Introducing debugger modes (run, breakpoint). (#1645)

This makes the code more robust and error prone, since certain
messages cannot be received in certain situations, e.g. an eval
command during garbage collection.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/debugger/jerry-debugger.c

@@ -225,6 +225,14 @@ jerry_debugger_process_message (uint8_t *recv_buffer_p, /**< pointer the the rec
 {
   /* Process the received message. */
 
+  if (recv_buffer_p[0] >= JERRY_DEBUGGER_CONTINUE
+      && !(JERRY_CONTEXT (debugger_flags) & JERRY_DEBUGGER_BREAKPOINT_MODE))
+  {
+    jerry_port_log (JERRY_LOG_LEVEL_ERROR, "Message requires breakpoint mode\n");
+    jerry_debugger_close_connection ();
+    return false;
+  }
+
   if (*expected_message_type_p != 0)
   {
     JERRY_ASSERT (*expected_message_type_p == JERRY_DEBUGGER_EVAL_PART);
@@ -466,10 +474,14 @@ jerry_debugger_breakpoint_hit (void)
     return;
   }
 
+  JERRY_CONTEXT (debugger_flags) = (uint8_t) (JERRY_CONTEXT (debugger_flags) | JERRY_DEBUGGER_BREAKPOINT_MODE);
+
   while (!jerry_debugger_receive ())
   {
   }
 
+  JERRY_CONTEXT (debugger_flags) = (uint8_t) (JERRY_CONTEXT (debugger_flags) & ~JERRY_DEBUGGER_BREAKPOINT_MODE);
+
   JERRY_CONTEXT (debugger_message_delay) = JERRY_DEBUGGER_MESSAGE_FREQUENCY;
 } /* jerry_debugger_breakpoint_hit */
 

jerry-core/debugger/jerry-debugger.h

@@ -43,15 +43,40 @@
 #define JERRY_DEBUGGER_SEND_MAX(type) \
  ((JERRY_DEBUGGER_MAX_SEND_SIZE - sizeof (jerry_debugger_send_header_t) - 1) / sizeof (type))
 
+/**
+ * Debugger operation modes:
+ *
+ * The debugger has two operation modes: run mode and breakpoint mode.
+ *
+ * In run mode the debugger server accepts only a limited number of message
+ * types from the debugger client (e.g. stop execution, set breakpoint).
+ *
+ * In breakpoint mode the JavaScript execution is stopped at a breakpoint and
+ * more message types are accepted (e.g. get backtrace, evaluate expression).
+ *
+ * Switching between modes:
+ *
+ * When the JavaScript execution stops at a breakpoint the server sends a
+ * JERRY_DEBUGGER_BREAKPOINT_HIT message to the client. The client can only
+ * issue breakpoint mode commands after this message is received.
+ *
+ * Certain breakpoint mode commands (e.g. continue) resumes the JavaScript
+ * execution and the client must not send any breakpoint mode messages
+ * until the JERRY_DEBUGGER_BREAKPOINT_HIT is received again.
+ *
+ * The debugger server starts in run mode but stops at the first available
+ * breakpoint.
+ */
+
 /**
  * Debugger option flags.
  */
 typedef enum
 {
   JERRY_DEBUGGER_CONNECTED = 1u << 0, /**< debugger is connected */
-  JERRY_DEBUGGER_VM_STOP = 1u << 1, /**< stop at the next breakpoint
+  JERRY_DEBUGGER_BREAKPOINT_MODE = 1u << 1, /**< debugger waiting at a breakpoint */
-                                     *   regardless it is enabled */
+  JERRY_DEBUGGER_VM_STOP = 1u << 2, /**< stop at the next breakpoint regardless it is enabled */
-  JERRY_DEBUGGER_VM_IGNORE = 1u << 2, /**< ignore all breakpoints */
+  JERRY_DEBUGGER_VM_IGNORE = 1u << 3, /**< ignore all breakpoints */
 } jerry_debugger_flags_t;
 
 /**
@@ -82,12 +107,18 @@ typedef enum
   JERRY_DEBUGGER_EVAL_ERROR_END = 20, /**< last part of eval result when an error is occured */
 
