From a21978e073dced0860862aec80d322f0564ed3e3 Mon Sep 17 00:00:00 2001
From: Felipe Oliveira Carvalho <felipekde@gmail.com>
Date: Sat, 15 Feb 2025 02:43:30 +0000
Subject: [PATCH] ffi_stream.rs: Align buffers when importing arrays

---
 arrow-array/src/ffi_stream.rs |  8 +++++++-
 arrow-data/src/data.rs        | 22 +++++++++++++---------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/arrow-array/src/ffi_stream.rs b/arrow-array/src/ffi_stream.rs
index 3d4e89e80b89..6c7bc8152484 100644
--- a/arrow-array/src/ffi_stream.rs
+++ b/arrow-array/src/ffi_stream.rs
@@ -364,7 +364,13 @@ impl Iterator for ArrowArrayStreamReader {
             let result = unsafe {
                 from_ffi_and_data_type(array, DataType::Struct(self.schema().fields().clone()))
             };
-            Some(result.map(|data| RecordBatch::from(StructArray::from(data))))
+            Some(result.map(|mut data| {
+                // Ensure data is aligned (by potentially copying some buffers).
+                // This is needed because some Arrow C Data Interface sources(e.g.
+                // ADBC drivers) may produce unaligned buffers.
+                data.align_buffers();
+                RecordBatch::from(StructArray::from(data))
+            }))
         } else {
             let last_error = self.get_stream_last_error();
             let err = ArrowError::CDataInterface(last_error.unwrap());
diff --git a/arrow-data/src/data.rs b/arrow-data/src/data.rs
index e123d0cef902..e919e24fed60 100644
--- a/arrow-data/src/data.rs
+++ b/arrow-data/src/data.rs
@@ -697,17 +697,21 @@ impl ArrayData {
     ///
     /// This also aligns buffers of children data
     pub fn align_buffers(&mut self) {
-        let layout = layout(&self.data_type);
-        for (buffer, spec) in self.buffers.iter_mut().zip(&layout.buffers) {
-            if let BufferSpec::FixedWidth { alignment, .. } = spec {
-                if buffer.as_ptr().align_offset(*alignment) != 0 {
-                    *buffer = Buffer::from_slice_ref(buffer.as_ref());
+        // use a dynamic stack to avoid stack overflow for very deeply nested arrays
+        let mut stack: Vec<&mut ArrayData> = vec![self];
+        while let Some(data) = stack.pop() {
+            let layout = layout(&data.data_type);
+            for (buffer, spec) in data.buffers.iter_mut().zip(&layout.buffers) {
+                if let BufferSpec::FixedWidth { alignment, .. } = spec {
+                    if buffer.as_ptr().align_offset(*alignment) != 0 {
+                        *buffer = Buffer::from_slice_ref(buffer.as_ref());
+                    }
                 }
             }
-        }
-        // align children data recursively
-        for data in self.child_data.iter_mut() {
-            data.align_buffers()
+            // align children data recursively
+            for child in data.child_data.iter_mut() {
+                stack.push(child);
+            }
         }
     }