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