   /* Messages sent by the client to server. */
+
+  /* The following messages are accepted in both run and breakpoint modes. */
   JERRY_DEBUGGER_FREE_BYTE_CODE_CP = 1, /**< free byte code compressed pointer */
   JERRY_DEBUGGER_UPDATE_BREAKPOINT = 2, /**< update breakpoint status */
   JERRY_DEBUGGER_STOP = 3, /**< stop execution */
+  /* The following messages are only available in breakpoint
+   * mode and they switch the engine to run mode. */
   JERRY_DEBUGGER_CONTINUE = 4, /**< continue execution */
   JERRY_DEBUGGER_STEP = 5, /**< next breakpoint, step into functions */
   JERRY_DEBUGGER_NEXT = 6, /**< next breakpoint in the same context */
+  /* The following messages are only available in breakpoint
+   * mode and this mode is kept after the message is processed. */
   JERRY_DEBUGGER_GET_BACKTRACE = 7, /**< get backtrace */
   JERRY_DEBUGGER_EVAL = 8, /**< first message of evaluating a string */
   JERRY_DEBUGGER_EVAL_PART = 9, /**< next message of evaluating a string */

jerry-core/vm/vm.c

@@ -2321,19 +2321,7 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
 
           JERRY_ASSERT (JERRY_CONTEXT (debugger_flags) & JERRY_DEBUGGER_CONNECTED);
 
-          if (frame_ctx_p->bytecode_header_p->status_flags & CBC_CODE_FLAGS_DEBUGGER_IGNORE)
+          JERRY_ASSERT (!(frame_ctx_p->bytecode_header_p->status_flags & CBC_CODE_FLAGS_DEBUGGER_IGNORE));
-          {
-            /* Messages are still processed regardless of ignore. */
-            if (JERRY_CONTEXT (debugger_message_delay) > 0)
-            {
-              JERRY_CONTEXT (debugger_message_delay)--;
-              continue;
-            }
-
-            JERRY_CONTEXT (debugger_message_delay) = JERRY_DEBUGGER_MESSAGE_FREQUENCY;
-            jerry_debugger_receive ();
-            continue;
-          }
 
           frame_ctx_p->byte_code_p = byte_code_start_p;
 
@@ -2351,19 +2339,7 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
 
           JERRY_ASSERT (JERRY_CONTEXT (debugger_flags) & JERRY_DEBUGGER_CONNECTED);
 
-          if (frame_ctx_p->bytecode_header_p->status_flags & CBC_CODE_FLAGS_DEBUGGER_IGNORE)
+          JERRY_ASSERT (!(frame_ctx_p->bytecode_header_p->status_flags & CBC_CODE_FLAGS_DEBUGGER_IGNORE));
-          {
-            /* Messages are still processed regardless of ignore. */
-            if (JERRY_CONTEXT (debugger_message_delay) > 0)
-            {
-              JERRY_CONTEXT (debugger_message_delay)--;
-              continue;
-            }
-
-            JERRY_CONTEXT (debugger_message_delay) = JERRY_DEBUGGER_MESSAGE_FREQUENCY;
-            jerry_debugger_receive ();
-            continue;
-          }
 
           frame_ctx_p->byte_code_p = byte_code_start_p;
 

jerry-debugger/jerry-client-ws.html

@@ -894,10 +894,43 @@ function DebuggerClient(address)
     }
   }
 
+  this.sendResumeExec = function(command)
+  {
+    if (!lastBreakpointHit)
+    {
+      appendLog("This command is allowed only if JavaScript execution is stopped at a breakpoint.");
+      return;
+    }
+
+    encodeMessage("B", [ command ]);
+
+    lastBreakpointHit = null;
+  }
+
+  this.sendGetBacktrace = function(depth)
+  {
+    if (!lastBreakpointHit)
+    {
+      appendLog("This command is allowed only if JavaScript execution is stopped at a breakpoint.");
+      return;
+    }
+
+    encodeMessage("BI", [ JERRY_DEBUGGER_GET_BACKTRACE, max_depth ]);
+
+    appendLog("Backtrace:");
+  }
+
   this.sendEval = function(str)
   {
+    if (!lastBreakpointHit)
+    {
+      appendLog("This command is allowed only if JavaScript execution is stopped at a breakpoint.");
+      return;
+    }
+
     if (str == "")
     {
+      appendLog("Argument required");
       return;
     }
 
