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
  32 void __split_expr(struct expression *expr)
  33 {
  34         if (!expr)
  35                 return;
  36
  37         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
  38
  39         __smatch_lineno = expr->pos.line;
  40         __pass_to_client(expr, EXPR_HOOK);
  41
  42         switch (expr->type) {
  43         case EXPR_PREOP:
  44         case EXPR_POSTOP:
  45                 __pass_to_client(expr, OP_HOOK);
  46                 __split_expr(expr->unop);
  47                 return;
  48         case EXPR_STATEMENT:
  49                 __split_statements(expr->statement);
  50                 return;
  51         case EXPR_LOGICAL:
  52                 __split_whole_condition(expr);
  53                 __push_true_states();
  54                 __use_false_states();
  55                 __merge_true_states();
  56                 __pop_false_only_stack();
  57                 return;
  58
  59                 return;
  60         case EXPR_BINOP:
  61         case EXPR_COMMA:
  62         case EXPR_COMPARE:
  63         case EXPR_ASSIGNMENT:
  64                 if (expr->type == EXPR_ASSIGNMENT)
  65                         __pass_to_client(expr, ASSIGNMENT_HOOK);
  66                 __split_expr(expr->left);
  67                 __split_expr(expr->right);
  68                 if (expr->type == EXPR_ASSIGNMENT)
  69                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
  70                 return;
  71         case EXPR_DEREF:
  72                 __pass_to_client(expr, DEREF_HOOK);
  73                 __split_expr(expr->deref);
  74                 return;
  75         case EXPR_SLICE:
  76                 __split_expr(expr->base);
  77                 return;
  78         case EXPR_CAST:
  79                 __split_expr(expr->cast_expression);
  80                 return;
  81         case EXPR_SIZEOF:
  82                 /* there isn't anything to pass a client from inside a sizeof() */
  83                 return;
  84         case EXPR_CONDITIONAL:
  85         case EXPR_SELECT:
  86                 __split_whole_condition(expr->conditional);
  87                 __split_expr(expr->cond_true);
  88                 __push_true_states();
  89                 __use_false_states();
  90                 __split_expr(expr->cond_false);
  91                 __merge_true_states();
  92                 __pop_false_only_stack();
  93                 return;
  94         case EXPR_CALL:
  95                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
  96                 __split_expr(expr->fn);
  97                 split_expr_list(expr->args);
  98                 __pass_to_client(expr, FUNCTION_CALL_AFTER_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 (known_condition_true(stmt->if_conditional)) {
 270                         smatch_msg("info: this condition is true.");
 271                         __split_statements(stmt->if_true);
 272                         return;
 273                 }
 274                 if (known_condition_false(stmt->if_conditional)) {
 275                         smatch_msg("info: this condition is false.");
 276                         __split_statements(stmt->if_false);
 277                         return;
 278                 }
 279                 __split_whole_condition(stmt->if_conditional);
 280                 __split_statements(stmt->if_true);
 281                 __push_true_states();
 282                 __use_false_states();
 283                 __split_statements(stmt->if_false);
 284                 __merge_true_states();
 285                 __pop_false_only_stack();
 286                 return;
 287         case STMT_ITERATOR:
 288                 if (stmt->iterator_pre_condition)
 289                         handle_pre_loop(stmt);
 290                 else if (stmt->iterator_post_condition)
 291                         handle_post_loop(stmt);
 292                 else {
 293                         // these are for(;;) type loops.
