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Diffstat (limited to 'vendor/base64/src/write/encoder.rs')
| -rw-r--r-- | vendor/base64/src/write/encoder.rs | 407 |
1 files changed, 0 insertions, 407 deletions
diff --git a/vendor/base64/src/write/encoder.rs b/vendor/base64/src/write/encoder.rs deleted file mode 100644 index 1c19bb42..00000000 --- a/vendor/base64/src/write/encoder.rs +++ /dev/null @@ -1,407 +0,0 @@ -use crate::engine::Engine; -use std::{ - cmp, fmt, io, - io::{ErrorKind, Result}, -}; - -pub(crate) const BUF_SIZE: usize = 1024; -/// The most bytes whose encoding will fit in `BUF_SIZE` -const MAX_INPUT_LEN: usize = BUF_SIZE / 4 * 3; -// 3 bytes of input = 4 bytes of base64, always (because we don't allow line wrapping) -const MIN_ENCODE_CHUNK_SIZE: usize = 3; - -/// A `Write` implementation that base64 encodes data before delegating to the wrapped writer. -/// -/// Because base64 has special handling for the end of the input data (padding, etc), there's a -/// `finish()` method on this type that encodes any leftover input bytes and adds padding if -/// appropriate. It's called automatically when deallocated (see the `Drop` implementation), but -/// any error that occurs when invoking the underlying writer will be suppressed. If you want to -/// handle such errors, call `finish()` yourself. -/// -/// # Examples -/// -/// ``` -/// use std::io::Write; -/// use base64::engine::general_purpose; -/// -/// // use a vec as the simplest possible `Write` -- in real code this is probably a file, etc. -/// let mut enc = base64::write::EncoderWriter::new(Vec::new(), &general_purpose::STANDARD); -/// -/// // handle errors as you normally would -/// enc.write_all(b"asdf").unwrap(); -/// -/// // could leave this out to be called by Drop, if you don't care -/// // about handling errors or getting the delegate writer back -/// let delegate = enc.finish().unwrap(); -/// -/// // base64 was written to the writer -/// assert_eq!(b"YXNkZg==", &delegate[..]); -/// -/// ``` -/// -/// # Panics -/// -/// Calling `write()` (or related methods) or `finish()` after `finish()` has completed without -/// error is invalid and will panic. -/// -/// # Errors -/// -/// Base64 encoding itself does not generate errors, but errors from the wrapped writer will be -/// returned as per the contract of `Write`. -/// -/// # Performance -/// -/// It has some minor performance loss compared to encoding slices (a couple percent). -/// It does not do any heap allocation. -/// -/// # Limitations -/// -/// Owing to the specification of the `write` and `flush` methods on the `Write` trait and their -/// implications for a buffering implementation, these methods may not behave as expected. In -/// particular, calling `write_all` on this interface may fail with `io::ErrorKind::WriteZero`. -/// See the documentation of the `Write` trait implementation for further details. -pub struct EncoderWriter<'e, E: Engine, W: io::Write> { - engine: &'e E, - /// Where encoded data is written to. It's an Option as it's None immediately before Drop is - /// called so that finish() can return the underlying writer. None implies that finish() has - /// been called successfully. - delegate: Option<W>, - /// Holds a partial chunk, if any, after the last `write()`, so that we may then fill the chunk - /// with the next `write()`, encode it, then proceed with the rest of the input normally. - extra_input: [u8; MIN_ENCODE_CHUNK_SIZE], - /// How much of `extra` is occupied, in `[0, MIN_ENCODE_CHUNK_SIZE]`. - extra_input_occupied_len: usize, - /// Buffer to encode into. May hold leftover encoded bytes from a previous write call that the underlying writer - /// did not write last time. - output: [u8; BUF_SIZE], - /// How much of `output` is occupied with encoded data that couldn't be written last time - output_occupied_len: usize, - /// panic safety: don't write again in destructor if writer panicked while we were writing to it - panicked: bool, -} - -impl<'e, E: Engine, W: io::Write> fmt::Debug for EncoderWriter<'e, E, W> { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - write!