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