smatch_flow.c

   1 /*
   2  * sparse/smatch_flow.c
   3  *
   4  * Copyright (C) 2006,2008 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdio.h>
  11 #include "token.h"
  12 #include "smatch.h"
  13
  14 int __smatch_lineno = 0;
  15
  16 static char *filename;
  17 static char *cur_func;
  18 static int line_func_start;
  19
  20 char *get_filename() {  return filename; }
  21 char *get_function() { return cur_func; }
  22 int get_lineno() { return __smatch_lineno; }
  23 int get_func_pos() { return __smatch_lineno - line_func_start; }
  24
  25 static void split_symlist(struct symbol_list *sym_list);
  26 static void split_expr_list(struct expression_list *expr_list);
  27
  28 void __split_expr(struct expression *expr)
  29 {
  30         if (!expr)
  31                 return;
  32
  33         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
  34
  35         __smatch_lineno = expr->pos.line;
  36         __pass_to_client(expr, EXPR_HOOK);
  37
  38         switch (expr->type) {
  39         case EXPR_PREOP:
  40         case EXPR_POSTOP:
  41                 __pass_to_client(expr, OP_HOOK);
  42                 __split_expr(expr->unop);
  43                 return;
  44         case EXPR_STATEMENT:
  45                 __split_statements(expr->statement);
  46                 return;
  47         case EXPR_LOGICAL:
  48                 __split_whole_condition(expr);
  49                 __push_true_states();
  50                 __use_false_states();
  51                 __merge_true_states();
  52                 __pop_false_only_stack();
  53                 return;
  54
  55                 return;
  56         case EXPR_BINOP:
  57         case EXPR_COMMA:
  58         case EXPR_COMPARE:
  59         case EXPR_ASSIGNMENT:
  60                 if (expr->type == EXPR_ASSIGNMENT)
  61                         __pass_to_client(expr, ASSIGNMENT_HOOK);
  62                 __split_expr(expr->left);
  63                 __split_expr(expr->right);
  64                 if (expr->type == EXPR_ASSIGNMENT)
  65                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
  66                 return;
  67         case EXPR_DEREF:
  68                 __pass_to_client(expr, DEREF_HOOK);
  69                 __split_expr(expr->deref);
  70                 return;
  71         case EXPR_SLICE:
  72                 __split_expr(expr->base);
  73                 return;
  74         case EXPR_CAST:
  75                 __split_expr(expr->cast_expression);
  76                 return;
  77         case EXPR_SIZEOF:
  78                 /* there isn't anything to pass a client from inside a sizeof() */
  79                 return;
  80         case EXPR_CONDITIONAL:
  81         case EXPR_SELECT:
  82                 __split_whole_condition(expr->conditional);
  83                 __split_expr(expr->cond_true);
  84                 __push_true_states();
  85                 __use_false_states();
  86                 __split_expr(expr->cond_false);
  87                 __merge_true_states();
  88                 __pop_false_only_stack();
  89                 return;
  90         case EXPR_CALL:
  91                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
  92                 __split_expr(expr->fn);
  93                 split_expr_list(expr->args);
  94                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
  95 #ifdef KERNEL
  96                 if (expr->fn->type == EXPR_SYMBOL &&
  97                     !strcmp(expr->fn->symbol_name->name, "panic"))
  98                         nullify_path();
  99 #endif
 100                 return;
 101         case EXPR_INITIALIZER:
 102                 split_expr_list(expr->expr_list);
 103                 return;
 104         case EXPR_IDENTIFIER:
 105                 __split_expr(expr->ident_expression);
 106                 return;
 107         case EXPR_INDEX:
 108                 __split_expr(expr->idx_expression);
 109                 return;
 110         case EXPR_POS:
 111                 __split_expr(expr->init_expr);
 112                 return;
 113         default:
 114                 return;
 115         };
 116 }
 117
 118 static int is_forever_loop(struct statement *stmt)
 119 {
 120
 121         struct expression *expr;
 122
 123         expr = strip_expr(stmt->iterator_pre_condition);
 124         if (!expr)
 125                 expr = stmt->iterator_post_condition;
 126         if (!expr) {
 127                 /* this is a for(;;) loop... */
 128                 return 1;
 129         }
 130
 131         if (expr->type == EXPR_VALUE && expr->value == 1) {
 132                 return 1;
 133         }
 134
 135         return 0;
 136 }
 137
 138 /*
 139  * Pre Loops are while and for loops.