( - f, - "extra_input: {:?} extra_input_occupied_len:{:?} output[..5]: {:?} output_occupied_len: {:?}", - self.extra_input, - self.extra_input_occupied_len, - &self.output[0..5], - self.output_occupied_len - ) - } -} - -impl<'e, E: Engine, W: io::Write> EncoderWriter<'e, E, W> { - /// Create a new encoder that will write to the provided delegate writer. - pub fn new(delegate: W, engine: &'e E) -> EncoderWriter<'e, E, W> { - EncoderWriter { - engine, - delegate: Some(delegate), - extra_input: [0u8; MIN_ENCODE_CHUNK_SIZE], - extra_input_occupied_len: 0, - output: [0u8; BUF_SIZE], - output_occupied_len: 0, - panicked: false, - } - } - - /// Encode all remaining buffered data and write it, including any trailing incomplete input - /// triples and associated padding. - /// - /// Once this succeeds, no further writes or calls to this method are allowed. - /// - /// This may write to the delegate writer multiple times if the delegate writer does not accept - /// all input provided to its `write` each invocation. - /// - /// If you don't care about error handling, it is not necessary to call this function, as the - /// equivalent finalization is done by the Drop impl. - /// - /// Returns the writer that this was constructed around. - /// - /// # Errors - /// - /// The first error that is not of `ErrorKind::Interrupted` will be returned. - pub fn finish(&mut self) -> Result<W> { - // If we could consume self in finish(), we wouldn't have to worry about this case, but - // finish() is retryable in the face of I/O errors, so we can't consume here. - if self.delegate.is_none() { - panic!("Encoder has already had finish() called"); - }; - - self.write_final_leftovers()?; - - let writer = self.delegate.take().expect("Writer must be present"); - - Ok(writer) - } - - /// Write any remaining buffered data to the delegate writer. - fn write_final_leftovers(&mut self) -> Result<()> { - if self.delegate.is_none() { - // finish() has already successfully called this, and we are now in drop() with a None - // writer, so just no-op - return Ok(()); - } - - self.write_all_encoded_output()?; - - if self.extra_input_occupied_len > 0 { - let encoded_len = self - .engine - .encode_slice( - &self.extra_input[..self.extra_input_occupied_len], - &mut self.output[..], - ) - .expect("buffer is large enough"); - - self.output_occupied_len = encoded_len; - - self.write_all_encoded_output()?; - - // write succeeded, do not write the encoding of extra again if finish() is retried - self.extra_input_occupied_len = 0; - } - - Ok(()) - } - - /// Write as much of the encoded output to the delegate writer as it will accept, and store the - /// leftovers to be attempted at the next write() call. Updates `self.output_occupied_len`. - /// - /// # Errors - /// - /// Errors from the delegate writer are returned. In the case of an error, - /// `self.output_occupied_len` will not be updated, as errors from `write` are specified to mean - /// that no write took place. - fn write_to_delegate(&mut self, current_output_len: usize) -> Result<()> { - self.panicked = true; - let res = self - .delegate - .as_mut() - .expect("Writer must be present") - .write(&self.output[..current_output_len]); - self.panicked = false; - - res.map(|consumed| { - debug_assert!