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