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use super::{IntoBuf, Writer}; use byteorder::ByteOrder; use iovec::IoVec; use std::{cmp, io, ptr, usize}; /// A trait for values that provide sequential write access to bytes. /// /// Write bytes to a buffer /// /// A buffer stores bytes in memory such that write operations are infallible. /// The underlying storage may or may not be in contiguous memory. A `BufMut` /// value is a cursor into the buffer. Writing to `BufMut` advances the cursor /// position. /// /// The simplest `BufMut` is a `Vec<u8>`. /// /// ``` /// use bytes::BufMut; /// /// let mut buf = vec![]; /// /// buf.put("hello world"); /// /// assert_eq!(buf, b"hello world"); /// ``` pub trait BufMut { /// Returns the number of bytes that can be written from the current /// position until the end of the buffer is reached. /// /// This value is greater than or equal to the length of the slice returned /// by `bytes_mut`. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// use std::io::Cursor; /// /// let mut dst = [0; 10]; /// let mut buf = Cursor::new(&mut dst[..]); /// /// assert_eq!(10, buf.remaining_mut()); /// buf.put("hello"); /// /// assert_eq!(5, buf.remaining_mut()); /// ``` /// /// # Implementer notes /// /// Implementations of `remaining_mut` should ensure that the return value /// does not change unless a call is made to `advance_mut` or any other /// function that is documented to change the `BufMut`'s current position. fn remaining_mut(&self) -> usize; /// Advance the internal cursor of the BufMut /// /// The next call to `bytes_mut` will return a slice starting `cnt` bytes /// further into the underlying buffer. /// /// This function is unsafe because there is no guarantee that the bytes /// being advanced past have been initialized. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// /// let mut buf = Vec::with_capacity(16); /// /// unsafe { /// buf.bytes_mut()[0] = b'h'; /// buf.bytes_mut()[1] = b'e'; /// /// buf.advance_mut(2); /// /// buf.bytes_mut()[0] = b'l'; /// buf.bytes_mut()[1..3].copy_from_slice(b"lo"); /// /// buf.advance_mut(3); /// } /// /// assert_eq!(5, buf.len()); /// assert_eq!(buf, b"hello"); /// ``` /// /// # Panics /// /// This function **may** panic if `cnt > self.remaining_mut()`. /// /// # Implementer notes /// /// It is recommended for implementations of `advance_mut` to panic if /// `cnt > self.remaining_mut()`. If the implementation does not panic, /// the call must behave as if `cnt == self.remaining_mut()`. /// /// A call with `cnt == 0` should never panic and be a no-op. unsafe fn advance_mut(&mut self, cnt: usize); /// Returns true if there is space in `self` for more bytes. /// /// This is equivalent to `self.remaining_mut() != 0`. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// use std::io::Cursor; /// /// let mut dst = [0; 5]; /// let mut buf = Cursor::new(&mut dst); /// /// assert!(buf.has_remaining_mut()); /// /// buf.put("hello"); /// /// assert!(!buf.has_remaining_mut()); /// ``` fn has_remaining_mut(&self) -> bool { self.remaining_mut() > 0 } /// Returns a mutable slice starting at the current BufMut position and of /// length between 0 and `BufMut::remaining_mut()`. /// /// This is a lower level function. Most operations are done with other /// functions. /// /// The returned byte slice may represent uninitialized memory. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// /// let mut buf = Vec::with_capacity(16); /// /// unsafe { /// buf.bytes_mut()[0] = b'h'; /// buf.bytes_mut()[1] = b'e'; /// /// buf.advance_mut(2); /// /// buf.bytes_mut()[0] = b'l'; /// buf.bytes_mut()[1..3].copy_from_slice(b"lo"); /// /// buf.advance_mut(3); /// } /// /// assert_eq!(5, buf.len()); /// assert_eq!