[Lldb-commits] [lldb] [lldb][windows] bound ReadProcessMemory (PR #200230)

[Charles Zablit via lldb-commits]

================
@@ -614,44 +614,82 @@ static std::optional<std::string> GetFileNameByLoadAddress(HANDLE hProcess,
   return dos_path;
 }
 
+// Determine how many bytes can be read at `addr` in `hProcess` before crossing
+// out of the committed memory region containing it. Returns 0 if the address is
+// not within a committed region.
+static SIZE_T BytesReadableAt(HANDLE hProcess, LPCVOID addr) {
+  MEMORY_BASIC_INFORMATION mbi{};
+  if (!::VirtualQueryEx(hProcess, addr, &mbi, sizeof(mbi)))
+    return 0;
+  if (mbi.State != MEM_COMMIT)
+    return 0;
+  uintptr_t region_end =
+      reinterpret_cast<uintptr_t>(mbi.BaseAddress) + mbi.RegionSize;
+  uintptr_t a = reinterpret_cast<uintptr_t>(addr);
+  if (a >= region_end)
+    return 0;
+  return region_end - a;
+}
+
+static std::optional<std::string> ReadRemoteStringW(HANDLE hProcess,
+                                                    LPCVOID addr) {
+  SIZE_T to_read = std::min<SIZE_T>((MAX_PATH + 1) * sizeof(wchar_t),
+                                    BytesReadableAt(hProcess, addr));
+  to_read &= ~SIZE_T(1); // round down to a wchar_t boundary
+  if (to_read < sizeof(wchar_t))
+    return std::nullopt;
+
+  std::array<wchar_t, MAX_PATH + 1> buf{};
+  SIZE_T bytes_read = 0;
+  if (!::ReadProcessMemory(hProcess, addr, buf.data(), to_read, &bytes_read))
+    return std::nullopt;
+
+  size_t max_chars = bytes_read / sizeof(wchar_t);
+  size_t len = ::wcsnlen(buf.data(), max_chars);
+  if (len == 0 || len == max_chars) // no null terminator found
----------------
charles-zablit wrote:

What I meant was to return `std::nullopt` whether the string is empty or no null terminator were found. I added another if branch to make the intent more explicit.

https://github.com/llvm/llvm-project/pull/200230