macrotest/
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 = test_binary_lossy
36        .get(test_binary_lossy.len() - 17..)
37        .ok_or(Ignored)?;
38    if !hash.starts_with('-') || !hash[1..].bytes().all(is_lower_hex_digit) {
39        return Err(Ignored);
40    }
41
42    let binary_path = PathBuf::from(&test_binary);
43
44    // Feature selection is saved in:
45    //   /path/to/crate_name/target/debug/.fingerprint/*-HASH/*-HASH.json
46    let up = binary_path
47        .parent()
48        .ok_or(Ignored)?
49        .parent()
50        .ok_or(Ignored)?;
51    let fingerprint_dir = up.join(".fingerprint");
52    if !fingerprint_dir.is_dir() {
53        return Err(Ignored);
54    }
55
56    let mut hash_matches = Vec::new();
57    for entry in fingerprint_dir.read_dir()? {
58        let entry = entry?;
59        let is_dir = entry.file_type()?.is_dir();
60        let matching_hash = entry.file_name().to_string_lossy().ends_with(hash);
61        if is_dir && matching_hash {
62            hash_matches.push(entry.path());
63        }
64    }
65
66    if hash_matches.len() != 1 {
67        return Err(Ignored);
68    }
69
70    let mut json_matches = Vec::new();
71    for entry in hash_matches[0].read_dir()? {
72        let entry = entry?;
73        let is_file = entry.file_type()?.is_file();
74        let is_json = entry.path().extension() == Some(OsStr::new("json"));
75        if is_file && is_json {
76            json_matches.push(entry.path());
77        }
78    }
79
80    if json_matches.len() != 1 {
81        return Err(Ignored);
82    }
83
84    let build_json = fs::read_to_string(&json_matches[0])?;
85    let build: Build = serde_json::from_str(&build_json)?;
86    Ok(build.features)
87}
88
89fn is_lower_hex_digit(byte: u8) -> bool {
90    matches!(byte, b'0'..=b'9' | b'a'..=b'f')
91}
92
93fn from_json<'de, T, D>(deserializer: D) -> Result<T, D::Error>
94where
95    T: DeserializeOwned,
96    D: Deserializer<'de>,
97{
98    let json = String::deserialize(deserializer)?;
99    serde_json::from_str(&json).map_err(de::Error::custom)
100}
macrotest/features.rs

macrotest/
features.rs
