Fix Python gdb.Breakpoint.location crash

I noticed today that gdb.Breakpoint.location will crash when applied
to a catchpoint made with "catch throw".

The bug is that "catch throw" makes a breakpoint that is of type
bp_breakpoint, but which does not have a location.

Regression tested on x86-64 Fedora 28.

gdb/ChangeLog
2018-10-06  Tom Tromey  <tom@tromey.com>

	* python/py-breakpoint.c (bppy_get_location): Handle a
	bp_breakpoint without a location.

gdb/testsuite/ChangeLog
2018-10-06  Tom Tromey  <tom@tromey.com>

	* gdb.python/py-breakpoint.exp (check_last_event): Check location
	of a "throw" catchpoint.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7196472..e6f821d 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2018-10-06  Tom Tromey  <tom@tromey.com>
 
+       * python/py-breakpoint.c (bppy_get_location): Handle a
+       bp_breakpoint without a location.
+
+2018-10-06  Tom Tromey  <tom@tromey.com>
+
        * python/lib/gdb/function/strfns.py (_MemEq, _StrLen, _StrEq)
        (_RegEx): Reformat help text.
        * python/lib/gdb/function/caller_is.py (CallerIs, CallerMatches)

diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index e1db674..94afd50 100644 (file)
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -391,7 +391,12 @@ bppy_get_location (PyObject *self, void *closure)
   if (obj->bp->type != bp_breakpoint)
     Py_RETURN_NONE;
 
-  str = event_location_to_string (obj->bp->location.get ());
+  struct event_location *location = obj->bp->location.get ();
+  /* "catch throw" makes a breakpoint of type bp_breakpoint that does
+     not have a location.  */
+  if (location == nullptr)
+    Py_RETURN_NONE;
+  str = event_location_to_string (location);
   if (! str)
     str = "";
   return host_string_to_python_string (str);

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c78c09a..fc37967 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-10-06  Tom Tromey  <tom@tromey.com>
+
+       * gdb.python/py-breakpoint.exp (check_last_event): Check location
+       of a "throw" catchpoint.
+
 2018-10-06  Sergio Durigan Junior  <sergiodj@redhat.com>
 
        * gdb.base/info-proc.exp: Update string expected from "help info

diff --git a/gdb/testsuite/gdb.python/py-breakpoint.exp b/gdb/testsuite/gdb.python/py-breakpoint.exp
index 3ce0ea1..7d5fbcc 100644 (file)
--- a/gdb/testsuite/gdb.python/py-breakpoint.exp
+++ b/gdb/testsuite/gdb.python/py-breakpoint.exp
@@ -616,6 +616,11 @@ proc_with_prefix test_bkpt_explicit_loc {} {
     gdb_test "python bp1 = gdb.Breakpoint (function=\"blah\")" \
        "Function \"blah\" not defined.*" \
        "set invalid explicit breakpoint by missing function"
+
+    delete_breakpoints
+    gdb_test "catch throw" "Catchpoint .* \\(throw\\)"
+    gdb_test "python print (gdb.breakpoints()\[0\].location)" None \
+       "Examine location of catchpoint"
 }
 
 proc_with_prefix test_bkpt_qualified {} {