Add plugin.process.gdb-remote.use-libraries-svr4 option

[aadsm]

Summary

This option allow the toggling of the libraries-svr4 usage in ProcessGDBRemote. It's a follow up of https://reviews.llvm.org/D62503#1564296 and it's meant to test / tweak this new packet with, hopefully, minimum impact and in a faster way.

Enable it with settings set plugin.process.gdb-remote.use-libraries-svr4 true. For now, by default it's false.

I didn't put tests up for this but I did test it manually.

[labath]

Thank you.

I don't think tests are necessary right now, since this is effectively NFC for any in-tree server stub. Once we flip the value of the setting to true, it would be nice to add a test or two which loads some libraries with this setting explicitly set to false (emulating a no-libxml build). You can probably just adapt some tests in TestLoadUnload.py for that purpose.

lldb/trunk/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

void DumpProcessGDBRemotePacketHistory(void *p, const char *path) {
   if (error.Success())
     ((ProcessGDBRemote *)p)->GetGDBRemote().DumpHistory(strm);
 }
 } // namespace lldb
 
 namespace {
 
 static constexpr PropertyDefinition g_properties[] = {
-    {"packet-timeout", OptionValue::eTypeUInt64, true, 5
+    {"packet-timeout",
+     OptionValue::eTypeUInt64,
+     true,
+     5
 #if defined(__has_feature)
 #if __has_feature(address_sanitizer)
          * 2
 #endif
 #endif
-     , nullptr, {},
+     ,
+     nullptr,
+     {},
      "Specify the default packet timeout in seconds."},
-    {"target-definition-file", OptionValue::eTypeFileSpec, true, 0, nullptr, {},
-     "The file that provides the description for remote target registers."}};
-
-enum { ePropertyPacketTimeout, ePropertyTargetDefinitionFile };
+    {"target-definition-file",
+     OptionValue::eTypeFileSpec,
+     true,
+     0,
+     nullptr,
+     {},
+     "The file that provides the description for remote target registers."},
+    {"use-libraries-svr4",
+     OptionValue::eTypeBoolean,
+     true,
+     false,
+     nullptr,
+     {},
+     "If true, the libraries-svr4 feature will be used to get a hold of the "
+     "process's loaded modules."}};
+
+enum {
+  ePropertyPacketTimeout,
+  ePropertyTargetDefinitionFile,
+  ePropertyUseSVR4
+};
 
 class PluginProperties : public Properties {
 public:
   static ConstString GetSettingName() {
     return ProcessGDBRemote::GetPluginNameStatic();
   }
 
   PluginProperties() : Properties() {
bool SetPacketTimeout(uint64_t timeout) {
     const uint32_t idx = ePropertyPacketTimeout;
     return m_collection_sp->SetPropertyAtIndexAsUInt64(nullptr, idx, timeout);
   }
 
   FileSpec GetTargetDefinitionFile() const {
     const uint32_t idx = ePropertyTargetDefinitionFile;
     return m_collection_sp->GetPropertyAtIndexAsFileSpec(nullptr, idx);
   }
+
+  bool GetUseSVR4() const {
+    const uint32_t idx = ePropertyUseSVR4;
+    return m_collection_sp->GetPropertyAtIndexAsBoolean(
+        nullptr, idx, g_properties[idx].default_uint_value != 0);
+  }
 };
 
 typedef std::shared_ptr<PluginProperties> ProcessKDPPropertiesSP;
 
 static const ProcessKDPPropertiesSP &GetGlobalPluginProperties() {
   static ProcessKDPPropertiesSP g_settings_sp;
   if (!g_settings_sp)
     g_settings_sp = std::make_shared<PluginProperties>();
Status ProcessGDBRemote::GetLoadedModuleList(LoadedModuleInfoList &list) {
   if (!XMLDocument::XMLEnabled())
     return Status(0, ErrorType::eErrorTypeGeneric);
 
   Log *log = GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS);
   if (log)
     log->Printf("ProcessGDBRemote::%s", __FUNCTION__);
 
   GDBRemoteCommunicationClient &comm = m_gdb_comm;
+  bool can_use_svr4 = GetGlobalPluginProperties()->GetUseSVR4();
 
   // check that we have extended feature read support
-  if (comm.GetQXferLibrariesSVR4ReadSupported()) {
+  if (can_use_svr4 && comm.GetQXferLibrariesSVR4ReadSupported()) {
     list.clear();
 
     // request the loaded library list
     std::string raw;
     lldb_private::Status lldberr;
 
     if (!comm.ReadExtFeature(ConstString("libraries-svr4"), ConstString(""),
                              raw, lldberr))