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use super::{IntoBuf, Take, Reader, Iter, FromBuf, Chain}; use byteorder::ByteOrder; use iovec::IoVec; use std::{cmp, io, ptr}; /// Read bytes from a buffer. /// /// A buffer stores bytes in memory such that read operations are infallible. /// The underlying storage may or may not be in contiguous memory. A `Buf` value /// is a cursor into the buffer. Reading from `Buf` advances the cursor /// position. It can be thought of as an efficient `Iterator` for collections of /// bytes. /// /// The simplest `Buf` is a `Cursor` wrapping a `[u8]`. /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"hello world"); /// /// assert_eq!(b'h', buf.get_u8()); /// assert_eq!(b'e', buf.get_u8()); /// assert_eq!(b'l', buf.get_u8()); /// /// let mut rest = [0; 8]; /// buf.copy_to_slice(&mut rest); /// /// assert_eq!(&rest[..], b"lo world"); /// ``` pub trait Buf { /// Returns the number of bytes between the current position and the end of /// the buffer. /// /// This value is greater than or equal to the length of the slice returned /// by `bytes`. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"hello world"); /// /// assert_eq!(buf.remaining(), 11); /// /// buf.get_u8(); /// /// assert_eq!(buf.remaining(), 10); /// ``` /// /// # Implementer notes /// /// Implementations of `remaining` should ensure that the return value does /// not change unless a call is made to `advance` or any other function that /// is documented to change the `Buf`'s current position. fn remaining(&self) -> usize; /// Returns a slice starting at the current position and of length between 0 /// and `Buf::remaining()`. /// /// This is a lower level function. Most operations are done with other /// functions. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"hello world"); /// /// assert_eq!(buf.bytes(), b"hello world"); /// /// buf.advance(6); /// /// assert_eq!(buf.bytes(), b"world"); /// ``` /// /// # Implementer notes /// /// This function should never panic. Once the end of the buffer is reached, /// i.e., `Buf::remaining` returns 0, calls to `bytes` should return an /// empty slice. fn bytes(&self) -> &[u8]; /// Fills `dst` with potentially multiple slices starting at `self`'s /// current position. /// /// If the `Buf` is backed by disjoint slices of bytes, `bytes_vec` enables /// fetching more than one slice at once. `dst` is a slice of `IoVec` /// references, enabling the slice to be directly used with [`writev`] /// without any further conversion. The sum of the lengths of all the /// buffers in `dst` will be less than or equal to `Buf::remaining()`. /// /// The entries in `dst` will be overwritten, but the data **contained** by /// the slices **will not** be modified. If `bytes_vec` does not fill every /// entry in `dst`, then `dst` is guaranteed to contain all remaining slices /// in `self. /// /// This is a lower level function. Most operations are done with other /// functions. /// /// # Implementer notes /// /// This function should never panic. Once the end of the buffer is reached, /// i.e., `Buf::remaining` returns 0, calls to `bytes_vec` must return 0 /// without mutating `dst`. /// /// Implementations should also take care to properly handle being called /// with `dst` being a zero length slice. /// /// [`writev`]: http://man7.org/linux/man-pages/man2/readv.2.html fn bytes_vec<'a>(&'a self, dst: &mut [&'a IoVec]) -> usize { if dst.is_empty() { return 0; } if self.has_remaining() { dst[0] = self.bytes().into(); 1 } else { 0 } } /// Advance the internal cursor of the Buf /// /// The next call to `bytes` will return a slice starting `cnt` bytes /// further into the underlying buffer. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"hello world"); /// /// assert_eq!