Extend FromPyObject to support any object supporting the buffer proto…

…col when possible.

src/types/bytes.rs

@@ -5,7 +5,10 @@ use std::os::raw::c_char;
 use std::slice::SliceIndex;
 use std::str;
 
-use super::bytearray::PyByteArray;
+#[cfg(any(not(Py_LIMITED_API), Py_3_11))]
+use crate::buffer::PyBuffer;
+#[cfg(all(Py_LIMITED_API, not(Py_3_11)))]
+use crate::types::PyByteArray;
 
 /// Represents a Python `bytes` object.
 ///
@@ -129,7 +132,21 @@ impl<I: SliceIndex<[u8]>> Index<I> for PyBytes {
 /// If the source object is a `bytes` object, the `Cow` will be borrowed and
 /// pointing into the source object, and no copying or heap allocations will happen.
 /// If it is a `bytearray`, its contents will be copied to an owned `Cow`.
+///
+/// When not using the limited API or Python 3.11 or later, this will accept any object
+/// containing bytes and supporting the buffer protocol in addition to`bytearray`.
 impl<'source> FromPyObject<'source> for Cow<'source, [u8]> {
+    #[cfg(any(not(Py_LIMITED_API), Py_3_11))]
+    fn extract(ob: &'source PyAny) -> PyResult<Self> {
+        if let Ok(bytes) = ob.downcast::<PyBytes>() {
+            return Ok(Cow::Borrowed(bytes.as_bytes()));
+        }
+
+        let buffer = PyBuffer::<u8>::get(ob)?;
+        buffer.to_vec(ob.py()).map(Cow::Owned)
+    }
+
+    #[cfg(all(Py_LIMITED_API, not(Py_3_11)))]
     fn extract(ob: &'source PyAny) -> PyResult<Self> {
         if let Ok(bytes) = ob.downcast::<PyBytes>() {
             return Ok(Cow::Borrowed(bytes.as_bytes()));
@@ -215,6 +232,15 @@ mod tests {
             let cow = byte_array.extract::<Cow<'_, [u8]>>().unwrap();
             assert_eq!(cow, Cow::<[u8]>::Owned(b"foobar".to_vec()));
 
+            #[cfg(any(not(Py_LIMITED_API), Py_3_11))]
+            {
+                let array = py
+                    .eval(r#"__import__("array").array('B', b"foobar")"#, None, None)
+                    .unwrap();
+                let cow = array.extract::<Cow<'_, [u8]>>().unwrap();
+                assert_eq!(cow, Cow::<[u8]>::Owned(b"foobar".to_vec()));
+            }
+
             let something_else_entirely = py.eval("42", None, None).unwrap();
             something_else_entirely
                 .extract::<Cow<'_, [u8]>>()