From f9453e33c0a15a86a5044663bf91d605f01636e3 Mon Sep 17 00:00:00 2001 From: Ben Kimock Date: Sun, 10 Dec 2023 23:04:50 -0500 Subject: [PATCH] Apply suggestions from code review Co-authored-by: Waffle Maybe --- crates/proc-macro-api/src/version.rs | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/crates/proc-macro-api/src/version.rs b/crates/proc-macro-api/src/version.rs index 238fb561554..87118a62650 100644 --- a/crates/proc-macro-api/src/version.rs +++ b/crates/proc-macro-api/src/version.rs @@ -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 { } 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 { // 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)?;