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 #include "smatch_expression_stacks.h"
  14 #include "smatch_extra.h"
  15
  16 static int __smatch_lineno = 0;
  17
  18 static char *filename;
  19 static char *cur_func;
  20 static int line_func_start;
  21 static struct expression_stack *switch_expr_stack = NULL;
  22
  23 char *get_filename(void) {      return filename; }
  24 char *get_function(void) { return cur_func; }
  25 int get_lineno(void) { return __smatch_lineno; }
  26 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  27
  28 static void split_symlist(struct symbol_list *sym_list);
  29 static void split_declaration(struct symbol_list *sym_list);
  30 static void split_expr_list(struct expression_list *expr_list);
  31
  32 int option_assume_loops = 0;
  33 int option_known_conditions = 0;
  34
  35 void __split_expr(struct expression *expr)
  36 {
  37         if (!expr)
  38                 return;
  39
  40         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
  41
  42         __smatch_lineno = expr->pos.line;
  43         __pass_to_client(expr, EXPR_HOOK);
  44
  45         switch (expr->type) {
  46         case EXPR_PREOP:
  47         case EXPR_POSTOP:
  48                 __pass_to_client(expr, OP_HOOK);
  49                 __split_expr(expr->unop);
  50                 return;
  51         case EXPR_STATEMENT:
  52                 __split_statements(expr->statement);
  53                 return;
  54         case EXPR_LOGICAL:
  55                 __split_whole_condition(expr);
  56                 __push_true_states();
  57                 __use_false_states();
  58                 __merge_true_states();
  59                 __pop_false_only_stack();
  60                 return;
  61
  62                 return;
  63         case EXPR_BINOP:
  64         case EXPR_COMMA:
  65         case EXPR_COMPARE:
  66                 __split_expr(expr->left);
  67                 __split_expr(expr->right);
  68                 return;
  69         case EXPR_ASSIGNMENT: {
  70                 struct expression *tmp;
  71
  72                 __split_expr(expr->right);
  73                 __pass_to_client(expr, ASSIGNMENT_HOOK);
  74                 tmp = strip_expr(expr->right);
  75                 if (tmp->type == EXPR_CALL)
  76                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
  77                 __split_expr(expr->left);
  78                 return;
  79         }
  80         case EXPR_DEREF:
  81                 __pass_to_client(expr, DEREF_HOOK);
  82                 __split_expr(expr->deref);
  83                 return;
  84         case EXPR_SLICE:
  85                 __split_expr(expr->base);
  86                 return;
  87         case EXPR_CAST:
  88                 __split_expr(expr->cast_expression);
  89                 return;
  90         case EXPR_SIZEOF:
  91                 /* there isn't anything to pass a client from inside a sizeof() */
  92                 return;
  93         case EXPR_CONDITIONAL:
  94         case EXPR_SELECT:
  95                 __split_whole_condition(expr->conditional);
  96                 __split_expr(expr->cond_true);
  97                 __push_true_states();
  98                 __use_false_states();
  99                 __split_expr(expr->cond_false);
 100                 __merge_true_states();
 101                 __pop_false_only_stack();
 102                 return;
 103         case EXPR_CALL:
 104                 split_expr_list(expr->args);
 105                 __split_expr(expr->fn);
 106                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 107                 return;
 108         case EXPR_INITIALIZER:
 109                 split_expr_list(expr->expr_list);
 110                 return;
 111         case EXPR_IDENTIFIER:
 112                 __split_expr(expr->ident_expression);
 113                 return;
 114         case EXPR_INDEX:
 115                 __split_expr(expr->idx_expression);
 116                 return;
 117         case EXPR_POS:
 118                 __split_expr(expr->init_expr);
 119                 return;
 120         default:
 121                 return;
 122         };
 123 }
 124
 125 static int is_forever_loop(struct statement *stmt)
 126 {
 127
 128         struct expression *expr;
 129
 130         expr = strip_expr(stmt->iterator_pre_condition);
 131         if (!expr)
 132                 expr = stmt->iterator_post_condition;
 133         if (!expr) {
 134                 /* this is a for(;;) loop... */
 135                 return 1;
 136         }
 137
 138         if (expr->type == EXPR_VALUE && expr->value == 1) {
 139                 return 1;
 140         }
 141
 142         return 0;
 143 }
 144
 145 /*
 146  * Pre Loops are while and for loops.
