[PATCH v2 3/4] gdb/breakpoint: add a 'force_condition' parameter to 'create_breakpoint'

[Tankut Baris Aktemur via Gdb-patches <gdb-patches@sourceware.org>]

The 'create_breakpoint' function takes a 'parse_extra' argument that
determines whether the condition, thread, and force-condition
specifiers should be parsed from the extra string or be used from the
function arguments.  However, for the case when 'parse_extra' is
false, there is no way to pass the force-condition specifier.  This
patch adds it as a new argument.

Also, in the case when parse_extra is false, the current behavior is
as if the condition is being forced.  This is a bug.  The default
behavior should reject the breakpoint.  See below for a demo of this
incorrect behavior.  (The MI command '-break-insert' uses the
'create_breakpoint' function with parse_extra=0.)

  $ gdb -q --interpreter=mi3 /tmp/simple
  =thread-group-added,id="i1"
  =cmd-param-changed,param="history save",value="on"
  =cmd-param-changed,param="auto-load safe-path",value="/"
  ~"Reading symbols from /tmp/simple...\n"
  (gdb)
  -break-insert -c junk -f main
  &"warning: failed to validate condition at location 1, disabling:\n  "
  &"No symbol \"junk\" in current context.\n"
  ^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",cond="junk",times="0",original-location="main",locations=[{number="1.1",enabled="N",addr="0x000000000000114e",func="main",file="/tmp/simple.c",fullname="/tmp/simple.c",line="2",thread-groups=["i1"]}]}
  (gdb)
  break main if junk
  &"break main if junk\n"
  &"No symbol \"junk\" in current context.\n"
  ^error,msg="No symbol \"junk\" in current context."
  (gdb)
  break main -force-condition if junk
  &"break main -force-condition if junk\n"
  ~"Note: breakpoint 1 also set at pc 0x114e.\n"
  &"warning: failed to validate condition at location 1, disabling:\n  "
  &"No symbol \"junk\" in current context.\n"
  ~"Breakpoint 2 at 0x114e: file /tmp/simple.c, line 2.\n"
  =breakpoint-created,bkpt={number="2",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",cond="junk",times="0",original-location="main",locations=[{number="2.1",enabled="N",addr="0x000000000000114e",func="main",file="/tmp/simple.c",fullname="/tmp/simple.c",line="2",thread-groups=["i1"]}]}
  ^done
  (gdb)

After applying this patch, we get the behavior below:

  (gdb)
  -break-insert -c junk -f main
  ^error,msg="No symbol \"junk\" in current context."

This restores the behavior that is present in the existing releases.

gdb/ChangeLog:
2021-04-06  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* breakpoint.h (create_breakpoint): Add a new parameter,
	'force_condition'.
	* breakpoint.c (create_breakpoint): Use the 'force_condition'
	argument when 'parse_extra' is false to check if the condition
	is invalid at all of the breakpoint locations.
	Update the users below.
	(break_command_1)
	(dprintf_command)
	(trace_command)
	(ftrace_command)
	(strace_command)
	(create_tracepoint_from_upload): Update.
	* guile/scm-breakpoint.c (gdbscm_register_breakpoint_x): Update.
	* mi/mi-cmd-break.c (mi_cmd_break_insert_1): Update.
	* python/py-breakpoint.c (bppy_init): Update.
	* python/py-finishbreakpoint.c (bpfinishpy_init): Update.

gdb/testsuite/ChangeLog:
2021-04-06  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.mi/mi-break.exp: Extend with checks for invalid breakpoint
	conditions.
---
 gdb/breakpoint.c                  | 40 ++++++++++++++++++++++++++-----
 gdb/breakpoint.h                  |  6 +++++
 gdb/guile/scm-breakpoint.c        |  2 +-
 gdb/mi/mi-cmd-break.c             |  1 +
 gdb/python/py-breakpoint.c        |  2 +-
 gdb/python/py-finishbreakpoint.c  |  2 +-
 gdb/testsuite/gdb.mi/mi-break.exp | 13 ++++++++++
 7 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 0136019b4ae..e5a5f6b0c6a 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -9460,7 +9460,7 @@ create_breakpoint (struct gdbarch *gdbarch,
 		   struct event_location *location,
 		   const char *cond_string,
 		   int thread, const char *extra_string,
-		   int parse_extra,
+		   bool force_condition, int parse_extra,
 		   int tempflag, enum bptype type_wanted,
 		   int ignore_count,
 		   enum auto_boolean pending_break_support,
@@ -9558,6 +9558,33 @@ create_breakpoint (struct gdbarch *gdbarch,
 	      && extra_string != NULL && *extra_string != '\0')
 		error (_("Garbage '%s' at end of location"), extra_string);
 
