The methods `Take::get_mut` and `Chain::get_mut` include comments
warning about modifying the I/O state of the underlying reader. However,
many readers (e.g. `File`) allow I/O using a shared reference (e.g.
`&File`). So, add the same caveat to the `get_ref` methods.
Optimize `io::Write::write_fmt` for constant strings
When the formatting args to `fmt::Write::write_fmt` are a statically known string, it simplifies to only calling `write_str` without a runtime branch. Do the same in `io::Write::write_fmt` with `write_all`.
Also, match the convention of `fmt::Write` for the name of `args`.
When the formatting args to `fmt::Write::write_fmt` are a statically
known string, it simplifies to only calling `write_str` without a
runtime branch. Do the same in `io::Write::write_fmt` with `write_all`.
Also, match the convention of `fmt::Write` for the name of `args`.
- Simplify some of the language
- Minor grammar fixes
- Don't imply that pipes *only* work across multiple processes; instead,
*suggest* that they're typically used across two or more separate
processes.
- Specify that portable applications cannot use multiple readers or
multiple writers for messages larger than a byte, due to potential
interleaving.
- Remove no-longer-referenced footnote URLs.
Improve several `Read` implementations
- `read_to_end` and `read_to_string` for `Cursor`
- Error on OOM in `read_to_string` of `&[u8]` and `VecDeque<u8>`
- Avoid making the slices contiguous in `VecDeque::read_to_string`
- ~`read_exact` and (unstable) `read_buf_exact` for `Take`~
- ~`read_buf` for `UnixStream` and `&UnixStream`~ (moved to #123084)
- `read_to_end` for `ChildStdErr`
Avoid a panic in `set_output_capture` in the default panic handler
This avoid a panic in the default panic handler by not using `set_output_capture` as `OUTPUT_CAPTURE.with` may panic once `OUTPUT_CAPTURE` is dropped.
A new non-panicking `try_set_output_capture` variant of `set_output_capture` is added for use in the default panic handler.
impl From<TryReserveError> for io::Error
There's an obvious mapping between these two errors, and it makes I/O code less noisy.
I've chosen to use simple `ErrorKind::OutOfMemory` `io::Error`, without keeping `TryReserveError` for the `source()`, because:
* It matches current uses in libstd,
* `ErrorData::Custom` allocates, which is a risky proposition for handling OOM errors specifically.
* Currently `TryReserveError` has no public fields/methods, so it's usefulness is limited. How allocators should report errors, especially custom and verbose ones is still an open question.
Just in case I've added note in the doccomment that this may change.
The compiler forced me to declare stability of this impl. I think this implementation is simple enough that it doesn't need full-blown stabilization period, and I've marked it for the next release, but of course I can adjust the attribute if needed.
Currently all architecture-specific memchr code is only used in
`std::io`. Most of the actual `memchr` capacity exposed to the user
through the slice API is instead implemented in core::slice::memchr.
Hence this commit deletes memchr from std::sys[_common] and replace
calls to it by calls to core::slice::memchr functions. This deletes
(r)memchr from the list of symbols linked to libc.
Specialize some methods of `io::Chain`
This PR specializes the implementation of some methods of `io::Chain`, which could bring performance improvements when using it.
