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_simple(tmp->unop, &sym);
  44                         if (name) {
  45                                 name = alloc_string(name);
  46                                 set_state(name, my_id, sym, &undefined);
  47                         }
  48                 }
  49                 i++;
  50         } END_FOR_EACH_PTR(tmp);
  51 }
  52
  53 static void match_assign(struct expression *expr)
  54 {
  55         struct expression *left;
  56         struct symbol *sym;
  57         char *name;
  58
  59         left = strip_expr(expr->left);
  60         name = get_variable_from_expr_simple(left, &sym);
  61         if (!name)
  62                 return;
  63         name = alloc_string(name);
  64         set_state(name, my_id, sym, alloc_state(get_value(expr->right, NULL)));
  65 }
  66
  67 static void undef_expr(struct expression *expr)
  68 {
  69         struct symbol *sym;
  70         char *name;
  71
  72         name = get_variable_from_expr_simple(expr->unop, &sym);
  73         if (!name)
  74                 return;
  75         if (!get_state(name, my_id, sym))
  76                 return;
  77         name = alloc_string(name);
  78         set_state(name, my_id, sym, &undefined);
  79 }
  80
  81 static void match_declarations(struct symbol *sym)
  82 {
  83         const char *name;
  84
  85         if (sym->ident) {
  86                 name = sym->ident->name;
  87                 if (sym->initializer) {
  88                         set_state(name, my_id, sym, alloc_state(get_value(sym->initializer, NULL)));
  89                 }
  90         }
  91 }
  92
  93 void register_smatch_extra(int id)
  94 {
  95         my_id = id;
  96         add_merge_hook(my_id, &merge_func);
  97         add_hook(&undef_expr, OP_HOOK);
  98         add_hook(&match_function_call_after, FUNCTION_CALL_AFTER_HOOK);
  99         add_hook(&match_assign, ASSIGNMENT_AFTER_HOOK);
 100         add_hook(&match_declarations, DECLARATION_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, NULL);
 111         if (val != UNDEFINED)
 112                 return val;
 113
 114         name = get_variable_from_expr_simple(expr, &sym);
 115         if (!name)
 116                 return UNDEFINED;
 117         state = get_state(name, my_id, sym);
 118         if (!state || !state->data)
 119                 return UNDEFINED;
 120         return *(int *)state->data;
 121 }
 122
 123 static int true_comparison(int left, int comparison, int right)
 124 {
 125         switch(comparison){
 126         case '<':
 127         case SPECIAL_UNSIGNED_LT:
 128                 if (left < right)
 129                         return 1;
 130                 return 0;
 131         case SPECIAL_UNSIGNED_LTE:
 132         case SPECIAL_LTE:
 133                 if (left < right)
 134                         return 1;
 135         case SPECIAL_EQUAL:
 136                 if (left == right)
 137                         return 1;
 138                 return 0;
 139         case SPECIAL_UNSIGNED_GTE:
 140         case SPECIAL_GTE:
 141                 if (left == right)
 142                         return 1;
 143         case '>':
 144         case SPECIAL_UNSIGNED_GT:
 145                 if (left > right)
 146                         return 1;
 147                 return 0;
 148         case SPECIAL_NOTEQUAL:
 149                 if (left != right)
 150                         return 1;
 151                 return 0;
 152         default:
 153                 smatch_msg("unhandled comparison %d\n", comparison);
 154         }
 155         return 0;
 156 }
 157
 158 int known_condition_true(struct expression *expr)
 159 {
 160         int left, right, ret;
 161
 162         if (!expr || expr->type != EXPR_COMPARE)
 163                 return 0;
 164
 165         if ((left = expr_to_val(expr->left)) == UNDEFINED)
 166                 return 0;
 167
 168         if ((right = expr_to_val(expr->right)) == UNDEFINED)
 169                 return 0;
 170
 171         ret = true_comparison(left, expr->op, right);
 172         smatch_msg("known condition: %d & %d => %s", left, right, (ret?"true":"false"));
 173
 174         return ret;
 175 }