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 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() {  return filename; }
  21 char *get_function() { return cur_func; }
  22 int get_lineno() { return __smatch_lineno; }
  23 int get_func_pos() { 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         case EXPR_ASSIGNMENT:
  65                 if (expr->type == EXPR_ASSIGNMENT)
  66                         __pass_to_client(expr, ASSIGNMENT_HOOK);
  67                 __split_expr(expr->left);
  68                 __split_expr(expr->right);
  69                 if (expr->type == EXPR_ASSIGNMENT)
  70                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
  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                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
  97                 __split_expr(expr->fn);
  98                 split_expr_list(expr->args);
  99                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
 100 #ifdef KERNEL
 101                 if (expr->fn->type == EXPR_SYMBOL &&
 102                     !strcmp(expr->fn->symbol_name->name, "panic"))
 103                         nullify_path();
 104 #endif
 105                 return;
 106         case EXPR_INITIALIZER:
 107                 split_expr_list(expr->expr_list);
 108                 return;
 109         case EXPR_IDENTIFIER:
 110                 __split_expr(expr->ident_expression);
 111                 return;
 112         case EXPR_INDEX:
 113                 __split_expr(expr->idx_expression);
 114                 return;
 115         case EXPR_POS:
 116                 __split_expr(expr->init_expr);
 117                 return;
 118         default:
 119                 return;
 120         };
 121 }
 122
 123 static int is_forever_loop(struct statement *stmt)
 124 {
 125
 126         struct expression *expr;
 127
 128         expr = strip_expr(stmt->iterator_pre_condition);
 129         if (!expr)
 130                 expr = stmt->iterator_post_condition;
 131         if (!expr) {
 132                 /* this is a for(;;) loop... */
 133                 return 1;
 134         }
 135
 136         if (expr->type == EXPR_VALUE && expr->value == 1) {
 137                 return 1;
 138         }
 139
 140         return 0;
 141 }
 142
 143 /*
 144  * Pre Loops are while and for loops.
 145  */
 146
 147 static void handle_pre_loop(struct statement *stmt)
 148 {
 149         int once_through; /* we go through the loop at least once */
 150
 151         __split_statements(stmt->iterator_pre_statement);
 152
 153         once_through = known_condition_true(stmt->iterator_pre_condition);
 154         if (option_assume_loops)
 155                 once_through = 1;
 156
 157         __push_continues();
 158         __push_breaks();
 159
 160         __split_whole_condition(stmt->iterator_pre_condition);
 161
 162         __split_statements(stmt->iterator_statement);
 163         __warn_on_silly_pre_loops();
 164         if (is_forever_loop(stmt)) {
 165                 __pop_false_only_stack();
 166                 /* forever loops don't have an iterator_post_statement */
 167                 __pop_continues();
 168                 __pop_false_states();
 169                 __use_breaks();
 170         } else if (once_through) {
 171                 __merge_continues();
 172                 __split_statements(stmt->iterator_post_statement);
 173                 __pop_false_states();
 174                 __use_false_only_stack();
 175                 __merge_breaks();
 176         } else {
 177                 __merge_continues();
 178                 __split_statements(stmt->iterator_post_statement);
 179                 __merge_false_states();
 180                 __use_false_only_stack();
 181                 __merge_breaks();
 182         }
 183 }
 184
 185 /*
 186  * Post loops are do {} while();
 187  */
 188 static void handle_post_loop(struct statement *stmt)
 189 {
 190         __push_continues();
 191         __push_breaks();
 192         __split_statements(stmt->iterator_statement);
 193         if (is_forever_loop(stmt)) {
 194                 __pop_continues();
 195                 __use_breaks();
 196
 197         } else {
 198                 __merge_continues();
 199                 __split_whole_condition(stmt->iterator_post_condition);
 200                 __use_false_states();
 201                 __merge_breaks();
 202         }
 203         __pop_false_only_stack();
 204 }
 205
 206 static void print_unreached(struct statement *stmt)
 207 {
 208
 209         /*
 210          * GCC insists on a return statement even where it is never
 211          * reached.  Also BUG() sometimes is a forever loop and
 212          * sometimes not so people put code after a BUG().  There
 213          * are way to many false positives.
 214          */
 215 #ifdef KERNEL
 216         return;
 217 #endif
 218         if (__path_is_null()) {
 219                 switch(stmt->type) {
 220                 case STMT_COMPOUND: /* after a switch before a case stmt */
 221                 case STMT_CASE:
 222                 case STMT_LABEL:
 223                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 224                         break;
 225                 default:
 226                         smatch_msg("unreachable code. %d", stmt->type);
 227                 }
 228         }
 229 }
 230
 231 void __split_statements(struct statement *stmt)
 232 {
 233         if (!stmt)
 234                 return;
 235
 236         if (__get_allocations() > MAXSMSTATES) {
 237                 static char *printed = NULL;
 238
 239                 if (printed != cur_func)
 240                         smatch_msg("Function too big.  Giving up.");
 241                 printed = cur_func;
 242                 return;
 243         }
 244
 245         __smatch_lineno = stmt->pos.line;
 246         print_unreached(stmt);
 247         __pass_to_client(stmt, STMT_HOOK);
 248
 249         switch (stmt->type) {
 250         case STMT_DECLARATION:
 251                 __pass_declarations_to_client(stmt->declaration);
 252                 split_symlist(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_functions(struct symbol_list *sym_list)
 397 {
 398         struct symbol *sym;
 399
 400         FOR_EACH_PTR(sym_list, sym) {
 401                 struct symbol *base_type;
 402                 base_type = get_base_type(sym);
 403                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 404                         if (base_type->stmt)
 405                                 line_func_start = base_type->stmt->pos.line;
 406                         if (sym->ident)
 407                                 cur_func = sym->ident->name;
 408                         __smatch_lineno = sym->pos.line;
 409                         SM_DEBUG("new function:  %s\n", cur_func);
 410                         __unnullify_path();
 411                         __pass_to_client(sym, FUNC_DEF_HOOK);
 412                         __split_statements(base_type->stmt);
 413                         __pass_to_client(sym, END_FUNC_HOOK);
 414                         cur_func = NULL;
 415                         line_func_start = 0;
 416                         clear_all_states();
 417
 418                 } else {
 419                         __pass_to_client(sym, BASE_HOOK);
 420                 }
 421         } END_FOR_EACH_PTR(sym);
 422         __pass_to_client_no_data(END_FILE_HOOK);
 423 }
 424
 425 void smatch (int argc, char **argv)
 426 {
 427
 428         struct string_list *filelist = NULL;
 429         struct symbol_list *sym_list;
 430
 431         if (argc < 2) {
 432                 printf("Usage:  smatch [--debug] <filename.c>\n");
 433                 exit(1);
 434         }
 435         sparse_initialize(argc, argv, &filelist);
 436         FOR_EACH_PTR_NOTAG(filelist, filename) {
 437                 sym_list = __sparse(filename);
 438                 split_functions(sym_list);
 439         } END_FOR_EACH_PTR_NOTAG(filename);
 440 }