 140  */
 141
 142 static void handle_pre_loop(struct statement *stmt)
 143 {
 144         int once_through; /* we go through the loop at least once */
 145
 146         __split_statements(stmt->iterator_pre_statement);
 147
 148         once_through = known_condition_true(stmt->iterator_pre_condition);
 149
 150         __push_continues();
 151         __push_breaks();
 152
 153         __split_whole_condition(stmt->iterator_pre_condition);
 154
 155         __split_statements(stmt->iterator_statement);
 156         if (is_forever_loop(stmt)) {
 157                 __pop_false_only_stack();
 158                 /* forever loops don't have an iterator_post_statement */
 159                 __pop_continues();
 160                 __pop_false_states();
 161                 __use_breaks();
 162         } else if (once_through) {
 163                 __merge_continues();
 164                 __split_statements(stmt->iterator_post_statement);
 165                 __pop_false_states();
 166                 __use_false_only_stack();
 167                 __merge_breaks();
 168         } else {
 169                 __merge_continues();
 170                 __split_statements(stmt->iterator_post_statement);
 171                 __merge_false_states();
 172                 __use_false_only_stack();
 173                 __merge_breaks();
 174         }
 175 }
 176
 177 /*
 178  * Post loops are do {} while();
 179  */
 180 static void handle_post_loop(struct statement *stmt)
 181 {
 182         __push_continues();
 183         __push_breaks();
 184         __split_statements(stmt->iterator_statement);
 185         if (is_forever_loop(stmt)) {
 186                 __pop_continues();
 187                 __use_breaks();
 188
 189         } else {
 190                 __merge_continues();
 191                 __split_whole_condition(stmt->iterator_post_condition);
 192                 __use_false_states();
 193                 __merge_breaks();
 194         }
 195         __pop_false_only_stack();
 196 }
 197
 198 static void print_unreached(struct statement *stmt)
 199 {
 200
 201         /*
 202          * GCC insists on a return statement even where it is never
 203          * reached.  Also BUG() sometimes is a forever loop and
 204          * sometimes not so people put code after a BUG().  There
 205          * are way to many false positives.
 206          */
 207 #ifdef KERNEL
 208         return;
 209 #endif
 210         if (__path_is_null()) {
 211                 switch(stmt->type) {
 212                 case STMT_COMPOUND: /* after a switch before a case stmt */
 213                 case STMT_CASE:
 214                 case STMT_LABEL:
 215                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 216                         break;
 217                 default:
 218                         smatch_msg("unreachable code. %d", stmt->type);
 219                 }
 220         }
 221 }
 222
 223 void __split_statements(struct statement *stmt)
 224 {
 225         if (!stmt)
 226                 return;
 227
 228         __smatch_lineno = stmt->pos.line;
 229         print_unreached(stmt);
 230         __pass_to_client(stmt, STMT_HOOK);
 231
 232         switch (stmt->type) {
 233         case STMT_DECLARATION:
 234                 __pass_declarations_to_client(stmt->declaration);
 235                 split_symlist(stmt->declaration);
 236                 return;
 237         case STMT_RETURN:
 238                 __pass_to_client(stmt, RETURN_HOOK);
 239                 __split_expr(stmt->ret_value);
 240                 nullify_path();
 241                 return;
 242         case STMT_EXPRESSION:
 243                 __split_expr(stmt->expression);
 244                 return;
 245         case STMT_COMPOUND: {
 246                 struct statement *s;
 247                 FOR_EACH_PTR(stmt->stmts, s) {
 248                         __split_statements(s);
 249                 } END_FOR_EACH_PTR(s);
 250                 return;
 251         }
 252         case STMT_IF:
 253                 __split_whole_condition(stmt->if_conditional);
 254                 __split_statements(stmt->if_true);
 255                 __push_true_states();
 256                 __use_false_states();
 257                 __split_statements(stmt->if_false);
 258                 __merge_true_states();
 259                 __pop_false_only_stack();
 260                 return;
 261         case STMT_ITERATOR:
 262                 if (stmt->iterator_pre_condition)
 263                         handle_pre_loop(stmt);
 264                 else if (stmt->iterator_post_condition)
 265                         handle_post_loop(stmt);
 266                 else {
 267                         // these are for(;;) type loops.
