[lldb/interpreter] Add REPL-specific init file

This patch adds the infrastructure to have language specific REPL init
files. It's the foundation work to a following patch that will introduce
Swift REPL init file.

When lldb is launched with the `--repl` option, it will look for a REPL
init file in the home directory and source it. This overrides the
default `~/.lldbinit`, which content might make the REPL behave
unexpectedly. If the REPL init file doesn't exists, lldb will fall back
to the default init file.

rdar://65836048

Differential Revision: https://reviews.llvm.org/D86242

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/docs/man/lldb.rst

@@ -305,11 +305,15 @@ CONFIGURATION FILES
 :program:`lldb` reads things like settings, aliases and commands from the
 .lldbinit file.
 
-First, it will read the application specific init file whose name is
-~/.lldbinit followed by a "-" and the name of the current program. This would
-be ~/.lldbinit-lldb for the command line :program:`lldb` and ~/.lldbinit-Xcode
-for Xcode. If there is no application specific init file, the global
-~/.lldbinit is read.
+First, :program:`lldb` will try to read the application specific init file
+whose name is ~/.lldbinit followed by a "-" and the name of the current
+program. This would be ~/.lldbinit-lldb for the command line :program:`lldb`
+and ~/.lldbinit-Xcode for Xcode. If there is no application specific init
+file, :program:`lldb` will look for an init file in the home directory.
+If launched with a `REPL`_ option, it will first look for a REPL configuration
+file, specific to the REPL language. If this file doesn't exist, or :program:`lldb`
+wasn't launch with `REPL`_, meaning there is neither a REPL init file nor an
+application specific init file, `lldb` will fallback to the global ~/.lldbinit.
 
 Secondly, it will look for an .lldbinit file in the current working directory.
 For security reasons, :program:`lldb` will print a warning and not source this

lldb/include/lldb/API/SBCommandInterpreter.h

@@ -146,6 +146,8 @@ public:
                              const char *auto_repeat_command);
 
   void SourceInitFileInHomeDirectory(lldb::SBCommandReturnObject &result);
+  void SourceInitFileInHomeDirectory(lldb::SBCommandReturnObject &result,
+                                     bool is_repl);
 
   void
   SourceInitFileInCurrentWorkingDirectory(lldb::SBCommandReturnObject &result);

lldb/include/lldb/Interpreter/CommandInterpreter.h

@@ -256,7 +256,7 @@ public:
   }
 
   void SourceInitFileCwd(CommandReturnObject &result);
-  void SourceInitFileHome(CommandReturnObject &result);
+  void SourceInitFileHome(CommandReturnObject &result, bool is_repl = false);
 
   bool AddCommand(llvm::StringRef name, const lldb::CommandObjectSP &cmd_sp,
                   bool can_replace);

lldb/source/API/SBCommandInterpreter.cpp

@@ -478,6 +478,24 @@ void SBCommandInterpreter::SourceInitFileInHomeDirectory(
   }
 }
 
+void SBCommandInterpreter::SourceInitFileInHomeDirectory(
+    SBCommandReturnObject &result, bool is_repl) {
+  LLDB_RECORD_METHOD(void, SBCommandInterpreter, SourceInitFileInHomeDirectory,
+                     (lldb::SBCommandReturnObject &, bool), result, is_repl);
+
+  result.Clear();
+  if (IsValid()) {
+    TargetSP target_sp(m_opaque_ptr->GetDebugger().GetSelectedTarget());
+    std::unique_lock<std::recursive_mutex> lock;
+    if (target_sp)
+      lock = std::unique_lock<std::recursive_mutex>(target_sp->GetAPIMutex());
+    m_opaque_ptr->SourceInitFileHome(result.ref(), is_repl);
+  } else {
+    result->AppendError("SBCommandInterpreter is not valid");
+    result->SetStatus(eReturnStatusFailed);
+  }
+}
+
 void SBCommandInterpreter::SourceInitFileInCurrentWorkingDirectory(
     SBCommandReturnObject &result) {
   LLDB_RECORD_METHOD(void, SBCommandInterpreter,
@@ -806,6 +824,9 @@ template <> void RegisterMethods<SBCommandInterpreter>(Registry &R) {
   LLDB_REGISTER_METHOD(void, SBCommandInterpreter,
                        SourceInitFileInHomeDirectory,
                        (lldb::SBCommandReturnObject &));
+  LLDB_REGISTER_METHOD(void, SBCommandInterpreter,
+                       SourceInitFileInHomeDirectory,
+                       (lldb::SBCommandReturnObject &, bool));
   LLDB_REGISTER_METHOD(void, SBCommandInterpreter,
                        SourceInitFileInCurrentWorkingDirectory,
                        (lldb::SBCommandReturnObject &));

