Initial commit.

.gitignore

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+/target
+Cargo.lock

Cargo.toml

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+[package]
+name = "io-decompress"
+version = "0.1.0"
+authors = ["Anders Olsson <anders.e.olsson@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+bzip2 = "0.4"
+flate2 = "1.0"
+mime = "0.3"
+mime_guess = "2.0"

src/lib.rs

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+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
+
+use bzip2::read::BzDecoder;
+use flate2::read::GzDecoder;
+
+pub enum Reader {
+    Raw(File),
+    Gz(GzDecoder<File>),
+    Bz(BzDecoder<File>),
+}
+
+impl Read for Reader {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        match self {
+            Reader::Raw(file) => file.read(buf),
+            Reader::Gz(file) => file.read(buf),
+            Reader::Bz(file) => file.read(buf),
+        }
+    }
+}
+
+pub fn open<P>(path: P) -> Result<Reader, std::io::Error>
+where
+    P: AsRef<Path>,
+{
+    let file = File::open(&path)?;
+
+    Ok(match mime_guess::from_path(path).first_raw() {
+        Some("application/x-gzip") => Reader::Gz(GzDecoder::new(file)),
+        Some("application/x-bzip2") => Reader::Bz(BzDecoder::new(file)),
+        _ => Reader::Raw(file),
+    })
+}