+	  /* Check the validity of the condition.  We should error out
+	     if the condition is invalid at all of the locations and
+	     if it is not forced.  In the PARSE_EXTRA case above, this
+	     check is done when parsing the EXTRA_STRING.  */
+	  if (cond_string != nullptr && !force_condition)
+	    {
+	      int num_failures = 0;
+	      const linespec_sals &lsal = canonical.lsals[0];
+	      for (auto &sal : lsal.sals)
+		{
+		  const char *cond = cond_string;
+		  try
+		    {
+		      parse_exp_1 (&cond, sal.pc, block_for_pc (sal.pc), 0);
+		      /* One success is sufficient to keep going.  */
+		      break;
+		    }
+		  catch (const gdb_exception_error &)
+		    {
+		      num_failures++;
+		      /* If this is the last sal, error out.  */
+		      if (num_failures == lsal.sals.size ())
+			throw;
+		    }
+		}
+	    }
+
 	  /* Create a private copy of condition string.  */
 	  if (cond_string)
 	    cond_string_copy.reset (xstrdup (cond_string));
@@ -9636,7 +9663,7 @@ break_command_1 (const char *arg, int flag, int from_tty)
 
   create_breakpoint (get_current_arch (),
 		     location.get (),
-		     NULL, 0, arg, 1 /* parse arg */,
+		     NULL, 0, arg, false, 1 /* parse arg */,
 		     tempflag, type_wanted,
 		     0 /* Ignore count */,
 		     pending_break_support,
@@ -9823,7 +9850,7 @@ dprintf_command (const char *arg, int from_tty)
 
   create_breakpoint (get_current_arch (),
 		     location.get (),
-		     NULL, 0, arg, 1 /* parse arg */,
+		     NULL, 0, arg, false, 1 /* parse arg */,
 		     0, bp_dprintf,
 		     0 /* Ignore count */,
 		     pending_break_support,
@@ -14721,7 +14748,7 @@ trace_command (const char *arg, int from_tty)
 
   create_breakpoint (get_current_arch (),
 		     location.get (),
-		     NULL, 0, arg, 1 /* parse arg */,
+		     NULL, 0, arg, false, 1 /* parse arg */,
 		     0 /* tempflag */,
 		     bp_tracepoint /* type_wanted */,
 		     0 /* Ignore count */,
@@ -14739,7 +14766,7 @@ ftrace_command (const char *arg, int from_tty)
 							 current_language);
   create_breakpoint (get_current_arch (),
 		     location.get (),
-		     NULL, 0, arg, 1 /* parse arg */,
+		     NULL, 0, arg, false, 1 /* parse arg */,
 		     0 /* tempflag */,
 		     bp_fast_tracepoint /* type_wanted */,
 		     0 /* Ignore count */,
@@ -14773,7 +14800,7 @@ strace_command (const char *arg, int from_tty)
 
   create_breakpoint (get_current_arch (),
 		     location.get (),
-		     NULL, 0, arg, 1 /* parse arg */,
+		     NULL, 0, arg, false, 1 /* parse arg */,
 		     0 /* tempflag */,
 		     bp_static_tracepoint /* type_wanted */,
 		     0 /* Ignore count */,
@@ -14843,6 +14870,7 @@ create_tracepoint_from_upload (struct uploaded_tp *utp)
   if (!create_breakpoint (get_current_arch (),
 			  location.get (),
 			  utp->cond_string.get (), -1, addr_str,
+			  false /* force_condition */,
 			  0 /* parse cond/thread */,
 			  0 /* tempflag */,
 			  utp->type /* type_wanted */,
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index c30656971bb..ded498f5562 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -1409,6 +1409,11 @@ enum breakpoint_create_flags
    the condition, thread, and extra string from EXTRA_STRING, ignoring
    the similarly named parameters.
 
