[Lldb-commits] [lldb] [debugserver] Implement MultiMemRead packet (PR #162670)

[Jason Molenda via lldb-commits]

================
@@ -3160,6 +3165,140 @@ rnb_err_t RNBRemote::HandlePacket_m(const char *p) {
   return SendPacket(ostrm.str());
 }
 
+/// Returns true if `str` starts with `prefix`.
+static bool starts_with(std::string_view str, std::string_view prefix) {
+  return str.size() >= prefix.size() &&
+         str.compare(0, prefix.size(), prefix) == 0;
+}
+
+/// Attempts to parse a prefix of `number_str` as a number of type `T`. If
+/// successful, the number is returned and the prefix is dropped from
+/// `number_str`.
+template <typename T>
+static std::optional<T> extract_number(std::string_view &number_str) {
+  static_assert(std::is_integral<T>());
+  char *str_end = nullptr;
+  errno = 0;
+  nub_addr_t number = strtoull(number_str.data(), &str_end, 16);
+  if (errno != 0)
+    return std::nullopt;
+  assert(str_end);
+  number_str.remove_prefix(str_end - number_str.data());
+  return number;
+}
+
+/// Splits `list_str` into multiple string_views separated by `,`.
+static std::vector<std::string_view>
+parse_comma_separated_list(std::string_view list_str) {
+  std::vector<std::string_view> list;
+  while (!list_str.empty()) {
+    auto pos = list_str.find(',');
+    list.push_back(list_str.substr(0, pos));
+    if (pos == list_str.npos)
+      break;
+    list_str.remove_prefix(pos + 1);
+  }
+  return list;
+}
+
+rnb_err_t RNBRemote::HandlePacket_MultiMemRead(const char *p) {
+  const std::string_view packet_name("MultiMemRead:");
+  std::string_view packet(p);
+
+  if (!starts_with(packet, packet_name))
+    return HandlePacket_ILLFORMED(__FILE__, __LINE__, p,
+                                  "Invalid MultiMemRead packet prefix");
+
+  packet.remove_prefix(packet_name.size());
+
+  const std::string_view ranges_prefix("ranges:");
+  if (!starts_with(packet, ranges_prefix))
+    return HandlePacket_ILLFORMED(__FILE__, __LINE__, packet.data(),
+                                  "Missing 'ranges' in MultiMemRead packet");
+  packet.remove_prefix(ranges_prefix.size());
+
+  std::vector<std::pair<nub_addr_t, std::size_t>> ranges;
+  std::size_t total_length = 0;
+
+  // Ranges should have the form: <addr>,<size>[,<addr>,<size>]*;
+  auto end_of_ranges_pos = packet.find(';');
+  if (end_of_ranges_pos == packet.npos)
+    return HandlePacket_ILLFORMED(__FILE__, __LINE__, packet.data(),
+                                  "MultiMemRead missing end of ranges marker");
+
+  std::vector<std::string_view> numbers_list =
+      parse_comma_separated_list(packet.substr(0, end_of_ranges_pos));
+  packet.remove_prefix(end_of_ranges_pos + 1);
+
+  // Ranges are pairs, so the number of elements must be even.
+  if (numbers_list.size() % 2 == 1)
+    return HandlePacket_ILLFORMED(
+        __FILE__, __LINE__, p,
+        "MultiMemRead has an odd number of numbers for the ranges");
+
+  for (unsigned idx = 0; idx < numbers_list.size(); idx += 2) {
+    std::optional<nub_addr_t> maybe_addr =
+        extract_number<nub_addr_t>(numbers_list[idx]);
+    std::optional<size_t> maybe_length =
+        extract_number<size_t>(numbers_list[idx + 1]);
+    if (!maybe_addr || !maybe_length)
+      return HandlePacket_ILLFORMED(__FILE__, __LINE__, packet.data(),
+                                    "Invalid MultiMemRead range");
+    // A sanity check that the packet requested is not too large or a negative
+    // number.
+    if (*maybe_length > 4 * 1024 * 1024)
+      return HandlePacket_ILLFORMED(__FILE__, __LINE__, packet.data(),
+                                    "MultiMemRead length is too large");
+
+    ranges.emplace_back(*maybe_addr, *maybe_length);
+    total_length += *maybe_length;
+  }
+
+  if (ranges.empty())
+    return HandlePacket_ILLFORMED(__FILE__, __LINE__, p,
+                                  "MultiMemRead has an empty range list");
+
+  // If 'options:' is present, ensure it's empty.
+  const std::string_view options_prefix("options:");
+  if (starts_with(packet, options_prefix)) {
----------------
jasonmolenda wrote:

This hardcodes that `options` key must come after `ranges` key.  I'd `find` these from the start of the original packet string.

https://github.com/llvm/llvm-project/pull/162670