@@ -1054,23 +1087,24 @@ function debuggerCommand(event)
       debuggerObj.deleteBreakpoint(args[2]);
       break;
 
+    case "st":
     case "stop":
       debuggerObj.encodeMessage("B", [ JERRY_DEBUGGER_STOP ]);
       break;
 
     case "c":
     case "continue":
-      debuggerObj.encodeMessage("B", [ JERRY_DEBUGGER_CONTINUE ]);
+      debuggerObj.sendResumeExec(JERRY_DEBUGGER_CONTINUE);
       break;
 
     case "s":
     case "step":
-      debuggerObj.encodeMessage("B", [ JERRY_DEBUGGER_STEP ]);
+      debuggerObj.sendResumeExec(JERRY_DEBUGGER_STEP);
       break;
 
     case "n":
     case "next":
-      debuggerObj.encodeMessage("B", [ JERRY_DEBUGGER_NEXT ]);
+      debuggerObj.sendResumeExec(JERRY_DEBUGGER_NEXT);
       break;
 
     case "e":
@@ -1095,9 +1129,7 @@ function debuggerCommand(event)
         }
       }
 
-      appendLog("Backtrace:");
+      debuggerObj.sendGetBacktrace(max_depth);
-
-      debuggerObj.encodeMessage("BI", [ JERRY_DEBUGGER_GET_BACKTRACE, max_depth ]);
       break;
 
     case "src":

jerry-debugger/jerry-client-ws.py

@@ -68,6 +68,7 @@ def arguments_parse():
 
     parser.add_argument("address", action="store", nargs="?", default="localhost:5001", help="specify a unique network address for connection (default: %(default)s)")
     parser.add_argument("-v", "--verbose", action="store_true", default=False, help="increase verbosity (default: %(default)s)")
+    parser.add_argument("--non-interactive", action="store_true", default=False, help="disable stop when newline is pressed (default: %(default)s)")
 
     args = parser.parse_args()
 
@@ -140,7 +141,7 @@ class DebuggerPrompt(Cmd):
         self.debugger = debugger
         self.stop = False
         self.quit = False
-        self.cont = False
+        self.cont = True
 
     def precmd(self, line):
         self.stop = False
@@ -188,12 +189,14 @@ class DebuggerPrompt(Cmd):
     def do_step(self, args):
         """ Next breakpoint, step into functions """
         self.exec_command(args, JERRY_DEBUGGER_STEP)
+        self.cont = True
 
     do_s = do_step
 
     def do_next(self, args):
         """ Next breakpoint in the same context """
         self.exec_command(args, JERRY_DEBUGGER_NEXT)
+        self.cont = True
 
     do_n = do_next
 
@@ -669,13 +672,15 @@ def main():
 
     debugger = JerryDebugger(args.address)
 
+    non_interactive = args.non_interactive
+
     logging.debug("Connected to JerryScript on %d port" % (debugger.port))
 
     prompt = DebuggerPrompt(debugger)
     prompt.prompt = "(jerry-debugger) "
 
     while True:
-        if prompt.cont:
+        if not non_interactive and prompt.cont:
             if sys.stdin in select.select([sys.stdin], [], [], 0)[0]:
                 sys.stdin.readline()
                 prompt.cont = False

tools/runners/run-debugger-test.sh

@@ -24,7 +24,7 @@ echo "$START_DEBUG_SERVER"
 eval "$START_DEBUG_SERVER"
 sleep 1s
 
-RESULT=$((cat "${TEST_CASE}.cmd" | ${DEBUGGER_CLIENT}) 2>&1)
+RESULT=$((cat "${TEST_CASE}.cmd" | ${DEBUGGER_CLIENT} --non-interactive) 2>&1)
 DIFF=$(diff -u0 ${TEST_CASE}.expected <(echo "$RESULT"))
 
 if [ -n "$DIFF" ]