 147  */
 148
 149 static void handle_pre_loop(struct statement *stmt)
 150 {
 151         int once_through; /* we go through the loop at least once */
 152         struct sm_state *extra_state = NULL;
 153         int unchanged = 0;
 154
 155
 156         __split_statements(stmt->iterator_pre_statement);
 157
 158         once_through = implied_condition_true(stmt->iterator_pre_condition);
 159
 160         __push_continues();
 161         __push_breaks();
 162
 163         __split_whole_condition(stmt->iterator_pre_condition);
 164         if (once_through)
 165                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 166         if (option_assume_loops)
 167                 once_through = 1;
 168         __split_statements(stmt->iterator_statement);
 169
 170         __warn_on_silly_pre_loops();
 171         if (is_forever_loop(stmt)) {
 172                 __pop_false_only_stack();
 173                 /* forever loops don't have an iterator_post_statement */
 174                 __pop_continues();
 175                 __pop_false_states();
 176                 __use_breaks();
 177         } else if (once_through) {
 178                 __merge_continues();
 179                 if (extra_state)
 180                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 181                 __split_statements(stmt->iterator_post_statement);
 182                 __split_whole_condition(stmt->iterator_pre_condition);
 183                 nullify_path();
 184                 __merge_false_states();
 185                 if (extra_state && unchanged)
 186                         __extra_pre_loop_hook_after(extra_state,
 187                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 188                 __pop_false_states();
 189                 __pop_false_only_stack();
 190                 __pop_false_only_stack();
 191                 __merge_breaks();
 192         } else {
 193                 __merge_continues();
 194                 __split_statements(stmt->iterator_post_statement);
 195                 __merge_false_states();
 196                 __use_false_only_stack();
 197                 __merge_breaks();
 198         }
 199 }
 200
 201 /*
 202  * Post loops are do {} while();
 203  */
 204 static void handle_post_loop(struct statement *stmt)
 205 {
 206         __push_continues();
 207         __push_breaks();
 208         __split_statements(stmt->iterator_statement);
 209         if (is_forever_loop(stmt)) {
 210                 __pop_continues();
 211                 __use_breaks();
 212
 213         } else {
 214                 __merge_continues();
 215                 __split_whole_condition(stmt->iterator_post_condition);
 216                 __use_false_states();
 217                 __merge_breaks();
 218         }
 219         __pop_false_only_stack();
 220 }
 221
 222 static void print_unreached(struct statement *stmt)
 223 {
 224
 225         /*
 226          * GCC insists on a return statement even where it is never
 227          * reached.  Also BUG() sometimes is a forever loop and
 228          * sometimes not so people put code after a BUG().  There
 229          * are way to many false positives.
