[lldb] Refactor DataBuffer so we can map files as read-only

Currently, all data buffers are assumed to be writable. This is a
problem on macOS where it's not allowed to load unsigned binaries in
memory as writable. To be more precise, MAP_RESILIENT_CODESIGN and
MAP_RESILIENT_MEDIA need to be set for mapped (unsigned) binaries on our
platform.

Binaries are mapped through FileSystem::CreateDataBuffer which returns a
DataBufferLLVM. The latter is backed by a llvm::WritableMemoryBuffer
because every DataBuffer in LLDB is considered to be writable. In order
to use a read-only llvm::MemoryBuffer I had to split our abstraction
around it.

This patch distinguishes between a DataBuffer (read-only) and
WritableDataBuffer (read-write) and updates LLDB to use the appropriate
one.

rdar://74890607

Differential revision: https://reviews.llvm.org/D122856

1 files changed, 1 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Language/ObjC/CF.cpp b/lldb/source/Plugins/Language/ObjC/CF.cpp
index 6a4631e69387..fa2130e4b01e 100644
--- a/lldb/source/Plugins/Language/ObjC/CF.cpp
+++ b/lldb/source/Plugins/Language/ObjC/CF.cpp
@@ -158,7 +158,7 @@ bool lldb_private::formatters::CFBitVectorSummaryProvider(
   // make sure we do not try to read huge amounts of data
   if (num_bytes > 1024)
     num_bytes = 1024;
-  DataBufferSP buffer_sp(new DataBufferHeap(num_bytes, 0));
+  WritableDataBufferSP buffer_sp(new DataBufferHeap(num_bytes, 0));
   num_bytes =
       process_sp->ReadMemory(data_ptr, buffer_sp->GetBytes(), num_bytes, error);
   if (error.Fail() || num_bytes == 0)