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Auto merge of #15301 - bjorn3:uncompressed_dylib_metadata, r=lnicola

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Support reading uncompressed proc macro metadata

rust-lang/rust#113695 makes the dylib metadata uncompressed for perf reasons. This commit allows reading both the current compressed and future uncompressed dylib metadata.
This commit is contained in:
bors 2023-07-17 13:31:41 +00:00
commit 37f84c101b
1 changed files with 8 additions and 3 deletions
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11
crates/proc-macro-api/src/version.rs
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@ -135,7 +135,12 @@ pub fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
}
};
let mut snappy_decoder = SnapDecoder::new(snappy_portion);
let mut uncompressed: Box<dyn Read> = if &snappy_portion[0..4] == b"rust" {
// Not compressed.
Box::new(snappy_portion)
} else {
Box::new(SnapDecoder::new(snappy_portion))
};
// the bytes before version string bytes, so this basically is:
// 8 bytes for [b'r',b'u',b's',b't',0,0,0,5]
@ -144,11 +149,11 @@ pub fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
// so 13 bytes in total, and we should check the 13th byte
// to know the length
let mut bytes_before_version = [0u8; 13];
snappy_decoder.read_exact(&mut bytes_before_version)?;
uncompressed.read_exact(&mut bytes_before_version)?;
let length = bytes_before_version[12];
let mut version_string_utf8 = vec![0u8; length as usize];
snappy_decoder.read_exact(&mut version_string_utf8)?;
uncompressed.read_exact(&mut version_string_utf8)?;
let version_string = String::from_utf8(version_string_utf8);
version_string.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
}