(buf.bytes(), b"hello world"); /// /// buf.advance(6); /// /// assert_eq!(buf.bytes(), b"world"); /// ``` /// /// # Panics /// /// This function **may** panic if `cnt > self.remaining()`. /// /// # Implementer notes /// /// It is recommended for implementations of `advance` to panic if `cnt > /// self.remaining()`. If the implementation does not panic, the call must /// behave as if `cnt == self.remaining()`. /// /// A call with `cnt == 0` should never panic and be a no-op. fn advance(&mut self, cnt: usize); /// Returns true if there are any more bytes to consume /// /// This is equivalent to `self.remaining() != 0`. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"a"); /// /// assert!(buf.has_remaining()); /// /// buf.get_u8(); /// /// assert!(!buf.has_remaining()); /// ``` fn has_remaining(&self) -> bool { self.remaining() > 0 } /// Copies bytes from `self` into `dst`. /// /// The cursor is advanced by the number of bytes copied. `self` must have /// enough remaining bytes to fill `dst`. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"hello world"); /// let mut dst = [0; 5]; /// /// buf.copy_to_slice(&mut dst); /// assert_eq!(b"hello", &dst); /// assert_eq!(6, buf.remaining()); /// ``` /// /// # Panics /// /// This function panics if `self.remaining() < dst.len()` fn copy_to_slice(&mut self, dst: &mut [u8]) { let mut off = 0; assert!(self.remaining() >= dst.len()); while off < dst.len() { let cnt; unsafe { let src = self.bytes(); cnt = cmp::min(src.len(), dst.len() - off); ptr::copy_nonoverlapping( src.as_ptr(), dst[off..].as_mut_ptr(), cnt); off += src.len(); } self.advance(cnt); } } /// Gets an unsigned 8 bit integer from `self`. /// /// The current position is advanced by 1. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08 hello"); /// assert_eq!(8, buf.get_u8()); /// ``` /// /// # Panics /// /// This function panics if there is no more remaining data in `self`. fn get_u8(&mut self) -> u8 { let mut buf = [0; 1]; self.copy_to_slice(&mut buf); buf[0] } /// Gets a signed 8 bit integer from `self`. /// /// The current position is advanced by 1. /// /// # Examples /// /// ``` /// use bytes::Buf; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08 hello"); /// assert_eq!(8, buf.get_i8()); /// ``` /// /// # Panics /// /// This function panics if there is no more remaining data in `self`. fn get_i8(&mut self) -> i8 { let mut buf = [0; 1]; self.copy_to_slice(&mut buf); buf[0] as i8 } /// Gets an unsigned 16 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 2. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08\x09 hello"); /// assert_eq!(0x0809, buf.get_u16::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_u16<T: ByteOrder>(&mut self) -> u16 { let mut buf = [0; 2]; self.copy_to_slice(&mut buf); T::read_u16(&buf) } /// Gets a signed 16 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 2. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08\x09 hello"); /// assert_eq!(0x0809, buf.get_i16::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_i16<T: ByteOrder>(&mut self) -> i16 { let mut buf = [0; 2]; self.copy_to_slice(&mut buf); T::read_i16(&buf) } /// Gets an unsigned 32 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08\x09\xA0\xA1 hello"); /// assert_eq!(0x0809A0A1, buf.get_u32::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_u32<T: ByteOrder>(&mut self) -> u32 { let mut buf = [0; 4]; self.copy_to_slice(&mut buf); T::read_u32(&buf) } /// Gets a signed 32 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x08\x09\xA0\xA1 hello"); /// assert_eq!(0x0809A0A1, buf.get_i32::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_i32<T: ByteOrder>(&mut self) -> i32 { let mut buf = [0; 4]; self.copy_to_slice(&mut buf); T::read_i32(&buf) } /// Gets an unsigned 64 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"); /// assert_eq!