| 1 | use crate::encoding::varint::{Signed, SignedVarInt, VarInt}; |
| 2 | use std::any::type_name; |
| 3 | use std::collections::TryReserveError; |
| 4 | use thiserror::Error; |
| 5 | |
| 6 | #[derive(Error, Debug)] |
| 7 | pub enum Error { |
| 8 | #[error("failed to decode variable length integer")] |
| 9 | InvalidVarInt, |
| 10 | |
| 11 | #[error("while trying to read more data (expected: {0} bytes), an unexpected end of buffer was reached")] |
| 12 | EndOfBuffer(usize), |
| 13 | |
| 14 | #[error("while reading, an unexpected value was found")] |
| 15 | UnexpectedValue, |
| 16 | |
| 17 | #[error("failed to allocate memory: {0}")] |
| 18 | NotEnoughMemory(#[from] TryReserveError), |
| 19 | |
| 20 | #[error("JSON parsing error: {0}")] |
| 21 | InvalidJSON(#[from] serde_json::Error), |
| 22 | |
| 23 | #[error("couldn't deserialize to target type of {0}")] |
| 24 | TypeMismatch(&'static str), |
| 25 | |
| 26 | #[error("{0}")] |
| 27 | Custom(String), |
| 28 | } |
| 29 | |
| 30 | impl Error { |
| 31 | pub fn type_mismatch<T>() -> Self { |
| 32 | Error::TypeMismatch(type_name::<T>()) |
| 33 | } |
| 34 | } |
| 35 | |
| 36 | #[derive(Default)] |
| 37 | pub struct Cursor<'a> { |
| 38 | pub buf: &'a [u8], |
| 39 | pub next: usize, |
| 40 | } |
| 41 | |
| 42 | impl<'a> Cursor<'a> { |
| 43 | pub fn new(buf: &'a [u8]) -> Cursor<'a> { |
| 44 | Cursor { buf, next: 0 } |
| 45 | } |
| 46 | |
| 47 | pub fn has_content(&self) -> bool { |
| 48 | self.next != self.buf.len() |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | impl<'a, R> From<&'a R> for Cursor<'a> |
| 53 | where |
| 54 | R: AsRef<[u8]>, |
| 55 | { |
| 56 | fn from(buf: &'a R) -> Self { |
| 57 | Self::new(buf.as_ref()) |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | impl<'a> Read for Cursor<'a> { |
| 62 | /// Take a slice of the next `len` bytes and advance the position by `len`. |
| 63 | fn read_exact(&mut self, len: usize) -> Result<&[u8], Error> { |
| 64 | if self.next + len > self.buf.len() { |
| 65 | Err(Error::EndOfBuffer(len)) |
| 66 | } else { |
| 67 | let slice = &self.buf[self.next..(self.next + len)]; |
| 68 | self.next += len as usize; |
| 69 | Ok(slice) |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | /// Read a single byte. |
| 74 | fn read_u8(&mut self) -> Result<u8, Error> { |
| 75 | if let Some(&b) = self.buf.get(self.next) { |
| 76 | self.next += 1; |
| 77 | Ok(b) |
| 78 | } else { |
| 79 | Err(Error::EndOfBuffer(1)) |
| 80 | } |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | pub trait Read: Sized { |
| 85 | fn read_exact(&mut self, len: usize) -> Result<&[u8], Error>; |
| 86 | |
| 87 | /// Read a single byte. |
| 88 | fn read_u8(&mut self) -> Result<u8, Error> { |
| 89 | let buf = self.read_exact(1)?; |
| 90 | Ok(buf[0]) |
| 91 | } |
| 92 | |
| 93 | /// Read a variable length buffer. |
| 94 | fn read_buf(&mut self) -> Result<&[u8], Error> { |
| 95 | let len: u32 = self.read_var()?; |
