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//! Low level Postgres protocol APIs.
//!
//! This crate implements the low level components of Postgres's communication
//! protocol, including message and value serialization and deserialization.
//! It is designed to be used as a building block by higher level APIs such as
//! `rust-postgres`, and should not typically be used directly.
//!
//! # Note
//!
//! This library assumes that the `client_encoding` backend parameter has been
//! set to `UTF8`. It will most likely not behave properly if that is not the case.
#![warn(missing_docs, rust_2018_idioms, clippy::all)]
use byteorder::{BigEndian, ByteOrder};
use bytes::{BufMut, BytesMut};
use std::io;
pub mod authentication;
pub mod escape;
pub mod message;
pub mod password;
pub mod types;
/// A Postgres OID.
pub type Oid = u32;
/// A Postgres Log Sequence Number (LSN).
pub type Lsn = u64;
/// An enum indicating if a value is `NULL` or not.
pub enum IsNull {
/// The value is `NULL`.
Yes,
/// The value is not `NULL`.
No,
}
fn write_nullable<F, E>(serializer: F, buf: &mut BytesMut) -> Result<(), E>
where
F: FnOnce(&mut BytesMut) -> Result<IsNull, E>,
E: From<io::Error>,
{
let base = buf.len();
buf.put_i32(0);
let size = match serializer(buf)? {
IsNull::No => i32::from_usize(buf.len() - base - 4)?,
IsNull::Yes => -1,
};
BigEndian::write_i32(&mut buf[base..], size);
Ok(())
}
trait FromUsize: Sized {
fn from_usize(x: usize) -> Result<Self, io::Error>;
}
macro_rules! from_usize {
($t:ty) => {
impl FromUsize for $t {
#[inline]
fn from_usize(x: usize) -> io::Result<$t> {
if x > <$t>::MAX as usize {
Err(io::Error::new(
io::ErrorKind::InvalidInput,
"value too large to transmit",
))
} else {
Ok(x as $t)
}
}
}
};
}
from_usize!(i16);
from_usize!(i32);