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