uv/crates/uv-python/src/py_launcher.rs

99 lines
3.4 KiB
Rust

use crate::PythonVersion;
use std::cmp::Ordering;
use std::path::PathBuf;
use std::str::FromStr;
use tracing::debug;
use windows_registry::{Key, CURRENT_USER, LOCAL_MACHINE};
/// A Python interpreter found in the Windows registry through PEP 514 or from a known Microsoft
/// Store path.
///
/// There are a lot more (optional) fields defined in PEP 514, but we only care about path and
/// version here, for everything else we probe with a Python script.
#[derive(Debug, Clone)]
pub(crate) struct WindowsPython {
pub(crate) path: PathBuf,
pub(crate) version: Option<PythonVersion>,
}
/// Find all Pythons registered in the Windows registry following PEP 514.
pub(crate) fn registry_pythons() -> Result<Vec<WindowsPython>, windows_result::Error> {
let mut registry_pythons = Vec::new();
for root_key in [CURRENT_USER, LOCAL_MACHINE] {
let Ok(key_python) = root_key.open(r"Software\Python") else {
continue;
};
for company in key_python.keys()? {
// Reserved name according to the PEP.
if company == "PyLauncher" {
continue;
}
let Ok(company_key) = key_python.open(&company) else {
// Ignore invalid entries
continue;
};
for tag in company_key.keys()? {
let tag_key = company_key.open(&tag)?;
if let Some(registry_python) = read_registry_entry(&company, &tag, &tag_key) {
registry_pythons.push(registry_python);
}
}
}
}
// The registry has no natural ordering, so we're processing the latest version first.
registry_pythons.sort_by(|a, b| {
match (&a.version, &b.version) {
// Place entries with a version before those without a version.
(Some(_), None) => Ordering::Greater,
(None, Some(_)) => Ordering::Less,
// We want the highest version on top, which is the inverse from the regular order. The
// path is an arbitrary but stable tie-breaker.
(Some(version_a), Some(version_b)) => {
version_a.cmp(version_b).reverse().then(a.path.cmp(&b.path))
}
// Sort the entries without a version arbitrarily, but stable (by path).
(None, None) => a.path.cmp(&b.path),
}
});
Ok(registry_pythons)
}
fn read_registry_entry(company: &str, tag: &str, tag_key: &Key) -> Option<WindowsPython> {
// `ExecutablePath` is mandatory for executable Pythons.
let Ok(executable_path) = tag_key
.open("InstallPath")
.and_then(|install_path| install_path.get_value("ExecutablePath"))
.and_then(String::try_from)
else {
debug!(
r"Python interpreter in the registry is not executable: `Software\Python\{}\{}",
company, tag
);
return None;
};
// `SysVersion` is optional.
let version = tag_key
.get_value("SysVersion")
.and_then(String::try_from)
.ok()
.and_then(|s| match PythonVersion::from_str(&s) {
Ok(version) => Some(version),
Err(err) => {
debug!(
"Skipping Python interpreter ({executable_path}) \
with invalid registry version {s}: {err}",
);
None
}
});
Some(WindowsPython {
path: PathBuf::from(executable_path),
version,
})
}