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_statements(struct statement *stmt);
  26 static void split_symlist(struct symbol_list *sym_list);
  27 static void split_expr_list(struct expression_list *expr_list);
  28
  29 void __split_expr(struct expression *expr)
  30 {
  31         if (!expr)
  32                 return;
  33
  34         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
  35
  36         __smatch_lineno = expr->pos.line;
  37         __pass_to_client(expr, EXPR_HOOK);
  38
  39         switch (expr->type) {
  40         case EXPR_PREOP:
  41         case EXPR_POSTOP:
  42                 __pass_to_client(expr, OP_HOOK);
  43                 __split_expr(expr->unop);
  44                 return;
  45         case EXPR_STATEMENT:
  46                 split_statements(expr->statement);
  47                 return;
  48         case EXPR_LOGICAL:
  49                 __split_whole_condition(expr);
  50                 __push_true_states();
  51                 __use_false_states();
  52                 __merge_true_states();
  53                 __pop_false_only_stack();
  54                 return;
  55
  56                 return;
  57         case EXPR_BINOP:
  58         case EXPR_COMMA:
  59         case EXPR_COMPARE:
  60         case EXPR_ASSIGNMENT:
  61                 if (expr->type == EXPR_ASSIGNMENT)
  62                         __pass_to_client(expr, ASSIGNMENT_HOOK);
  63                 __split_expr(expr->left);
  64                 __split_expr(expr->right);
  65                 if (expr->type == EXPR_ASSIGNMENT)
  66                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
  67                 return;
  68         case EXPR_DEREF:
  69                 __pass_to_client(expr, DEREF_HOOK);
  70                 __split_expr(expr->deref);
  71                 return;
  72         case EXPR_SLICE:
  73                 __split_expr(expr->base);
  74                 return;
  75         case EXPR_CAST:
  76                 __split_expr(expr->cast_expression);
  77                 return;
  78         case EXPR_SIZEOF:
  79                 /* there isn't anything to pass a client from inside a sizeof() */
  80                 return;
  81         case EXPR_CONDITIONAL:
  82         case EXPR_SELECT:
  83                 __split_whole_condition(expr->conditional);
  84                 __split_expr(expr->cond_true);
  85                 __push_true_states();
  86                 __use_false_states();
  87                 __split_expr(expr->cond_false);
  88                 __merge_true_states();
  89                 __pop_false_only_stack();
  90                 return;
  91         case EXPR_CALL:
  92                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
  93                 __split_expr(expr->fn);
  94                 split_expr_list(expr->args);
  95                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
  96 #ifdef KERNEL
  97                 if (expr->fn->type == EXPR_SYMBOL &&
  98                     !strcmp(expr->fn->symbol_name->name, "panic"))
  99                         nullify_path();
 100 #endif
 101                 return;
 102         case EXPR_INITIALIZER:
 103                 split_expr_list(expr->expr_list);
 104                 return;
 105         case EXPR_IDENTIFIER:
 106                 __split_expr(expr->ident_expression);
 107                 return;
 108         case EXPR_INDEX:
 109                 __split_expr(expr->idx_expression);
 110                 return;
 111         case EXPR_POS:
 112                 __split_expr(expr->init_expr);
 113                 return;
 114         default:
 115                 return;
 116         };
 117 }
 118
 119 static int is_forever_loop(struct statement *stmt)
 120 {
 121
 122         struct expression *expr;
 123
 124         expr = strip_expr(stmt->iterator_pre_condition);
 125         if (!expr)
 126                 expr = stmt->iterator_post_condition;
 127         if (!expr) {
 128                 /* this is a for(;;) loop... */
 129                 return 1;
 130         }
 131
 132         if (expr->type == EXPR_VALUE && expr->value == 1) {
 133                 return 1;
 134         }
 135
 136         return 0;
 137 }
 138
 139 /*
 140  * Pre Loops are while and for loops.
