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/* * BSD 3-Clause License * * Copyright (c) 2020, InterlockLedger Network * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * * Neither the name of the copyright holder nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ //! This module implements the I/O abstraction used by this library. It allows //! the usage of multiple data sources and/or repositories to perform the //! operations. pub mod array; pub mod data; #[cfg(test)] mod tests; /// Types of erros generated by this module. pub enum ErrorKind { /// Unable to read data. UnableToReadData, /// Unable to write data. UnableToWriteData, /// The data is corrupted. CorruptedData, /// Wrapper to standard `std::io::Error`. IOError(std::io::Error), /// Wrapper to a boxed error `std::error::Error`. BoxedError(Box<dyn std::error::Error>), } /// A specialized [`std::result::Result`] generated by functions and methods from this package. pub type Result<T> = std::result::Result<T, ErrorKind>; /// The [`Reader`] trait is allows the extraction of bytes from a source. /// /// It differs from most IO library as it defines all operations as /// all-or-nothing operations. No partial reads are allowed. /// /// Implementations of this trait are not required to be thread-safe. pub trait Reader { /// Reads a single byte from the source. /// /// Returns: /// * `Ok(v)`: The value read; /// * `Err(ErrorKind)`: In case of error; fn read(&mut self) -> Result<u8>; /// Reads the specified number of bytes from the source. /// /// The default implementation just calls read() repeatedly, /// so each implementation is advised to provide a better /// implementation of this method if possible. /// /// Arguments: /// * `buff`: The output buffer; /// /// Returns: /// * `Ok(())`: On success; /// * `Err(ErrorKind)`: In case of error; fn read_all(&mut self, buff: &mut [u8]) -> Result<()> { for b in buff { *b = self.read()?; } Ok(()) } /// Skips some bytes from the source. /// /// The default implementation just calls read_all() repeatedly /// using 512 byte chunks. So it is recommended provide better /// implementations whenever possible. /// /// Arguments: /// * `count`: Number of byte to skip; /// /// Returns: /// * `Ok(())`: On success; /// * `Err(ErrorKind)`: In case of error; fn skip(&mut self, count: usize) -> Result<()> { let mut buff: [u8; 512] = [0; 512]; let mut r = count; while r > 0 { let chunk = std::cmp::min(r, buff.len()); self.read_all(&mut buff[0..chunk])?; r -= chunk; } Ok(()) } } /// The [`Writer`] trait allows the addition of bytes into the destination. /// /// It differs from most IO library as it defines all operations as /// all-or-nothing operations. No partial writes are allowed. /// /// Implementations of this trait are not required to be thread-safe. pub trait Writer { /// Writes a single byte. /// /// Arguments: /// * `value`: The value to be written; /// /// Returns: /// * `Ok(())`: On success; /// * `Err(ErrorKind)`: In case of error; fn write(&mut self, value: u8) -> Result<()>; /// Writes a byte slice. As this default implementation /// calls `write()` multiple times, so it is strongly recommended /// that each implementation provides a more efficient version for /// this method if possible. /// /// Arguments: /// * `buff`: The value to be written; /// /// Returns: /// * `Ok(())`: On success; /// * `Err(ErrorKind)`: In case of error; fn write_all(&mut self, buff: &[u8]) -> Result<()> { for b in buff { self.write(*b)?; } Ok(()) } fn as_writer(&mut self) -> &mut dyn Writer; } /// The `LimitedReader` implements a [`Reader`] that wraps another /// [`Reader`] but defines a limited to the amount of bytes that can be /// extracted from it. /// /// This wrapper was designed to ease the implementation of