use crate::repo::Repo; use std::io; #[derive(Debug)] pub enum RequirementsError { // TODO: include a path? Io(io::Error), /// The `requires` file is corrupted Corrupted, /// The repository requires a feature that we don't support Unsupported { feature: String, }, } fn parse(bytes: &[u8]) -> Result, ()> { // The Python code reading this file uses `str.splitlines` // which looks for a number of line separators (even including a couple of // non-ASCII ones), but Python code writing it always uses `\n`. let lines = bytes.split(|&byte| byte == b'\n'); lines .filter(|line| !line.is_empty()) .map(|line| { // Python uses Unicode `str.isalnum` but feature names are all // ASCII if line[0].is_ascii_alphanumeric() && line.is_ascii() { Ok(String::from_utf8(line.into()).unwrap()) } else { Err(()) } }) .collect() } pub fn load(repo: &Repo) -> Result, RequirementsError> { match repo.hg_vfs().read("requires") { Ok(bytes) => parse(&bytes).map_err(|()| RequirementsError::Corrupted), // Treat a missing file the same as an empty file. // From `mercurial/localrepo.py`: // > requires file contains a newline-delimited list of // > features/capabilities the opener (us) must have in order to use // > the repository. This file was introduced in Mercurial 0.9.2, // > which means very old repositories may not have one. We assume // > a missing file translates to no requirements. Err(error) if error.kind() == std::io::ErrorKind::NotFound => { Ok(Vec::new()) } Err(error) => Err(RequirementsError::Io(error))?, } } pub fn check(repo: &Repo) -> Result<(), RequirementsError> { for feature in load(repo)? { if !SUPPORTED.contains(&&*feature) { return Err(RequirementsError::Unsupported { feature }); } } Ok(()) } // TODO: set this to actually-supported features const SUPPORTED: &[&str] = &[ "dotencode", "fncache", "generaldelta", "revlogv1", "sparserevlog", "store", // As of this writing everything rhg does is read-only. // When it starts writing to the repository, it’ll need to either keep the // persistent nodemap up to date or remove this entry: "persistent-nodemap", ];