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#![no_std]
use core::str;
#[derive(Debug, PartialEq, Eq, Copy, Clone)]
#[repr(u8)]
pub enum WireType {
Varint = 0,
Bit64 = 1,
Bytes = 2,
Bit32 = 5,
}
impl WireType {
pub fn from_u8(b: u8) -> Option<Self> {
match b {
0 => Some(WireType::Varint),
1 => Some(WireType::Bit64),
2 => Some(WireType::Bytes),
5 => Some(WireType::Bit32),
_ => None,
}
}
}
#[derive(Debug)]
pub enum Error {
Eof,
UnexpectedEof,
InvalidWireType(u8),
InvalidFieldNumber(u8),
VarintOverflow,
InvalidUtf8String,
BufferOverflow,
}
impl Error {
pub fn is_eof(&self) -> bool {
match self {
Error::Eof => true,
_ => false,
}
}
}
pub struct PbReader<'a> {
buf: &'a [u8],
pos: usize,
}
impl PbReader<'_> {
pub fn new<'a>(buf: &'a [u8]) -> PbReader<'a> {
PbReader { buf, pos: 0 }
}
pub fn is_eof(&self) -> bool {
self.pos == self.buf.len()
}
pub fn peek_next_key(&self) -> Result<(u8, WireType), Error> {
let key = self.peek_next_u8().ok_or(Error::Eof)?;
match WireType::from_u8(key & 0b111) {
Some(wt) => Ok((key >> 3, wt)),
None => Err(Error::InvalidWireType(key & 0b111)),
}
}
pub fn next_key(&mut self) -> Result<(u8, WireType), Error> {
let key = self.next_u8().ok_or(Error::Eof)?;
match WireType::from_u8(key & 0b111) {
Some(wt) => Ok((key >> 3, wt)),
None => Err(Error::InvalidWireType(key & 0b111)),
}
}
pub fn skip_next_field(&mut self) -> Result<(), Error> {
match self.next_key()? {
(_, WireType::Varint) => {
let _ = self.next_varint()?;
}
(_, WireType::Bytes) => {
let _ = self.next_bytes()?;
}
(_, WireType::Bit32) => {
let _ = self.next_fixed32()?;
}
(_, WireType::Bit64) => {
let _ = self.next_fixed64()?;
}
}
Ok(())
}
pub fn next_fixed32(&mut self) -> Result<[u8; 4], Error> {
if self.pos + 4 > self.buf.len() {
Err(Error::UnexpectedEof)
} else {
let mut ret = [0u8; 4];
ret.copy_from_slice(&self.buf[self.pos..self.pos + 4]);
self.pos += 4;
Ok(ret)
}
}
pub fn next_fixed64(&mut self) -> Result<[u8; 8], Error> {
if self.pos + 8 > self.buf.len() {
Err(Error::UnexpectedEof)
} else {
let mut ret = [0u8; 8];
ret.copy_from_slice(&self.buf[self.pos..self.pos + 8]);
self.pos += 8;
Ok(ret)
}
}
pub fn next_varint(&mut self) -> Result<u64, Error> {
let mut result = 0;
let mut bitpos = 0;
loop {
let b = self.next_u8().ok_or(Error::UnexpectedEof)?;
let tmp = ((b & 0x7f) as u64)
.checked_shl(bitpos)
.ok_or(Error::VarintOverflow)?;
result += tmp;
if b & 0x80 == 0 {
return Ok(result);
}
bitpos += 7;
}
}
pub fn next_bytes(&mut self) -> Result<&[u8], Error> {
let len = self.next_varint()? as usize;
if self.pos + len > self.buf.len() {
Err(Error::UnexpectedEof)
} else {
let bytes = &self.buf[self.pos..self.pos + len];
self.pos += len;
Ok(bytes)
}
}
pub fn next_string(&mut self) -> Result<&str, Error> {
self.next_bytes()
.and_then(|raw| str::from_utf8(raw).map_err(|_| Error::InvalidUtf8String))
}
pub fn next_embedded_message(&mut self) -> Result<PbReader<'_>, Error> {
self.next_bytes().map(PbReader::new)
}
pub fn next_svarint(&mut self) -> Result<i64, Error> {
let val = self.next_varint()?;
Ok(varint_to_svarint(val))
}
fn peek_next_u8(&self) -> Option<u8> {
if self.has_next() {
Some(self.buf[self.pos])
} else {
None
}
}
fn next_u8(&mut self) -> Option<u8> {
if self.has_next() {
let i = self.pos;
self.pos += 1;
Some(self.buf[i])
} else {
None
}
}
fn has_next(&self) -> bool {
self.pos < self.buf.len()
}
}
pub struct PbWriter<'a> {
buf: &'a mut [u8],
pos: usize,
}
impl PbWriter<'_> {
pub fn new<'a>(buf: &'a mut [u8]) -> PbWriter<'a> {
PbWriter { buf, pos: 0 }
}
pub fn is_eof(&self) -> bool {
self.pos == self.buf.len()
}
pub fn write_varint(&mut self, value: u64) -> Result<(), Error> {
let mut value = value;
let fallback_pos = self.pos;
if value == 0 {
return self.write_u8(0x00);
}
while value > 0 {
self.write_u8(((value & 0x7f) as u8) | 0x80)
.map_err(|err| {
self.pos = fallback_pos;
err
})?;
value >>= 7;
}
*self.last_u8_mut() &= 0x7f;
Ok(())
}
pub fn encode_varint_field(&mut self, field_number: u8, value: u64) -> Result<(), Error> {
let key = field_number
.checked_shl(3)
.ok_or(Error::InvalidFieldNumber(field_number))?
+ WireType::Varint as u8;
self.write_u8(key)?;
self.write_varint(value)
}
pub fn encode_svarint_field(&mut self, field_number: u8, value: i64) -> Result<(), Error> {
self.encode_varint_field(field_number, svarint_to_varint(value))
}
pub fn encode_bytes_field(&mut self, field_number: u8, value: &[u8]) -> Result<(), Error> {
let key = field_number
.checked_shl(3)
.ok_or(Error::InvalidFieldNumber(field_number))?
+ WireType::Bytes as u8;
self.write_u8(key)?;
self.write_varint(value.len() as _)?;
self.write_bytes(value)
}
pub fn encode_string_field(&mut self, field_number: u8, value: &str) -> Result<(), Error> {
self.encode_bytes_field(field_number, value.as_bytes())
}
pub fn as_bytes(&self) -> &[u8] {
&self.buf[..self.pos]
}
fn write_u8(&mut self, val: u8) -> Result<(), Error> {
if self.pos < self.buf.len() {
self.buf[self.pos] = val;
self.pos += 1;
Ok(())
} else {
Err(Error::BufferOverflow)
}
}
fn write_bytes(&mut self, val: &[u8]) -> Result<(), Error> {
if self.pos + val.len() < self.buf.len() {
self.buf[self.pos..self.pos + val.len()].copy_from_slice(val);
self.pos += val.len();
Ok(())
} else {
Err(Error::BufferOverflow)
}
}
fn last_u8_mut(&mut self) -> &mut u8 {
&mut self.buf[self.pos - 1]
}
}
#[inline]
fn varint_to_svarint(n: u64) -> i64 {
if n & 0b1 == 1 {
-((n >> 1) as i64 + 1)
} else {
(n >> 1) as i64
}
}
#[inline]
fn svarint_to_varint(n: i64) -> u64 {
((n << 1) ^ (n >> 63)) as u64
}