Improve mime detection

src/common/mime_types.rs

@@ -26,16 +26,38 @@ impl TryFrom<&str> for MimeType {
     }
 }
 
+fn read_mb(path: &Path) -> Result<(std::fs::Metadata, Vec<u8>)> {
+    let metadata = std::fs::metadata(path)?;
+    let data = if metadata.len() <= 1024 {
+        std::fs::read(path)?
+    } else {
+        use std::io::prelude::*;
+        let mut buffer = Vec::with_capacity(1024);
+        let reader = std::io::BufReader::new(std::fs::File::open(path)?);
+        reader.take(1024).read_exact(&mut buffer)?;
+        buffer
+    };
+    Ok((metadata, data))
+}
+
 impl TryFrom<&Path> for MimeType {
     type Error = Error;
     fn try_from(path: &Path) -> Result<Self> {
-        let guess = SHARED_MIME_DB.guess_mime_type().path(path).guess();
-        let guess = guess.mime_type().clone();
+        let file_name = path.file_name().unwrap_or_default().to_string_lossy();
 
-        if guess == mime::APPLICATION_OCTET_STREAM {
-            Err(Error::Ambiguous(path.to_string_lossy().into()))
-        } else {
-            Ok(Self(guess))
+        match &*SHARED_MIME_DB.get_mime_types_from_file_name(&file_name) {
+            [t, ..] if t == &mime::APPLICATION_OCTET_STREAM => Ok(Self({
+                let (meta, data) = read_mb(path)?;
+                SHARED_MIME_DB
+                    .guess_mime_type()
+                    .metadata(meta)
+                    .data(&data)
+                    .guess()
+                    .mime_type()
+                    .clone()
+            })),
+            [other, ..] => Ok(Self(other.clone())),
+            _ => Err(Error::Ambiguous(path.to_string_lossy().into())),
         }
     }
 }