 230          */
 231 #ifdef KERNEL
 232         return;
 233 #endif
 234         if (__path_is_null()) {
 235                 switch(stmt->type) {
 236                 case STMT_COMPOUND: /* after a switch before a case stmt */
 237                 case STMT_CASE:
 238                 case STMT_LABEL:
 239                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 240                         break;
 241                 default:
 242                         smatch_msg("unreachable code. %d", stmt->type);
 243                 }
 244         }
 245 }
 246
 247 void __split_statements(struct statement *stmt)
 248 {
 249         if (!stmt)
 250                 return;
 251
 252         if (out_of_memory()) {
 253                 static char *printed = NULL;
 254
 255                 if (printed != cur_func)
 256                         smatch_msg("Function too big.  Giving up.");
 257                 printed = cur_func;
 258                 return;
 259         }
 260
 261         __smatch_lineno = stmt->pos.line;
 262         print_unreached(stmt);
 263         __pass_to_client(stmt, STMT_HOOK);
 264
 265         switch (stmt->type) {
 266         case STMT_DECLARATION:
 267                 split_declaration(stmt->declaration);
 268                 return;
 269         case STMT_RETURN:
 270                 __split_expr(stmt->ret_value);
 271                 __pass_to_client(stmt, RETURN_HOOK);
 272                 nullify_path();
 273                 return;
 274         case STMT_EXPRESSION:
 275                 __split_expr(stmt->expression);
 276                 return;
 277         case STMT_COMPOUND: {
 278                 struct statement *s;
 279                 FOR_EACH_PTR(stmt->stmts, s) {
 280                         __split_statements(s);
 281                 } END_FOR_EACH_PTR(s);
 282                 return;
 283         }
 284         case STMT_IF:
 285                 if (known_condition_true(stmt->if_conditional)) {
 286                         __split_statements(stmt->if_true);
 287                         return;
 288                 }
 289                 if (known_condition_false(stmt->if_conditional)) {
 290                         __split_statements(stmt->if_false);
 291                         return;
 292                 }
 293                 if (option_known_conditions &&
 294                     implied_condition_true(stmt->if_conditional)) {
 295                         smatch_msg("info: this condition is true.");
 296                         __split_statements(stmt->if_true);
 297                         return;
 298                 }
 299                 if (option_known_conditions &&
 300                     implied_condition_false(stmt->if_conditional)) {
 301                         smatch_msg("info: this condition is false.");
 302                         __split_statements(stmt->if_false);
 303                         return;
 304                 }
 305                 __split_whole_condition(stmt->if_conditional);
 306                 __split_statements(stmt->if_true);
 307                 __push_true_states();
 308                 __use_false_states();
 309                 __split_statements(stmt->if_false);
 310                 __merge_true_states();
 311                 __pop_false_only_stack();
 312                 return;
 313         case STMT_ITERATOR:
 314                 if (stmt->iterator_pre_condition)
 315                         handle_pre_loop(stmt);
 316                 else if (stmt->iterator_post_condition)
 317                         handle_post_loop(stmt);
 318                 else {
 319                         // these are for(;;) type loops.
 320                         handle_pre_loop(stmt);
 321                 }
 322                 return;
 323         case STMT_SWITCH:
 324                 __split_expr(stmt->switch_expression);
 325                 push_expression(&switch_expr_stack, stmt->switch_expression);
 326                 __save_switch_states(top_expression(switch_expr_stack));
 327                 nullify_path();
 328                 __push_default();
 329                 __push_breaks();
 330                 __split_statements(stmt->switch_statement);
 331                 if (!__pop_default())
 332                         __merge_switches(top_expression(switch_expr_stack),
 333                                       NULL);
 334                 __pop_switches();
 335                 __merge_breaks();
 336                 pop_expression(&switch_expr_stack);
 337                 return;
 338         case STMT_CASE:
 339                 __merge_switches(top_expression(switch_expr_stack),
 340                                       stmt->case_expression);
 341                 __pass_case_to_client(top_expression(switch_expr_stack),
 342                                       stmt->case_expression);
 343                 if (!stmt->case_expression)
 344                         __set_default();
 345                 __split_expr(stmt->case_expression);
 346                 __split_expr(stmt->case_to);
 347                 __split_statements(stmt->case_statement);
 348                 return;
 349         case STMT_LABEL:
 350                 if (stmt->label &&
 351                     stmt->label->type == SYM_LABEL &&
