[lldb][core] Fix getting summary of a variable pointing to r/o memory

lldb/source/ValueObject/ValueObject.cpp

@@ -734,15 +734,22 @@ size_t ValueObject::GetPointeeData(DataExtractor &data, uint32_t item_idx,
     } break;
     case eAddressTypeLoad: {
       ExecutionContext exe_ctx(GetExecutionContextRef());
-      Process *process = exe_ctx.GetProcessPtr();
-      if (process) {
-        heap_buf_ptr->SetByteSize(bytes);
-        size_t bytes_read = process->ReadMemory(
+      heap_buf_ptr->SetByteSize(bytes);
+      size_t bytes_read = 0;
+      if (Process *process = exe_ctx.GetProcessPtr();
+          process && process->IsLiveDebugSession()) {
+        bytes_read = process->ReadMemory(
             addr + offset, heap_buf_ptr->GetBytes(), bytes, error);
-        if (error.Success() || bytes_read > 0) {
-          data.SetData(data_sp);
-          return bytes_read;
-        }
+      } else if (Target *target = exe_ctx.GetTargetPtr()) {
+        Address target_addr;
+        target_addr.SetLoadAddress(addr + offset, target);
+        bytes_read =
+            target->ReadMemory(target_addr, heap_buf_ptr->GetBytes(), bytes,
+                               error, /*force_live_memory=*/true);
+      }
+      if (error.Success() || bytes_read > 0) {
+        data.SetData(data_sp);
+        return bytes_read;
       }
     } break;
     case eAddressTypeHost: {

lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py

@@ -977,6 +977,34 @@ def test_get_core_file_api(self):
         self.assertEqual(process.GetCoreFile().GetFilename(), core_file_name)
         self.dbg.DeleteTarget(target)
 
+    @skipIfLLVMTargetMissing("X86")
+    def test_read_only_cstring(self):
+        """
+        Test that we can show the summary for a cstring variable that points
+        to a read-only memory page which is not dumped to a core file.
+        """
+        target = self.dbg.CreateTarget("altmain2.out")
+        process = target.LoadCore("altmain2.core")
+        self.assertTrue(process, PROCESS_IS_VALID)
+
+        frame = process.GetSelectedThread().GetFrameAtIndex(0)
+        self.assertEqual(frame.GetFunctionName(), "_start")
+
+        var = frame.FindVariable("F")
+
+        # The variable points to a read-only segment that is not dumped to
+        # the core file and thus 'process.ReadCStringFromMemory()' cannot get
+        # the value.
+        error = lldb.SBError()
+        cstr = process.ReadCStringFromMemory(var.GetValueAsUnsigned(), 256, error)
+        self.assertFailure(error, error_str="core file does not contain 0x804a000")
+        self.assertEqual(cstr, "")
+
+        # Nevertheless, when getting the summary, the value can be read from the
+        # application binary.
+        cstr = var.GetSummary()
+        self.assertEqual(cstr, '"_start"')
+
     def check_memory_regions(self, process, region_count):
         region_list = process.GetMemoryRegions()
         self.assertEqual(region_list.GetSize(), region_count)