Simon noticed a crash that could be caused via new Python
gdb.execute_mi function. Looking into this, I found a few unchecked
casts to mi_interp, like:
- struct mi_interp *mi = (struct mi_interp *) command_interp ();
This patch replaces all such casts with safer variants.
For -gdb-exit and mi_load_progress, I chose to have the functions
simply not generate any output. It didn't seem useful to do so.
Some casts I eliminated by adding a parameter to a function. Then, in
mi_execute_command, I changed the code to use
gdb::checked_static_cast. This is appropriate because this particular
overload can only be called by the MI interpreter.
There does not seem to be a very good way to test -gdb-exit.
Regression tested on x86-64 Fedora 36.
---
gdb/mi/mi-interp.c | 9 ---------
gdb/mi/mi-interp.h | 9 +++++++++
gdb/mi/mi-main.c | 48 +++++++++++++++++++++++++++++-----------------
3 files changed, 39 insertions(+), 27 deletions(-)
@@ -72,15 +72,6 @@ display_mi_prompt (struct mi_interp *mi)
ui->prompt_state = PROMPTED;
}
-/* Returns the INTERP's data cast as mi_interp if INTERP is an MI, and
- returns NULL otherwise. */
-
-static struct mi_interp *
-as_mi_interp (struct interp *interp)
-{
- return dynamic_cast<mi_interp *> (interp);
-}
-
void
mi_interp::on_command_error ()
{
@@ -107,4 +107,13 @@ class mi_interp final : public interp
void mi_output_solib_attribs (ui_out *uiout, struct so_list *solib);
+/* Returns the INTERP's data cast as mi_interp if INTERP is an MI, and
+ returns NULL otherwise. */
+
+static inline struct mi_interp *
+as_mi_interp (struct interp *interp)
+{
+ return dynamic_cast<mi_interp *> (interp);
+}
+
#endif /* MI_MI_INTERP_H */
@@ -144,14 +144,21 @@ static void print_diff (struct ui_file *file, struct mi_timestamp *start,
void
mi_cmd_gdb_exit (const char *command, const char *const *argv, int argc)
{
- struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
-
- /* We have to print everything right here because we never return. */
- if (current_token)
- gdb_puts (current_token, mi->raw_stdout);
- gdb_puts ("^exit\n", mi->raw_stdout);
- mi_out_put (current_uiout, mi->raw_stdout);
- gdb_flush (mi->raw_stdout);
+ struct mi_interp *mi = as_mi_interp (current_interpreter ());
+
+ /* If the current interpreter is not an MI interpreter, then just
+ don't bother printing anything. This case can arise from using
+ the Python gdb.execute_mi function -- but here the result does
+ not matter, as gdb is about to exit anyway. */
+ if (mi != nullptr)
+ {
+ /* We have to print everything right here because we never return. */
+ if (current_token)
+ gdb_puts (current_token, mi->raw_stdout);
+ gdb_puts ("^exit\n", mi->raw_stdout);
+ mi_out_put (current_uiout, mi->raw_stdout);
+ gdb_flush (mi->raw_stdout);
+ }
/* FIXME: The function called is not yet a formal libgdb function. */
quit_force (NULL, FROM_TTY);
}
@@ -1802,10 +1809,9 @@ mi_cmd_remove_inferior (const char *command, const char *const *argv, int argc)
prompt, display error). */
static void
-captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
+captured_mi_execute_command (struct mi_interp *mi, struct ui_out *uiout,
+ struct mi_parse *context)
{
- struct mi_interp *mi = (struct mi_interp *) command_interp ();
-
if (do_timings)
current_command_ts = context->cmd_start;
@@ -1890,10 +1896,9 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
/* Print a gdb exception to the MI output stream. */
static void
-mi_print_exception (const char *token, const struct gdb_exception &exception)
+mi_print_exception (struct mi_interp *mi, const char *token,
+ const struct gdb_exception &exception)
{
- struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
-
gdb_puts (token, mi->raw_stdout);
gdb_puts ("^error,msg=\"", mi->raw_stdout);
if (exception.message == NULL)
@@ -1925,13 +1930,15 @@ mi_execute_command (const char *cmd, int from_tty)
target_log_command (cmd);
+ struct mi_interp *mi
+ = gdb::checked_static_cast<mi_interp *> (command_interp ());
try
{
command = mi_parse::make (cmd, &token);
}
catch (const gdb_exception &exception)
{
- mi_print_exception (token, exception);
+ mi_print_exception (mi, token, exception);
xfree (token);
}
@@ -1947,7 +1954,7 @@ mi_execute_command (const char *cmd, int from_tty)
try
{
- captured_mi_execute_command (current_uiout, command.get ());
+ captured_mi_execute_command (mi, current_uiout, command.get ());
}
catch (const gdb_exception &result)
{
@@ -1960,7 +1967,7 @@ mi_execute_command (const char *cmd, int from_tty)
/* The command execution failed and error() was called
somewhere. */
- mi_print_exception (command->token, result);
+ mi_print_exception (mi, command->token, result);
mi_out_rewind (current_uiout);
/* Throw to a higher level catch for SIGTERM sent to GDB. */
@@ -2189,7 +2196,12 @@ mi_load_progress (const char *section_name,
static steady_clock::time_point last_update;
static char *previous_sect_name = NULL;
int new_section;
- struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
+ struct mi_interp *mi = as_mi_interp (current_interpreter ());
+
+ /* If the current interpreter is not an MI interpreter, then just
+ don't bother printing anything. */
+ if (mi == nullptr)
+ return;
/* This function is called through deprecated_show_load_progress
which means uiout may not be correct. Fix it for the duration