[PATCH smatch-devel 3/5] smatch: track functions variables are passed to

Record every direct variable argument handled by FUNCTION_CALL_HOOK.
Keep the call expression, zero-based parameter index, and previous
sm_state in a linked smatch_state data payload.

Expose print_passed_to() to walk linear and merged histories.
Deduplicate shared states and print each function with its $N index.

Assisted-by: Codex:5.6
Signed-off-by: Harshit Mogalapalli <[email protected]>
---
 Makefile           |   1 +
 smatch.h           |   1 +
 smatch_modules.h   |   1 +
 smatch_passed_to.c | 111 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 114 insertions(+)
 create mode 100644 smatch_passed_to.c

diff --git a/Makefile b/Makefile
index eabaef4c8e01..85517e4660e6 100644
--- a/Makefile
+++ b/Makefile
@@ -353,6 +353,7 @@ SMATCH_OBJS += smatch_parents.o
 SMATCH_OBJS += smatch_parse_call_math.o
 SMATCH_OBJS += smatch_parsed_conditions.o
 SMATCH_OBJS += smatch_passes_array_size.o
+SMATCH_OBJS += smatch_passed_to.o
 SMATCH_OBJS += smatch_points_to_container.o
 SMATCH_OBJS += smatch_points_to_user_data.o
 SMATCH_OBJS += smatch_points_to_host_data.o
diff --git a/smatch.h b/smatch.h
index 681be3354bc1..58edc256965a 100644
--- a/smatch.h
+++ b/smatch.h
@@ -1050,6 +1050,7 @@ void __call_array_initialized_hooks(struct expression *array, int nr);
 /* smatch_function_hooks.c */
 const char *get_fn_name(struct expression *fn);
 struct expression *get_current_fn_call(void);
+void print_passed_to(struct expression *expr);
 void add_fake_call_after_return(struct expression *call);
 struct expression *get_real_call(void);
 struct expression *get_this_fn_call(void);
diff --git a/smatch_modules.h b/smatch_modules.h
index c8fd14f5dca0..dbc8fa4dd0dc 100644
--- a/smatch_modules.h
+++ b/smatch_modules.h
@@ -107,6 +107,7 @@ CK(smatch_parameter_names)
 CK(smatch_param_filter)
 CK(smatch_param_to_mtag_data)
 CK(smatch_parse_call_math)
+CK(smatch_passed_to)
 CK(smatch_points_to_container)
 CK(smatch_points_to_host_data)
 CK(smatch_points_to_user_data)
diff --git a/smatch_passed_to.c b/smatch_passed_to.c
new file mode 100644
index 000000000000..06b1e2a77fec
--- /dev/null
+++ b/smatch_passed_to.c
@@ -0,0 +1,111 @@
+#include "smatch.h"
+
+static int my_id;
+
+struct smatch_state_data {
+	struct sm_state *previous;
+	struct expression *expr;
+	int param;
+};
+
+static struct smatch_state *alloc_passed_to_state(const char *fn_name,
+						  struct expression *expr,
+						  int param,
+						  struct sm_state *previous)
+{
+	struct smatch_state_data *data;
+	struct smatch_state *state;
+
+	state = __alloc_smatch_state(sizeof(*data));
+	data = (struct smatch_state_data *)(state + 1);
+
+	state->name = alloc_sname(fn_name);
+	state->data = data;
+	data->previous = previous;
+	data->expr = expr;
+	data->param = param;
+
+	return state;
+}
+
+static void save_passed_to(const char *fn_name, struct expression *expr, int param,
+			   struct expression *arg)
+{
+	struct smatch_state *state;
+	struct sm_state *previous;
+	struct symbol *sym;
+	char *name;
+
+	name = expr_to_var_sym(arg, &sym);
+	if (!name || !sym)
+		goto free;
+
+	previous = get_sm_state(my_id, name, sym);
+	state = alloc_passed_to_state(fn_name, expr, param, previous);
+	set_state(my_id, name, sym, state);
+free:
+	free_string(name);
+}
+
+static void match_call(struct expression *expr)
+{
+	struct expression *arg;
+	char *fn_name;
+	int param = -1;
+
+	if (sym_name_is(expr->fn, "__smatch_passed_to"))
+		return;
+
+	fn_name = expr_to_str(expr->fn);
+	if (!fn_name)
+		return;
+
+	FOR_EACH_PTR(expr->args, arg) {
+		save_passed_to(fn_name, expr, ++param, arg);
+	} END_FOR_EACH_PTR(arg);
+
+	free_string(fn_name);
+}
+
+static void print_passed_to_sm(struct sm_state *sm, struct state_list **printed)
+{
+	struct smatch_state_data *data;
+	char *fn_name;
+
+	if (!sm)
+		return;
+	if (lookup_ptr_list_entry((struct ptr_list *)*printed, sm))
+		return;
+	add_ptr_list(printed, sm);
+
+	data = sm->state->data;
+	if (!data) {
+		print_passed_to_sm(sm->left, printed);
+		print_passed_to_sm(sm->right, printed);
+		return;
+	}
+
+	print_passed_to_sm(data->previous, printed);
+
+	fn_name = expr_to_str(data->expr->fn);
+	if (!fn_name)
+		return;
+	sm_msg("passed to %s $%d", fn_name, data->param);
+	free_string(fn_name);
+}
+
+void print_passed_to(struct expression *expr)
+{
+	struct state_list *printed = NULL;
+
+	print_passed_to_sm(get_sm_state_expr(my_id, expr), &printed);
+	free_slist(&printed);
+}
+
+void smatch_passed_to(int id)
+{
+	my_id = id;
+
+	set_dynamic_states(my_id);
+	add_hook(&match_call, FUNCTION_CALL_HOOK);
+}
-- 
2.52.0