300 lines
10 KiB
Rust
300 lines
10 KiB
Rust
#![unstable(issue = "none", feature = "windows_stdio")]
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use crate::char::decode_utf16;
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use crate::cmp;
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use crate::io;
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use crate::os::windows::io::{FromRawHandle, IntoRawHandle};
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use crate::ptr;
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use crate::str;
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use crate::sys::c;
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use crate::sys::cvt;
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use crate::sys::handle::Handle;
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// Don't cache handles but get them fresh for every read/write. This allows us to track changes to
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// the value over time (such as if a process calls `SetStdHandle` while it's running). See #40490.
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pub struct Stdin {
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surrogate: u16,
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}
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pub struct Stdout;
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pub struct Stderr;
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// Apparently Windows doesn't handle large reads on stdin or writes to stdout/stderr well (see
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// #13304 for details).
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//
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// From MSDN (2011): "The storage for this buffer is allocated from a shared heap for the
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// process that is 64 KB in size. The maximum size of the buffer will depend on heap usage."
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//
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// We choose the cap at 8 KiB because libuv does the same, and it seems to be acceptable so far.
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const MAX_BUFFER_SIZE: usize = 8192;
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// The standard buffer size of BufReader for Stdin should be able to hold 3x more bytes than there
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// are `u16`'s in MAX_BUFFER_SIZE. This ensures the read data can always be completely decoded from
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// UTF-16 to UTF-8.
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pub const STDIN_BUF_SIZE: usize = MAX_BUFFER_SIZE / 2 * 3;
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pub fn get_handle(handle_id: c::DWORD) -> io::Result<c::HANDLE> {
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let handle = unsafe { c::GetStdHandle(handle_id) };
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if handle == c::INVALID_HANDLE_VALUE {
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Err(io::Error::last_os_error())
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} else if handle.is_null() {
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Err(io::Error::from_raw_os_error(c::ERROR_INVALID_HANDLE as i32))
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} else {
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Ok(handle)
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}
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}
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fn is_console(handle: c::HANDLE) -> bool {
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// `GetConsoleMode` will return false (0) if this is a pipe (we don't care about the reported
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// mode). This will only detect Windows Console, not other terminals connected to a pipe like
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// MSYS. Which is exactly what we need, as only Windows Console needs a conversion to UTF-16.
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let mut mode = 0;
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unsafe { c::GetConsoleMode(handle, &mut mode) != 0 }
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}
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fn write(handle_id: c::DWORD, data: &[u8]) -> io::Result<usize> {
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let handle = get_handle(handle_id)?;
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if !is_console(handle) {
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unsafe {
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let handle = Handle::from_raw_handle(handle);
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let ret = handle.write(data);
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handle.into_raw_handle(); // Don't close the handle
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return ret;
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}
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}
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// As the console is meant for presenting text, we assume bytes of `data` come from a string
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// and are encoded as UTF-8, which needs to be encoded as UTF-16.
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//
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// If the data is not valid UTF-8 we write out as many bytes as are valid.
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// Only when there are no valid bytes (which will happen on the next call), return an error.
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let len = cmp::min(data.len(), MAX_BUFFER_SIZE / 2);
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let utf8 = match str::from_utf8(&data[..len]) {
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Ok(s) => s,
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Err(ref e) if e.valid_up_to() == 0 => {
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return Err(io::Error::new_const(
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io::ErrorKind::InvalidData,
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&"Windows stdio in console mode does not support writing non-UTF-8 byte sequences",
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));
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}
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Err(e) => str::from_utf8(&data[..e.valid_up_to()]).unwrap(),
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};
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let mut utf16 = [0u16; MAX_BUFFER_SIZE / 2];
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let mut len_utf16 = 0;
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for (chr, dest) in utf8.encode_utf16().zip(utf16.iter_mut()) {
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*dest = chr;
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len_utf16 += 1;
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}
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let utf16 = &utf16[..len_utf16];
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let mut written = write_u16s(handle, &utf16)?;
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// Figure out how many bytes of as UTF-8 were written away as UTF-16.
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if written == utf16.len() {
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Ok(utf8.len())
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} else {
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// Make sure we didn't end up writing only half of a surrogate pair (even though the chance
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// is tiny). Because it is not possible for user code to re-slice `data` in such a way that
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// a missing surrogate can be produced (and also because of the UTF-8 validation above),
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// write the missing surrogate out now.
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// Buffering it would mean we have to lie about the number of bytes written.
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let first_char_remaining = utf16[written];
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if first_char_remaining >= 0xDCEE && first_char_remaining <= 0xDFFF {
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// low surrogate
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// We just hope this works, and give up otherwise
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let _ = write_u16s(handle, &utf16[written..written + 1]);
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written += 1;
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}
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// Calculate the number of bytes of `utf8` that were actually written.
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let mut count = 0;
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for ch in utf16[..written].iter() {
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count += match ch {
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0x0000..=0x007F => 1,
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0x0080..=0x07FF => 2,
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0xDCEE..=0xDFFF => 1, // Low surrogate. We already counted 3 bytes for the other.
