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 #include "smatch_slist.h" // just for sname.
  16
  17 int final_pass;
  18
  19 static int __smatch_lineno = 0;
  20
  21 static char *filename;
  22 static char *cur_func;
  23 static int line_func_start;
  24 static struct expression_stack *switch_expr_stack = NULL;
  25
  26 char *get_filename(void) {      return filename; }
  27 char *get_function(void) { return cur_func; }
  28 int get_lineno(void) { return __smatch_lineno; }
  29 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  30
  31 static void split_symlist(struct symbol_list *sym_list);
  32 static void split_declaration(struct symbol_list *sym_list);
  33 static void split_expr_list(struct expression_list *expr_list);
  34
  35 int option_assume_loops = 0;
  36 int option_known_conditions = 0;
  37 int option_two_passes = 0;
  38
  39 void __split_expr(struct expression *expr)
  40 {
  41         if (!expr)
  42                 return;
  43
  44         // printf("%d Debug expr_type %d %s\n", get_lineno(), expr->type, show_special(expr->op));
  45
  46         __smatch_lineno = expr->pos.line;
  47         __pass_to_client(expr, EXPR_HOOK);
  48
  49         switch (expr->type) {
  50         case EXPR_PREOP:
  51         case EXPR_POSTOP:
  52                 __pass_to_client(expr, OP_HOOK);
  53                 __split_expr(expr->unop);
  54                 return;
  55         case EXPR_STATEMENT:
  56                 __split_statements(expr->statement);
  57                 return;
  58         case EXPR_LOGICAL:
  59                 __split_whole_condition(expr);
  60                 __push_true_states();
  61                 __use_false_states();
  62                 __merge_true_states();
  63                 __pop_false_only_stack();
  64                 return;
  65
  66                 return;
  67         case EXPR_BINOP:
  68         case EXPR_COMMA:
  69         case EXPR_COMPARE:
  70                 __split_expr(expr->left);
  71                 __split_expr(expr->right);
  72                 return;
  73         case EXPR_ASSIGNMENT: {
  74                 struct expression *tmp;
  75
  76                 __split_expr(expr->right);
  77                 __pass_to_client(expr, ASSIGNMENT_HOOK);
  78                 tmp = strip_expr(expr->right);
  79                 if (tmp->type == EXPR_CALL)
  80                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
  81                 __split_expr(expr->left);
  82                 return;
  83         }
  84         case EXPR_DEREF:
  85                 __pass_to_client(expr, DEREF_HOOK);
  86                 __split_expr(expr->deref);
  87                 return;
  88         case EXPR_SLICE:
  89                 __split_expr(expr->base);
  90                 return;
  91         case EXPR_CAST:
  92                 __split_expr(expr->cast_expression);
  93                 return;
  94         case EXPR_SIZEOF:
  95                 /* there isn't anything to pass a client from inside a sizeof() */
  96                 return;
  97         case EXPR_CONDITIONAL:
  98         case EXPR_SELECT:
  99                 __split_whole_condition(expr->conditional);
 100                 __split_expr(expr->cond_true);
 101                 __push_true_states();
 102                 __use_false_states();
 103                 __split_expr(expr->cond_false);
 104                 __merge_true_states();
 105                 __pop_false_only_stack();
 106                 return;
 107         case EXPR_CALL:
 108                 split_expr_list(expr->args);
 109                 __split_expr(expr->fn);
 110                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 111                 return;
 112         case EXPR_INITIALIZER:
 113                 split_expr_list(expr->expr_list);
 114                 return;
 115         case EXPR_IDENTIFIER:
 116                 __split_expr(expr->ident_expression);
 117                 return;
 118         case EXPR_INDEX:
 119                 __split_expr(expr->idx_expression);
 120                 return;
 121         case EXPR_POS:
 122                 __split_expr(expr->init_expr);
 123                 return;
 124         default:
 125                 return;
 126         };
 127 }
 128
 129 static int is_forever_loop(struct statement *stmt)
 130 {
 131
 132         struct expression *expr;
 133
 134         expr = strip_expr(stmt->iterator_pre_condition);
 135         if (!expr)
 136                 expr = stmt->iterator_post_condition;
 137         if (!expr) {
 138                 /* this is a for(;;) loop... */
 139                 return 1;
 140         }
 141
 142         if (expr->type == EXPR_VALUE && expr->value == 1) {
 143                 return 1;
 144         }
 145
 146         return 0;
 147 }
 148
 149 static int loop_num;
 150 static char *get_loop_name(int num)
 151 {
 152         char buf[256];
 153
 154         snprintf(buf, 255, "-loop%d", num);
 155         buf[255] = '\0';
 156         return alloc_sname(buf);;
 157 }
 158
 159 /*
 160  * Pre Loops are while and for loops.
