From ab00ee1bc3f3fcfae3b1d6ce51e76960b98f7748 Mon Sep 17 00:00:00 2001
From: Divjot Arora <div.arora@databricks.com>
Date: Tue, 13 Oct 2026 09:56:08 +0000
Subject: [PATCH] Reject unsupported compression codecs

---
 cpp/src/parquet/metadata_test.cc  | 21 +++++++++++++++++++++
 cpp/src/parquet/thrift_internal.h |  2 +-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/cpp/src/parquet/metadata_test.cc b/cpp/src/parquet/metadata_test.cc
index e6ff1f929d45..ee2f0619ebf2 100644
--- a/cpp/src/parquet/metadata_test.cc
+++ b/cpp/src/parquet/metadata_test.cc
@@ -17,9 +17,13 @@
 
 #include "parquet/metadata.h"
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+#include <cstring>
+
 #include "arrow/util/key_value_metadata.h"
+#include "parquet/exception.h"
 #include "parquet/file_reader.h"
 #include "parquet/file_writer.h"
 #include "parquet/schema.h"
@@ -344,6 +348,23 @@ void AssertColumnChunkMinMax(const FileMetaData& metadata,
 
 }  // namespace
 
+TEST(Metadata, UnknownCompressionCodecThrows) {
+  format::FileMetaData thrift_metadata = SingleInt32MetadataWithStats();
+  auto metadata = ParseMetadata(SerializeMetadata(thrift_metadata));
+
+  auto& column_chunk = thrift_metadata.row_groups.at(0).columns.at(0);
+  const int32_t raw_codec = 8;
+  static_assert(sizeof(column_chunk.meta_data.codec) == sizeof(raw_codec));
+  std::memcpy(&column_chunk.meta_data.codec, &raw_codec, sizeof(raw_codec));
+
+  auto column = ColumnChunkMetaData::Make(&column_chunk, metadata->schema()->Column(0));
+
+  EXPECT_THROW_THAT([&]() { column->compression(); }, ParquetException,
+                    ::testing::Property(
+                        &ParquetException::what,
+                        ::testing::HasSubstr("Unsupported compression codec value: 8")));
+}
+
 TEST(Metadata, UnknownColumnOrderIgnoresMinMax) {
   format::FileMetaData thrift_metadata = SingleInt32MetadataWithStats();
   // Simulate an unsupported ColumnOrder value: unknown union fields are skipped by
diff --git a/cpp/src/parquet/thrift_internal.h b/cpp/src/parquet/thrift_internal.h
index a74d97c1e287..5a0fc7d70e69 100644
--- a/cpp/src/parquet/thrift_internal.h
+++ b/cpp/src/parquet/thrift_internal.h
@@ -227,7 +227,7 @@ inline typename Compression::type LoadEnumSafe(const format::CompressionCodec::t
   const auto max_value =
       static_cast<decltype(raw_value)>(format::CompressionCodec::LZ4_RAW);
   if (raw_value < min_value || raw_value > max_value) {
-    return Compression::UNCOMPRESSED;
+    throw ParquetException("Unsupported compression codec value: ", raw_value);
   }
   return FromThriftUnsafe(*in);
 }