prost/encoding/
length_delimiter.rs

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1pub use crate::error::{DecodeError, EncodeError, UnknownEnumValue};
2pub use crate::message::Message;
3pub use crate::name::Name;
4
5use bytes::{Buf, BufMut};
6
7use crate::encoding::varint::{decode_varint, encode_varint, encoded_len_varint};
8
9/// Encodes a length delimiter to the buffer.
10///
11/// See [Message.encode_length_delimited] for more info.
12///
13/// An error will be returned if the buffer does not have sufficient capacity to encode the
14/// delimiter.
15pub fn encode_length_delimiter(length: usize, buf: &mut impl BufMut) -> Result<(), EncodeError> {
16    let length = length as u64;
17    let required = encoded_len_varint(length);
18    let remaining = buf.remaining_mut();
19    if required > remaining {
20        return Err(EncodeError::new(required, remaining));
21    }
22    encode_varint(length, buf);
23    Ok(())
24}
25
26/// Returns the encoded length of a length delimiter.
27///
28/// Applications may use this method to ensure sufficient buffer capacity before calling
29/// `encode_length_delimiter`. The returned size will be between 1 and 10, inclusive.
30pub fn length_delimiter_len(length: usize) -> usize {
31    encoded_len_varint(length as u64)
32}
33
34/// Decodes a length delimiter from the buffer.
35///
36/// This method allows the length delimiter to be decoded independently of the message, when the
37/// message is encoded with [Message.encode_length_delimited].
38///
39/// An error may be returned in two cases:
40///
41///  * If the supplied buffer contains fewer than 10 bytes, then an error indicates that more
42///    input is required to decode the full delimiter.
43///  * If the supplied buffer contains 10 bytes or more, then the buffer contains an invalid
44///    delimiter, and typically the buffer should be considered corrupt.
45pub fn decode_length_delimiter(mut buf: impl Buf) -> Result<usize, DecodeError> {
46    let length = decode_varint(&mut buf)?;
47    if length > usize::MAX as u64 {
48        return Err(DecodeError::new(
49            "length delimiter exceeds maximum usize value",
50        ));
51    }
52    Ok(length as usize)
53}
prost/encoding/length_delimiter.rs

prost/encoding/
length_delimiter.rs
