of a writer to a standard output stream
pub struct StdWriter {
inner: StdSource
}
impl StdWriter {
/// Gets the size of this output window, if possible. This is typically used
/// when the writer is attached to something like a terminal, this is used
/// to fetch the dimensions of the terminal.
///
/// If successful, returns `Ok((width, height))`.
///
/// # Error
///
/// This function will return an error if the output stream is not actually
/// connected to a TTY instance, or if querying the TTY instance fails.
pub fn winsize(&mut self) -> IoResult<(int, int)> {
match self.inner {
TTY(ref mut tty) => {
tty.get_winsize().map_err(IoError::from_rtio_error)
}
File(..) => {
Err(IoError {
kind: OtherIoError,
desc: "stream is not a tty",
detail: None,
})
}
}
}
/// Controls whether this output stream is a "raw stream" or simply a normal
/// stream.
///
/// # Error
///
/// This function will return an error if the output stream is not actually
/// connected to a TTY instance, or if querying the TTY instance fails.
pub fn set_raw(&mut self, raw: bool) -> IoResult<()> {
match self.inner {
TTY(ref mut tty) => {
tty.set_raw(raw).map_err(IoError::from_rtio_error)
}
File(..) => {
Err(IoError {
kind: OtherIoError,
desc: "stream is not a tty",
detail: None,
})
}
}
}
/// Returns whether this stream is attached to a TTY instance or not.
pub fn isatty(&self) -> bool {
match self.inner {
TTY(..) => true,
File(..) => false,
}
}
}
impl Writer for StdWriter {
fn write(&mut self, buf: &[u8]) -> IoResult<()> {
// As with stdin on windows, stdout often can't handle writes of large
// sizes. For an example, see #14940. For this reason, chunk the output
// buffer on windows, but on unix we can just write the whole buffer all
// at once.
let max_size = if cfg!(windows) {64 * 1024} else {uint::MAX};
for chunk in buf.chunks(max_size) {
try!(match self.inner {
TTY(ref mut tty) => tty.write(chunk),
File(ref mut file) => file.write(chunk),
}.map_err(IoError::from_rtio_error))
}
Ok(())
}
}
#[cfg(test)]
mod tests {
iotest!(fn smoke() {
// Just make sure we can acquire handles
stdin();
stdout();
stderr();
})
iotest!(fn capture_stdout() {
use io::{ChanReader, ChanWriter};
let (tx, rx) = channel();
let (mut r, w) = (ChanReader::new(rx), ChanWriter::new(tx));
spawn(proc() {
set_stdout(box w);
println!("hello!");
});
assert_eq!(r.read_to_string().unwrap(), "hello!\n".to_string());
})
iotest!(fn capture_stderr() {
use realstd::comm::channel;
use realstd::io::{Writer, ChanReader, ChanWriter, Reader};
let (tx, rx) = channel();
let (mut r, w) = (ChanReader::new(rx), ChanWriter::new(tx));
spawn(proc() {
::realstd::io::stdio::set_stderr(box w);
fail!("my special message");
});
let s = r.read_to_string().unwrap();
assert!(s.as_slice().contains("my special message"));
})
}