Apply suggestions from code review

Co-authored-by: Waffle Maybe <waffle.lapkin@gmail.com>
This commit is contained in:
Ben Kimock 2023-12-10 23:04:50 -05:00
parent 5ef5e55749
commit f9453e33c0

View File

@ -85,8 +85,8 @@ fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'
}
/// Check the version of rustc that was used to compile a proc macro crate's
///
/// binary file.
///
/// A proc macro crate binary's ".rustc" section has following byte layout:
/// * [b'r',b'u',b's',b't',0,0,0,5] is the first 8 bytes
/// * ff060000 734e6150 is followed, it's the snappy format magic bytes,
@ -96,8 +96,8 @@ fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'
/// The bytes you get after decompressing the snappy format portion has
/// following layout:
/// * [b'r',b'u',b's',b't',0,0,0,5] is the first 8 bytes(again)
/// * [crate root bytes] next 4 bytes is to store crate root position,
/// according to rustc's source code comment
/// * [crate root bytes] next 8 bytes (4 in old versions) is to store
/// crate root position, according to rustc's source code comment
/// * [length byte] next 1 byte tells us how many bytes we should read next
/// for the version string's utf8 bytes
/// * [version string bytes encoded in utf8] <- GET THIS BOI
@ -119,7 +119,7 @@ pub fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
}
let version = u32::from_be_bytes([dot_rustc[4], dot_rustc[5], dot_rustc[6], dot_rustc[7]]);
// Last supported version is:
// https://github.com/rust-lang/rust/commit/0696e79f2740ad89309269b460579e548a5cd632
// https://github.com/rust-lang/rust/commit/b94cfefc860715fb2adf72a6955423d384c69318
let (snappy_portion, bytes_before_version) = match version {
5 | 6 => (&dot_rustc[8..], 13),
7 | 8 => {
@ -153,9 +153,9 @@ pub fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
// 1 byte for length of version string
// so 13 or 17 bytes in total, and we should check the last of those bytes
// to know the length
let mut bytes_before_version = vec![0u8; bytes_before_version];
uncompressed.read_exact(&mut bytes_before_version)?;
let length = *bytes_before_version.last().unwrap();
let mut bytes = [0u8; 17];
uncompressed.read_exact(&mut bytes[..bytes_before_version])?;
let length = bytes[bytes_before_version - 1];
let mut version_string_utf8 = vec![0u8; length as usize];
uncompressed.read_exact(&mut version_string_utf8)?;