Update from_buffer_copy to accept an IBufferProtocol

Src/IronPython.Modules/_ctypes/ArrayType.cs

@@ -15,6 +15,7 @@
 using IronPython.Runtime.Operations;
 using IronPython.Runtime.Types;
 
+using Microsoft.Scripting.Runtime;
 using Microsoft.Scripting.Utils;
 
 namespace IronPython.Modules {
@@ -109,35 +110,16 @@ public _Array from_buffer(CodeContext/*!*/ context, ArrayModule.array array, [De
                 return res;
             }
 
-            public _Array from_buffer_copy(CodeContext/*!*/ context, ArrayModule.array array, [DefaultParameterValue(0)] int offset) {
-                ValidateArraySizes(array, offset, ((INativeType)this).Size);
-
-                _Array res = (_Array)CreateInstance(context);
-                res.MemHolder = new MemoryHolder(((INativeType)this).Size);
-                res.MemHolder.CopyFrom(array.GetArrayAddress().Add(offset), new IntPtr(((INativeType)this).Size));
-                GC.KeepAlive(array);
-                return res;
-            }
-
-            public _Array from_buffer_copy(CodeContext/*!*/ context, Bytes array, [DefaultParameterValue(0)] int offset) {
-                ValidateArraySizes(array, offset, ((INativeType)this).Size);
+            public _Array from_buffer_copy(CodeContext/*!*/ context, [NotNull] IBufferProtocol data, int offset = 0) {
+                using var buffer = data.GetBuffer();
+                var span = buffer.AsReadOnlySpan();
+                var size = ((INativeType)this).Size;
+                ValidateArraySizes(span.Length, offset, size);
+                span = span.Slice(offset, size);
 
                 _Array res = (_Array)CreateInstance(context);
-                res.MemHolder = new MemoryHolder(((INativeType)this).Size);
-                for (int i = 0; i < ((INativeType)this).Size; i++) {
-                    res.MemHolder.WriteByte(i, ((IList<byte>)array)[i]);
-                }
-                return res;
-            }
-
-            public _Array from_buffer_copy(CodeContext/*!*/ context, string data, int offset = 0) {
-                ValidateArraySizes(data, offset, ((INativeType)this).Size);
-
-                _Array res = (_Array)CreateInstance(context);
-                res.MemHolder = new MemoryHolder(((INativeType)this).Size);
-                for (int i = 0; i < ((INativeType)this).Size; i++) {
-                    res.MemHolder.WriteByte(i, (byte)data[i]);
-                }
+                res.MemHolder = new MemoryHolder(size);
+                res.MemHolder.WriteSpan(0, span);
                 return res;
             }
 

Src/IronPython.Modules/_ctypes/MemoryHolder.cs

@@ -10,7 +10,6 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.ConstrainedExecution;
 using System.Runtime.InteropServices;
-using System.Text;
 using System.Threading;
 
 using IronPython.Runtime;
@@ -282,10 +281,13 @@ internal void WriteUnicodeString(int offset, string value) {
                 WriteInt16(checked(offset + i * 2), (short)value[i]);
             }
         }
+
         internal void WriteSpan(int offset, ReadOnlySpan<byte> value) {
-            for (int i = 0; i < value.Length; i++) {
-                WriteByte(checked(offset + i), value[i]);
+            unsafe {
+                var dest = new Span<byte>((void*)_data, _size).Slice(offset);
+                value.CopyTo(dest);
             }
+            GC.KeepAlive(this);
         }
 
         public MemoryHolder GetSubBlock(int offset) {

Src/IronPython.Modules/_ctypes/SimpleType.cs

@@ -141,13 +141,16 @@ public SimpleCData from_buffer(ArrayModule.array array, int offset = 0) {
                 return res;
             }
 
-            public SimpleCData from_buffer_copy(ArrayModule.array array, int offset = 0) {
-                ValidateArraySizes(array, offset, ((INativeType)this).Size);
+            public SimpleCData from_buffer_copy(CodeContext/*!*/ context, [NotNull] IBufferProtocol data, int offset = 0) {
+                using var buffer = data.GetBuffer();
+                var span = buffer.AsReadOnlySpan();
+                var size = ((INativeType)this).Size;
+                ValidateArraySizes(span.Length, offset, size);
+                span = span.Slice(offset, size);
 
-                SimpleCData res = (SimpleCData)CreateInstance(Context.SharedContext);
-                res.MemHolder = new MemoryHolder(((INativeType)this).Size);
-                res.MemHolder.CopyFrom(array.GetArrayAddress().Add(offset), new IntPtr(((INativeType)this).Size));
-                GC.KeepAlive(array);
+                SimpleCData res = (SimpleCData)CreateInstance(context);
+                res.MemHolder = new MemoryHolder(size);
+                res.MemHolder.WriteSpan(0, span);
                 return res;
             }
 