(0x0102030405060708, buf.get_u64::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_u64<T: ByteOrder>(&mut self) -> u64 { let mut buf = [0; 8]; self.copy_to_slice(&mut buf); T::read_u64(&buf) } /// Gets a signed 64 bit integer from `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"); /// assert_eq!(0x0102030405060708, buf.get_i64::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_i64<T: ByteOrder>(&mut self) -> i64 { let mut buf = [0; 8]; self.copy_to_slice(&mut buf); T::read_i64(&buf) } /// Gets an unsigned n-byte integer from `self` in the specified byte order. /// /// The current position is advanced by `nbytes`. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x01\x02\x03 hello"); /// assert_eq!(0x010203, buf.get_uint::<BigEndian>(3)); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_uint<T: ByteOrder>(&mut self, nbytes: usize) -> u64 { let mut buf = [0; 8]; self.copy_to_slice(&mut buf[..nbytes]); T::read_uint(&buf[..nbytes], nbytes) } /// Gets a signed n-byte integer from `self` in the specified byte order. /// /// The current position is advanced by `nbytes`. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x01\x02\x03 hello"); /// assert_eq!(0x010203, buf.get_int::<BigEndian>(3)); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_int<T: ByteOrder>(&mut self, nbytes: usize) -> i64 { let mut buf = [0; 8]; self.copy_to_slice(&mut buf[..nbytes]); T::read_int(&buf[..nbytes], nbytes) } /// Gets an IEEE754 single-precision (4 bytes) floating point number from /// `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x3F\x99\x99\x9A hello"); /// assert_eq!(1.2f32, buf.get_f32::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_f32<T: ByteOrder>(&mut self) -> f32 { let mut buf = [0; 4]; self.copy_to_slice(&mut buf); T::read_f32(&buf) } /// Gets an IEEE754 double-precision (8 bytes) floating point number from /// `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{Buf, BigEndian}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new(b"\x3F\xF3\x33\x33\x33\x33\x33\x33 hello"); /// assert_eq!(1.2f64, buf.get_f64::<BigEndian>()); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining data in `self`. fn get_f64<T: ByteOrder>(&mut self) -> f64 { let mut buf = [0; 8]; self.copy_to_slice(&mut buf); T::read_f64(&buf) } /// Transforms a `Buf` into a concrete buffer. /// /// `collect()` can operate on any value that implements `Buf`, and turn it /// into the relevent concrete buffer type. /// /// # Examples /// /// Collecting a buffer and loading the contents into a `Vec<u8>`. /// /// ``` /// use bytes::{Buf, Bytes, IntoBuf}; /// /// let buf = Bytes::from(&b"hello world"[..]).into_buf(); /// let vec: Vec<u8> = buf.collect(); /// /// assert_eq!(vec, &b"hello world"[..]); /// ``` fn collect<B>(self) -> B where Self: Sized, B: FromBuf, { B::from_buf(self) } /// Creates an adaptor which will read at most `limit` bytes from `self`. /// /// This function returns a new instance of `Buf` which will read at most /// `limit` bytes. /// /// # Examples /// /// ``` /// use bytes::{Buf, BufMut}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new("hello world").take(5); /// let mut dst = vec![]; /// /// dst.put(&mut buf); /// assert_eq!(dst, b"hello"); /// /// let mut buf = buf.into_inner(); /// dst.clear(); /// dst.put(&mut buf); /// assert_eq!(dst, b" world"); /// ``` fn take(self, limit: usize) -> Take<Self> where Self: Sized { super::take::new(self, limit) } /// Creates an adaptor which will chain this buffer with another. /// /// The returned `Buf` instance will first consume all bytes from `self`. /// Afterwards the output is equivalent to the output of next. /// /// # Examples /// /// ``` /// use bytes::{Bytes, Buf, IntoBuf}; /// use bytes::buf::Chain; /// /// let buf = Bytes::from(&b"hello "[..]).into_buf() /// .chain(Bytes::from(&b"world"[..])); /// /// let full: Bytes = buf.collect(); /// assert_eq!