+   If FORCE_CONDITION is true, the condition is accepted even when it is
+   invalid at all of the locations.  However, if PARSE_EXTRA is non-zero,
+   the FORCE_CONDITION parameter is ignored and the corresponding argument
+   is parsed from EXTRA_STRING.
+
    If INTERNAL is non-zero, the breakpoint number will be allocated
    from the internal breakpoint count.
 
@@ -1418,6 +1423,7 @@ extern int create_breakpoint (struct gdbarch *gdbarch,
 			      struct event_location *location,
 			      const char *cond_string, int thread,
 			      const char *extra_string,
+			      bool force_condition,
 			      int parse_extra,
 			      int tempflag, enum bptype wanted_type,
 			      int ignore_count,
diff --git a/gdb/guile/scm-breakpoint.c b/gdb/guile/scm-breakpoint.c
index 99098e7e155..af63893461b 100644
--- a/gdb/guile/scm-breakpoint.c
+++ b/gdb/guile/scm-breakpoint.c
@@ -440,7 +440,7 @@ gdbscm_register_breakpoint_x (SCM self)
 	    const breakpoint_ops *ops =
 	      breakpoint_ops_for_event_location (eloc.get (), false);
 	    create_breakpoint (get_current_arch (),
-			       eloc.get (), NULL, -1, NULL,
+			       eloc.get (), NULL, -1, NULL, false,
 			       0,
 			       0, bp_breakpoint,
 			       0,
diff --git a/gdb/mi/mi-cmd-break.c b/gdb/mi/mi-cmd-break.c
index 1c3e9209a74..5a4a62ce8c3 100644
--- a/gdb/mi/mi-cmd-break.c
+++ b/gdb/mi/mi-cmd-break.c
@@ -353,6 +353,7 @@ mi_cmd_break_insert_1 (int dprintf, const char *command, char **argv, int argc)
 
   create_breakpoint (get_current_arch (), location.get (), condition, thread,
 		     extra_string.c_str (),
+		     false,
 		     0 /* condition and thread are valid.  */,
 		     temp_p, type_wanted,
 		     ignore_count,
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 3fbb1c633ff..9650bd023b5 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -835,7 +835,7 @@ bppy_init (PyObject *self, PyObject *args, PyObject *kwargs)
 	      breakpoint_ops_for_event_location (location.get (), false);
 
 	    create_breakpoint (python_gdbarch,
-			       location.get (), NULL, -1, NULL,
+			       location.get (), NULL, -1, NULL, false,
 			       0,
 			       temporary_bp, type,
 			       0,
diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index d01b84273fc..38b4cc67901 100644
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -294,7 +294,7 @@ bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs)
       event_location_up location
 	= new_address_location (get_frame_pc (prev_frame), NULL, 0);
       create_breakpoint (python_gdbarch,
-			 location.get (), NULL, thread, NULL,
+			 location.get (), NULL, thread, NULL, false,
 			 0,
 			 1 /*temp_flag*/,
 			 bp_breakpoint,
diff --git a/gdb/testsuite/gdb.mi/mi-break.exp b/gdb/testsuite/gdb.mi/mi-break.exp
index 19438f21f63..e46a6cc0ec6 100644
--- a/gdb/testsuite/gdb.mi/mi-break.exp
+++ b/gdb/testsuite/gdb.mi/mi-break.exp
@@ -224,6 +224,19 @@ proc_with_prefix test_error {} {
     mi_gdb_test "-break-insert -c i==4 \"callme if i < 4\"" \
         ".*\\^error,msg=\"Garbage 'if i < 4' at end of location\"" \
         "conditional breakpoint with garbage after location"
+
+    # Try using an invalid condition.
+    mi_gdb_test "-break-insert -c bad callme" \
+        ".*\\^error,msg=\"No symbol \\\\\"bad\\\\\" in current context.\"" \
+        "breakpoint with bad condition"
+
+    mi_gdb_test "-dprintf-insert -c bad callme 123" \
+        ".*\\^error,msg=\"No symbol \\\\\"bad\\\\\" in current context.\"" \
+        "dprintf with bad condition"
+
+    mi_gdb_test "-break-condition 5 bad" \
+        ".*\\^error,msg=\"No symbol \\\\\"bad\\\\\" in current context.\"" \
+        "invalid condition"
 }
 
 proc_with_prefix test_disabled_creation {} {
-- 
2.17.1