Src/IronPython.Modules/_ctypes/StructType.cs

@@ -50,10 +50,15 @@ public StructType(CodeContext/*!*/ context, string name, PythonTuple bases, Pyth
                 }
 
                 if (members.TryGetValue("_pack_", out object pack)) {
-                    if (!(pack is int) || ((int)pack < 0)) {
+                    object index = PythonOps.Index(pack); // since 3.8
+                    _pack = index switch {
+                        int i => i,
+                        BigInteger bi => (int)bi, // CPython throws the ValueError below on overflow
+                        _ => throw new InvalidOperationException(),
+                    };
+                    if (_pack < 0) {
                         throw PythonOps.ValueError("pack must be a non-negative integer");
                     }
-                    _pack = (int)pack;
                 }
 
                 if (members.TryGetValue("_fields_", out object fields)) {
@@ -99,13 +104,16 @@ public _Structure from_buffer(CodeContext/*!*/ context, ArrayModule.array array,
                 return res;
             }
 
-            public _Structure from_buffer_copy(CodeContext/*!*/ context, ArrayModule.array array, int offset = 0) {
-                ValidateArraySizes(array, offset, ((INativeType)this).Size);
+            public _Structure from_buffer_copy(CodeContext/*!*/ context, [NotNull] IBufferProtocol data, int offset = 0) {
+                using var buffer = data.GetBuffer();
+                var span = buffer.AsReadOnlySpan();
+                var size = ((INativeType)this).Size;
+                ValidateArraySizes(span.Length, offset, size);
+                span = span.Slice(offset, size);
 
-                _Structure res = (_Structure)CreateInstance(Context.SharedContext);
-                res.MemHolder = new MemoryHolder(((INativeType)this).Size);
-                res.MemHolder.CopyFrom(array.GetArrayAddress().Add(offset), new IntPtr(((INativeType)this).Size));
-                GC.KeepAlive(array);
+                _Structure res = (_Structure)CreateInstance(context);
+                res.MemHolder = new MemoryHolder(size);
+                res.MemHolder.WriteSpan(0, span);
                 return res;
             }
 

Src/IronPython.Modules/_ctypes/_ctypes.cs

@@ -683,27 +683,11 @@ private static void ValidateArraySizes(ArrayModule.array array, int offset, int
             ValidateArraySizes(array.__len__() * array.itemsize, offset, size);
         }
 
-        private static void ValidateArraySizes(Bytes bytes, int offset, int size) {
-            ValidateArraySizes(bytes.Count, offset, size);
-        }
-
-        private static void ValidateArraySizes(string data, int offset, int size) {
-            ValidateArraySizes(data.Length, offset, size);
-        }
-
         private static void ValidateArraySizes(int arraySize, int offset, int size) {
             if (offset < 0) {
                 throw PythonOps.ValueError("offset cannot be negative");
             } else if (arraySize < size + offset) {
-                throw PythonOps.ValueError($"Buffer size too small ({arraySize} instead of at least {size} bytes)");
-            }
-        }
-
-        private static void ValidateArraySizes(BigInteger arraySize, int offset, int size) {
-            if (offset < 0) {
-                throw PythonOps.ValueError("offset cannot be negative");
-            } else if (arraySize < size + offset) {
-                throw PythonOps.ValueError($"Buffer size too small ({arraySize} instead of at least {size} bytes)");
+                throw PythonOps.ValueError($"Buffer size too small ({arraySize} instead of at least {offset + size} bytes)");
             }
         }
 

Src/IronPythonTest/Cases/CPythonCasesManifest.ini

@@ -17,7 +17,7 @@ Ignore=true # blocked by https://github.com/IronLanguages/ironpython3/issues/129
 Ignore=true
 Reason=Current implementation of get_last_error needs to be debugged
 
-[CPython.ctypes.test_frombuffer]
+[CPython.ctypes.test_frombuffer] # IronPython.test_ctypes_frombuffer_stdlib
 Ignore=true # blocked by https://github.com/IronLanguages/ironpython3/issues/1297
 
 [CPython.ctypes.test_functions]

Tests/test_ctypes_frombuffer_stdlib.py

@@ -0,0 +1,30 @@
+# Licensed to the .NET Foundation under one or more agreements.
+# The .NET Foundation licenses this file to you under the Apache 2.0 License.
+# See the LICENSE file in the project root for more information.
+
+##
+## Run selected tests from ctypes.test.test_frombuffer from StdLib
+##
+
+import unittest
+import sys
+
+from iptest import run_test
+
+import ctypes.test.test_frombuffer
+
+def load_tests(loader, standard_tests, pattern):
+    if sys.implementation.name == 'ironpython':
+        suite = unittest.TestSuite()
+        suite.addTest(ctypes.test.test_frombuffer.Test('test_fortran_contiguous'))
+        suite.addTest(unittest.expectedFailure(ctypes.test.test_frombuffer.Test('test_from_buffer')))
+        suite.addTest(ctypes.test.test_frombuffer.Test('test_from_buffer_copy'))
+        suite.addTest(ctypes.test.test_frombuffer.Test('test_from_buffer_copy_with_offset'))
+        suite.addTest(unittest.expectedFailure(ctypes.test.test_frombuffer.Test('test_from_buffer_memoryview')))
+        suite.addTest(ctypes.test.test_frombuffer.Test('test_from_buffer_with_offset'))
+        return suite
+
+    else:
+        return loader.loadTestsFromModule(ctypes.test.test_frombuffer, pattern)
+
+run_test(__name__)