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This commit is contained in:
Edwin Cheng 2021-03-10 04:54:31 +08:00
parent cc8c40480a
commit ad34e79bb9
1 changed files with 22 additions and 21 deletions
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43
crates/proc_macro_api/src/version.rs
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@ -64,8 +64,8 @@ pub(crate) fn read_info(dylib_path: &Path) -> io::Result<RustCInfo> {
Ok(RustCInfo { version, channel, commit, date })
}
// This is used inside read_version() to locate the ".rustc" section
// from a proc macro crate's binary file.
/// This is used inside read_version() to locate the ".rustc" section
/// from a proc macro crate's binary file.
fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'a [u8]> {
BinaryFile::parse(dylib_binary)
.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?
@ -75,25 +75,26 @@ fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'
.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
}
// 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,
// means bytes from here(including this sequence) are compressed in
// snappy compression format. Version info is inside here, so decompress
// this.
// 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
// * [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
// * [some more bytes that we don really care but still there] :-)
// Check this issue for more about the bytes layout:
// https://github.com/rust-analyzer/rust-analyzer/issues/6174
/// 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,
/// means bytes from here(including this sequence) are compressed in
/// snappy compression format. Version info is inside here, so decompress
/// this.
/// 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
/// * [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
/// * [some more bytes that we don really care but still there] :-)
/// Check this issue for more about the bytes layout:
/// https://github.com/rust-analyzer/rust-analyzer/issues/6174
fn read_version(dylib_path: &Path) -> io::Result<String> {
let dylib_file = File::open(dylib_path)?;
let dylib_mmaped = unsafe { Mmap::map(&dylib_file) }?;