WIP: Trepan-Debuggers#107: Debugger "watchpoints": break when the com…

…mand executed matches a certain regex.

debug-test/Makefile

@@ -1,4 +1,7 @@
 
+# Run as ./make -f debug-test/Makefile -X --debugger-stop=preaction,
+# then do `watch Hell.`.
+
 UNEXPANDED=expanded
 
 all: test

libdebugger/break.c

@@ -30,7 +30,7 @@ Boston, MA 02111-1307, USA.  */
 enum breakpoint_type
 {
   LINE,
-  COMMAND
+  COMMAND_WATCH
 };
 
 /*! Node for an item in the target call stack */
@@ -138,8 +138,8 @@ remove_breakpoint (unsigned int i, bool silent)
 
       if (p_prev) p_prev->p_next = p->p_next;
 
-      if (p->type == COMMAND) {
-          dbg_msg(_("Command watchpoint %u cleared."), i);  // on regex `%s' TODO: Save the original regex?
+      if (p->type == COMMAND_WATCH) {
+          dbg_msg(_("Command watchpoint %u cleared."), i);
           regfree(&p->regex);
           free(p->psz_text);
           free(p);
@@ -201,16 +201,19 @@ add_command_breakpoint(const char *psz_regex)
 
   if (!p_new) return false;
 
-  re_compile_status          = regcomp(&p_new->regex, "psz_regex", REG_EXTENDED | REG_NOSUB);
+  re_compile_status          = regcomp(&p_new->regex, psz_regex, REG_EXTENDED | REG_NOSUB);
 
-  // Not sure if regex_t can be memmoved, so initializing it in allocated breakpoint_node_t.
+  // Not sure if regex_t can be memmoved, so initializing it in the allocated breakpoint_node_t.
   if (re_compile_status != 0) {
-    dbg_msg("Could not compile regex: %s", psz_regex);
+    char reg_error_message[100];
+    regerror(re_compile_status, &p_new->regex, reg_error_message, sizeof(reg_error_message)-1);
+    dbg_msg("Could not compile regex: %s: %s", psz_regex, reg_error_message);
+    regfree(&p_new->regex);
     free(p_new);
     return false;
   }
 
-  p_new->type                   = COMMAND;
+  p_new->type                   = COMMAND_WATCH;
   p_new->psz_text               = strdup(psz_regex);
   p_new->i_num                  = ++i_breakpoints;
   p_new->p_target               = NULL;
@@ -234,10 +237,9 @@ any_command_breakpoint_matches(const char *psz_expanded_command)
   breakpoint_node_t *p;
 
   for (p = p_breakpoint_top; p; p = p->p_next) {
-    if (p->type == COMMAND) {
-      int matches = regexec(&p->regex, psz_expanded_command, (size_t) 0, NULL, 0);
-      printf("DEBUG: Checking if command %s matches %s: %s\n", psz_expanded_command, p->psz_text, matches ? "yes" : "no");
-      if (matches == 0) {
+    if (p->type == COMMAND_WATCH) {
+      int match_status = regexec(&p->regex, psz_expanded_command, (size_t) 0, NULL, 0);
+      if (match_status == 0) {
         return true;
       }
     }
@@ -250,8 +252,7 @@ void
 check_command_breakpoint(target_stack_node_t *p_call_stack, const char *psz_expanded_command)
 {
   if (any_command_breakpoint_matches (psz_expanded_command)) {
-    // TODO: Probably we need a new reason, other than DEBUG_BRKPT_AFTER_PREREQ.
-    enter_debugger (p_call_stack, p_call_stack->p_target, 0, DEBUG_BRKPT_AFTER_PREREQ);
+    enter_debugger (p_call_stack, p_call_stack->p_target, 0, DEBUG_WATCHPOINT);
   }
 }
 

libdebugger/cmd.c

@@ -264,8 +264,10 @@ debug_return_t enter_debugger (target_stack_node_t *p,
     if (!p_target->tracing) return continue_execution;
   } else if ( !debugger_on_error
 	      && !(i_debugger_stepping || i_debugger_nexting)
-	      && p_target && !p_target->tracing && -2 != errcode )
+	      && p_target && !p_target->tracing && -2 != errcode
+	      && reason != DEBUG_WATCHPOINT) {
     return continue_execution;
+  }
 
   /* Clear temporary breakpoints. */
   if (p_target && p_target->tracing & BRK_TEMP)
@@ -274,6 +276,7 @@ debug_return_t enter_debugger (target_stack_node_t *p,
       case DEBUG_BRKPT_AFTER_CMD:
       case DEBUG_BRKPT_BEFORE_PREREQ:
       case DEBUG_BRKPT_AFTER_PREREQ:
+      case DEBUG_WATCHPOINT: // FIXME: I have about no idea what I'm doing here. Should this reason be "cleared"?
         p_target->tracing = BRK_NONE;
       default:
         ;

libdebugger/command/watch.c

@@ -18,9 +18,9 @@ dbg_cmd_watch (char *psz_regex)
 
   added = add_command_breakpoint(psz_regex);
   if (added) {
-    printf("Added command watchpoint %s\n", psz_regex);
+    printf("Added command watchpoint: '%s'\n", psz_regex);
   } else {
-    printf("Error adding command watchpoint %s\n", psz_regex);
+    printf("Error adding command watchpoint: '%s'\n", psz_regex);
   }
 
   return debug_readloop;

libdebugger/fns.c

@@ -292,7 +292,8 @@ static const char *reason2str[] = {
     "!!",
     "--",
     "++",
-    ":o"
+    ":o",
+    "re"
 };
 
 

src/trace.h

@@ -54,6 +54,7 @@ typedef enum
     DEBUG_STEP_HIT                = 6,
     DEBUG_STEP_COMMAND            = 7,
     DEBUG_EXPLICIT_CALL           = 8,
+    DEBUG_WATCHPOINT              = 9,
     DEBUG_STACK_CHANGING          = 99,
     DEBUG_NOT_GIVEN               = 100
   } debug_enter_reason_t;