[RFA] Fix segfault on Python convenience functions which call GDB commands
Thiago Jung Bauermann
bauerman@br.ibm.com
Fri May 13 04:37:00 GMT 2011
On Thu, 2011-05-12 at 14:19 -0600, Tom Tromey wrote:
> >>>>> "Thiago" == Thiago Jung Bauermann <bauerman@br.ibm.com> writes:
>
> Thiago> 2011-05-11 Thiago Jung Bauermann <bauerman@br.ibm.com>
> Thiago> gdb/
> Thiago> * mi/mi-main.c (mi_cmd_execute): Use cleanup from
> Thiago> prepare_execute_command.
> Thiago> top.c (prepare_execute_command): Return cleanup.
> Thiago> (execute_command): Use cleanup from prepare_execute_command.
> Thiago> * top.h (prepare_execute_command): Change prototype to return
> Thiago> cleanup.
> Thiago> * defs.h (struct value): Add opaque declaration.
> Thiago> (make_cleanup_value_free_to_mark): Add prototype.
> Thiago> * utils.c (do_value_free_to_mark): New function.
> Thiago> (make_cleanup_value_free_to_mark): Likewise.
>
> Looks good.
> Just one tiny nit.
>
> Thiago> +extern struct cleanup * make_cleanup_value_free_to_mark (struct value *);
>
> Extra space after the "*".
>
> Ok with this change.
Thanks! I committed the following.
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center
2011-05-13 Thiago Jung Bauermann <bauerman@br.ibm.com>
gdb/
* mi/mi-main.c (mi_cmd_execute): Use cleanup from
prepare_execute_command.
* top.c (prepare_execute_command): Return cleanup.
(execute_command): Use cleanup from prepare_execute_command.
* top.h (prepare_execute_command): Change prototype to return
cleanup.
* defs.h (struct value): Add opaque declaration.
(make_cleanup_value_free_to_mark): Add prototype.
* utils.c (do_value_free_to_mark): New function.
(make_cleanup_value_free_to_mark): Likewise.
gdb/testsuite/
* gdb.python/py-function.exp: Test setting a value from a function
which executes a command.
Index: src/gdb/mi/mi-main.c
===================================================================
--- src.orig/gdb/mi/mi-main.c 2011-05-06 15:37:27.000000000 -0300
+++ src/gdb/mi/mi-main.c 2011-05-13 01:30:00.000000000 -0300
@@ -2025,9 +2025,7 @@ mi_cmd_execute (struct mi_parse *parse)
{
struct cleanup *cleanup;
- prepare_execute_command ();
-
- cleanup = make_cleanup (null_cleanup, NULL);
+ cleanup = prepare_execute_command ();
if (parse->all && parse->thread_group != -1)
error (_("Cannot specify --thread-group together with --all"));
Index: src/gdb/top.c
===================================================================
--- src.orig/gdb/top.c 2011-05-06 15:36:42.000000000 -0300
+++ src/gdb/top.c 2011-05-13 01:30:00.000000000 -0300
@@ -339,10 +339,14 @@ do_chdir_cleanup (void *old_dir)
}
#endif
-void
+struct cleanup *
prepare_execute_command (void)
{
- free_all_values ();
+ struct value *mark;
+ struct cleanup *cleanup;
+
+ mark = value_mark ();
+ cleanup = make_cleanup_value_free_to_mark (mark);
/* With multiple threads running while the one we're examining is
stopped, the dcache can get stale without us being able to detect
@@ -350,6 +354,8 @@ prepare_execute_command (void)
help things like backtrace. */
if (non_stop)
target_dcache_invalidate ();
+
+ return cleanup;
}
/* Execute the line P as a command, in the current user context.
