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