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_ => 3,
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};
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}
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debug_assert!(String::from_utf16(&utf16[..written]).unwrap() == utf8[..count]);
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Ok(count)
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}
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}
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fn write_u16s(handle: c::HANDLE, data: &[u16]) -> io::Result<usize> {
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let mut written = 0;
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cvt(unsafe {
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c::WriteConsoleW(
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handle,
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data.as_ptr() as c::LPCVOID,
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data.len() as u32,
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&mut written,
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ptr::null_mut(),
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)
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})?;
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Ok(written as usize)
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}
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impl Stdin {
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pub const fn new() -> Stdin {
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Stdin { surrogate: 0 }
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}
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}
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impl io::Read for Stdin {
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fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
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let handle = get_handle(c::STD_INPUT_HANDLE)?;
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if !is_console(handle) {
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unsafe {
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let handle = Handle::from_raw_handle(handle);
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let ret = handle.read(buf);
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handle.into_raw_handle(); // Don't close the handle
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return ret;
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}
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}
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if buf.len() == 0 {
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return Ok(0);
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} else if buf.len() < 4 {
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return Err(io::Error::new_const(
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io::ErrorKind::InvalidInput,
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&"Windows stdin in console mode does not support a buffer too small to \
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guarantee holding one arbitrary UTF-8 character (4 bytes)",
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));
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}
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let mut utf16_buf = [0u16; MAX_BUFFER_SIZE / 2];
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// In the worst case, a UTF-8 string can take 3 bytes for every `u16` of a UTF-16. So
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// we can read at most a third of `buf.len()` chars and uphold the guarantee no data gets
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// lost.
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let amount = cmp::min(buf.len() / 3, utf16_buf.len());
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let read = read_u16s_fixup_surrogates(handle, &mut utf16_buf, amount, &mut self.surrogate)?;
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utf16_to_utf8(&utf16_buf[..read], buf)
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}
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}
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// We assume that if the last `u16` is an unpaired surrogate they got sliced apart by our
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// buffer size, and keep it around for the next read hoping to put them together.
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// This is a best effort, and might not work if we are not the only reader on Stdin.
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fn read_u16s_fixup_surrogates(
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handle: c::HANDLE,
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buf: &mut [u16],
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mut amount: usize,
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surrogate: &mut u16,
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) -> io::Result<usize> {
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// Insert possibly remaining unpaired surrogate from last read.
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let mut start = 0;
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if *surrogate != 0 {
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buf[0] = *surrogate;
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*surrogate = 0;
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start = 1;
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if amount == 1 {
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// Special case: `Stdin::read` guarantees we can always read at least one new `u16`
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// and combine it with an unpaired surrogate, because the UTF-8 buffer is at least
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// 4 bytes.
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amount = 2;
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}
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}
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let mut amount = read_u16s(handle, &mut buf[start..amount])? + start;
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if amount > 0 {
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let last_char = buf[amount - 1];
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if last_char >= 0xD800 && last_char <= 0xDBFF {
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// high surrogate
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*surrogate = last_char;
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amount -= 1;
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}
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}
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Ok(amount)
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}
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fn read_u16s(handle: c::HANDLE, buf: &mut [u16]) -> io::Result<usize> {
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// Configure the `pInputControl` parameter to not only return on `\r\n` but also Ctrl-Z, the
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// traditional DOS method to indicate end of character stream / user input (SUB).
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// See #38274 and https://stackoverflow.com/questions/43836040/win-api-readconsole.
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const CTRL_Z: u16 = 0x1A;
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const CTRL_Z_MASK: c::ULONG = 1 << CTRL_Z;
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let mut input_control = c::CONSOLE_READCONSOLE_CONTROL {
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nLength: crate::mem::size_of::<c::CONSOLE_READCONSOLE_CONTROL>() as c::ULONG,
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nInitialChars: 0,
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dwCtrlWakeupMask: CTRL_Z_MASK,
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dwControlKeyState: 0,
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};
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let mut amount = 0;
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cvt(unsafe {
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c::ReadConsoleW(
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handle,
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buf.as_mut_ptr() as c::LPVOID,
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buf.len() as u32,
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&mut amount,
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&mut input_control as c::PCONSOLE_READCONSOLE_CONTROL,
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)
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})?;
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if amount > 0 && buf[amount as usize - 1] == CTRL_Z {
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amount -= 1;
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}
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Ok(amount as usize)
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}
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#[allow(unused)]
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fn utf16_to_utf8(utf16: &[u16], utf8: &mut [u8]) -> io::Result<usize> {
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let mut written = 0;
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for chr in decode_utf16(utf16.iter().cloned()) {
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match chr {
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Ok(chr) => {
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chr.encode_utf8(&mut utf8[written..]);
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written += chr.len_utf8();
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}
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Err(_) => {
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// We can't really do any better than forget all data and return an error.
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return Err(io::Error::new_const(
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io::ErrorKind::InvalidData,
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&"Windows stdin in console mode does not support non-UTF-16 input; \
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encountered unpaired surrogate",
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));
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}
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}
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}
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Ok(written)
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}
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impl Stdout {
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pub const fn new() -> Stdout {
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Stdout
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}
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}
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impl io::Write for Stdout {
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fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
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write(c::STD_OUTPUT_HANDLE, buf)
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}
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fn flush(&mut self) -> io::Result<()> {
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Ok(())
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}
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}
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impl Stderr {
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pub const fn new() -> Stderr {
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Stderr
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}
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}
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impl io::Write for Stderr {
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fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
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write(c::STD_ERROR_HANDLE, buf)
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}
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fn flush(&mut self) -> io::Result<()> {
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Ok(())
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}
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}
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pub fn is_ebadf(err: &io::Error) -> bool {
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err.raw_os_error() == Some(c::ERROR_INVALID_HANDLE as i32)
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}
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pub fn panic_output() -> Option<impl io::Write> {
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Some(Stderr::new())
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}
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