@@ -358,12 +364,13 @@ prepare_execute_command (void)
void
execute_command (char *p, int from_tty)
{
+ struct cleanup *cleanup;
struct cmd_list_element *c;
enum language flang;
static int warned = 0;
char *line;
- prepare_execute_command ();
+ cleanup = prepare_execute_command ();
/* Force cleanup of any alloca areas if using C alloca instead of
a builtin alloca. */
@@ -462,6 +469,8 @@ execute_command (char *p, int from_tty)
warned = 1;
}
}
+
+ do_cleanups (cleanup);
}
/* Run execute_command for P and FROM_TTY. Capture its output into the
Index: src/gdb/top.h
===================================================================
--- src.orig/gdb/top.h 2011-01-11 16:51:50.000000000 -0200
+++ src/gdb/top.h 2011-05-13 01:30:00.000000000 -0300
@@ -48,8 +48,9 @@ extern int quit_cover (void *);
extern void execute_command (char *, int);
/* Prepare for execution of a command.
- Call this before every command, CLI or MI. */
-extern void prepare_execute_command (void);
+ Call this before every command, CLI or MI.
+ Returns a cleanup to be run after the command is completed. */
+extern struct cleanup *prepare_execute_command (void);
/* This function returns a pointer to the string that is used
by gdb for its command prompt. */
Index: src/gdb/defs.h
===================================================================
--- src.orig/gdb/defs.h 2011-05-13 01:29:52.000000000 -0300
+++ src/gdb/defs.h 2011-05-13 01:31:58.000000000 -0300
@@ -281,6 +281,7 @@ struct symtab;
struct breakpoint;
struct frame_info;
struct gdbarch;
+struct value;
/* From main.c. */
@@ -360,6 +361,8 @@ extern struct cleanup *make_cleanup_unpu
extern struct cleanup *
make_cleanup_restore_ui_file (struct ui_file **variable);
+extern struct cleanup *make_cleanup_value_free_to_mark (struct value *);
+
extern struct cleanup *make_final_cleanup (make_cleanup_ftype *, void *);
extern struct cleanup *make_my_cleanup (struct cleanup **,
Index: src/gdb/utils.c
===================================================================
--- src.orig/gdb/utils.c 2011-05-06 15:36:44.000000000 -0300
+++ src/gdb/utils.c 2011-05-13 01:30:00.000000000 -0300
@@ -431,6 +431,23 @@ make_cleanup_restore_ui_file (struct ui_
return make_cleanup_dtor (do_restore_ui_file, (void *) c, xfree);
}
+/* Helper for make_cleanup_value_free_to_mark. */
+
+static void
+do_value_free_to_mark (void *value)
+{
+ value_free_to_mark ((struct value *) value);
+}
+
+/* Free all values allocated since MARK was obtained by value_mark
+ (except for those released) when the cleanup is run. */
+
+struct cleanup *
+make_cleanup_value_free_to_mark (struct value *mark)
+{
+ return make_my_cleanup (&cleanup_chain, do_value_free_to_mark, mark);
+}
+
struct cleanup *
make_my_cleanup2 (struct cleanup **pmy_chain, make_cleanup_ftype *function,
void *arg, void (*free_arg) (void *))
Index: src/gdb/testsuite/gdb.python/py-function.exp
===================================================================
--- src.orig/gdb/testsuite/gdb.python/py-function.exp 2011-03-31 11:49:11.000000000 -0300
+++ src/gdb/testsuite/gdb.python/py-function.exp 2011-05-13 01:30:00.000000000 -0300
@@ -95,3 +95,17 @@ gdb_py_test_multiple "Test Normal Error"
gdb_test "print \$normalerror()" "Traceback.*File.*line 5.*in invoke.*RuntimeError.*This is a Normal Error.*" \
"Test a Runtime error. There should be a stack trace."
+
+gdb_py_test_multiple "input command-calling function" \
+ "python" "" \
+ "class CallCommand(gdb.Function):" "" \
+ " def __init__(self):" "" \
+ " gdb.Function.__init__(self, 'call_command')" "" \
+ " def invoke(self):" "" \
+ " return gdb.execute('print 1', to_string=True)" "" \
+ "CallCommand ()" "" \
+ "end" ""
+
+gdb_test_no_output "set var \$foo = \$call_command()" "Setting a value from a function which executes a command."
+# There was a bug where GDB would segfault in the second call, so try calling again.
+gdb_test_no_output "set var \$foo = \$call_command()" "Setting a value from a function which executes a command, again."
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