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