Reader shouldn't require its inner type to be a mutable reference

[wgreenberg]

This makes Reader more general, so it can e.g. take ownership of a Read + Seek type.

[wcampbell0x2a]

Seem plausible, I needed to do the following in backhand for this patch:

diff --git a/backhand/src/metadata.rs b/backhand/src/metadata.rs
index 89b4994..bf76adf 100644
--- a/backhand/src/metadata.rs
+++ b/backhand/src/metadata.rs
@@ -117,12 +117,13 @@ pub fn read_block<R: Read + Seek>(
     superblock: &SuperBlock,
     kind: &Kind,
 ) -> Result<Vec<u8>, BackhandError> {
-    let mut deku_reader = Reader::new(reader);
+    let mut deku_reader = Reader::new(&mut *reader);
     let metadata_len = u16::from_reader_with_ctx(&mut deku_reader, kind.inner.data_endian)?;

     let byte_len = len(metadata_len);
     tracing::trace!("len: 0x{:02x?}", byte_len);
     let mut buf = vec![0u8; byte_len as usize];
+    // deku_reader.as_mut().read_exact(&mut buf)?; // or this instead of the above
     reader.read_exact(&mut buf)?;

     let bytes = if is_compressed(metadata_len) {
diff --git a/backhand/src/squashfs.rs b/backhand/src/squashfs.rs
index b4420c5..2240d3c 100644
--- a/backhand/src/squashfs.rs
+++ b/backhand/src/squashfs.rs
@@ -225,7 +225,7 @@ impl<'b> Squashfs<'b> {
         kind: &Kind,
     ) -> Result<(SuperBlock, Option<CompressionOptions>), BackhandError> {
         // Parse SuperBlock
-        let mut container = Reader::new(reader);
+        let mut container = Reader::new(&mut *reader);
         let superblock = SuperBlock::from_reader_with_ctx(
             &mut container,
             (

[wgreenberg]

ack, it turns out this is something of a compiler limitation: rust won't automatically reborrow generics, hence why you have to manually reborrow. one way to rewrite backhand's usage would be:

            let mut my_reader = Reader::new(reader);
            _ = u16::from_reader_with_ctx(&mut my_reader, ()).unwrap();

            let reader = my_reader.into_inner();
            reader.read_exact(&mut vec![0; 10]).unwrap();

but i understand if you think this is too obtuse

[wcampbell0x2a]

ack, it turns out this is something of a compiler limitation: rust won't automatically reborrow generics, hence why you have to manually reborrow. one way to rewrite backhand's usage would be:

            let mut my_reader = Reader::new(reader);
            _ = u16::from_reader_with_ctx(&mut my_reader, ()).unwrap();

            let reader = my_reader.into_inner();
            reader.read_exact(&mut vec![0; 10]).unwrap();

but i understand if you think this is too obtuse

I'm not against the change, it's technically less restrictive. Do you have a source for the "rust won't automatically reborrow generics"?, I've run into this before and never went any further into research of the problem.