 268                         handle_pre_loop(stmt);
 269                 }
 270                 return;
 271         case STMT_SWITCH:
 272                 __split_expr(stmt->switch_expression);
 273                 __save_switch_states();
 274                 __push_default();
 275                 __push_breaks();
 276                 __split_statements(stmt->switch_statement);
 277                 if (!__pop_default())
 278                         __merge_switches();
 279                 __pop_switches();
 280                 __merge_breaks();
 281                 return;
 282         case STMT_CASE:
 283                 __merge_switches();
 284                 if (!stmt->case_expression)
 285                         __set_default();
 286                 __split_expr(stmt->case_expression);
 287                 __split_expr(stmt->case_to);
 288                 __split_statements(stmt->case_statement);
 289                 return;
 290         case STMT_LABEL:
 291                 if (stmt->label &&
 292                     stmt->label->type == SYM_LABEL &&
 293                     stmt->label->ident) {
 294                         __merge_gotos(stmt->label->ident->name);
 295                 }
 296                 __split_statements(stmt->label_statement);
 297                 return;
 298         case STMT_GOTO:
 299                 __split_expr(stmt->goto_expression);
 300                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 301                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 302                                 __process_breaks();
 303                         } else if (!strcmp(stmt->goto_label->ident->name,
 304                                            "continue")) {
 305                                 __process_continues();
 306                         }
 307                 } else if (stmt->goto_label &&
 308                            stmt->goto_label->type == SYM_LABEL &&
 309                            stmt->goto_label->ident) {
 310                         __save_gotos(stmt->goto_label->ident->name);
 311                 }
 312                 nullify_path();
 313                 return;
 314         case STMT_NONE:
 315                 return;
 316         case STMT_ASM:
 317                 __split_expr(stmt->asm_string);
 318                 //__split_expr(stmt->asm_outputs);
 319                 //__split_expr(stmt->asm_inputs);
 320                 //__split_expr(stmt->asm_clobbers);
 321                 return;
 322         case STMT_CONTEXT:
 323                 return;
 324         case STMT_RANGE:
 325                 __split_expr(stmt->range_expression);
 326                 __split_expr(stmt->range_low);
 327                 __split_expr(stmt->range_high);
 328                 return;
 329         }
 330 }
 331
 332 static void split_expr_list(struct expression_list *expr_list)
 333 {
 334         struct expression *expr;
 335         FOR_EACH_PTR(expr_list, expr) {
 336                 __split_expr(expr);
 337         } END_FOR_EACH_PTR(expr);
 338 }
 339
 340
 341 static void split_sym(struct symbol *sym)
 342 {
 343         if (!sym)
 344                 return;
 345         if (!(sym->namespace & NS_SYMBOL))
 346                 return;
 347
 348         __pass_to_client(sym, SYM_HOOK);
 349         __split_statements(sym->stmt);
 350         __split_expr(sym->array_size);
 351         split_symlist(sym->arguments);
 352         split_symlist(sym->symbol_list);
 353         __split_statements(sym->inline_stmt);
 354         split_symlist(sym->inline_symbol_list);
 355         __split_expr(sym->initializer);
 356 }
 357
 358 static void split_symlist(struct symbol_list *sym_list)
 359 {
 360         struct symbol *sym;
 361
 362         FOR_EACH_PTR(sym_list, sym) {
 363                 split_sym(sym);
 364         } END_FOR_EACH_PTR(sym);
 365 }
 366
 367 static void split_functions(struct symbol_list *sym_list)
 368 {
 369         struct symbol *sym;
 370
 371         FOR_EACH_PTR(sym_list, sym) {
 372                 struct symbol *base_type;
 373                 base_type = get_base_type(sym);
 374                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 375                         if (base_type->stmt)
 376                                 line_func_start = base_type->stmt->pos.line;
 377                         if (sym->ident)
 378                                 cur_func = sym->ident->name;
 379                         __smatch_lineno = sym->pos.line;
 380                         SM_DEBUG("new function:  %s\n", cur_func);
 381                         __unnullify_path();
 382                         __pass_to_client(sym, FUNC_DEF_HOOK);
 383                         __split_statements(base_type->stmt);
 384                         __pass_to_client(sym, END_FUNC_HOOK);
 385                         cur_func = NULL;
 386                         line_func_start = 0;
 387                         clear_all_states();
 388
 389                 } else {
 390                         __pass_to_client(sym, BASE_HOOK);
 391                 }
 392         } END_FOR_EACH_PTR(sym);
 393         __pass_to_client_no_data(END_FILE_HOOK);
 394 }
 395
 396 void smatch (int argc, char **argv)
 397 {
 398
 399         struct string_list *filelist = NULL;
 400         struct symbol_list *sym_list;
 401
 402         if (argc < 2) {
 403                 printf("Usage:  smatch [--debug] <filename.c>\n");
 404                 exit(1);
 405         }
 406         sparse_initialize(argc, argv, &filelist);
 407         FOR_EACH_PTR_NOTAG(filelist, filename) {
 408                 sym_list = __sparse(filename);
 409                 split_functions(sym_list);
 410         } END_FOR_EACH_PTR_NOTAG(filename);
 411 }