 161  */
 162
 163 static void handle_pre_loop(struct statement *stmt)
 164 {
 165         int once_through; /* we go through the loop at least once */
 166         struct sm_state *extra_state = NULL;
 167         int unchanged = 0;
 168         char *loop_name;
 169
 170         loop_name = get_loop_name(loop_num);
 171         loop_num++;
 172
 173         __split_statements(stmt->iterator_pre_statement);
 174
 175         once_through = implied_condition_true(stmt->iterator_pre_condition);
 176
 177         __push_continues();
 178         __push_breaks();
 179
 180         __merge_gotos(loop_name);
 181         __split_whole_condition(stmt->iterator_pre_condition);
 182         if (once_through)
 183                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 184         if (option_assume_loops)
 185                 once_through = 1;
 186         __split_statements(stmt->iterator_statement);
 187
 188         __warn_on_silly_pre_loops();
 189         if (is_forever_loop(stmt)) {
 190                 __save_gotos(loop_name);
 191                 __pop_false_only_stack();
 192                 /* forever loops don't have an iterator_post_statement */
 193                 __pop_continues();
 194                 __pop_false_states();
 195                 __use_breaks();
 196         } else if (once_through) {
 197                 __merge_continues();
 198                 if (extra_state)
 199                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 200                 __split_statements(stmt->iterator_post_statement);
 201                 __save_gotos(loop_name);
 202                 __split_whole_condition(stmt->iterator_pre_condition);
 203                 nullify_path();
 204                 __merge_false_states();
 205                 if (extra_state && unchanged)
 206                         __extra_pre_loop_hook_after(extra_state,
 207                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 208                 __pop_false_states();
 209                 __pop_false_only_stack();
 210                 __pop_false_only_stack();
 211                 __merge_breaks();
 212         } else {
 213                 __merge_continues();
 214                 __split_statements(stmt->iterator_post_statement);
 215                 __save_gotos(loop_name);
 216                 __merge_false_states();
 217                 __use_false_only_stack();
 218                 __merge_breaks();
 219         }
 220 }
 221
 222 /*
 223  * Post loops are do {} while();
 224  */
 225 static void handle_post_loop(struct statement *stmt)
 226 {
 227         char *loop_name;
 228
 229         loop_name = get_loop_name(loop_num);
 230         loop_num++;
 231
 232         __push_continues();
 233         __push_breaks();
 234         __merge_gotos(loop_name);
 235         __split_statements(stmt->iterator_statement);
 236         __merge_continues();
 237         if (!is_zero(stmt->iterator_post_condition))
 238                 __save_gotos(loop_name);
 239
 240         if (is_forever_loop(stmt)) {
 241                 __use_breaks();
 242         } else {
 243                 __split_whole_condition(stmt->iterator_post_condition);
 244                 __use_false_states();
 245                 __merge_breaks();
 246         }
 247         __pop_false_only_stack();
 248 }
 249
 250 static void print_unreached(struct statement *stmt)
 251 {
 252
 253         /*
 254          * GCC insists on a return statement even where it is never
 255          * reached.  Also BUG() sometimes is a forever loop and
 256          * sometimes not so people put code after a BUG().  There
 257          * are way to many false positives.
