smatch_extra.c

   1 /*
   2  * sparse/smatch_extra.c
   3  *
   4  * Copyright (C) 2008 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdlib.h>
  11 #include "parse.h"
  12 #include "smatch.h"
  13
  14 static int my_id;
  15
  16 static struct smatch_state *alloc_state(int val)
  17 {
  18         struct smatch_state *state;
  19
  20         state = malloc(sizeof(*state));
  21         state->name = "value";
  22         state->data = malloc(sizeof(int));
  23         *(int *)state->data = val;
  24         return state;
  25 }
  26
  27 static struct smatch_state *merge_func(const char *name, struct symbol *sym,
  28                                        struct smatch_state *s1,
  29                                        struct smatch_state *s2)
  30 {
  31         return &undefined;
  32 }
  33
  34 static void match_function_call_after(struct expression *expr)
  35 {
  36         struct expression *tmp;
  37         struct symbol *sym;
  38         char *name;
  39         int i = 0;
  40
  41         FOR_EACH_PTR(expr->args, tmp) {
  42                 if (tmp->op == '&') {
  43                         name = get_variable_from_expr(tmp->unop, &sym);
  44                         if (name) {
  45                                 set_state(name, my_id, sym, &undefined);
  46                         }
  47                 }
  48                 i++;
  49         } END_FOR_EACH_PTR(tmp);
  50 }
  51
  52 static void match_assign(struct expression *expr)
  53 {
  54         struct expression *left;
  55         struct symbol *sym;
  56         char *name;
  57
  58         left = strip_expr(expr->left);
  59         name = get_variable_from_expr(left, &sym);
  60         if (!name)
  61                 return;
  62         set_state(name, my_id, sym, alloc_state(get_value(expr->right)));
  63 }
  64
  65 static void undef_expr(struct expression *expr)
  66 {
  67         struct symbol *sym;
  68         char *name;
  69
  70         name = get_variable_from_expr(expr->unop, &sym);
  71         if (!name)
  72                 return;
  73         if (!get_state(name, my_id, sym)) {
  74                 free_string(name);
  75                 return;
  76         }
  77         set_state(name, my_id, sym, &undefined);
  78 }
  79
  80 static void match_declarations(struct symbol *sym)
  81 {
  82         const char *name;
  83
  84         if (sym->ident) {
  85                 name = sym->ident->name;
  86                 if (sym->initializer) {
  87                         set_state(name, my_id, sym, alloc_state(get_value(sym->initializer)));
  88                 }
  89         }
  90 }
  91
  92 void register_smatch_extra(int id)
  93 {
  94         my_id = id;
  95         add_merge_hook(my_id, &merge_func);
  96         add_hook(&undef_expr, OP_HOOK);
  97         add_hook(&match_function_call_after, FUNCTION_CALL_AFTER_HOOK);
  98         add_hook(&match_assign, ASSIGNMENT_AFTER_HOOK);
  99         add_hook(&match_declarations, DECLARATION_HOOK);
 100         add_hook(&__implied_states_hook, WHOLE_CONDITION_HOOK);
 101 }
 102
 103 static int expr_to_val(struct expression *expr)
 104 {
 105         struct smatch_state *state;
 106         int val;
 107         struct symbol *sym;
 108         char *name;
 109
 110         val = get_value(expr);
 111         if (val != UNDEFINED)
 112                 return val;
 113
 114         name = get_variable_from_expr(expr, &sym);
 115         if (!name)
 116                 return UNDEFINED;
 117         state = get_state(name, my_id, sym);
 118         free_string(name);
 119         if (!state || !state->data)
 120                 return UNDEFINED;
 121         return *(int *)state->data;
 122 }
 123
 124 static int true_comparison(int left, int comparison, int right)
 125 {
 126         switch(comparison){
 127         case '<':
 128         case SPECIAL_UNSIGNED_LT:
 129                 if (left < right)
 130                         return 1;
 131                 return 0;
 132         case SPECIAL_UNSIGNED_LTE:
 133         case SPECIAL_LTE:
 134                 if (left < right)
 135                         return 1;
 136         case SPECIAL_EQUAL:
 137                 if (left == right)
 138                         return 1;
 139                 return 0;
 140         case SPECIAL_UNSIGNED_GTE:
 141         case SPECIAL_GTE:
 142                 if (left == right)
 143                         return 1;
 144         case '>':
 145         case SPECIAL_UNSIGNED_GT:
 146                 if (left > right)
 147                         return 1;
 148                 return 0;
 149         case SPECIAL_NOTEQUAL:
 150                 if (left != right)
 151                         return 1;
 152                 return 0;
 153         default:
 154                 smatch_msg("unhandled comparison %d\n", comparison);
 155         }
 156         return 0;
 157 }
 158
 159 int known_condition_true(struct expression *expr)
 160 {
 161         int left, right, ret;
 162
 163         if (!expr || expr->type != EXPR_COMPARE)
 164                 return 0;
 165
 166         if ((left = expr_to_val(expr->left)) == UNDEFINED)
 167                 return 0;
 168
 169         if ((right = expr_to_val(expr->right)) == UNDEFINED)
 170                 return 0;
 171
 172         ret = true_comparison(left, expr->op, right);
 173         if (ret)
 174                 SM_DEBUG("%d known condition: %d %s %d => true", get_lineno(),
 175                          left, show_special(expr->op), right);
 176         else
 177                 smatch_msg("known condition: %d %s %d => false", left,
 178                            show_special(expr->op), right);
 179
 180         return ret;
 181 }