Implement Read for Reader, wrapping archive_read_data()

src/reader.rs

@@ -63,6 +63,20 @@ pub trait Reader : Handle {
     }
 }
 
+impl Read for Reader {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let cbuf = buf.as_mut_ptr() as *mut c_void;
+        unsafe {
+            match ffi::archive_read_data(self.handle(), cbuf, buf.len()) {
+                n if n >= 0 => Ok(n as usize),
+                // Libarchive returns OS errors, but has more specific error strings (err_msg()).
+                // Not sure how to include that in the io::Error struct.
+                _ => Err(io::Error::from_raw_os_error(self.err_code().0)),
+            }
+        }
+    }
+}
+
 pub struct FileReader {
     handle: *mut ffi::Struct_archive,
     entry: ReaderEntry,