feat: better error message when reader feather v1

src/ffi/array.rs

@@ -209,7 +209,7 @@
     let ptr = *buffers.add(index);
     if ptr.is_null() {
         return Err(Error::oos(format!(
-            "An array of type {data_type:?}
+            "An array of type {data_type:?} 
             must have a non-null buffer {index}"
         )));
     }
@@ -235,9 +235,14 @@
     owner: InternalArrowArray,
     index: usize,
 ) -> Result<Buffer<T>> {
+    let len = buffer_len(array, data_type, index)?;
+
+    if len == 0 {
+        return Ok(Buffer::new());
+    }
+
     let ptr = get_buffer_ptr(array, data_type, index)?;
 
-    let len = buffer_len(array, data_type, index)?;
     let offset = buffer_offset(array, data_type, index);
     let bytes = Bytes::from_foreign(ptr, len, BytesAllocator::InternalArrowArray(owner));
 
@@ -258,9 +263,12 @@
     // we can use the null count directly
     is_validity: bool,
 ) -> Result<Bitmap> {
+    let len: usize = array.length.try_into().expect("length to fit in `usize`");
+    if len == 0 {
+        return Ok(Bitmap::new());
+    }
     let ptr = get_buffer_ptr(array, data_type, index)?;
 
-    let len: usize = array.length.try_into().expect("length to fit in `usize`");
     let offset: usize = array.offset.try_into().expect("offset to fit in `usize`");
     let bytes_len = bytes_for(offset + len);
     let bytes = Bytes::from_foreign(ptr, bytes_len, BytesAllocator::InternalArrowArray(owner));

src/io/ipc/mod.rs

@@ -80,7 +80,8 @@ pub mod append;
 pub mod read;
 pub mod write;
 
-const ARROW_MAGIC: [u8; 6] = [b'A', b'R', b'R', b'O', b'W', b'1'];
+const ARROW_MAGIC_V1: [u8; 4] = [b'F', b'E', b'A', b'1'];
+const ARROW_MAGIC_V2: [u8; 6] = [b'A', b'R', b'R', b'O', b'W', b'1'];
 pub(crate) const CONTINUATION_MARKER: [u8; 4] = [0xff; 4];
 
 /// Struct containing `dictionary_id` and nested `IpcField`, allowing users

src/io/ipc/read/file.rs

@@ -8,7 +8,7 @@
 use crate::error::{Error, Result};
 use crate::io::ipc::IpcSchema;
 
-use super::super::{ARROW_MAGIC, CONTINUATION_MARKER};
+use super::super::{ARROW_MAGIC_V1, ARROW_MAGIC_V2, CONTINUATION_MARKER};
 use super::common::*;
 use super::schema::fb_to_schema;
 use super::Dictionaries;
@@ -151,7 +151,7 @@
     reader.read_exact(&mut footer)?;
     let footer_len = i32::from_le_bytes(footer[..4].try_into().unwrap());
 
-    if footer[4..] != ARROW_MAGIC {
+    if footer[4..] != ARROW_MAGIC_V2 {
         return Err(Error::from(OutOfSpecKind::InvalidFooter));
     }
     let footer_len = footer_len
@@ -215,7 +215,10 @@
     let mut magic_buffer: [u8; 6] = [0; 6];
     let start = reader.stream_position()?;
     reader.read_exact(&mut magic_buffer)?;
-    if magic_buffer != ARROW_MAGIC {
+    if magic_buffer != ARROW_MAGIC_V2 {
+        if &magic_buffer[..4] == ARROW_MAGIC_V1 {
+            return Err(Error::NotYetImplemented("feather v1 not supported".into()));
+        }
         return Err(Error::from(OutOfSpecKind::InvalidHeader));
     }
 

src/io/ipc/read/file_async.rs

@@ -11,7 +11,7 @@ use crate::array::*;
 use crate::chunk::Chunk;
 use crate::datatypes::{Field, Schema};
 use crate::error::{Error, Result};
-use crate::io::ipc::{IpcSchema, ARROW_MAGIC, CONTINUATION_MARKER};
+use crate::io::ipc::{IpcSchema, ARROW_MAGIC_V2, CONTINUATION_MARKER};
 
 use super::common::{apply_projection, prepare_projection, read_dictionary, read_record_batch};
 use super::file::{deserialize_footer, get_record_batch};
@@ -135,7 +135,7 @@ async fn read_footer_len<R: AsyncRead + AsyncSeek + Unpin>(reader: &mut R) -> Re
     reader.read_exact(&mut footer).await?;
     let footer_len = i32::from_le_bytes(footer[..4].try_into().unwrap());
 
-    if footer[4..] != ARROW_MAGIC {
+    if footer[4..] != ARROW_MAGIC_V2 {
         return Err(Error::from(OutOfSpecKind::InvalidFooter));
     }
     footer_len

src/io/ipc/write/file_async.rs

@@ -11,7 +11,7 @@ use super::schema::serialize_schema;
 use super::{default_ipc_fields, schema_to_bytes, Record};
 use crate::datatypes::*;
 use crate::error::{Error, Result};
-use crate::io::ipc::{IpcField, ARROW_MAGIC};
+use crate::io::ipc::{IpcField, ARROW_MAGIC_V2};
 
 type WriteOutput<W> = (usize, Option<Block>, Vec<Block>, Option<W>);
 
@@ -105,7 +105,7 @@ where
     }
 
     async fn start(mut writer: W, encoded: EncodedData) -> Result<WriteOutput<W>> {
-        writer.write_all(&ARROW_MAGIC[..]).await?;
+        writer.write_all(&ARROW_MAGIC_V2[..]).await?;
         writer.write_all(&[0, 0]).await?;
         let (meta, data) = write_message(&mut writer, encoded).await?;
 
@@ -149,7 +149,7 @@ where
         writer
             .write_all(&(footer.len() as i32).to_le_bytes())
             .await?;
-        writer.write_all(&ARROW_MAGIC).await?;
+        writer.write_all(&ARROW_MAGIC_V2).await?;
         writer.close().await?;
 
         Ok((0, None, vec![], None))

src/io/ipc/write/writer.rs

@@ -4,7 +4,7 @@ use arrow_format::ipc::planus::Builder;
 
 use super::{
     super::IpcField,
-    super::ARROW_MAGIC,
+    super::ARROW_MAGIC_V2,
     common::{DictionaryTracker, EncodedData, WriteOptions},
     common_sync::{write_continuation, write_message},
     default_ipc_fields, schema, schema_to_bytes,
@@ -114,7 +114,7 @@ impl<W: Write> FileWriter<W> {
             return Err(Error::oos("The IPC file can only be started once"));
         }
         // write magic to header
-        self.writer.write_all(&ARROW_MAGIC[..])?;
+        self.writer.write_all(&ARROW_MAGIC_V2[..])?;
         // create an 8-byte boundary after the header
         self.writer.write_all(&[0, 0])?;
         // write the schema, set the written bytes to the schema
@@ -205,7 +205,7 @@ impl<W: Write> FileWriter<W> {
         self.writer.write_all(footer_data)?;
         self.writer
             .write_all(&(footer_data.len() as i32).to_le_bytes())?;
-        self.writer.write_all(&ARROW_MAGIC)?;
+        self.writer.write_all(&ARROW_MAGIC_V2)?;
         self.writer.flush()?;
         self.state = State::Finished;