the deserialization /// of the tags. /// /// It is important to notice that [`LimitedReader`] will test the /// limits prior to the attempt to read the data, thus failed /// attempts will not consume data from the inner reader. pub struct LimitedReader<'a> { source: &'a mut dyn Reader, available: usize, } impl<'a> LimitedReader<'a> { /// Creates a new instance of this struct. /// /// Parameters: /// * `src`: A mutable reference to the source Reader. /// * `available`: Number of bytes available for reading. pub fn new(src: &mut dyn Reader, available: usize) -> LimitedReader { LimitedReader { source: src, available, } } /// Verifies if it is possible to extract a given number of bytes /// from the source. /// /// Parameters: /// * `size`: The number of bytes to read. /// /// Returns: /// * `Ok(())`: On success. /// * `Err(ErrorKind)`: If the specified number of bytes is not available. pub fn can_read(&self, size: usize) -> Result<()> { if size > self.available { Err(ErrorKind::UnableToReadData) } else { Ok(()) } } /// Returns the number of available bytes. /// /// Returns: /// * The number of available bytes. pub fn available(&self) -> usize { self.available } /// Skips the required number of bytes required to achive the end /// of the specified limit. /// /// Returns: /// * `Ok(())`: On success. /// * `Err(ErrorKind)`: If the specified number of bytes is not available. pub fn goto_end(&mut self) -> Result<()> { if self.available > 0 { let ret = self.source.skip(self.available); if ret.is_ok() { self.available = 0; } ret } else { Ok(()) } } /// Verifies if the this reader is empty. /// /// Returns: /// - true: if it is empty; /// - false: if it is not empty; pub fn empty(&self) -> bool { self.available == 0 } } impl<'a> Reader for LimitedReader<'a> { fn read(&mut self) -> Result<u8> { self.can_read(1)?; let ret = self.source.read(); if ret.is_ok() { self.available -= 1; } ret } fn read_all(&mut self, buff: &mut [u8]) -> Result<()> { self.can_read(buff.len())?; let ret = self.source.read_all(buff); if ret.is_ok() { self.available -= buff.len(); } ret } } /// This struct implements a [`Reader`] that uses a /// [`std::io::Read`] as the source of bytes. pub struct ReadReader<'a, T: std::io::Read> { source: &'a mut T, } impl<'a, T: std::io::Read> ReadReader<'a, T> { /// Creates a new instance of ReadReader. /// /// Parameters: /// * `src`: The source of bytes. pub fn new(src: &'a mut T) -> ReadReader<'a, T> { ReadReader { source: src } } } impl<'a, T: std::io::Read> Reader for ReadReader<'a, T> { fn read(&mut self) -> Result<u8> { let mut buff: [u8; 1] = [0; 1]; match self.source.read_exact(&mut buff) { Ok(()) => Ok(buff[0]), Err(e) => Err(ErrorKind::IOError(e)), } } fn read_all(&mut self, buff: &mut [u8]) -> Result<()> { match self.source.read_exact(buff) { Ok(()) => Ok(()), Err(e) => Err(ErrorKind::IOError(e)), } } } /// This struct implements a [`Writer`] that uses a /// [`std::io::Write`] as the destination of bytes. pub struct WriteWriter<'a> { dest: &'a mut dyn std::io::Write, } impl<'a> WriteWriter<'a> { /// Creates a new instance of `WriteWriter`. /// /// Parameters: /// * `dst`: The destination for the bytes. pub fn new(dst: &'a mut dyn std::io::Write) -> WriteWriter<'a> { WriteWriter { dest: dst } } } impl<'a> Writer for WriteWriter<'a> { fn write(&mut self, value: u8) -> Result<()> { let tmp: [u8; 1] = [value]; match self.dest.write(&tmp) { Ok(1) => Ok(()), Ok(_) => Err(ErrorKind::UnableToWriteData), Err(e) => Err(ErrorKind::IOError(e)), } } fn write_all(&mut self, buff: &[u8]) -> Result<()> { match self.dest.write(&buff) { Ok(n) if n == buff.len() => Ok(()), Ok(_) => Err(ErrorKind::UnableToWriteData), Err(e) => Err(ErrorKind::IOError(e)), } } fn as_writer(&mut self) -> &mut dyn Writer { self } }