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 void __split_expr(struct expression *expr)
  31 {
  32         if (!expr)
  33                 return;
  34
  35         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
  36
  37         __smatch_lineno = expr->pos.line;
  38         __pass_to_client(expr, EXPR_HOOK);
  39
  40         switch (expr->type) {
  41         case EXPR_PREOP:
  42         case EXPR_POSTOP:
  43                 __pass_to_client(expr, OP_HOOK);
  44                 __split_expr(expr->unop);
  45                 return;
  46         case EXPR_STATEMENT:
  47                 __split_statements(expr->statement);
  48                 return;
  49         case EXPR_LOGICAL:
  50                 __split_whole_condition(expr);
  51                 __push_true_states();
  52                 __use_false_states();
  53                 __merge_true_states();
  54                 __pop_false_only_stack();
  55                 return;
  56
  57                 return;
  58         case EXPR_BINOP:
  59         case EXPR_COMMA:
  60         case EXPR_COMPARE:
  61         case EXPR_ASSIGNMENT:
  62                 if (expr->type == EXPR_ASSIGNMENT)
  63                         __pass_to_client(expr, ASSIGNMENT_HOOK);
  64                 __split_expr(expr->left);
  65                 __split_expr(expr->right);
  66                 if (expr->type == EXPR_ASSIGNMENT)
  67                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
  68                 return;
  69         case EXPR_DEREF:
  70                 __pass_to_client(expr, DEREF_HOOK);
  71                 __split_expr(expr->deref);
  72                 return;
  73         case EXPR_SLICE:
  74                 __split_expr(expr->base);
  75                 return;
  76         case EXPR_CAST:
  77                 __split_expr(expr->cast_expression);
  78                 return;
  79         case EXPR_SIZEOF:
  80                 /* there isn't anything to pass a client from inside a sizeof() */
  81                 return;
  82         case EXPR_CONDITIONAL:
  83         case EXPR_SELECT:
  84                 __split_whole_condition(expr->conditional);
  85                 __split_expr(expr->cond_true);
  86                 __push_true_states();
  87                 __use_false_states();
  88                 __split_expr(expr->cond_false);
  89                 __merge_true_states();
  90                 __pop_false_only_stack();
  91                 return;
  92         case EXPR_CALL:
  93                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
  94                 __split_expr(expr->fn);
  95                 split_expr_list(expr->args);
  96                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
  97 #ifdef KERNEL
  98                 if (expr->fn->type == EXPR_SYMBOL &&
  99                     !strcmp(expr->fn->symbol_name->name, "panic"))
 100                         nullify_path();
 101 #endif
 102                 return;
 103         case EXPR_INITIALIZER:
 104                 split_expr_list(expr->expr_list);
 105                 return;
 106         case EXPR_IDENTIFIER:
 107                 __split_expr(expr->ident_expression);
 108                 return;
 109         case EXPR_INDEX:
 110                 __split_expr(expr->idx_expression);
 111                 return;
 112         case EXPR_POS:
 113                 __split_expr(expr->init_expr);
 114                 return;
 115         default:
 116                 return;
 117         };
 118 }
 119
 120 static int is_forever_loop(struct statement *stmt)
 121 {
 122
 123         struct expression *expr;
 124
 125         expr = strip_expr(stmt->iterator_pre_condition);
 126         if (!expr)
 127                 expr = stmt->iterator_post_condition;
 128         if (!expr) {
 129                 /* this is a for(;;) loop... */
 130                 return 1;
 131         }
 132
 133         if (expr->type == EXPR_VALUE && expr->value == 1) {
 134                 return 1;
 135         }
 136
 137         return 0;
 138 }
 139
 140 /*
 141  * Pre Loops are while and for loops.
 142  */
 143
 144 static void handle_pre_loop(struct statement *stmt)
 145 {
 146         int once_through; /* we go through the loop at least once */
 147
 148         __split_statements(stmt->iterator_pre_statement);
 149
 150         once_through = known_condition_true(stmt->iterator_pre_condition);
 151
 152         __push_continues();
 153         __push_breaks();
 154
 155         __split_whole_condition(stmt->iterator_pre_condition);
 156
 157         __split_statements(stmt->iterator_statement);
 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                 __pass_to_client(stmt, RETURN_HOOK);
 250                 __split_expr(stmt->ret_value);
 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                 __split_whole_condition(stmt->if_conditional);
 265                 __split_statements(stmt->if_true);
 266                 __push_true_states();
 267                 __use_false_states();
 268                 __split_statements(stmt->if_false);
 269                 __merge_true_states();
 270                 __pop_false_only_stack();
 271                 return;
 272         case STMT_ITERATOR:
 273                 if (stmt->iterator_pre_condition)
 274                         handle_pre_loop(stmt);
 275                 else if (stmt->iterator_post_condition)
 276                         handle_post_loop(stmt);
 277                 else {
 278                         // these are for(;;) type loops.