(buf, b"hello"); /// ``` /// /// # Implementer notes /// /// This function should never panic. `bytes_mut` should return an empty /// slice **if and only if** `remaining_mut` returns 0. In other words, /// `bytes_mut` returning an empty slice implies that `remaining_mut` will /// return 0 and `remaining_mut` returning 0 implies that `bytes_mut` will /// return an empty slice. unsafe fn bytes_mut(&mut self) -> &mut [u8]; /// Fills `dst` with potentially multiple mutable slices starting at `self`'s /// current position. /// /// If the `BufMut` is backed by disjoint slices of bytes, `bytes_vec_mut` /// enables fetching more than one slice at once. `dst` is a slice of /// mutable `IoVec` references, enabling the slice to be directly used with /// [`readv`] without any further conversion. The sum of the lengths of all /// the buffers in `dst` will be less than or equal to /// `Buf::remaining_mut()`. /// /// The entries in `dst` will be overwritten, but the data **contained** by /// the slices **will not** be modified. If `bytes_vec_mut` 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., `BufMut::remaining_mut` returns 0, calls to `bytes_vec_mut` must /// return 0 without mutating `dst`. /// /// Implementations should also take care to properly handle being called /// with `dst` being a zero length slice. /// /// [`readv`]: http://man7.org/linux/man-pages/man2/readv.2.html unsafe fn bytes_vec_mut<'a>(&'a mut self, dst: &mut [&'a mut IoVec]) -> usize { if dst.is_empty() { return 0; } if self.has_remaining_mut() { dst[0] = self.bytes_mut().into(); 1 } else { 0 } } /// Transfer bytes into `self` from `src` and advance the cursor by the /// number of bytes written. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// /// let mut buf = vec![]; /// /// buf.put(b'h'); /// buf.put(&b"ello"[..]); /// buf.put(" world"); /// /// assert_eq!(buf, b"hello world"); /// ``` /// /// # Panics /// /// Panics if `self` does not have enough capacity to contain `src`. fn put<T: IntoBuf>(&mut self, src: T) where Self: Sized { use super::Buf; let mut src = src.into_buf(); assert!(self.remaining_mut() >= src.remaining()); while src.has_remaining() { let l; unsafe { let s = src.bytes(); let d = self.bytes_mut(); l = cmp::min(s.len(), d.len()); ptr::copy_nonoverlapping( s.as_ptr(), d.as_mut_ptr(), l); } src.advance(l); unsafe { self.advance_mut(l); } } } /// Transfer bytes into `self` from `src` and advance the cursor by the /// number of bytes written. /// /// `self` must have enough remaining capacity to contain all of `src`. /// /// ``` /// use bytes::BufMut; /// use std::io::Cursor; /// /// let mut dst = [0; 6]; /// /// { /// let mut buf = Cursor::new(&mut dst); /// buf.put_slice(b"hello"); /// /// assert_eq!(1, buf.remaining_mut()); /// } /// /// assert_eq!(b"hello\0", &dst); /// ``` fn put_slice(&mut self, src: &[u8]) { let mut off = 0; assert!(self.remaining_mut() >= src.len(), "buffer overflow"); while off < src.len() { let cnt; unsafe { let dst = self.bytes_mut(); cnt = cmp::min(dst.len(), src.len() - off); ptr::copy_nonoverlapping( src[off..].as_ptr(), dst.as_mut_ptr(), cnt); off += cnt; } unsafe { self.advance_mut(cnt); } } } /// Writes an unsigned 8 bit integer to `self`. /// /// The current position is advanced by 1. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// /// let mut buf = vec![]; /// buf.put_u8(0x01); /// assert_eq!(buf, b"\x01"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_u8(&mut self, n: u8) { let src = [n]; self.put_slice(&src); } /// Writes a signed 8 bit integer to `self`. /// /// The current position is advanced by 1. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// /// let mut buf = vec![]; /// buf.put_i8(0x01); /// assert_eq!