use std::convert::Infallible; use bstr::{BStr, BString, ByteSlice}; use crate::Scheme; /// The error returned by [parse()](crate::parse()).#[derive(Debug, thiserror::Error)]#[expect(missing_docs)]pub enum Error {    #[error("{} \"{url}\" is not valid UTF-8", kind.as_str())]    Utf8 {        url: BString,        kind: UrlKind,        source: std::str::Utf8Error,    },    #[error("{} {url:?} can not be parsed as valid URL", kind.as_str())]    Url {        url: String,        kind: UrlKind,        source: crate::simple_url::UrlParseError,    },     #[error("The host portion of the following URL is too long ({} bytes, {len} bytes total): {truncated_url:?}", truncated_url.len())]    TooLong { truncated_url: BString, len: usize },    #[error("{} \"{url}\" does not specify a path to a repository", kind.as_str())]    MissingRepositoryPath { url: BString, kind: UrlKind },    #[error("URL {url:?} is relative which is not allowed in this context")]    RelativeUrl { url: String },    #[error("{name:?} is not a valid remote-helper name")]    InvalidRemoteHelperName { name: String },} impl From<Infallible> for Error {    fn from(_: Infallible) -> Self {        unreachable!("Cannot actually happen, but it seems there can't be a blanket impl for this")    }} /// The syntax used to interpret an input location.#[derive(Debug, Clone, Copy)]pub enum UrlKind {    /// A URL containing a `scheme://` separator.    Url,    /// An SCP-like SSH location such as `user@host:path`.    Scp,    /// A local filesystem path.    Local,} impl UrlKind {    fn as_str(&self) -> &'static str {        match self {            UrlKind::Url => "URL",            UrlKind::Scp => "SCP-like target",            UrlKind::Local => "local path",        }    }} pub(crate) enum InputScheme {    Url { protocol_end: usize },    Scp { colon: usize },    Local,    RemoteHelper { helper_end: usize },} /// Return the length of the leading remote-helper name if `input` uses the `<helper>::<address>` syntax/// of [`gitremote-helpers`](https://git-scm.com/docs/gitremote-helpers).pub(crate) fn is_valid_remote_helper_name(input: &[u8]) -> bool {    input.first().is_some_and(u8::is_ascii_alphanumeric)        && input[1..]            .iter()            .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'+' | b'-' | b'.'))} fn find_remote_helper_end(input: &BStr) -> Option<usize> {    let helper_end = input.find("::")?;    // Unlike Git, empty helper names are not accepted.    is_valid_remote_helper_name(&input[..helper_end]).then_some(helper_end)} pub(crate) fn find_scheme(input: &BStr) -> InputScheme {    // Git looks for the `<helper>::<address>` form, which happens before the location is examined as a URL.    // Hence this has to be checked first as well, as the address of a helper may itself contain `://`.    if let Some(helper_end) = find_remote_helper_end(input) {        return InputScheme::RemoteHelper { helper_end };    }     // TODO: url's may only contain `:/`, we should additionally check if the characters used for    //       protocol are all valid    if let Some(protocol_end) = input.find("://") {        return InputScheme::Url { protocol_end };    }     // Find colon, but skip over IPv6 brackets if present    let colon = if input.starts_with(b"[") {        // IPv6 address, find the closing bracket first        if let Some(bracket_end) = input.find_byte(b']') {            // Look for colon after the bracket            input[bracket_end + 1..]                .find_byte(b':')                .map(|pos| bracket_end + 1 + pos)        } else {            // No closing bracket, treat as regular search            input.find_byte(b':')        }    } else {        input.find_byte(b':')    };     if let Some(colon) = colon {        // allow user to select files containing a `:` by passing them as absolute or relative path        // this is behavior explicitly mentioned by the scp and git manuals        let explicitly_local = &input[..colon].contains(&b'/');        let dos_driver_letter = cfg!(windows) && input[..colon].len() == 1;         if !explicitly_local && !dos_driver_letter {            return InputScheme::Scp { colon };        }    }     InputScheme::Local} /// Parse remote-helper syntax like `codecommit::eu-central-1://repository`, with `helper_end` pointing at the first/// colon. This is only for the `<helper>::<address>` form; `<helper>://<address>` is parsed as a URL instead.pub(crate) fn remote_helper(input: &BStr, helper_end: usize) -> crate::Url {    let helper = input[..helper_end]        .to_str()        .expect("remote helper names consist of ASCII characters only");    crate::Url {        serialize_alternative_form: true,        path_with_percent_escapes: None,        // `ext` is special because callers need to know that its address is an executable command line.        scheme: if helper == "ext" {            Scheme::Ext        } else {            Scheme::Helper(helper.to_owned())        },        user: None,        password: None,        host: None,        port: None,        // The address is only meaningful to the helper program, so it's kept verbatim.        