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