synapse/rust/build.rs

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//! This build script calculates the hash of all files in the `src/`
//! directory and adds it as an environment variable during build time.
//!
//! This is used so that the python code can detect when the built native module
//! does not match the source in-tree, helping to detect the case where the
//! source has been updated but the library hasn't been rebuilt.
use std::path::PathBuf;
use blake2::{Blake2b512, Digest};
fn main() -> Result<(), std::io::Error> {
let mut dirs = vec![PathBuf::from("src")];
let mut paths = Vec::new();
while let Some(path) = dirs.pop() {
let mut entries = std::fs::read_dir(path)?
.map(|res| res.map(|e| e.path()))
.collect::<Result<Vec<_>, std::io::Error>>()?;
entries.sort();
for entry in entries {
if entry.is_dir() {
dirs.push(entry);
} else {
paths.push(entry.to_str().expect("valid rust paths").to_string());
}
}
}
paths.sort();
let mut hasher = Blake2b512::new();
for path in paths {
let bytes = std::fs::read(path)?;
hasher.update(bytes);
}
let hex_digest = hex::encode(hasher.finalize());
println!("cargo:rustc-env=SYNAPSE_RUST_DIGEST={hex_digest}");
Ok(())
}