rewrite relative readme links to repo blob/raw urls

@@ -3,17 +3,69 @@//! you use in a README), then run through ammonia so any inline <script>//! or other dangerous HTML in the markdown source is stripped.use pulldown_cmark::{Options, Parser};use pulldown_cmark::{CowStr, Event, Options, Parser, Tag};pub fn render(input: &str) -> String {/// Render a README's markdown to sanitized HTML. Relative link targets are/// prefixed with `link_base` (typically `/<name>/blob/<branch>`) and relative/// image targets with `image_base` (typically `/<name>/raw/<branch>`) so they/// resolve against the repo instead of the page's URL.pub fn render(input: &str, link_base: &str, image_base: &str) -> String {    let mut opts = Options::empty();    opts.insert(Options::ENABLE_TABLES);    opts.insert(Options::ENABLE_FOOTNOTES);    opts.insert(Options::ENABLE_STRIKETHROUGH);    opts.insert(Options::ENABLE_TASKLISTS);    opts.insert(Options::ENABLE_SMART_PUNCTUATION);    let parser = Parser::new_ext(input, opts);    let parser = Parser::new_ext(input, opts).map(|event| match event {        Event::Start(Tag::Link { link_type, dest_url, title, id }) => Event::Start(Tag::Link {            link_type,            dest_url: rewrite(&dest_url, link_base),            title,            id,        }),        Event::Start(Tag::Image { link_type, dest_url, title, id }) => Event::Start(Tag::Image {            link_type,            dest_url: rewrite(&dest_url, image_base),            title,            id,        }),        other => other,    });    let mut html = String::with_capacity(input.len());    pulldown_cmark::html::push_html(&mut html, parser);    ammonia::clean(&html)}/// Prefix a URL with `base` if it's a relative path (i.e. not absolute,/// protocol-relative, scheme-bearing, or a bare fragment).fn rewrite<'a>(url: &CowStr<'a>, base: &str) -> CowStr<'a> {    if url.is_empty()        || url.starts_with('/')        || url.starts_with('#')        || url.starts_with("//")        || has_scheme(url)    {        return url.clone();    }    let mut path: &str = url;    while let Some(rest) = path.strip_prefix("./") {        path = rest;    }    CowStr::from(format!("{}/{}", base.trim_end_matches('/'), path))}/// True if `url` begins with an RFC 3986 scheme (`http:`, `mailto:`, etc.).fn has_scheme(url: &str) -> bool {    let bytes = url.as_bytes();    if bytes.first().is_none_or(|b| !b.is_ascii_alphabetic()) {        return false;    }    for (i, &b) in bytes.iter().enumerate().skip(1) {        match b {            b':' => return i > 0,            b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' | b'+' | b'.' | b'-' => continue,            _ => return false,        }    }    false}

@@ -31,7 +31,11 @@ async fn repo_page(Path(name): Path<String>, State(state): State<AppState>) -> R        let readme_html = head.as_ref().and_then(|h| {            crate::git::read_readme(&repo, h.id).map(|(_, bytes)| {                let text = String::from_utf8_lossy(&bytes).into_owned();                crate::markdown::render(&text)                let link_base =                    format!("/{}/blob/{}", name_for_blocking, summary.default_branch);                let image_base =                    format!("/{}/raw/{}", name_for_blocking, summary.default_branch);                crate::markdown::render(&text, &link_base, &image_base)            })        });        Ok((summary, commits, readme_html))