 258          */
 259 #ifdef KERNEL
 260         return;
 261 #endif
 262         if (__path_is_null()) {
 263                 switch(stmt->type) {
 264                 case STMT_COMPOUND: /* after a switch before a case stmt */
 265                 case STMT_CASE:
 266                 case STMT_LABEL:
 267                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 268                         break;
 269                 default:
 270                         sm_msg("unreachable code. %d", stmt->type);
 271                 }
 272         }
 273 }
 274
 275 void __split_statements(struct statement *stmt)
 276 {
 277         if (!stmt)
 278                 return;
 279
 280         if (out_of_memory()) {
 281                 static char *printed = NULL;
 282
 283                 if (printed != cur_func)
 284                         sm_msg("Function too big.  Giving up.");
 285                 printed = cur_func;
 286                 return;
 287         }
 288
 289         __smatch_lineno = stmt->pos.line;
 290         print_unreached(stmt);
 291         __pass_to_client(stmt, STMT_HOOK);
 292
 293         switch (stmt->type) {
 294         case STMT_DECLARATION:
 295                 split_declaration(stmt->declaration);
 296                 return;
 297         case STMT_RETURN:
 298                 __split_expr(stmt->ret_value);
 299                 __pass_to_client(stmt, RETURN_HOOK);
 300                 nullify_path();
 301                 return;
 302         case STMT_EXPRESSION:
 303                 __split_expr(stmt->expression);
 304                 return;
 305         case STMT_COMPOUND: {
 306                 struct statement *s;
 307                 __push_scope_hooks();
 308                 FOR_EACH_PTR(stmt->stmts, s) {
 309                         __split_statements(s);
 310                 } END_FOR_EACH_PTR(s);
 311                 __call_scope_hooks();
 312                 return;
 313         }
 314         case STMT_IF:
 315                 if (known_condition_true(stmt->if_conditional)) {
 316                         __split_statements(stmt->if_true);
 317                         return;
 318                 }
 319                 if (known_condition_false(stmt->if_conditional)) {
 320                         __split_statements(stmt->if_false);
 321                         return;
 322                 }
 323                 if (option_known_conditions &&
 324                     implied_condition_true(stmt->if_conditional)) {
 325                         sm_msg("info: this condition is true.");
 326                         __split_statements(stmt->if_true);
 327                         return;
 328                 }
 329                 if (option_known_conditions &&
 330                     implied_condition_false(stmt->if_conditional)) {
 331                         sm_msg("info: this condition is false.");
 332                         __split_statements(stmt->if_false);
 333                         return;
 334                 }
 335                 __split_whole_condition(stmt->if_conditional);
 336                 __split_statements(stmt->if_true);
 337                 __push_true_states();
 338                 __use_false_states();
 339                 __split_statements(stmt->if_false);
 340                 __merge_true_states();
 341                 __pop_false_only_stack();
 342                 return;
 343         case STMT_ITERATOR:
 344                 if (stmt->iterator_pre_condition)
 345                         handle_pre_loop(stmt);
 346                 else if (stmt->iterator_post_condition)
 347                         handle_post_loop(stmt);
 348                 else {
 349                         // these are for(;;) type loops.
 350                         handle_pre_loop(stmt);
 351                 }
 352                 return;
 353         case STMT_SWITCH:
 354                 __split_expr(stmt->switch_expression);
 355                 push_expression(&switch_expr_stack, stmt->switch_expression);
 356                 __save_switch_states(top_expression(switch_expr_stack));
 357                 nullify_path();
 358                 __push_default();
 359                 __push_breaks();
 360                 __split_statements(stmt->switch_statement);
 361                 if (!__pop_default())
 362                         __merge_switches(top_expression(switch_expr_stack),
 363                                       NULL);
 364                 __pop_switches();
 365                 __merge_breaks();
 366                 pop_expression(&switch_expr_stack);
 367                 return;
 368         case STMT_CASE:
 369                 __merge_switches(top_expression(switch_expr_stack),
 370                                       stmt->case_expression);
 371                 __pass_case_to_client(top_expression(switch_expr_stack),
 372                                       stmt->case_expression);
 373                 if (!stmt->case_expression)
 374                         __set_default();
 375                 __split_expr(stmt->case_expression);
 376                 __split_expr(stmt->case_to);
 377                 __split_statements(stmt->case_statement);
 378                 return;
 379         case STMT_LABEL:
 380                 if (stmt->label &&
 381                     stmt->label->type == SYM_LABEL &&
 382                     stmt->label->ident) {
 383                         __merge_gotos(stmt->label->ident->name);
 384                 }
 385                 __split_statements(stmt->label_statement);
 386                 return;
