Add proper options struct to simplified remote GDB

Author: fwsGonzo

lib/tinykvm/machine.hpp

@@ -212,7 +212,13 @@ struct Machine
 	void print_registers() const { vcpu.print_registers(); }
 	void print_pagetables() const;
 	void print_exception_handlers() const;
-	void print_remote_gdb_backtrace(const std::string& filename, const std::string& gdb_path = "/usr/bin/gdb");
+	struct RemoteGDBOptions {
+		std::string gdb_path = "/usr/bin/gdb";
+		std::string command = "bt";
+		bool verbose = false;
+		bool quit = false;
+	};
+	void print_remote_gdb_backtrace(const std::string& filename, const RemoteGDBOptions& opts);
 
 	void install_memory(uint32_t idx, const VirtualMem&, bool ro);
 	void delete_memory(uint32_t idx);

lib/tinykvm/machine_debug.cpp

@@ -9,7 +9,7 @@ extern char** environ;
 namespace tinykvm {
 void Machine::print_remote_gdb_backtrace(
 	const std::string& filename,
-	const std::string& gdb_path)
+	const RemoteGDBOptions& opts)
 {
 	const uint16_t port = 2159;
 
@@ -23,7 +23,7 @@ void Machine::print_remote_gdb_backtrace(
 			throw std::runtime_error("Unable to create script for debugging");
 		}
 
-		const std::string debugscript =
+		std::string debugscript =
 			// Delete the script file (after GDB closes it)
 			"shell unlink " + std::string(scrname)
 			+ "\n"
@@ -34,7 +34,9 @@ void Machine::print_remote_gdb_backtrace(
 			  "target remote localhost:"
 			+ std::to_string(port)
 			+ "\n"
-			+ "up\nbt\n";
+			+ opts.command + "\n";
+		if (opts.quit)
+			debugscript += "quit\n";
 
 		ssize_t len = write(fd, debugscript.c_str(), debugscript.size());
 		if (len < (ssize_t)debugscript.size())
@@ -45,7 +47,7 @@ void Machine::print_remote_gdb_backtrace(
 		close(fd);
 
 		const char* argv[]
-			= {gdb_path.c_str(), "-x", scrname, nullptr};
+			= {opts.gdb_path.c_str(), "-x", scrname, nullptr};
 		// XXX: This is not kosher, but GDB is open-source, safe and let's not
 		// pretend that anyone downloads gdb-multiarch from a website anyway.
 		// There is a finite list of things we should pass to GDB to make it
@@ -58,10 +60,15 @@ void Machine::print_remote_gdb_backtrace(
 	}
 
 	RSP server {filename, *this, port};
+	if (opts.verbose) {
+		printf("Waiting for GDB to connect on port %u...\n", port);
+	}
 	auto client = server.accept();
 	if (client != nullptr)
 	{
-		printf("GDB connected\n");
+		if (opts.verbose) {
+			printf("GDB connected\n");
+		}
 		// client->set_verbose(true);
 		while (client->process_one())
 			;