 294                         handle_pre_loop(stmt);
 295                 }
 296                 return;
 297         case STMT_SWITCH:
 298                 __split_expr(stmt->switch_expression);
 299                 __save_switch_states();
 300                 __push_default();
 301                 __push_breaks();
 302                 __split_statements(stmt->switch_statement);
 303                 if (!__pop_default())
 304                         __merge_switches();
 305                 __pop_switches();
 306                 __merge_breaks();
 307                 return;
 308         case STMT_CASE:
 309                 __merge_switches();
 310                 if (!stmt->case_expression)
 311                         __set_default();
 312                 __split_expr(stmt->case_expression);
 313                 __split_expr(stmt->case_to);
 314                 __split_statements(stmt->case_statement);
 315                 return;
 316         case STMT_LABEL:
 317                 if (stmt->label &&
 318                     stmt->label->type == SYM_LABEL &&
 319                     stmt->label->ident) {
 320                         __merge_gotos(stmt->label->ident->name);
 321                 }
 322                 __split_statements(stmt->label_statement);
 323                 return;
 324         case STMT_GOTO:
 325                 __split_expr(stmt->goto_expression);
 326                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 327                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 328                                 __process_breaks();
 329                         } else if (!strcmp(stmt->goto_label->ident->name,
 330                                            "continue")) {
 331                                 __process_continues();
 332                         }
 333                 } else if (stmt->goto_label &&
 334                            stmt->goto_label->type == SYM_LABEL &&
 335                            stmt->goto_label->ident) {
 336                         __save_gotos(stmt->goto_label->ident->name);
 337                 }
 338                 nullify_path();
 339                 return;
 340         case STMT_NONE:
 341                 return;
 342         case STMT_ASM:
 343                 __split_expr(stmt->asm_string);
 344                 //__split_expr(stmt->asm_outputs);
 345                 //__split_expr(stmt->asm_inputs);
 346                 //__split_expr(stmt->asm_clobbers);
 347                 return;
 348         case STMT_CONTEXT:
 349                 return;
 350         case STMT_RANGE:
 351                 __split_expr(stmt->range_expression);
 352                 __split_expr(stmt->range_low);
 353                 __split_expr(stmt->range_high);
 354                 return;
 355         }
 356 }
 357
 358 static void split_expr_list(struct expression_list *expr_list)
 359 {
 360         struct expression *expr;
 361         FOR_EACH_PTR(expr_list, expr) {
 362                 __split_expr(expr);
 363         } END_FOR_EACH_PTR(expr);
 364 }
 365
 366
 367 static void split_sym(struct symbol *sym)
 368 {
 369         if (!sym)
 370                 return;
 371         if (!(sym->namespace & NS_SYMBOL))
 372                 return;
 373
 374         __pass_to_client(sym, SYM_HOOK);
 375         __split_statements(sym->stmt);
 376         __split_expr(sym->array_size);
 377         split_symlist(sym->arguments);
 378         split_symlist(sym->symbol_list);
 379         __split_statements(sym->inline_stmt);
 380         split_symlist(sym->inline_symbol_list);
 381         __split_expr(sym->initializer);
 382 }
 383
 384 static void split_symlist(struct symbol_list *sym_list)
 385 {
 386         struct symbol *sym;
 387
 388         FOR_EACH_PTR(sym_list, sym) {
 389                 split_sym(sym);
 390         } END_FOR_EACH_PTR(sym);
 391 }
 392
 393 static void split_functions(struct symbol_list *sym_list)
 394 {
 395         struct symbol *sym;
 396
 397         FOR_EACH_PTR(sym_list, sym) {
 398                 struct symbol *base_type;
 399                 base_type = get_base_type(sym);
 400                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 401                         if (base_type->stmt)
 402                                 line_func_start = base_type->stmt->pos.line;
 403                         if (sym->ident)
 404                                 cur_func = sym->ident->name;
 405                         __smatch_lineno = sym->pos.line;
 406                         SM_DEBUG("new function:  %s\n", cur_func);
 407                         __unnullify_path();
 408                         __pass_to_client(sym, FUNC_DEF_HOOK);
 409                         __split_statements(base_type->stmt);
 410                         __pass_to_client(sym, END_FUNC_HOOK);
 411                         cur_func = NULL;
 412                         line_func_start = 0;
 413                         clear_all_states();
 414
 415                 } else {
 416                         __pass_to_client(sym, BASE_HOOK);
 417                 }
 418         } END_FOR_EACH_PTR(sym);
 419         __pass_to_client_no_data(END_FILE_HOOK);
 420 }
 421
 422 void smatch (int argc, char **argv)
 423 {
 424
 425         struct string_list *filelist = NULL;
 426         struct symbol_list *sym_list;
 427
 428         if (argc < 2) {
 429                 printf("Usage:  smatch [--debug] <filename.c>\n");
 430                 exit(1);
 431         }
 432         sparse_initialize(argc, argv, &filelist);
 433         FOR_EACH_PTR_NOTAG(filelist, filename) {
 434                 sym_list = __sparse(filename);
 435                 split_functions(sym_list);
 436         } END_FOR_EACH_PTR_NOTAG(filename);
 437 }