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Use u8 slice instead of Bytes in function argument.

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Bytes is handy, but in decode_pg_control's case it's just complicating
things. Also, pass ControlFileData by ref to encode_pg_control().
This commit is contained in:
Heikki Linnakangas
2021-06-04 23:05:20 +03:00
parent d18cc8a3a8
commit 8147aa7e93
2 changed files with 27 additions and 16 deletions
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9
pageserver/src/branches.rs
View File

@@ -5,7 +5,6 @@
//
use anyhow::{anyhow, bail, Context, Result};
use bytes::Bytes;
use fs::File;
use postgres_ffi::{controlfile_utils, pg_constants, xlog_utils};
use rand::Rng;
@@ -80,7 +79,7 @@ pub fn init_repo(conf: &'static PageServerConf, repo_dir: &Path) -> Result<()> {
// Read control file to extract the LSN and system id
let controlfile_path = tmppath.join("global").join("pg_control");
let controlfile = controlfile_utils::decode_pg_control(Bytes::from(fs::read(controlfile_path)?))?;
let controlfile = controlfile_utils::decode_pg_control(&fs::read(controlfile_path)?)?;
// let systemid = controlfile.system_identifier;
let lsn = controlfile.checkPoint;
let lsnstr = format!("{:016X}", lsn);
@@ -212,7 +211,7 @@ pub(crate) fn get_system_id(conf: &PageServerConf) -> Result<u64> {
let (_, main_snap_dir) = find_latest_snapshot(conf, *main_tli)?;
let controlfile_path = main_snap_dir.join("global").join("pg_control");
let controlfile = controlfile_utils::decode_pg_control(Bytes::from(fs::read(controlfile_path)?))?;
let controlfile = controlfile_utils::decode_pg_control(&fs::read(controlfile_path)?)?;
Ok(controlfile.system_identifier)
}
@@ -356,13 +355,13 @@ fn force_crash_recovery(datadir: &Path) -> Result<()> {
// Read in the control file
let controlfilepath = datadir.to_path_buf().join("global").join("pg_control");
let mut controlfile =
controlfile_utils::decode_pg_control(Bytes::from(fs::read(controlfilepath.as_path())?))?;
controlfile_utils::decode_pg_control(&fs::read(controlfilepath.as_path())?)?;
controlfile.state = postgres_ffi::DBState_DB_IN_PRODUCTION;
fs::write(
controlfilepath.as_path(),
controlfile_utils::encode_pg_control(controlfile),
controlfile_utils::encode_pg_control(&controlfile),
)?;
Ok(())

34
postgres_ffi/src/controlfile_utils.rs
View File

@@ -25,28 +25,36 @@
//!
use crate::{ControlFileData, PG_CONTROLFILEDATA_OFFSETOF_CRC, PG_CONTROL_FILE_SIZE};
use bytes::{Buf, Bytes, BytesMut};
use anyhow::{bail, Result};
use bytes::{Bytes, BytesMut};
// sizeof(ControlFileData)
const SIZEOF_CONTROLDATA: usize = std::mem::size_of::<ControlFileData>();
// offsetof(ControlFileData, crc)
const OFFSETOF_CRC: usize = PG_CONTROLFILEDATA_OFFSETOF_CRC as usize;
pub fn decode_pg_control(mut buf: Bytes) -> Result<ControlFileData, anyhow::Error> {
let mut b: [u8; SIZEOF_CONTROLDATA] = [0u8; SIZEOF_CONTROLDATA];
buf.copy_to_slice(&mut b);
///
/// Interpret a slice of bytes as a Postgres control file.
///
pub fn decode_pg_control(buf: &[u8]) -> Result<ControlFileData> {
// Check that the slice has the expected size. The control file is
// padded with zeros up to a 512 byte sector size, so accept a
// larger size too, so that the caller can just the whole file
// contents without knowing the exact size of the struct.
if buf.len() < SIZEOF_CONTROLDATA {
bail!("control file is too short");
}
let controlfile: ControlFileData;
// TODO: verify CRC
let mut data_without_crc: [u8; OFFSETOF_CRC] = [0u8; OFFSETOF_CRC];
data_without_crc.copy_from_slice(&b[0..OFFSETOF_CRC]);
let expectedcrc = crc32c::crc32c(&data_without_crc);
let mut b: [u8; SIZEOF_CONTROLDATA] = [0u8; SIZEOF_CONTROLDATA];
b.copy_from_slice(&buf[0..SIZEOF_CONTROLDATA]);
let expectedcrc = crc32c::crc32c(&b[0..OFFSETOF_CRC]);
controlfile = unsafe { std::mem::transmute::<[u8; SIZEOF_CONTROLDATA], ControlFileData>(b) };
if expectedcrc != controlfile.crc {
anyhow::bail!(
bail!(
"invalid CRC in control file: expected {:08X}, was {:08X}",
expectedcrc,
controlfile.crc
@@ -56,10 +64,14 @@ pub fn decode_pg_control(mut buf: Bytes) -> Result<ControlFileData, anyhow::Erro
Ok(controlfile)
}
pub fn encode_pg_control(controlfile: ControlFileData) -> Bytes {
///
/// Convert a struct representing a Postgres control file into raw bytes.
///
/// The CRC is recomputed to match the contents of the fields.
pub fn encode_pg_control(controlfile: &ControlFileData) -> Bytes {
let b: [u8; SIZEOF_CONTROLDATA];
b = unsafe { std::mem::transmute::<ControlFileData, [u8; SIZEOF_CONTROLDATA]>(controlfile) };
b = unsafe { std::mem::transmute::<ControlFileData, [u8; SIZEOF_CONTROLDATA]>(*controlfile) };
// Recompute the CRC
let mut data_without_crc: [u8; OFFSETOF_CRC] = [0u8; OFFSETOF_CRC];