[Lldb-commits] [lldb] 04ed12c - [lldb] Support partial memory reads on windows (#106981)

[via lldb-commits]

Author: Pavel Labath
Date: 2024-09-03T10:48:40+02:00
New Revision: 04ed12ca3f027a3a189d181e5e5880285ebc7916

URL: https://github.com/llvm/llvm-project/commit/04ed12ca3f027a3a189d181e5e5880285ebc7916
DIFF: https://github.com/llvm/llvm-project/commit/04ed12ca3f027a3a189d181e5e5880285ebc7916.diff

LOG: [lldb] Support partial memory reads on windows (#106981)

ReadProcessMemory will not perform the read if part of the memory is
unreadable (and even though the API has a `number_of_bytes_read`
argument). To make this work, I explicitly inspect the memory region
being read and only read the accessible part.

Added: 
    

Modified: 
    lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp
    lldb/test/API/functionalities/memory/holes/TestMemoryHoles.py

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp
index 04c7c0f826039d..9fc8077851d257 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp
@@ -276,16 +276,29 @@ Status ProcessDebugger::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
   LLDB_LOG(log, "attempting to read {0} bytes from address {1:x}", size,
            vm_addr);
 
-  HostProcess process = m_session_data->m_debugger->GetProcess();
+  lldb::process_t handle = m_session_data->m_debugger->GetProcess()
+                               .GetNativeProcess()
+                               .GetSystemHandle();
   void *addr = reinterpret_cast<void *>(vm_addr);
   SIZE_T num_of_bytes_read = 0;
-  if (!::ReadProcessMemory(process.GetNativeProcess().GetSystemHandle(), addr,
-                           buf, size, &num_of_bytes_read)) {
-    error = Status(GetLastError(), eErrorTypeWin32);
-    LLDB_LOG(log, "reading failed with error: {0}", error);
-  } else {
+  if (::ReadProcessMemory(handle, addr, buf, size, &num_of_bytes_read)) {
+    bytes_read = num_of_bytes_read;
+    return Status();
+  }
+  error = Status(GetLastError(), eErrorTypeWin32);
+  MemoryRegionInfo info;
+  if (GetMemoryRegionInfo(vm_addr, info).Fail() ||
+      info.GetMapped() != MemoryRegionInfo::OptionalBool::eYes)
+    return error;
+  size = info.GetRange().GetRangeEnd() - vm_addr;
+  LLDB_LOG(log, "retrying the read with size {0:x}", size);
+  if (::ReadProcessMemory(handle, addr, buf, size, &num_of_bytes_read)) {
+    LLDB_LOG(log, "success: read {0:x} bytes", num_of_bytes_read);
     bytes_read = num_of_bytes_read;
+    return Status();
   }
+  error = Status(GetLastError(), eErrorTypeWin32);
+  LLDB_LOG(log, "error: {0}", error);
   return error;
 }
 

diff  --git a/lldb/test/API/functionalities/memory/holes/TestMemoryHoles.py b/lldb/test/API/functionalities/memory/holes/TestMemoryHoles.py
index 6ecb25b2e4db28..1c2c90d483ea3f 100644
--- a/lldb/test/API/functionalities/memory/holes/TestMemoryHoles.py
+++ b/lldb/test/API/functionalities/memory/holes/TestMemoryHoles.py
@@ -50,7 +50,6 @@ def _prepare_inferior(self):
         ]
         self.assertEqual(len(self.positions), 5)
 
-    @expectedFailureWindows
     def test_memory_read(self):
         self._prepare_inferior()