| 96 | self.read_exact(len as usize) |
| 97 | } |
| 98 | |
| 99 | /// Read 2 bytes as unsigned integer |
| 100 | fn read_u16(&mut self) -> Result<u16, Error> { |
| 101 | let buf = self.read_exact(2)?; |
| 102 | Ok(buf[0] as u16 | ((buf[1] as u16) << 8)) |
| 103 | } |
| 104 | |
| 105 | /// Read 4 bytes as unsigned integer |
| 106 | fn read_u32(&mut self) -> Result<u32, Error> { |
| 107 | let buf = self.read_exact(4)?; |
| 108 | Ok(buf[0] as u32 | (buf[1] as u32) << 8 | (buf[2] as u32) << 16 | (buf[3] as u32) << 24) |
| 109 | } |
| 110 | |
| 111 | /// Read 4 bytes as unsigned integer in big endian order. |
| 112 | /// (most significant byte first) |
| 113 | fn read_u32_be(&mut self) -> Result<u32, Error> { |
| 114 | let buf = self.read_exact(4)?; |
| 115 | Ok((buf[0] as u32) << 24 | (buf[1] as u32) << 16 | (buf[2] as u32) << 8 | buf[3] as u32) |
| 116 | } |
| 117 | |
| 118 | /// Read unsigned integer with variable length. |
| 119 | /// * numbers < 2^7 are stored in one byte |
| 120 | /// * numbers < 2^14 are stored in two bytes |
| 121 | #[inline] |
| 122 | fn read_var<T: VarInt>(&mut self) -> Result<T, Error> { |
| 123 | T::read(self) |
| 124 | } |
| 125 | |
| 126 | /// Read unsigned integer with variable length. |
| 127 | /// * numbers < 2^7 are stored in one byte |
| 128 | /// * numbers < 2^14 are stored in two bytes |
| 129 | #[inline] |
| 130 | fn read_var_signed<T: SignedVarInt>(&mut self) -> Result<Signed<T>, Error> { |
| 131 | T::read_signed(self) |
| 132 | } |
| 133 | |
| 134 | /// Read string of variable length. |
| 135 | fn read_string(&mut self) -> Result<&str, Error> { |
| 136 | let buf = self.read_buf()?; |
| 137 | Ok(unsafe { std::str::from_utf8_unchecked(buf) }) |
| 138 | } |
| 139 | |
| 140 | /// Read float32 in big endian order |
| 141 | fn read_f32(&mut self) -> Result<f32, Error> { |
| 142 | let mut buf = [0; 4]; |
| 143 | let slice = self.read_exact(4)?; |
| 144 | buf.copy_from_slice(slice); |
| 145 | Ok(f32::from_be_bytes(buf)) |
| 146 | } |
| 147 | |
| 148 | /// Read float64 in big endian order |
| 149 | // @todo there must be a more elegant way to convert a slice to a fixed-length buffer. |
| 150 | fn read_f64(&mut self) -> Result<f64, Error> { |
| 151 | let mut buf = [0; 8]; |
| 152 | let slice = self.read_exact(8)?; |
| 153 | buf.copy_from_slice(slice); |
| 154 | Ok(f64::from_be_bytes(buf)) |
| 155 | } |
| 156 | |
| 157 | /// Read BigInt64 in big endian order |
| 158 | fn read_i64(&mut self) -> Result<i64, Error> { |
| 159 | let mut buf = [0; 8]; |
| 160 | let slice = self.read_exact(8)?; |
| 161 | buf.copy_from_slice(slice); |
| 162 | Ok(i64::from_be_bytes(buf)) |
| 163 | } |
| 164 | |
| 165 | /// read BigUInt64 in big endian order |
| 166 | fn read_u64(&mut self) -> Result<u64, Error> { |
| 167 | let mut buf = [0; 8]; |
| 168 | let slice = self.read_exact(8)?; |
| 169 | buf.copy_from_slice(slice); |
| 170 | Ok(u64::from_be_bytes(buf)) |
| 171 | } |
| 172 | } |
| 173 | |
amadan