smatch_impossible.c

   1 /*
   2  * Copyright (C) 2014 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 #include "smatch.h"
  19 #include "smatch_extra.h"
  20
  21 static int my_id;
  22 static int my_return_id;
  23
  24 unsigned long nothing_impossible;
  25
  26 STATE(impossible);
  27
  28 int is_impossible_path(void)
  29 {
  30         if (get_state(my_id, "impossible", NULL) == &impossible)
  31                 return 1;
  32         return 0;
  33 }
  34
  35 static void handle_compare(struct expression *left, int op, struct expression *right)
  36 {
  37         int true_impossible = 0;
  38         int false_impossible = 0;
  39
  40         left = strip_expr(left);
  41         while (left && left->type == EXPR_ASSIGNMENT)
  42                 left = strip_expr(left->left);
  43
  44         if (!possibly_true(left, op, right))
  45                 true_impossible = 1;
  46         if (!possibly_false(left, op, right))
  47                 false_impossible = 1;
  48
  49         if (!true_impossible && !false_impossible)
  50                 return;
  51
  52         set_true_false_states(my_id, "impossible", NULL,
  53                               true_impossible ? &impossible : NULL,
  54                               false_impossible ? &impossible : NULL);
  55
  56         if (inside_loop())
  57                 return;
  58
  59         set_true_false_states(my_return_id, "impossible", NULL,
  60                               true_impossible ? &impossible : NULL,
  61                               false_impossible ? &impossible : NULL);
  62 }
  63
  64 static void match_condition(struct expression *expr)
  65 {
  66         if (expr->type == EXPR_COMPARE)
  67                 handle_compare(expr->left, expr->op, expr->right);
  68         else
  69                 handle_compare(expr, SPECIAL_NOTEQUAL, zero_expr());
  70 }
  71
  72 void set_true_path_impossible(void)
  73 {
  74         set_true_false_states(my_id, "impossible", NULL, &impossible, NULL);
  75         if (inside_loop())
  76                 return;
  77         set_true_false_states(my_return_id, "impossible", NULL, &impossible, NULL);
  78 }
  79
  80 void set_false_path_impossible(void)
  81 {
  82         set_true_false_states(my_id, "impossible", NULL, NULL, &impossible);
  83         if (inside_loop())
  84                 return;
  85         set_true_false_states(my_return_id, "impossible", NULL, NULL, &impossible);
  86 }
  87
  88 void set_path_impossible(void)
  89 {
  90         set_state(my_id, "impossible", NULL, &impossible);
  91
  92         if (inside_loop())
  93                 return;
  94
  95         set_state(my_return_id, "impossible", NULL, &impossible);
  96 }
  97
  98 static void match_case(struct expression *expr, struct range_list *rl)
  99 {
 100         if (rl)
 101                 return;
 102         set_path_impossible();
 103 }
 104
 105 static void print_impossible_return(int return_id, char *return_ranges, struct expression *expr)
 106 {
 107         if (nothing_impossible)
 108                 return;
 109
 110         if (get_state(my_return_id, "impossible", NULL) == &impossible) {
 111                 if (option_debug)
 112                         sm_msg("impossible return.  return_id = %d return ranges = %s", return_id, return_ranges);
 113                 sql_insert_return_states(return_id, return_ranges, CULL_PATH, -1, "", "");
 114         }
 115 }
 116
 117 static void match_thread_stuff(const char *fn, struct expression *expr, void *unused)
 118 {
 119         nothing_impossible = true;
 120 }
 121
 122 void register_impossible(int id)
 123 {
 124         my_id = id;
 125
 126         add_hook(&match_condition, CONDITION_HOOK);
 127         add_hook(&match_case, CASE_HOOK);
 128 }
 129
 130 void register_impossible_return(int id)
 131 {
 132         my_return_id = id;
 133
 134         add_function_data(&nothing_impossible);
 135         if (option_project == PROJ_KERNEL) {
 136                 add_function_hook("wait_for_completion", &match_thread_stuff, NULL);
 137                 add_function_hook("wait_for_completion_timeout", &match_thread_stuff, NULL);
 138                 add_function_hook("wait_for_completion_io", &match_thread_stuff, NULL);
 139                 add_function_hook("wait_for_completion_io_timeout", &match_thread_stuff, NULL);
 140                 add_function_hook("wait_for_completion_interruptible", &match_thread_stuff, NULL);
 141                 add_function_hook("wait_for_completion_interruptible_timeout", &match_thread_stuff, NULL);
 142                 add_function_hook("wait_for_completion_killable", &match_thread_stuff, NULL);
 143                 add_function_hook("wait_for_completion_state", &match_thread_stuff, NULL);
 144                 add_function_hook("wait_for_completion_killable_timeout", &match_thread_stuff, NULL);
 145                 add_function_hook("try_wait_for_completion", &match_thread_stuff, NULL);
 146         }
 147
 148         add_split_return_callback(&print_impossible_return);
 149 }