Fix swallowed "Quit" when inserting breakpoints

If GDB is inserting a breakpoint and you type Ctrl-C at the exact
"right" time, you'll hit a QUIT call in target_read, and the
breakpoint insertion is cancelled.  However, the related TRY/CATCH
code in insert_bp_location does:

 		  CATCH (e, RETURN_MASK_ALL)
 		    {
		      bp_err = e.error;
		      bp_err_message = e.message;
		    }

The problem with that is that a RETURN_QUIT exception has e.error ==
0, which means that further below, in the places that check for error
with:

      if (bp_err != GDB_NO_ERROR)

because GDB_NO_ERROR == 0, GDB continues as if the breakpoint was
inserted succesfully, and resumes the inferior.  Since the breakpoint
wasn't inserted the inferior runs free, out of our control...

Fix this by having insert_bp_location store a copy of the whole
exception instead of just a error/message parts, and then checking
"gdb_exception::reason" instead.

This was exposed by the new gdb.base/bp-cmds-continue-ctrl-c.exp
testcase added later in the series.

gdb/ChangeLog:
2017-11-16  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (insert_bp_location): Replace bp_err and
	bp_err_message locals by a gdb_exception local.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 52bd6156254cb12c9a51c65abdd034e833e3f066..23403b6cfef7996410a83e32ff1f2c9f7ed08491 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-16  Pedro Alves  <palves@redhat.com>
+
+       * breakpoint.c (insert_bp_location): Replace bp_err and
+       bp_err_message locals by a gdb_exception local.
+
 2017-11-16  Pedro Alves  <palves@redhat.com>
 
        * inflow.c (scoped_ignore_sigttou): New class.

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index b170a14cb584aa44c28e845a028bfddd38a71775..516cccfd88c9944fd902899e791b2c8c35cd0b3b 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -2458,8 +2458,7 @@ insert_bp_location (struct bp_location *bl,
                    int *hw_breakpoint_error,
                    int *hw_bp_error_explained_already)
 {
-  enum errors bp_err = GDB_NO_ERROR;
-  const char *bp_err_message = NULL;
+  gdb_exception bp_excpt = exception_none;
 
   if (!should_be_inserted (bl) || (bl->inserted && !bl->needs_update))
     return 0;
@@ -2568,12 +2567,11 @@ insert_bp_location (struct bp_location *bl,
 
              val = bl->owner->ops->insert_location (bl);
              if (val)
-               bp_err = GENERIC_ERROR;
+               bp_excpt = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
            }
          CATCH (e, RETURN_MASK_ALL)
            {
-             bp_err = e.error;
-             bp_err_message = e.message;
+             bp_excpt = e;
            }
          END_CATCH
        }
@@ -2608,16 +2606,16 @@ insert_bp_location (struct bp_location *bl,
                      val = target_insert_breakpoint (bl->gdbarch,
                                                      &bl->overlay_target_info);
                      if (val)
-                       bp_err = GENERIC_ERROR;
+                       bp_excpt
+                         = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
                    }
                  CATCH (e, RETURN_MASK_ALL)
                    {
-                     bp_err = e.error;
-                     bp_err_message = e.message;
+                     bp_excpt = e;
                    }
                  END_CATCH
 
-                 if (bp_err != GDB_NO_ERROR)
+                 if (bp_excpt.reason != 0)
                    fprintf_unfiltered (tmp_error_stream,
                                        "Overlay breakpoint %d "
                                        "failed: in ROM?\n",
@@ -2634,12 +2632,11 @@ insert_bp_location (struct bp_location *bl,
 
                  val = bl->owner->ops->insert_location (bl);
                  if (val)
-                   bp_err = GENERIC_ERROR;
+                   bp_excpt = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
                }
              CATCH (e, RETURN_MASK_ALL)
                {
-                 bp_err = e.error;
-                 bp_err_message = e.message;
+                 bp_excpt = e;
                }
              END_CATCH
            }
@@ -2651,7 +2648,7 @@ insert_bp_location (struct bp_location *bl,
            }
        }
 
-      if (bp_err != GDB_NO_ERROR)
+      if (bp_excpt.reason != 0)
        {
          /* Can't set the breakpoint.  */
 
@@ -2663,7 +2660,9 @@ insert_bp_location (struct bp_location *bl,
             breakpoint insertion failed (e.g., the remote target
             doesn't define error codes), so we must treat generic
             errors as memory errors.  */
-         if ((bp_err == GENERIC_ERROR || bp_err == MEMORY_ERROR)
+         if (bp_excpt.reason == RETURN_ERROR
+             && (bp_excpt.error == GENERIC_ERROR
+                 || bp_excpt.error == MEMORY_ERROR)
              && bl->loc_type == bp_loc_software_breakpoint
              && (solib_name_from_address (bl->pspace, bl->address)
                  || shared_objfile_contains_address_p (bl->pspace,
@@ -2691,16 +2690,18 @@ insert_bp_location (struct bp_location *bl,
              if (bl->loc_type == bp_loc_hardware_breakpoint)
                {
                  *hw_breakpoint_error = 1;
-                 *hw_bp_error_explained_already = bp_err_message != NULL;
+                 *hw_bp_error_explained_already = bp_excpt.message != NULL;
                   fprintf_unfiltered (tmp_error_stream,
                                       "Cannot insert hardware breakpoint %d%s",
-                                      bl->owner->number, bp_err_message ? ":" : ".\n");
-                  if (bp_err_message != NULL)
-                    fprintf_unfiltered (tmp_error_stream, "%s.\n", bp_err_message);
+                                      bl->owner->number,
+                                     bp_excpt.message ? ":" : ".\n");
+                  if (bp_excpt.message != NULL)
+                    fprintf_unfiltered (tmp_error_stream, "%s.\n",
+                                       bp_excpt.message);
                }
              else
                {
-                 if (bp_err_message == NULL)
+                 if (bp_excpt.message == NULL)
                    {
                      std::string message
                        = memory_error_message (TARGET_XFER_E_IO,
@@ -2716,7 +2717,7 @@ insert_bp_location (struct bp_location *bl,
                      fprintf_unfiltered (tmp_error_stream,
                                          "Cannot insert breakpoint %d: %s\n",
                                          bl->owner->number,
-                                         bp_err_message);
+                                         bp_excpt.message);
                    }
                }
              return 1;