(buf, b"\x01"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_i8(&mut self, n: i8) { let src = [n as u8]; self.put_slice(&src) } /// Writes an unsigned 16 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 2. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_u16::<BigEndian>(0x0809); /// assert_eq!(buf, b"\x08\x09"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_u16<T: ByteOrder>(&mut self, n: u16) { let mut buf = [0; 2]; T::write_u16(&mut buf, n); self.put_slice(&buf) } /// Writes a signed 16 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 2. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_i16::<BigEndian>(0x0809); /// assert_eq!(buf, b"\x08\x09"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_i16<T: ByteOrder>(&mut self, n: i16) { let mut buf = [0; 2]; T::write_i16(&mut buf, n); self.put_slice(&buf) } /// Writes an unsigned 32 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_u32::<BigEndian>(0x0809A0A1); /// assert_eq!(buf, b"\x08\x09\xA0\xA1"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_u32<T: ByteOrder>(&mut self, n: u32) { let mut buf = [0; 4]; T::write_u32(&mut buf, n); self.put_slice(&buf) } /// Writes a signed 32 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_i32::<BigEndian>(0x0809A0A1); /// assert_eq!(buf, b"\x08\x09\xA0\xA1"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_i32<T: ByteOrder>(&mut self, n: i32) { let mut buf = [0; 4]; T::write_i32(&mut buf, n); self.put_slice(&buf) } /// Writes an unsigned 64 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_u64::<BigEndian>(0x0102030405060708); /// assert_eq!(buf, b"\x01\x02\x03\x04\x05\x06\x07\x08"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_u64<T: ByteOrder>(&mut self, n: u64) { let mut buf = [0; 8]; T::write_u64(&mut buf, n); self.put_slice(&buf) } /// Writes a signed 64 bit integer to `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_i64::<BigEndian>(0x0102030405060708); /// assert_eq!(buf, b"\x01\x02\x03\x04\x05\x06\x07\x08"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_i64<T: ByteOrder>(&mut self, n: i64) { let mut buf = [0; 8]; T::write_i64(&mut buf, n); self.put_slice(&buf) } /// Writes an unsigned n-byte integer to `self` in the specified byte order. /// /// The current position is advanced by `nbytes`. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_uint::<BigEndian>(0x010203, 3); /// assert_eq!(buf, b"\x01\x02\x03"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_uint<T: ByteOrder>(&mut self, n: u64, nbytes: usize) { let mut buf = [0; 8]; T::write_uint(&mut buf, n, nbytes); self.put_slice(&buf[0..nbytes]) } /// Writes a signed n-byte integer to `self` in the specified byte order. /// /// The current position is advanced by `nbytes`. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_int::<BigEndian>(0x010203, 3); /// assert_eq!(buf, b"\x01\x02\x03"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_int<T: ByteOrder>(&mut self, n: i64, nbytes: usize) { let mut buf = [0; 8]; T::write_int(&mut buf, n, nbytes); self.put_slice(&buf[0..nbytes]) } /// Writes an IEEE754 single-precision (4 bytes) floating point number to /// `self` in the specified byte order. /// /// The current position is advanced by 4. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_f32::<BigEndian>(1.2f32); /// assert_eq!(buf, b"\x3F\x99\x99\x9A"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_f32<T: ByteOrder>(&mut self, n: f32) { let mut buf = [0; 4]; T::write_f32(&mut buf, n); self.put_slice(&buf) } /// Writes an IEEE754 double-precision (8 bytes) floating point number to /// `self` in the specified byte order. /// /// The current position is advanced by 8. /// /// # Examples /// /// ``` /// use bytes::{BufMut, BigEndian}; /// /// let mut buf = vec![]; /// buf.put_f64::<BigEndian>(1.2f64); /// assert_eq!