check_continue_vs_break.c

   1 /*
   2  * Copyright (C) 2015 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 /*
  19  * If you have code like:
  20  * do {
  21  *    if (xxx)
  22  *        continue;
  23  * }
  24  * while (0);
  25  *
  26  * Then the continue is equivalent of a break.  So what was really intended?
  27  */
  28
  29 #include "smatch.h"
  30 #include "smatch_slist.h"
  31
  32 static int my_id;
  33
  34 static struct statement_list *iterator_stack;
  35
  36 static int is_do_while_zero(struct statement *stmt)
  37 {
  38         if (!stmt->iterator_post_condition)
  39                 return 0;
  40         if (!expr_is_zero(stmt->iterator_post_condition))
  41                 return 0;
  42         return 1;
  43 }
  44
  45 static void push_statement(struct statement_list **stack, struct statement *stmt)
  46 {
  47         add_ptr_list(stack, stmt);
  48 }
  49
  50 static void pop_statement(struct statement_list **stack)
  51 {
  52         delete_ptr_list_last((struct ptr_list **)stack);
  53 }
  54
  55 static int inside_do_while_zero(void)
  56 {
  57         struct statement *stmt;
  58
  59         stmt = last_ptr_list((struct ptr_list *)iterator_stack);
  60         return !!stmt;
  61 }
  62
  63 static int loop_is_macro(void)
  64 {
  65         struct statement *stmt;
  66
  67         stmt = last_ptr_list((struct ptr_list *)iterator_stack);
  68         if (!stmt)
  69                 return 0;
  70         if (get_macro_name(stmt->iterator_post_condition->pos))
  71                 return 1;
  72         return 0;
  73 }
  74
  75 static void match_stmt(struct statement *stmt)
  76 {
  77         if (stmt->type != STMT_ITERATOR)
  78                 return;
  79
  80         if (is_do_while_zero(stmt))
  81                 push_statement(&iterator_stack, stmt);
  82         else
  83                 push_statement(&iterator_stack, NULL);
  84 }
  85
  86 static void match_stmt_after(struct statement *stmt)
  87 {
  88         if (stmt->type != STMT_ITERATOR)
  89                 return;
  90
  91         pop_statement(&iterator_stack);
  92 }
  93
  94 static void match_inline_start(struct expression *expr)
  95 {
  96         push_statement(&iterator_stack, NULL);
  97 }
  98
  99 static void match_inline_end(struct expression *expr)
 100 {
 101         pop_statement(&iterator_stack);
 102 }
 103
 104 static void match_continue(struct statement *stmt)
 105 {
 106         if (stmt->type != STMT_GOTO)
 107                 return;
 108
 109         if (!stmt->goto_label || stmt->goto_label->type != SYM_NODE)
 110                 return;
 111         if (strcmp(stmt->goto_label->ident->name, "continue") != 0)
 112                 return;
 113         if (!inside_do_while_zero())
 114                 return;
 115         if (loop_is_macro())
 116                 return;
 117         sm_warning("continue to end of do { ... } while(0); loop");
 118 }
 119
 120 void check_continue_vs_break(int id)
 121 {
 122         my_id = id;
 123         add_hook(&match_stmt, STMT_HOOK);
 124         add_hook(&match_stmt_after, STMT_HOOK_AFTER);
 125         add_hook(&match_inline_start, INLINE_FN_START);
 126         add_hook(&match_inline_end, INLINE_FN_END);
 127
 128         add_hook(&match_continue, STMT_HOOK);
 129 }