94 lines
2.9 KiB
Rust
94 lines
2.9 KiB
Rust
use cfg_if::cfg_if;
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use mime_guess::Mime;
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pub trait MimeDb {
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fn init() -> Self;
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fn get_type(&self, data: &[u8]) -> Option<Mime>;
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}
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cfg_if! {
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if #[cfg(any(all(not(target_os = "linux"), not(feature = "xdg-mime-backend")), all(target_os = "linux", feature = "infer-backend")))] {
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use std::str::FromStr;
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pub struct InferDb {
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db: infer::Infer,
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}
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fn open_document_check(buf: &[u8], kind: &str) -> bool {
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let mime = format!("application/vnd.oasis.opendocument.{}", kind);
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let mime = mime.as_bytes();
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buf.len() > 38 + mime.len() && buf.starts_with(b"PK\x03\x04") && buf[38..mime.len() + 38] == mime[..]
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}
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impl MimeDb for InferDb {
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fn init() -> Self {
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let mut info = infer::Infer::new();
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info.add("application/vnd.oasis.opendocument.text", "odt", |buf| {
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open_document_check(buf, "text")
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});
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info.add("application/vnd.oasis.opendocument.spreadsheet", "ods", |buf| {
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open_document_check(buf, "spreadsheet")
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});
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info.add("application/vnd.oasis.opendocument.presentation", "odp", |buf| {
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open_document_check(buf, "presentation")
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});
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info.add("image/svg+xml", "svg", |buf| {
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// before doing the moderately expensive SVG check, we should make sure that the input is actually SGML-ish
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// by "SGML-ish", i mean starts with anywhere from zero to ∞-1 whitespace characters, and then a less than sign,
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// and then there's some other stuff we don't care about right now
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// so, here comes our fancy pants """""SGML-ish validator"""""
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for c in buf {
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match c {
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// whitespace (according to https://www.w3.org/TR/xml/#NT-S)
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b'\t' | b'\r' | b'\n' | b'\x20' => continue,
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b'<' => break,
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_ => return false,
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}
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}
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// finally, to check whether or not the file is an SVG:
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// - split the buffer up into chunks separated by the less than sign
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// - check to see if this chunk starts with any of these identifiers:
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let identifiers: Vec<&[u8]> = vec![b"svg", b"SVG", b"!DOCTYPE svg", b"!DOCTYPE SVG"];
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// - if it does, the nested `any` will short circuit and immediately return true, causing the parent `any` to do
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// the same
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// - and finally, if none of the chunks match, we'll return false
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// TODO: this is kind of messy, i'd like to clean it up somehow :(
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buf
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.split(|c| *c == b'<')
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.any(|buf| identifiers.iter().any(|id| buf.starts_with(id)))
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});
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// unmut
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let info = info;
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Self { db: info }
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}
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fn get_type(&self, data: &[u8]) -> Option<Mime> {
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self.db.get(data).map(|f| Mime::from_str(f.mime_type()).unwrap())
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}
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}
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} else {
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pub struct XdgDb {
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db: xdg_mime::SharedMimeInfo,
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}
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impl MimeDb for XdgDb {
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fn init() -> Self {
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Self { db: xdg_mime::SharedMimeInfo::new() }
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}
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fn get_type(&self, data: &[u8]) -> Option<Mime> {
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self.db.get_mime_type_for_data(data).map(|m| m.0)
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}
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}
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}
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}
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