(full[..], b"hello world"[..]); /// ``` fn chain<U>(self, next: U) -> Chain<Self, U::Buf> where U: IntoBuf, Self: Sized, { Chain::new(self, next.into_buf()) } /// Creates a "by reference" adaptor for this instance of `Buf`. /// /// The returned adaptor also implements `Buf` and will simply borrow `self`. /// /// # Examples /// /// ``` /// use bytes::{Buf, BufMut}; /// use std::io::Cursor; /// /// let mut buf = Cursor::new("hello world"); /// let mut dst = vec![]; /// /// { /// let mut reference = buf.by_ref(); /// dst.put(&mut reference.take(5)); /// assert_eq!(dst, b"hello"); /// } // drop our &mut reference so we can use `buf` again /// /// dst.clear(); /// dst.put(&mut buf); /// assert_eq!(dst, b" world"); /// ``` fn by_ref(&mut self) -> &mut Self where Self: Sized { self } /// Creates an adaptor which implements the `Read` trait for `self`. /// /// This function returns a new value which implements `Read` by adapting /// the `Read` trait functions to the `Buf` trait functions. Given that /// `Buf` operations are infallible, none of the `Read` functions will /// return with `Err`. /// /// # Examples /// /// ``` /// use bytes::{Buf, IntoBuf, Bytes}; /// use std::io::Read; /// /// let buf = Bytes::from("hello world").into_buf(); /// /// let mut reader = buf.reader(); /// let mut dst = [0; 1024]; /// /// let num = reader.read(&mut dst).unwrap(); /// /// assert_eq!(11, num); /// assert_eq!(&dst[..11], b"hello world"); /// ``` fn reader(self) -> Reader<Self> where Self: Sized { super::reader::new(self) } /// Returns an iterator over the bytes contained by the buffer. /// /// # Examples /// /// ``` /// use bytes::{Buf, IntoBuf, Bytes}; /// /// let buf = Bytes::from(&b"abc"[..]).into_buf(); /// let mut iter = buf.iter(); /// /// assert_eq!(iter.next(), Some(b'a')); /// assert_eq!(iter.next(), Some(b'b')); /// assert_eq!(iter.next(), Some(b'c')); /// assert_eq!(iter.next(), None); /// ``` fn iter(self) -> Iter<Self> where Self: Sized { super::iter::new(self) } } impl<'a, T: Buf + ?Sized> Buf for &'a mut T { fn remaining(&self) -> usize { (**self).remaining() } fn bytes(&self) -> &[u8] { (**self).bytes() } fn bytes_vec<'b>(&'b self, dst: &mut [&'b IoVec]) -> usize { (**self).bytes_vec(dst) } fn advance(&mut self, cnt: usize) { (**self).advance(cnt) } } impl<T: Buf + ?Sized> Buf for Box<T> { fn remaining(&self) -> usize { (**self).remaining() } fn bytes(&self) -> &[u8] { (**self).bytes() } fn bytes_vec<'b>(&'b self, dst: &mut [&'b IoVec]) -> usize { (**self).bytes_vec(dst) } fn advance(&mut self, cnt: usize) { (**self).advance(cnt) } } impl<T: AsRef<[u8]>> Buf for io::Cursor<T> { fn remaining(&self) -> usize { let len = self.get_ref().as_ref().len(); let pos = self.position(); if pos >= len as u64 { return 0; } len - pos as usize } fn bytes(&self) -> &[u8] { let len = self.get_ref().as_ref().len(); let pos = self.position() as usize; if pos >= len { return Default::default(); } &(self.get_ref().as_ref())[pos..] } fn advance(&mut self, cnt: usize) { let pos = (self.position() as usize) .checked_add(cnt).expect("overflow"); assert!(pos <= self.get_ref().as_ref().len()); self.set_position(pos as u64); } } impl Buf for Option<[u8; 1]> { fn remaining(&self) -> usize { if self.is_some() { 1 } else { 0 } } fn bytes(&self) -> &[u8] { self.as_ref().map(AsRef::as_ref) .unwrap_or(Default::default()) } fn advance(&mut self, cnt: usize) { if cnt == 0 { return; } if self.is_none() { panic!("overflow"); } else { assert_eq!(1, cnt); *self = None; } } }