trybuild_internals_api/
features.rs

1use serde::de::{self, Deserialize, DeserializeOwned, Deserializer};
2use serde_derive::Deserialize;
3use std::env;
4use std::error::Error;
5use std::ffi::OsStr;
6use std::fs;
7use std::path::PathBuf;
8
9pub fn find() -> Option<Vec<String>> {
10    try_find().ok()
11}
12
13struct Ignored;
14
15impl<E: Error> From<E> for Ignored {
16    fn from(_error: E) -> Self {
17        Ignored
18    }
19}
20
21#[derive(Deserialize)]
22struct Build {
23    #[serde(deserialize_with = "from_json")]
24    features: Vec<String>,
25}
26
27fn try_find() -> Result<Vec<String>, Ignored> {
28    // This will look something like:
29    //   /path/to/crate_name/target/debug/deps/test_name-HASH
30    let test_binary = env::args_os().next().ok_or(Ignored)?;
31
32    // The hash at the end is ascii so not lossy, rest of conversion doesn't
33    // matter.
34    let test_binary_lossy = test_binary.to_string_lossy();
35    let hash_range = if cfg!(windows) {
36        // Trim ".exe" from the binary name for windows.
37        test_binary_lossy.len() - 21..test_binary_lossy.len() - 4
38    } else {
39        test_binary_lossy.len() - 17..test_binary_lossy.len()
40    };
41    let hash = test_binary_lossy.get(hash_range).ok_or(Ignored)?;
42    if !hash.starts_with('-') || !hash[1..].bytes().all(is_lower_hex_digit) {
43        return Err(Ignored);
44    }
45
46    let binary_path = PathBuf::from(&test_binary);
47
48    // Feature selection is saved in:
49    //   /path/to/crate_name/target/debug/.fingerprint/*-HASH/*-HASH.json
50    let up = binary_path
51        .parent()
52        .ok_or(Ignored)?
53        .parent()
54        .ok_or(Ignored)?;
55    let fingerprint_dir = up.join(".fingerprint");
56    if !fingerprint_dir.is_dir() {
57        return Err(Ignored);
58    }
59
60    let mut hash_matches = Vec::new();
61    for entry in fingerprint_dir.read_dir()? {
62        let entry = entry?;
63        let is_dir = entry.file_type()?.is_dir();
64        let matching_hash = entry.file_name().to_string_lossy().ends_with(hash);
65        if is_dir && matching_hash {
66            hash_matches.push(entry.path());
67        }
68    }
69
70    if hash_matches.len() != 1 {
71        return Err(Ignored);
72    }
73
74    let mut json_matches = Vec::new();
75    for entry in hash_matches[0].read_dir()? {
76        let entry = entry?;
77        let is_file = entry.file_type()?.is_file();
78        let is_json = entry.path().extension() == Some(OsStr::new("json"));
79        if is_file && is_json {
80            json_matches.push(entry.path());
81        }
82    }
83
84    if json_matches.len() != 1 {
85        return Err(Ignored);
86    }
87
88    let build_json = fs::read_to_string(&json_matches[0])?;
89    let build: Build = serde_json::from_str(&build_json)?;
90    Ok(build.features)
91}
92
93fn is_lower_hex_digit(byte: u8) -> bool {
94    byte >= b'0' && byte <= b'9' || byte >= b'a' && byte <= b'f'
95}
96
97fn from_json<'de, T, D>(deserializer: D) -> Result<T, D::Error>
98where
99    T: DeserializeOwned,
100    D: Deserializer<'de>,
101{
102    let json = String::deserialize(deserializer)?;
103    serde_json::from_str(&json).map_err(de::Error::custom)
104}
trybuild_internals_api/features.rs

trybuild_internals_api/
features.rs
