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 symbol *sym;
  56         char *name;
  57
  58         name = get_variable_from_expr_simple(expr->left, &sym);
  59         if (!name)
  60                 return;
  61         name = alloc_string(name);
  62         set_state(name, my_id, sym, alloc_state(get_value(expr->right, NULL)));
  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_simple(expr->unop, &sym);
  71         if (!name)
  72                 return;
  73         if (!get_state(name, my_id, sym))
  74                 return;
  75         name = alloc_string(name);
  76         set_state(name, my_id, sym, &undefined);
  77 }
  78
  79 static void match_declarations(struct symbol *sym)
  80 {
  81         const char *name;
  82
  83         if (sym->ident) {
  84                 name = sym->ident->name;
  85                 if (sym->initializer) {
  86                         set_state(name, my_id, sym, alloc_state(get_value(sym->initializer, NULL)));
  87                 }
  88         }
  89 }
  90
  91 void register_smatch_extra(int id)
  92 {
  93         my_id = id;
  94         add_merge_hook(my_id, &merge_func);
  95         add_hook(&undef_expr, OP_HOOK);
  96         add_hook(&match_function_call_after, FUNCTION_CALL_AFTER_HOOK);
  97         add_hook(&match_assign, ASSIGNMENT_AFTER_HOOK);
  98         add_hook(&match_declarations, DECLARATION_HOOK);
  99 }
 100
 101 static int expr_to_val(struct expression *expr)
 102 {
 103         struct smatch_state *state;
 104         int val;
 105         struct symbol *sym;
 106         char *name;
 107
 108         val = get_value(expr, NULL);
 109         if (val != UNDEFINED)
 110                 return val;
 111
 112         name = get_variable_from_expr_simple(expr, &sym);
 113         if (!name)
 114                 return UNDEFINED;
 115         state = get_state(name, my_id, sym);
 116         if (!state || !state->data)
 117                 return UNDEFINED;
 118         return *(int *)state->data;
 119 }
 120
 121 static int true_comparison(int left, int comparison, int right)
 122 {
 123         switch(comparison){
 124         case '<':
 125         case SPECIAL_UNSIGNED_LT:
 126                 if (left < right)
 127                         return 1;
 128                 return 0;
 129         case SPECIAL_UNSIGNED_LTE:
 130         case SPECIAL_LTE:
 131                 if (left < right)
 132                         return 1;
 133         case SPECIAL_EQUAL:
 134                 if (left == right)
 135                         return 1;
 136                 return 0;
 137         case SPECIAL_UNSIGNED_GTE:
 138         case SPECIAL_GTE:
 139                 if (left == right)
 140                         return 1;
 141         case '>':
 142         case SPECIAL_UNSIGNED_GT:
 143                 if (left > right)
 144                         return 1;
 145                 return 0;
 146         case SPECIAL_NOTEQUAL:
 147                 if (left != right)
 148                         return 1;
 149                 return 0;
 150         default:
 151                 smatch_msg("unhandled comparison %d\n", comparison);
 152         }
 153         return 0;
 154 }
 155
 156 int known_condition_true(struct expression *expr)
 157 {
 158         int left, right, ret;
 159
 160         if (!expr || expr->type != EXPR_COMPARE)
 161                 return 0;
 162
 163         if ((left = expr_to_val(expr->left)) == UNDEFINED)
 164                 return 0;
 165
 166         if ((right = expr_to_val(expr->right)) == UNDEFINED)
 167                 return 0;
 168
 169         ret = true_comparison(left, expr->op, right);
 170         smatch_msg("known condition: %d & %d => %s", left, right, (ret?"true":"false"));
 171
 172         return ret;
 173 }