path: input[helper_end + "::".len()..].into(),    }} pub(crate) fn url(input: &BStr, protocol_end: usize) -> Result<crate::Url, Error> {    const MAX_LEN: usize = 1024;    let input_after_protocol = &input[protocol_end + "://".len()..];    let scheme = &input[..protocol_end];    let is_http = scheme == "http" || scheme == "https";    let bytes_to_path = input_after_protocol        .iter()        .filter(|b| !b.is_ascii_whitespace())        .skip_while(|b| **b == b'/' || **b == b'\\')        .position(|b| *b == b'/' || is_http && matches!(*b, b'?' | b'#'))        .unwrap_or(input_after_protocol.len());    if bytes_to_path > MAX_LEN || protocol_end > MAX_LEN {        return Err(Error::TooLong {            truncated_url: input[..(protocol_end + "://".len() + MAX_LEN).min(input.len())].into(),            len: input.len(),        });    }    let (input, url) = input_to_utf8_and_url(input, UrlKind::Url)?;    if url.scheme == "ext" {        return Ok(crate::Url {            serialize_alternative_form: true,            path_with_percent_escapes: None,            scheme: Scheme::Ext,            user: None,            password: None,            host: None,            port: None,            // Git passes the entire URL where git-remote-ext expects its command line. Keeping it verbatim makes            // `ext::ext://...` serialization preserve that argument while normalizing all uses to `Scheme::Ext`.            path: input.into(),        });    }    let scheme = Scheme::from(url.scheme.as_str());     if matches!(scheme, Scheme::Git | Scheme::Ssh) && url.path.is_empty() {        return Err(Error::MissingRepositoryPath {            url: input.into(),            kind: UrlKind::Url,        });    }     // Normalize empty path to "/" for http/https URLs only    let path: BString = if url.path.is_empty() && matches!(scheme, Scheme::Http | Scheme::Https) {        "/".into()    } else if matches!(scheme, Scheme::Ssh | Scheme::Git) && url.path.starts_with("/~") {        // For SSH and Git protocols, strip leading '/' from paths starting with '~'        // e.g., "ssh://host/~repo" -> path is "~repo", not "/~repo"        url.path[1..].into()    } else {        url.path.into()    };     let user = if url.username.is_empty() && url.password.is_none() {        None    } else {        Some(url.username)    };    let password = url.password;    let port = url.port;     // For SSH URLs, strip brackets from IPv6 addresses    let host = if scheme == Scheme::Ssh {        url.host.map(|mut h| {            // Bracketed IPv6 forms            if let Some(h2) = h.strip_prefix('[') {                if let Some(inner) = h2.strip_suffix("]:") {                    // "[::1]:" → "::1"                    h = inner.to_owned();                } else if let Some(inner) = h2.strip_suffix(']') {                    // "[::1]" → "::1"                    h = inner.to_owned();                }            } else {                // Non-bracketed host: strip a single trailing colon                let colon_count = h.chars().filter(|&c| c == ':').take(2).count();                if colon_count == 1                    && let Some(inner) = h.strip_suffix(':')                {                    h = inner.to_string();                }            }            h        })    } else {        url.host    };    let path_with_percent_escapes = url.path_with_percent_escapes.map(Into::into);    Ok(crate::Url {        serialize_alternative_form: false,        path_with_percent_escapes,        scheme,        user,        password,        host,        port,        path,    })} pub(crate) fn scp(input: &BStr, colon: usize) -> Result<crate::Url, Error> {    let input = input_to_utf8(input, UrlKind::Scp)?;     // TODO: this incorrectly splits at IPv6 addresses, check for `[]` before splitting    let (host, path) = input.split_at(colon);    debug_assert_eq!(path.get(..1), Some(":"), "{path} should start with :");    let path = &path[1..];     if path.is_empty() {        return Err(Error::MissingRepositoryPath {            url: input.to_owned().into(),            kind: UrlKind::Scp,        });    }     // The path returned by the parsed url often has the wrong number of leading `/` characters but    // should never differ in any other way (ssh URLs should not contain a query or fragment part).    // To avoid the various off-by-one errors caused by the `/` characters, we keep using the path    // determined above and can therefore skip parsing it here as well.    // Split at the last `@`, just as OpenSSH does. Feeding the user through URL parsing would mistake `:` for a    // password delimiter even though SCP-like syntax cannot represent passwords.    