 387         case STMT_GOTO:
 388                 __split_expr(stmt->goto_expression);
 389                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 390                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 391                                 __process_breaks();
 392                         } else if (!strcmp(stmt->goto_label->ident->name,
 393                                            "continue")) {
 394                                 __process_continues();
 395                         }
 396                 } else if (stmt->goto_label &&
 397                            stmt->goto_label->type == SYM_LABEL &&
 398                            stmt->goto_label->ident) {
 399                         __save_gotos(stmt->goto_label->ident->name);
 400                 }
 401                 nullify_path();
 402                 return;
 403         case STMT_NONE:
 404                 return;
 405         case STMT_ASM:
 406                 __split_expr(stmt->asm_string);
 407                 //__split_expr(stmt->asm_outputs);
 408                 //__split_expr(stmt->asm_inputs);
 409                 //__split_expr(stmt->asm_clobbers);
 410                 return;
 411         case STMT_CONTEXT:
 412                 return;
 413         case STMT_RANGE:
 414                 __split_expr(stmt->range_expression);
 415                 __split_expr(stmt->range_low);
 416                 __split_expr(stmt->range_high);
 417                 return;
 418         }
 419 }
 420
 421 static void split_expr_list(struct expression_list *expr_list)
 422 {
 423         struct expression *expr;
 424         FOR_EACH_PTR(expr_list, expr) {
 425                 __split_expr(expr);
 426         } END_FOR_EACH_PTR(expr);
 427 }
 428
 429
 430 static void split_sym(struct symbol *sym)
 431 {
 432         if (!sym)
 433                 return;
 434         if (!(sym->namespace & NS_SYMBOL))
 435                 return;
 436
 437         __pass_to_client(sym, SYM_HOOK);
 438         __split_statements(sym->stmt);
 439         __split_expr(sym->array_size);
 440         split_symlist(sym->arguments);
 441         split_symlist(sym->symbol_list);
 442         __split_statements(sym->inline_stmt);
 443         split_symlist(sym->inline_symbol_list);
 444         __split_expr(sym->initializer);
 445 }
 446
 447 static void split_symlist(struct symbol_list *sym_list)
 448 {
 449         struct symbol *sym;
 450
 451         FOR_EACH_PTR(sym_list, sym) {
 452                 split_sym(sym);
 453         } END_FOR_EACH_PTR(sym);
 454 }
 455
 456 static void split_declaration(struct symbol_list *sym_list)
 457 {
 458         struct symbol *sym;
 459
 460         FOR_EACH_PTR(sym_list, sym) {
 461                 __pass_to_client(sym, DECLARATION_HOOK);
 462                 __split_expr(sym->initializer);
 463                 if(sym->initializer && sym->initializer->type == EXPR_CALL) {
 464                         __match_initializer_call(sym);
 465                 }
 466                 split_sym(sym);
 467         } END_FOR_EACH_PTR(sym);
 468 }
 469
 470 static void split_functions(struct symbol_list *sym_list)
 471 {
 472         struct symbol *sym;
 473
 474         FOR_EACH_PTR(sym_list, sym) {
 475                 struct symbol *base_type;
 476                 base_type = get_base_type(sym);
 477                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 478                         if (base_type->stmt)
 479                                 line_func_start = base_type->stmt->pos.line;
 480                         if (sym->ident)
 481                                 cur_func = sym->ident->name;
 482                         __smatch_lineno = sym->pos.line;
 483                         sm_debug("new function:  %s\n", cur_func);
 484                         if (option_two_passes) {
 485                                 __unnullify_path();
 486                                 loop_num = 0;
 487                                 final_pass = 0;
 488                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 489                                 __split_statements(base_type->stmt);
 490                                 nullify_path();
 491                         }
 492                         __unnullify_path();
 493                         loop_num = 0;
 494                         final_pass = 1;
 495                         __pass_to_client(sym, FUNC_DEF_HOOK);
 496                         __split_statements(base_type->stmt);
 497                         __pass_to_client(sym, END_FUNC_HOOK);
 498                         cur_func = NULL;
 499                         line_func_start = 0;
 500                         clear_all_states();
 501                         free_expression_stack(&switch_expr_stack);
 502                 } else {
 503                         __pass_to_client(sym, BASE_HOOK);
 504                 }
 505         } END_FOR_EACH_PTR(sym);
 506         __pass_to_client_no_data(END_FILE_HOOK);
 507 }
 508
 509 void smatch (int argc, char **argv)
 510 {
 511
 512         struct string_list *filelist = NULL;
 513         struct symbol_list *sym_list;
 514
 515         if (argc < 2) {
 516                 printf("Usage:  smatch [--debug] <filename.c>\n");
 517                 exit(1);
 518         }
 519         sparse_initialize(argc, argv, &filelist);
 520         FOR_EACH_PTR_NOTAG(filelist, filename) {
 521                 sym_list = __sparse(filename);
 522                 split_functions(sym_list);
 523         } END_FOR_EACH_PTR_NOTAG(filename);
 524 }