(consumed <= current_output_len); - - if consumed < current_output_len { - self.output_occupied_len = current_output_len.checked_sub(consumed).unwrap(); - // If we're blocking on I/O, the minor inefficiency of copying bytes to the - // start of the buffer is the least of our concerns... - // TODO Rotate moves more than we need to; copy_within now stable. - self.output.rotate_left(consumed); - } else { - self.output_occupied_len = 0; - } - }) - } - - /// Write all buffered encoded output. If this returns `Ok`, `self.output_occupied_len` is `0`. - /// - /// This is basically write_all for the remaining buffered data but without the undesirable - /// abort-on-`Ok(0)` behavior. - /// - /// # Errors - /// - /// Any error emitted by the delegate writer abort the write loop and is returned, unless it's - /// `Interrupted`, in which case the error is ignored and writes will continue. - fn write_all_encoded_output(&mut self) -> Result<()> { - while self.output_occupied_len > 0 { - let remaining_len = self.output_occupied_len; - match self.write_to_delegate(remaining_len) { - // try again on interrupts ala write_all - Err(ref e) if e.kind() == ErrorKind::Interrupted => {} - // other errors return - Err(e) => return Err(e), - // success no-ops because remaining length is already updated - Ok(_) => {} - }; - } - - debug_assert_eq!(0, self.output_occupied_len); - Ok(()) - } - - /// Unwraps this `EncoderWriter`, returning the base writer it writes base64 encoded output - /// to. - /// - /// Normally this method should not be needed, since `finish()` returns the inner writer if - /// it completes successfully. That will also ensure all data has been flushed, which the - /// `into_inner()` function does *not* do. - /// - /// Calling this method after `finish()` has completed successfully will panic, since the - /// writer has already been returned. - /// - /// This method may be useful if the writer implements additional APIs beyond the `Write` - /// trait. Note that the inner writer might be in an error state or have an incomplete - /// base64 string written to it. - pub fn into_inner(mut self) -> W { - self.delegate - .take() - .expect("Encoder has already had finish() called") - } -} - -impl<'e, E: Engine, W: io::Write> io::Write for EncoderWriter<'e, E, W> { - /// Encode input and then write to the delegate writer. - /// - /// Under non-error circumstances, this returns `Ok` with the value being the number of bytes - /// of `input` consumed. The value may be `0`, which interacts poorly with `write_all`, which - /// interprets `Ok(0)` as an error, despite it being allowed by the contract of `write`. See - /// <https://github.com/rust-lang/rust/issues/56889> for more on that. - /// - /// If the previous call to `write` provided more (encoded) data than the delegate writer could - /// accept in a single call to its `write`, the remaining data is buffered. As long as buffered - /// data is present, subsequent calls to `write` will try to write the remaining buffered data - /// to the delegate and return either `Ok(0)` -- and therefore not consume any of `input` -- or - /// an error. - /// - /// # Errors - /// - /// Any errors emitted by the delegate writer are returned. - fn write(&mut self, input: &[u8]) -> Result<usize> { - if self.delegate.is_none() { - panic!("Cannot write more after calling finish()"); - } - - if input.is_empty() { - return Ok(0); - } - - // The contract of `Write::write` places some constraints on this implementation: - // - a call to `write()` represents at most one call to a wrapped `Write`, so we can't - // iterate over the input and encode multiple chunks. - // - Errors mean that "no bytes were written to this writer", so we need to reset the - // internal state to what it was before the error occurred - - // before reading any input, write any leftover encoded output from last time - if self.output_occupied_len > 0 { - let current_len = self.output_occupied_len; - return self - .write_to_delegate(current_len) - // did not read any input - .map(|_| 0); - } - - debug_assert_eq!(0, self.output_occupied_len); - - // how many bytes, if any, were read into `extra` to create a triple to encode - let mut extra_input_read_len = 0; - let mut input = input; - - let orig_extra_len = self.extra_input_occupied_len; - - let mut encoded_size = 0; - // always a multiple of MIN_ENCODE_CHUNK_SIZE - let mut max_input_len = MAX_INPUT_LEN; - - // process leftover un-encoded input from last write - if self.extra_input_occupied_len > 0 { - debug_assert!