lldb/source/API/SBDebugger.cpp

@@ -220,7 +220,7 @@ SBDebugger SBDebugger::Create(bool source_init_files,
     interp.get()->SkipLLDBInitFiles(false);
     interp.get()->SkipAppInitFiles(false);
     SBCommandReturnObject result;
-    interp.SourceInitFileInHomeDirectory(result);
+    interp.SourceInitFileInHomeDirectory(result, false);
   } else {
     interp.get()->SkipLLDBInitFiles(true);
     interp.get()->SkipAppInitFiles(true);

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -2090,6 +2090,22 @@ static void GetHomeInitFile(llvm::SmallVectorImpl<char> &init_file,
   FileSystem::Instance().Resolve(init_file);
 }
 
+static void GetHomeREPLInitFile(llvm::SmallVectorImpl<char> &init_file,
+                                LanguageType language) {
+  std::string init_file_name;
+
+  switch (language) {
+  // TODO: Add support for a language used with a REPL.
+  default:
+    return;
+  }
+
+  llvm::sys::path::home_directory(init_file);
+  llvm::sys::path::append(init_file, init_file_name);
+
+  FileSystem::Instance().Resolve(init_file);
+}
+
 static void GetCwdInitFile(llvm::SmallVectorImpl<char> &init_file) {
   llvm::StringRef s = ".lldbinit";
   init_file.assign(s.begin(), s.end());
@@ -2164,15 +2180,27 @@ void CommandInterpreter::SourceInitFileCwd(CommandReturnObject &result) {
 
 /// We will first see if there is an application specific ".lldbinit" file
 /// whose name is "~/.lldbinit" followed by a "-" and the name of the program.
-/// If this file doesn't exist, we fall back to just the "~/.lldbinit" file.
-void CommandInterpreter::SourceInitFileHome(CommandReturnObject &result) {
+/// If this file doesn't exist, we fall back to the REPL init file or the
+/// default home init file in "~/.lldbinit".
+void CommandInterpreter::SourceInitFileHome(CommandReturnObject &result,
+                                            bool is_repl) {
   if (m_skip_lldbinit_files) {
     result.SetStatus(eReturnStatusSuccessFinishNoResult);
     return;
   }
 
   llvm::SmallString<128> init_file;
-  GetHomeInitFile(init_file);
+
+  if (is_repl) {
+    LanguageType language = {};
+    TargetSP target_sp = GetDebugger().GetSelectedTarget();
+    if (target_sp)
+      language = target_sp->GetLanguage();
+    GetHomeREPLInitFile(init_file, language);
+  }
+
+  if (init_file.empty())
+    GetHomeInitFile(init_file);
 
   if (!m_skip_app_init_files) {
     llvm::StringRef program_name =

lldb/tools/driver/Driver.cpp

@@ -493,7 +493,7 @@ int Driver::MainLoop() {
   // Before we handle any options from the command line, we parse the
   // .lldbinit file in the user's home directory.
   SBCommandReturnObject result;
-  sb_interpreter.SourceInitFileInHomeDirectory(result);
+  sb_interpreter.SourceInitFileInHomeDirectory(result, m_option_data.m_repl);
   if (m_option_data.m_debug_mode) {
     result.PutError(m_debugger.GetErrorFile());
     result.PutOutput(m_debugger.GetOutputFile());