let (user, host) = host        .rsplit_once('@')        .map_or((None, host), |(user, host)| (Some(user.to_owned()), host));    // In SCP-like syntax `%` is literal host data, but the synthesized URL parser treats it as an escape introducer.    let url_string = format!("ssh://{}", host.replace('%', "%25"));    let url = crate::simple_url::ParsedUrl::parse(&url_string).map_err(|source| Error::Url {        url: input.to_owned(),        kind: UrlKind::Scp,        source,    })?;     // For SCP-like SSH URLs, strip leading '/' from paths starting with '/~'    // e.g., "user@host:/~repo" -> path is "~repo", not "/~repo"    let path = if path.starts_with("/~") { &path[1..] } else { path };     let port = url.port;     // For SCP-like SSH URLs, strip brackets from IPv6 addresses    let host = url.host.map(|h| {        if let Some(h) = h.strip_prefix("[").and_then(|h| h.strip_suffix("]")) {            h.to_string()        } else {            h        }    });     Ok(crate::Url {        serialize_alternative_form: true,        path_with_percent_escapes: None,        scheme: Scheme::from(url.scheme.as_str()),        user,        password: None,        host,        port,        path: path.into(),    })} pub(crate) fn file_url(input: &BStr, protocol_colon: usize) -> Result<crate::Url, Error> {    let input = input_to_utf8(input, UrlKind::Url)?;    let input_after_protocol = &input[protocol_colon + "://".len()..];     let Some(first_slash) = input_after_protocol        .find('/')        .or_else(|| cfg!(windows).then(|| input_after_protocol.find('\\')).flatten())    else {        return Err(Error::MissingRepositoryPath {            url: input.to_owned().into(),            kind: UrlKind::Url,        });    };     // We cannot use the url crate to parse host and path because it special cases Windows    // driver letters. With the url crate an input of `file://x:/path/to/git` is parsed as empty    // host and with `x:/path/to/git` as path. This behavior is wrong for Git which only follows    // that rule on Windows and parses `x:` as host on Unix platforms. Additionally, the url crate    // does not account for Windows special UNC path support.     // TODO: implement UNC path special case    let windows_special_path = if cfg!(windows) {        // Inputs created via url::Url::from_file_path contain an additional `/` between the        // protocol and the absolute path. Make sure we ignore that first slash character to avoid        // producing invalid paths.        let input_after_protocol = if first_slash == 0 {            &input_after_protocol[1..]        } else {            input_after_protocol        };        // parse `file://x:/path/to/git` as explained above        if input_after_protocol.chars().nth(1) == Some(':') {            Some(input_after_protocol)        } else {            None        }    } else {        None    };     let host = if windows_special_path.is_some() || first_slash == 0 {        // `file:///path/to/git` or a windows special case was triggered        None    } else {        // `file://host/path/to/git`        Some(&input_after_protocol[..first_slash])    };     // default behavior on Unix platforms and if no Windows special case was triggered    let path = windows_special_path.unwrap_or(&input_after_protocol[first_slash..]);     Ok(crate::Url {        serialize_alternative_form: false,        host: host.map(Into::into),        ..local(path.into())?    })} pub(crate) fn local(input: &BStr) -> Result<crate::Url, Error> {    if input.is_empty() {        return Err(Error::MissingRepositoryPath {            url: input.to_owned(),            kind: UrlKind::Local,        });    }     Ok(crate::Url {        serialize_alternative_form: true,        path_with_percent_escapes: None,        scheme: Scheme::File,        password: None,        user: None,        host: None,        port: None,        path: input.to_owned(),    })} fn input_to_utf8(input: &BStr, kind: UrlKind) -> Result<&str, Error> {    std::str::from_utf8(input).map_err(|source| Error::Utf8 {        url: input.to_owned(),        kind,        source,    })} fn input_to_utf8_and_url(input: &BStr, kind: UrlKind) -> Result<(&str, crate::simple_url::ParsedUrl), Error> {    let input = input_to_utf8(input, kind)?;    crate::simple_url::ParsedUrl::parse(input)        .map(|url| (input, url))        .map_err(|source| {            // If the parser rejected it as RelativeUrlWithoutBase, map to Error::RelativeUrl            // to match the expected error type for malformed URLs like "invalid:://"            match source {                crate::simple_url::UrlParseError::RelativeUrlWithoutBase => {                    Error::RelativeUrl { url: input.to_owned() }                }                _ => Error::Url {                    url: input.to_owned(),                    kind,                    source,                },            }        })}