(self.extra_input_occupied_len < 3); - if input.len() + self.extra_input_occupied_len >= MIN_ENCODE_CHUNK_SIZE { - // Fill up `extra`, encode that into `output`, and consume as much of the rest of - // `input` as possible. - // We could write just the encoding of `extra` by itself but then we'd have to - // return after writing only 4 bytes, which is inefficient if the underlying writer - // would make a syscall. - extra_input_read_len = MIN_ENCODE_CHUNK_SIZE - self.extra_input_occupied_len; - debug_assert!(extra_input_read_len > 0); - // overwrite only bytes that weren't already used. If we need to rollback extra_len - // (when the subsequent write errors), the old leading bytes will still be there. - self.extra_input[self.extra_input_occupied_len..MIN_ENCODE_CHUNK_SIZE] - .copy_from_slice(&input[0..extra_input_read_len]); - - let len = self.engine.internal_encode( - &self.extra_input[0..MIN_ENCODE_CHUNK_SIZE], - &mut self.output[..], - ); - debug_assert_eq!(4, len); - - input = &input[extra_input_read_len..]; - - // consider extra to be used up, since we encoded it - self.extra_input_occupied_len = 0; - // don't clobber where we just encoded to - encoded_size = 4; - // and don't read more than can be encoded - max_input_len = MAX_INPUT_LEN - MIN_ENCODE_CHUNK_SIZE; - - // fall through to normal encoding - } else { - // `extra` and `input` are non empty, but `|extra| + |input| < 3`, so there must be - // 1 byte in each. - debug_assert_eq!(1, input.len()); - debug_assert_eq!(1, self.extra_input_occupied_len); - - self.extra_input[self.extra_input_occupied_len] = input[0]; - self.extra_input_occupied_len += 1; - return Ok(1); - }; - } else if input.len() < MIN_ENCODE_CHUNK_SIZE { - // `extra` is empty, and `input` fits inside it - self.extra_input[0..input.len()].copy_from_slice(input); - self.extra_input_occupied_len = input.len(); - return Ok(input.len()); - }; - - // either 0 or 1 complete chunks encoded from extra - debug_assert!(encoded_size == 0 || encoded_size == 4); - debug_assert!( - // didn't encode extra input - MAX_INPUT_LEN == max_input_len - // encoded one triple - || MAX_INPUT_LEN == max_input_len + MIN_ENCODE_CHUNK_SIZE - ); - - // encode complete triples only - let input_complete_chunks_len = input.len() - (input.len() % MIN_ENCODE_CHUNK_SIZE); - let input_chunks_to_encode_len = cmp::min(input_complete_chunks_len, max_input_len); - debug_assert_eq!(0, max_input_len % MIN_ENCODE_CHUNK_SIZE); - debug_assert_eq!(0, input_chunks_to_encode_len % MIN_ENCODE_CHUNK_SIZE); - - encoded_size += self.engine.internal_encode( - &input[..(input_chunks_to_encode_len)], - &mut self.output[encoded_size..], - ); - - // not updating `self.output_occupied_len` here because if the below write fails, it should - // "never take place" -- the buffer contents we encoded are ignored and perhaps retried - // later, if the consumer chooses. - - self.write_to_delegate(encoded_size) - // no matter whether we wrote the full encoded buffer or not, we consumed the same - // input - .map(|_| extra_input_read_len + input_chunks_to_encode_len) - .map_err(|e| { - // in case we filled and encoded `extra`, reset extra_len - self.extra_input_occupied_len = orig_extra_len; - - e - }) - } - - /// Because this is usually treated as OK to call multiple times, it will *not* flush any - /// incomplete chunks of input or write padding. - /// # Errors - /// - /// The first error that is not of [`ErrorKind::Interrupted`] will be returned. - fn flush(&mut self) -> Result<()> { - self.write_all_encoded_output()?; - self.delegate - .as_mut() - .expect("Writer must be present") - .flush() - } -} - -impl<'e, E: Engine, W: io::Write> Drop for EncoderWriter<'e, E, W> { - fn drop(&mut self) { - if !self.panicked { - // like `BufWriter`, ignore errors during drop - let _ = self.write_final_leftovers(); - } - } -} |