[lldb] Drop support for the Buffer Protocol (#168144)

This is an alternative solution to the issue described in #167990, which
can be summarized as that we cannot target Python 3.8 with the stable
API and support building for Python 3.13 and later due to the buffer
protocol.

The approach taken in this PR, and proposed by Ismail, is to sidesteps
the issue by dropping support for the buffer protocol. The only two
users are SBFile::Read and SBFile::Write. Instead, we support PyBytes
and PyByteArray which are the builtin types that conform to the buffer
protocol. Technically, this means a small regression, where those
methods could previously take custom types that conform to Python's
buffer protocol. Like Ismail, I think this is acceptable given the
alternatives.

Co-authored-by: Med Ismail Bennani <[email protected]>

Author: JDevlieghere

lldb/bindings/python/python-typemaps.swig

@@ -628,61 +628,34 @@ template <> bool SetNumberFromPyObject<double>(double &number, PyObject *obj) {
   }
 }
 
-// These two pybuffer macros are copied out of swig/Lib/python/pybuffer.i,
-// and fixed so they will not crash if PyObject_GetBuffer fails.
-// https://github.com/swig/swig/issues/1640
-//
-// I've also moved the call to PyBuffer_Release to the end of the SWIG wrapper,
-// doing it right away is not legal according to the python buffer protocol.
-%inline %{
-struct Py_buffer_RAII {
-  Py_buffer buffer = {};
-  Py_buffer_RAII(){};
-  Py_buffer &operator=(const Py_buffer_RAII &) = delete;
-  Py_buffer_RAII(const Py_buffer_RAII &) = delete;
-  ~Py_buffer_RAII() {
-    if (buffer.obj)
-      PyBuffer_Release(&buffer);
-  }
-};
-%}
 
-%define %pybuffer_mutable_binary(TYPEMAP, SIZE)
-%typemap(in) (TYPEMAP, SIZE) (Py_buffer_RAII view) {
-  int res;
-  Py_ssize_t size = 0;
-  void *buf = 0;
-  res = PyObject_GetBuffer($input, &view.buffer, PyBUF_WRITABLE);
-  if (res < 0) {
-    PyErr_Clear();
-    %argument_fail(res, "(TYPEMAP, SIZE)", $symname, $argnum);
-  }
-  size = view.buffer.len;
-  buf = view.buffer.buf;
-  $1 = ($1_ltype)buf;
-  $2 = ($2_ltype)(size / sizeof($*1_type));
-}
-%enddef
-
-%define %pybuffer_binary(TYPEMAP, SIZE)
-%typemap(in) (TYPEMAP, SIZE) (Py_buffer_RAII view) {
-  int res;
-  Py_ssize_t size = 0;
-  const void *buf = 0;
-  res = PyObject_GetBuffer($input, &view.buffer, PyBUF_CONTIG_RO);
-  if (res < 0) {
-    PyErr_Clear();
-    %argument_fail(res, "(TYPEMAP, SIZE)", $symname, $argnum);
+// Typemap for SBFile::Write.
+%typemap(in) (const uint8_t *buf, size_t num_bytes) {
+  if (PythonByteArray::Check($input)) {
+    PythonByteArray bytearray(PyRefType::Borrowed, $input);
+    $1 = (uint8_t *)bytearray.GetBytes().data();
+    $2 = bytearray.GetSize();
+  } else if (PythonBytes::Check($input)) {
+    PythonBytes bytes(PyRefType::Borrowed, $input);
+    $1 = (uint8_t *)bytes.GetBytes().data();
+    $2 = bytes.GetSize();
+  } else {
+    PyErr_SetString(PyExc_ValueError, "Expecting a bytes or bytearray object");
+    SWIG_fail;
   }
-  size = view.buffer.len;
-  buf = view.buffer.buf;
-  $1 = ($1_ltype)buf;
-  $2 = ($2_ltype)(size / sizeof($*1_type));
 }
-%enddef
 
-%pybuffer_binary(const uint8_t *buf, size_t num_bytes);
-%pybuffer_mutable_binary(uint8_t *buf, size_t num_bytes);
+// Typemap for SBFile::Read.
+%typemap(in) (uint8_t *buf, size_t num_bytes) {
+  if (PythonByteArray::Check($input)) {
+    PythonByteArray bytearray(PyRefType::Borrowed, $input);
+    $1 = (uint8_t *)bytearray.GetBytes().data();
+    $2 = bytearray.GetSize();
+  } else {
+    PyErr_SetString(PyExc_ValueError, "Expecting a bytearray");
+    SWIG_fail;
+  }
+}
 
 %typemap(in) (const char **symbol_name, uint32_t num_names) {
   using namespace lldb_private;