aboutsummaryrefslogtreecommitdiff
path: root/crates/proc_macro_api/src/version.rs
diff options
context:
space:
mode:
Diffstat (limited to 'crates/proc_macro_api/src/version.rs')
-rw-r--r--crates/proc_macro_api/src/version.rs131
1 files changed, 131 insertions, 0 deletions
diff --git a/crates/proc_macro_api/src/version.rs b/crates/proc_macro_api/src/version.rs
new file mode 100644
index 000000000..80cd183a0
--- /dev/null
+++ b/crates/proc_macro_api/src/version.rs
@@ -0,0 +1,131 @@
1//! Reading proc-macro rustc version information from binary data
2
3use std::{
4 fs::File,
5 io::{self, Read},
6 path::Path,
7};
8
9use memmap::Mmap;
10use object::read::{File as BinaryFile, Object, ObjectSection};
11use snap::read::FrameDecoder as SnapDecoder;
12
13#[derive(Debug)]
14pub(crate) struct RustCInfo {
15 pub(crate) version: (usize, usize, usize),
16 pub(crate) channel: String,
17 pub(crate) commit: String,
18 pub(crate) date: String,
19}
20
21pub(crate) fn read_info(dylib_path: &Path) -> io::Result<RustCInfo> {
22 macro_rules! err {
23 ($e:literal) => {
24 io::Error::new(io::ErrorKind::InvalidData, $e)
25 };
26 }
27
28 let ver_str = read_version(dylib_path)?;
29 let mut items = ver_str.split_whitespace();
30 let tag = items.next().ok_or(err!("version format error"))?;
31 if tag != "rustc" {
32 return Err(err!("version format error (No rustc tag)"));
33 }
34
35 let version_part = items.next().ok_or(err!("no version string"))?;
36 let mut version_parts = version_part.split("-");
37 let version = version_parts.next().ok_or(err!("no version"))?;
38 let channel = version_parts.next().unwrap_or_default().to_string();
39
40 let commit = items.next().ok_or(err!("no commit info"))?;
41 // remove (
42 if commit.len() == 0 {
43 return Err(err!("commit format error"));
44 }
45 let commit = commit[1..].to_string();
46 let date = items.next().ok_or(err!("no date info"))?;
47 // remove )
48 if date.len() == 0 {
49 return Err(err!("date format error"));
50 }
51 let date = date[0..date.len() - 2].to_string();
52
53 let version_numbers = version
54 .split(".")
55 .map(|it| it.parse::<usize>())
56 .collect::<Result<Vec<_>, _>>()
57 .map_err(|_| err!("version number error"))?;
58
59 if version_numbers.len() != 3 {
60 return Err(err!("version number format error"));
61 }
62 let version = (version_numbers[0], version_numbers[1], version_numbers[2]);
63
64 Ok(RustCInfo { version, channel, commit, date })
65}
66
67// This is used inside read_version() to locate the ".rustc" section
68// from a proc macro crate's binary file.
69fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'a [u8]> {
70 BinaryFile::parse(dylib_binary)
71 .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?
72 .section_by_name(section_name)
73 .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, "section read error"))?
74 .data()
75 .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
76}
77
78// Check the version of rustc that was used to compile a proc macro crate's
79// binary file.
80// A proc macro crate binary's ".rustc" section has following byte layout:
81// * [b'r',b'u',b's',b't',0,0,0,5] is the first 8 bytes
82// * ff060000 734e6150 is followed, it's the snappy format magic bytes,
83// means bytes from here(including this sequence) are compressed in
84// snappy compression format. Version info is inside here, so decompress
85// this.
86// The bytes you get after decompressing the snappy format portion has
87// following layout:
88// * [b'r',b'u',b's',b't',0,0,0,5] is the first 8 bytes(again)
89// * [crate root bytes] next 4 bytes is to store crate root position,
90// according to rustc's source code comment
91// * [length byte] next 1 byte tells us how many bytes we should read next
92// for the version string's utf8 bytes
93// * [version string bytes encoded in utf8] <- GET THIS BOI
94// * [some more bytes that we don really care but still there] :-)
95// Check this issue for more about the bytes layout:
96// https://github.com/rust-analyzer/rust-analyzer/issues/6174
97fn read_version(dylib_path: &Path) -> io::Result<String> {
98 let dylib_file = File::open(dylib_path)?;
99 let dylib_mmaped = unsafe { Mmap::map(&dylib_file) }?;
100
101 let dot_rustc = read_section(&dylib_mmaped, ".rustc")?;
102
103 let header = &dot_rustc[..8];
104 const EXPECTED_HEADER: [u8; 8] = [b'r', b'u', b's', b't', 0, 0, 0, 5];
105 // check if header is valid
106 if header != EXPECTED_HEADER {
107 return Err(io::Error::new(
108 io::ErrorKind::InvalidData,
109 format!("only metadata version 5 is supported, section header was: {:?}", header),
110 ));
111 }
112
113 let snappy_portion = &dot_rustc[8..];
114
115 let mut snappy_decoder = SnapDecoder::new(snappy_portion);
116
117 // the bytes before version string bytes, so this basically is:
118 // 8 bytes for [b'r',b'u',b's',b't',0,0,0,5]
119 // 4 bytes for [crate root bytes]
120 // 1 byte for length of version string
121 // so 13 bytes in total, and we should check the 13th byte
122 // to know the length
123 let mut bytes_before_version = [0u8; 13];
124 snappy_decoder.read_exact(&mut bytes_before_version)?;
125 let length = bytes_before_version[12]; // what? can't use -1 indexing?
126
127 let mut version_string_utf8 = vec![0u8; length as usize];
128 snappy_decoder.read_exact(&mut version_string_utf8)?;
129 let version_string = String::from_utf8(version_string_utf8);
130 version_string.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
131}