(buf, b"\x3F\xF3\x33\x33\x33\x33\x33\x33"); /// ``` /// /// # Panics /// /// This function panics if there is not enough remaining capacity in /// `self`. fn put_f64<T: ByteOrder>(&mut self, n: f64) { let mut buf = [0; 8]; T::write_f64(&mut buf, n); self.put_slice(&buf) } /// Creates a "by reference" adaptor for this instance of `BufMut`. /// /// The returned adapter also implements `BufMut` and will simply borrow /// `self`. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// use std::io; /// /// let mut buf = vec![]; /// /// { /// let mut reference = buf.by_ref(); /// /// // Adapt reference to `std::io::Write`. /// let mut writer = reference.writer(); /// /// // Use the buffer as a writter /// io::Write::write(&mut writer, &b"hello world"[..]).unwrap(); /// } // drop our &mut reference so that we can use `buf` again /// /// assert_eq!(buf, &b"hello world"[..]); /// ``` fn by_ref(&mut self) -> &mut Self where Self: Sized { self } /// Creates an adaptor which implements the `Write` trait for `self`. /// /// This function returns a new value which implements `Write` by adapting /// the `Write` trait functions to the `BufMut` trait functions. Given that /// `BufMut` operations are infallible, none of the `Write` functions will /// return with `Err`. /// /// # Examples /// /// ``` /// use bytes::BufMut; /// use std::io::Write; /// /// let mut buf = vec![].writer(); /// /// let num = buf.write(&b"hello world"[..]).unwrap(); /// assert_eq!(11, num); /// /// let buf = buf.into_inner(); /// /// assert_eq!(*buf, b"hello world"[..]); /// ``` fn writer(self) -> Writer<Self> where Self: Sized { super::writer::new(self) } } impl<'a, T: BufMut + ?Sized> BufMut for &'a mut T { fn remaining_mut(&self) -> usize { (**self).remaining_mut() } unsafe fn bytes_mut(&mut self) -> &mut [u8] { (**self).bytes_mut() } unsafe fn bytes_vec_mut<'b>(&'b mut self, dst: &mut [&'b mut IoVec]) -> usize { (**self).bytes_vec_mut(dst) } unsafe fn advance_mut(&mut self, cnt: usize) { (**self).advance_mut(cnt) } } impl<T: BufMut + ?Sized> BufMut for Box<T> { fn remaining_mut(&self) -> usize { (**self).remaining_mut() } unsafe fn bytes_mut(&mut self) -> &mut [u8] { (**self).bytes_mut() } unsafe fn bytes_vec_mut<'b>(&'b mut self, dst: &mut [&'b mut IoVec]) -> usize { (**self).bytes_vec_mut(dst) } unsafe fn advance_mut(&mut self, cnt: usize) { (**self).advance_mut(cnt) } } impl<T: AsMut<[u8]> + AsRef<[u8]>> BufMut for io::Cursor<T> { fn remaining_mut(&self) -> usize { use Buf; self.remaining() } /// Advance the internal cursor of the BufMut unsafe fn advance_mut(&mut self, cnt: usize) { use Buf; self.advance(cnt); } /// Returns a mutable slice starting at the current BufMut position and of /// length between 0 and `BufMut::remaining()`. /// /// The returned byte slice may represent uninitialized memory. unsafe fn bytes_mut(&mut self) -> &mut [u8] { let len = self.get_ref().as_ref().len(); let pos = self.position() as usize; if pos >= len { return Default::default(); } &mut (self.get_mut().as_mut())[pos..] } } impl BufMut for Vec<u8> { #[inline] fn remaining_mut(&self) -> usize { usize::MAX - self.len() } #[inline] unsafe fn advance_mut(&mut self, cnt: usize) { let len = self.len(); let remaining = self.capacity() - len; if cnt > remaining { // Reserve additional capacity, and ensure that the total length // will not overflow usize. self.reserve(cnt); } self.set_len(len + cnt); } #[inline] unsafe fn bytes_mut(&mut self) -> &mut [u8] { use std::slice; if self.capacity() == self.len() { self.reserve(64); // Grow the vec } let cap = self.capacity(); let len = self.len(); let ptr = self.as_mut_ptr(); &mut slice::from_raw_parts_mut(ptr, cap)[len..] } }