use std::convert::Infallible; use bstr::{BStr, BString, ByteSlice}; use crate::Scheme; /// The error returned by [parse()](crate::parse()).#[derive(Debug, thiserror::Error)]#[allow(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: url::ParseError,    },     #[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 },} 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")    }} ///#[derive(Debug, Clone, Copy)]pub enum UrlKind {    ///    Url,    ///    Scp,    ///    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,} pub(crate) fn find_scheme(input: &BStr) -> InputScheme {    // 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 };    }     if let Some(colon) = input.find_byte(b':') {        // 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} pub(crate) fn url(input: &BStr, protocol_end: usize) -> Result<crate::Url, Error> {    const MAX_LEN: usize = 1024;    let bytes_to_path = input[protocol_end + "://".len()..]        .iter()        .filter(|b| !b.is_ascii_whitespace())        .skip_while(|b| **b == b'/' || **b == b'\\')        .position(|b| *b == b'/')        .unwrap_or(input.len() - protocol_end);    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)?;    let scheme = url.scheme().into();     if matches!(scheme, Scheme::Git | Scheme::Ssh) && url.path().is_empty() {        return Err(Error::MissingRepositoryPath {            url: input.into(),            kind: UrlKind::Url,        });    }     if url.cannot_be_a_base() {        return Err(Error::RelativeUrl { url: input.to_owned() });    }     Ok(crate::Url {        serialize_alternative_form: false,        scheme,        user: url_user(&url),        password: url.password().map(Into::into),        host: url.host_str().map(Into::into),        port: url.port(),        path: url.path().into(),    })} 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.    let url = url::Url::parse(&format!("ssh://{host}")).map_err(|source| Error::Url {        url: input.to_owned(),        kind: UrlKind::Scp,        source,    })?;     Ok(crate::Url {        serialize_alternative_form: true,        scheme: url.scheme().into(),        user: url_user(&url),        password: url.password().map(Into::into),        host: url.host_str().map(Into::into),        port: url.port(),        path: path.into(),    })} fn url_user(url: &url::Url) -> Option<String> {    if url.username().is_empty() && url.password().is_none() {        None    } else {        Some(url.username().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,        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, url::Url), Error> {    let input = input_to_utf8(input, kind)?;    url::Url::parse(input)        .map(|url| (input, url))        .map_err(|source| Error::Url {            url: input.to_owned(),            kind,            source,        })}