 352                     stmt->label->ident) {
 353                         __merge_gotos(stmt->label->ident->name);
 354                 }
 355                 __split_statements(stmt->label_statement);
 356                 return;
 357         case STMT_GOTO:
 358                 __split_expr(stmt->goto_expression);
 359                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 360                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 361                                 __process_breaks();
 362                         } else if (!strcmp(stmt->goto_label->ident->name,
 363                                            "continue")) {
 364                                 __process_continues();
 365                         }
 366                 } else if (stmt->goto_label &&
 367                            stmt->goto_label->type == SYM_LABEL &&
 368                            stmt->goto_label->ident) {
 369                         __save_gotos(stmt->goto_label->ident->name);
 370                 }
 371                 nullify_path();
 372                 return;
 373         case STMT_NONE:
 374                 return;
 375         case STMT_ASM:
 376                 __split_expr(stmt->asm_string);
 377                 //__split_expr(stmt->asm_outputs);
 378                 //__split_expr(stmt->asm_inputs);
 379                 //__split_expr(stmt->asm_clobbers);
 380                 return;
 381         case STMT_CONTEXT:
 382                 return;
 383         case STMT_RANGE:
 384                 __split_expr(stmt->range_expression);
 385                 __split_expr(stmt->range_low);
 386                 __split_expr(stmt->range_high);
 387                 return;
 388         }
 389 }
 390
 391 static void split_expr_list(struct expression_list *expr_list)
 392 {
 393         struct expression *expr;
 394         FOR_EACH_PTR(expr_list, expr) {
 395                 __split_expr(expr);
 396         } END_FOR_EACH_PTR(expr);
 397 }
 398
 399
 400 static void split_sym(struct symbol *sym)
 401 {
 402         if (!sym)
 403                 return;
 404         if (!(sym->namespace & NS_SYMBOL))
 405                 return;
 406
 407         __pass_to_client(sym, SYM_HOOK);
 408         __split_statements(sym->stmt);
 409         __split_expr(sym->array_size);
 410         split_symlist(sym->arguments);
 411         split_symlist(sym->symbol_list);
 412         __split_statements(sym->inline_stmt);
 413         split_symlist(sym->inline_symbol_list);
 414         __split_expr(sym->initializer);
 415 }
 416
 417 static void split_symlist(struct symbol_list *sym_list)
 418 {
 419         struct symbol *sym;
 420
 421         FOR_EACH_PTR(sym_list, sym) {
 422                 split_sym(sym);
 423         } END_FOR_EACH_PTR(sym);
 424 }
 425
 426 static void split_declaration(struct symbol_list *sym_list)
 427 {
 428         struct symbol *sym;
 429
 430         FOR_EACH_PTR(sym_list, sym) {
 431                 __pass_to_client(sym, DECLARATION_HOOK);
 432                 __split_expr(sym->initializer);
 433                 if(sym->initializer && sym->initializer->type == EXPR_CALL) {
 434                         __match_initializer_call(sym);
 435                 }
 436                 split_sym(sym);
 437         } END_FOR_EACH_PTR(sym);
 438 }
 439
 440 static void split_functions(struct symbol_list *sym_list)
 441 {
 442         struct symbol *sym;
 443
 444         FOR_EACH_PTR(sym_list, sym) {
 445                 struct symbol *base_type;
 446                 base_type = get_base_type(sym);
 447                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 448                         if (base_type->stmt)
 449                                 line_func_start = base_type->stmt->pos.line;
 450                         if (sym->ident)
 451                                 cur_func = sym->ident->name;
 452                         __smatch_lineno = sym->pos.line;
 453                         SM_DEBUG("new function:  %s\n", cur_func);
 454                         __unnullify_path();
 455                         __pass_to_client(sym, FUNC_DEF_HOOK);
 456                         __split_statements(base_type->stmt);
 457                         __pass_to_client(sym, END_FUNC_HOOK);
 458                         cur_func = NULL;
 459                         line_func_start = 0;
 460                         clear_all_states();
 461                         free_expression_stack(&switch_expr_stack);
 462                 } else {
 463                         __pass_to_client(sym, BASE_HOOK);
 464                 }
 465         } END_FOR_EACH_PTR(sym);
 466         __pass_to_client_no_data(END_FILE_HOOK);
 467 }
 468
 469 void smatch (int argc, char **argv)
 470 {
 471
 472         struct string_list *filelist = NULL;
 473         struct symbol_list *sym_list;
 474
 475         if (argc < 2) {
 476                 printf("Usage:  smatch [--debug] <filename.c>\n");
 477                 exit(1);
 478         }
 479         sparse_initialize(argc, argv, &filelist);
 480         FOR_EACH_PTR_NOTAG(filelist, filename) {
 481                 sym_list = __sparse(filename);
 482                 split_functions(sym_list);
 483         } END_FOR_EACH_PTR_NOTAG(filename);
 484 }