 279                         handle_pre_loop(stmt);
 280                 }
 281                 return;
 282         case STMT_SWITCH:
 283                 __split_expr(stmt->switch_expression);
 284                 __save_switch_states();
 285                 __push_default();
 286                 __push_breaks();
 287                 __split_statements(stmt->switch_statement);
 288                 if (!__pop_default())
 289                         __merge_switches();
 290                 __pop_switches();
 291                 __merge_breaks();
 292                 return;
 293         case STMT_CASE:
 294                 __merge_switches();
 295                 if (!stmt->case_expression)
 296                         __set_default();
 297                 __split_expr(stmt->case_expression);
 298                 __split_expr(stmt->case_to);
 299                 __split_statements(stmt->case_statement);
 300                 return;
 301         case STMT_LABEL:
 302                 if (stmt->label &&
 303                     stmt->label->type == SYM_LABEL &&
 304                     stmt->label->ident) {
 305                         __merge_gotos(stmt->label->ident->name);
 306                 }
 307                 __split_statements(stmt->label_statement);
 308                 return;
 309         case STMT_GOTO:
 310                 __split_expr(stmt->goto_expression);
 311                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 312                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 313                                 __process_breaks();
 314                         } else if (!strcmp(stmt->goto_label->ident->name,
 315                                            "continue")) {
 316                                 __process_continues();
 317                         }
 318                 } else if (stmt->goto_label &&
 319                            stmt->goto_label->type == SYM_LABEL &&
 320                            stmt->goto_label->ident) {
 321                         __save_gotos(stmt->goto_label->ident->name);
 322                 }
 323                 nullify_path();
 324                 return;
 325         case STMT_NONE:
 326                 return;
 327         case STMT_ASM:
 328                 __split_expr(stmt->asm_string);
 329                 //__split_expr(stmt->asm_outputs);
 330                 //__split_expr(stmt->asm_inputs);
 331                 //__split_expr(stmt->asm_clobbers);
 332                 return;
 333         case STMT_CONTEXT:
 334                 return;
 335         case STMT_RANGE:
 336                 __split_expr(stmt->range_expression);
 337                 __split_expr(stmt->range_low);
 338                 __split_expr(stmt->range_high);
 339                 return;
 340         }
 341 }
 342
 343 static void split_expr_list(struct expression_list *expr_list)
 344 {
 345         struct expression *expr;
 346         FOR_EACH_PTR(expr_list, expr) {
 347                 __split_expr(expr);
 348         } END_FOR_EACH_PTR(expr);
 349 }
 350
 351
 352 static void split_sym(struct symbol *sym)
 353 {
 354         if (!sym)
 355                 return;
 356         if (!(sym->namespace & NS_SYMBOL))
 357                 return;
 358
 359         __pass_to_client(sym, SYM_HOOK);
 360         __split_statements(sym->stmt);
 361         __split_expr(sym->array_size);
 362         split_symlist(sym->arguments);
 363         split_symlist(sym->symbol_list);
 364         __split_statements(sym->inline_stmt);
 365         split_symlist(sym->inline_symbol_list);
 366         __split_expr(sym->initializer);
 367 }
 368
 369 static void split_symlist(struct symbol_list *sym_list)
 370 {
 371         struct symbol *sym;
 372
 373         FOR_EACH_PTR(sym_list, sym) {
 374                 split_sym(sym);
 375         } END_FOR_EACH_PTR(sym);
 376 }
 377
 378 static void split_functions(struct symbol_list *sym_list)
 379 {
 380         struct symbol *sym;
 381
 382         FOR_EACH_PTR(sym_list, sym) {
 383                 struct symbol *base_type;
 384                 base_type = get_base_type(sym);
 385                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 386                         if (base_type->stmt)
 387                                 line_func_start = base_type->stmt->pos.line;
 388                         if (sym->ident)
 389                                 cur_func = sym->ident->name;
 390                         __smatch_lineno = sym->pos.line;
 391                         SM_DEBUG("new function:  %s\n", cur_func);
 392                         __unnullify_path();
 393                         __pass_to_client(sym, FUNC_DEF_HOOK);
 394                         __split_statements(base_type->stmt);
 395                         __pass_to_client(sym, END_FUNC_HOOK);
 396                         cur_func = NULL;
 397                         line_func_start = 0;
 398                         clear_all_states();
 399
 400                 } else {
 401                         __pass_to_client(sym, BASE_HOOK);
 402                 }
 403         } END_FOR_EACH_PTR(sym);
 404         __pass_to_client_no_data(END_FILE_HOOK);
 405 }
 406
 407 void smatch (int argc, char **argv)
 408 {
 409
 410         struct string_list *filelist = NULL;
 411         struct symbol_list *sym_list;
 412
 413         if (argc < 2) {
 414                 printf("Usage:  smatch [--debug] <filename.c>\n");
 415                 exit(1);
 416         }
 417         sparse_initialize(argc, argv, &filelist);
 418         FOR_EACH_PTR_NOTAG(filelist, filename) {
 419                 sym_list = __sparse(filename);
 420                 split_functions(sym_list);
 421         } END_FOR_EACH_PTR_NOTAG(filename);
 422 }