check_returns_negative_error_code.c

   1 /*
   2  * Copyright (C) 2022 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 #include "smatch_slist.h"
  21
  22 static int my_id;
  23
  24 STATE(error_code);
  25
  26 static void clear_state(struct sm_state *sm, struct expression *mod_expr)
  27 {
  28         set_state(my_id, sm->name, sm->sym, &undefined);
  29 }
  30
  31 static bool is_error_macro(struct expression *expr)
  32 {
  33         char *macro;
  34         sval_t sval;
  35
  36         if (!expr)
  37                 return false;
  38         if (expr->type != EXPR_PREOP || expr->op != '-')
  39                 return false;
  40
  41         if (!get_value(expr, &sval))
  42                 return false;
  43         if (sval.value < -4095 || sval.value >= 0)
  44                 return false;
  45
  46         expr = expr->unop;
  47         macro = get_macro_name(expr->pos);
  48         if (!macro || macro[0] != 'E')
  49                 return false;
  50
  51         return true;
  52 }
  53
  54 static void match_assign(struct expression *expr)
  55 {
  56         if (expr->op != '=')
  57                 return;
  58
  59         if (!is_error_macro(expr->right))
  60                 return;
  61
  62         set_state_expr(my_id, expr->left, &error_code);
  63 }
  64
  65 static bool is_empty_state(struct expression *expr)
  66 {
  67         struct smatch_state *state;
  68
  69         state = get_extra_state(expr);
  70         if (!state)
  71                 return false;
  72         if (estate_rl(state))
  73                 return false;
  74         return true;
  75 }
  76
  77 bool holds_kernel_error_codes(struct expression *expr)
  78 {
  79         struct range_list *rl;
  80
  81         if (!expr)
  82                 return false;
  83
  84         if (is_error_macro(expr))
  85                 return true;
  86
  87         if (is_empty_state(expr))
  88                 return false;
  89
  90         if (get_implied_rl(expr, &rl)) {
  91                 if (rl_min(rl).value >= 0 &&
  92                     rl_max(rl).uvalue <= INT_MAX)
  93                         return false;
  94
  95                 if (type_positive_bits(rl_type(rl)) >= 63 &&
  96                     !sval_is_negative(rl_min(rl)) &&
  97                     rl_max(rl).uvalue <= UINT_MAX)
  98                         return false;
  99         }
 100
 101         return expr_has_possible_state(my_id, expr, &error_code);
 102 }
 103
 104 static void match_return(int return_id, char *return_ranges, struct expression *expr)
 105 {
 106         if (!expr)
 107                 return;
 108
 109         if (!holds_kernel_error_codes(expr))
 110                 return;
 111
 112         sql_insert_return_states(return_id, return_ranges, NEGATIVE_ERROR,
 113                                  -1, "$", "");
 114 }
 115
 116 static void set_error_code(struct expression *expr, const char *name, struct symbol *sym, void *data)
 117 {
 118         set_state(my_id, name, sym, &error_code);
 119 }
 120
 121 void check_returns_negative_error_code(int id)
 122 {
 123         my_id = id;
 124
 125         if (option_project != PROJ_KERNEL)
 126                 return;
 127
 128         add_hook(&match_assign, ASSIGNMENT_HOOK);
 129         add_modification_hook(my_id, &clear_state);
 130         add_split_return_callback(&match_return);
 131         select_return_param_key(NEGATIVE_ERROR, &set_error_code);
 132 }