fix(csharp/src/Apache.Arrow.Adbc): Fix marshaling in three functions …

…where it was broken (#1758)

Closes #1694.

csharp/src/Apache.Arrow.Adbc/C/CAdbcDriverExporter.cs

@@ -17,10 +17,12 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Runtime.InteropServices;
 using Apache.Arrow.C;
 using Apache.Arrow.Ipc;
 
+
 #if NETSTANDARD
 using Apache.Arrow.Adbc.Extensions;
 #endif
@@ -663,7 +665,7 @@ private unsafe AdbcStatusCode NewConnection(CAdbcConnection* nativeConnection, C
  nativeConnection->private_data = (void*)GCHandle.ToIntPtr(handle);
  return AdbcStatusCode.Success;
  }
- catch(Exception e)
+ catch (Exception e)
  {
  return SetError(error, e);
  }
@@ -773,9 +775,31 @@ public unsafe void GetObjects(ref CAdbcConnection nativeConnection, int depth, b
  columnNamePattern = Marshal.PtrToStringUTF8((IntPtr)column_name);
 #endif
 
- // TODO (GH-1694): Marshaling is incorrect
- GCHandle gch = GCHandle.FromIntPtr((IntPtr)table_type);
- List<string> tableTypes = (List<string>)gch.Target;
+ List<string> tableTypes = null;
+ const int maxTableTypeCount = 100;
+ if (table_type != null)
+ {
+ int count = 0;
+ while (table_type[count] != null && count <= maxTableTypeCount)
+ {
+ count++;
+ }
+
+ if (count > maxTableTypeCount)
+ {
+ throw new InvalidOperationException($"We do not expect to get more than {maxTableTypeCount} table types");
+ }
+
+ tableTypes = new List<string>(count);
+ for (int i = 0; i < count; i++)
+ {
+#if NETSTANDARD
+ tableTypes.Add(MarshalExtensions.PtrToStringUTF8((IntPtr)table_type[i]));
+#else
+ tableTypes.Add(Marshal.PtrToStringUTF8((IntPtr)table_type[i]));
+#endif
+ }
+ }
 
  AdbcConnection.GetObjectsDepth goDepth = (AdbcConnection.GetObjectsDepth)depth;
 
@@ -812,20 +836,25 @@ public unsafe void GetTableTypes(CArrowArrayStream* cArrayStream)
 
  public unsafe void ReadPartition(byte* serializedPartition, int serialized_length, CArrowArrayStream* stream)
  {
- // TODO (GH-1694): Marshaling is incorrect
- GCHandle gch = GCHandle.FromIntPtr((IntPtr)serializedPartition);
- PartitionDescriptor descriptor = (PartitionDescriptor)gch.Target;
+ byte[] partition = new byte[serialized_length];
+ fixed (byte* partitionPtr = partition)
+ {
+ Buffer.MemoryCopy(serializedPartition, partitionPtr, serialized_length, serialized_length);
+ }
 
- CArrowArrayStreamExporter.ExportArrayStream(connection.ReadPartition(descriptor), stream);
+ CArrowArrayStreamExporter.ExportArrayStream(connection.ReadPartition(new PartitionDescriptor(partition)), stream);
  }
 
  public unsafe void GetInfo(int* info_codes, int info_codes_length, CArrowArrayStream* stream)
  {
- // TODO (GH-1694): Marshaling is incorrect
- GCHandle gch = GCHandle.FromIntPtr((IntPtr)info_codes);
- List<int> codes = (List<int>)gch.Target;
+ int[] infoCodes = new int[info_codes_length];
+ fixed (int* infoCodesPtr = infoCodes)
+ {
+ long length = (long)info_codes_length * sizeof(int);
+ Buffer.MemoryCopy(info_codes, infoCodesPtr, length, length);
+ }
 
- CArrowArrayStreamExporter.ExportArrayStream(connection.GetInfo(codes), stream);
+ CArrowArrayStreamExporter.ExportArrayStream(connection.GetInfo(infoCodes.ToList()), stream);
  }
 
  public unsafe void InitConnection(ref CAdbcDatabase nativeDatabase)