 141  */
 142
 143 static void handle_pre_loop(struct statement *stmt)
 144 {
 145         int once_through; /* we go through the loop at least once */
 146
 147         split_statements(stmt->iterator_pre_statement);
 148
 149         once_through = known_condition_true(stmt->iterator_pre_condition);
 150
 151         __push_continues();
 152         __push_breaks();
 153
 154         __split_whole_condition(stmt->iterator_pre_condition);
 155
 156         split_statements(stmt->iterator_statement);
 157         split_statements(stmt->iterator_post_statement);
 158         if (is_forever_loop(stmt)) {
 159                 __pop_false_only_stack();
 160                 __pop_continues();
 161                 __pop_false_states();
 162                 __use_breaks();
 163         } else if (once_through) {
 164                 __merge_continues();
 165                 __pop_false_states();
 166                 __use_false_only_stack();
 167                 __merge_breaks();
 168         } else {
 169                 __merge_continues();
 170                 __merge_false_states();
 171                 __use_false_only_stack();
 172                 __merge_breaks();
 173         }
 174 }
 175
 176 /*
 177  * Post loops are do {} while();
 178  */
 179 static void handle_post_loop(struct statement *stmt)
 180 {
 181         __push_continues();
 182         __push_breaks();
 183         split_statements(stmt->iterator_statement);
 184
 185         __split_whole_condition(stmt->iterator_post_condition);
 186         __use_false_states();
 187
 188         if (is_forever_loop(stmt)) {
 189                 __pop_continues();
 190                 __use_breaks();
 191
 192         } else {
 193                 __merge_continues();
 194                 __merge_breaks();
 195         }
 196         __pop_false_only_stack();
 197 }
 198
 199 static void print_unreached(struct statement *stmt)
 200 {
 201
 202         /*
 203          * GCC insists on a return statement even where it is never
 204          * reached.  Also BUG() sometimes is a forever loop and
 205          * sometimes not so people put code after a BUG().  There
 206          * are way to many false positives.
 207          */
 208 #ifdef KERNEL
 209         return;
 210 #endif
 211         if (__path_is_null()) {
 212                 switch(stmt->type) {
 213                 case STMT_COMPOUND: /* after a switch before a case stmt */
 214                 case STMT_CASE:
 215                 case STMT_LABEL:
 216                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 217                         break;
 218                 default:
 219                         smatch_msg("unreachable code. %d", stmt->type);
 220                 }
 221         }
 222 }
 223
 224 static void split_statements(struct statement *stmt)
 225 {
 226         if (!stmt)
 227                 return;
 228
 229         __smatch_lineno = stmt->pos.line;
 230         print_unreached(stmt);
 231         __pass_to_client(stmt, STMT_HOOK);
 232
 233         switch (stmt->type) {
 234         case STMT_DECLARATION:
 235                 __pass_declarations_to_client(stmt->declaration);
 236                 split_symlist(stmt->declaration);
 237                 return;
 238         case STMT_RETURN:
 239                 __pass_to_client(stmt, RETURN_HOOK);
 240                 __split_expr(stmt->ret_value);
 241                 nullify_path();
 242                 return;
 243         case STMT_EXPRESSION:
 244                 __split_expr(stmt->expression);
 245                 return;
 246         case STMT_COMPOUND: {
 247                 struct statement *s;
 248                 FOR_EACH_PTR(stmt->stmts, s) {
 249                         split_statements(s);
 250                 } END_FOR_EACH_PTR(s);
 251                 return;
 252         }
 253         case STMT_IF:
 254                 __split_whole_condition(stmt->if_conditional);
 255                 split_statements(stmt->if_true);
 256                 __push_true_states();
 257                 __use_false_states();
 258                 split_statements(stmt->if_false);
 259                 __merge_true_states();
 260                 __pop_false_only_stack();
 261                 return;
 262         case STMT_ITERATOR:
 263                 if (stmt->iterator_pre_condition)
 264                         handle_pre_loop(stmt);
 265                 else if (stmt->iterator_post_condition)
 266                         handle_post_loop(stmt);
 267                 else {
 268                         // these are for(;;) type loops.
 269                         handle_pre_loop(stmt);
 270                 }
 271                 return;
 272         case STMT_SWITCH:
 273                 __split_expr(stmt->switch_expression);
 274                 __save_switch_states();
 275                 __push_default();
 276                 __push_breaks();
 277                 nullify_path();
 278                 split_statements(stmt->switch_statement);
 279                 if (!__pop_default())
 280                         __merge_switches();
 281                 __pop_switches();
 282                 __merge_breaks();
 283                 return;
 284         case STMT_CASE:
 285                 __merge_switches();
 286                 if (!stmt->case_expression)
 287                         __set_default();
 288                 __split_expr(stmt->case_expression);
 289                 __split_expr(stmt->case_to);
 290                 split_statements(stmt->case_statement);
 291                 return;
 292         case STMT_LABEL:
 293                 if (stmt->label &&
 294                     stmt->label->type == SYM_LABEL &&
 295                     stmt->label->ident) {
 296                         __merge_gotos(stmt->label->ident->name);
 297                 }
 298                 split_statements(stmt->label_statement);
 299                 return;
 300         case STMT_GOTO:
 301                 __split_expr(stmt->goto_expression);
 302                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 303                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 304                                 __process_breaks();
 305                         } else if (!strcmp(stmt->goto_label->ident->name,
 306                                            "continue")) {
 307                                 __process_continues();
 308                         }
 309                 } else if (stmt->goto_label &&
 310                            stmt->goto_label->type == SYM_LABEL &&
 311                            stmt->goto_label->ident) {
 312                         __save_gotos(stmt->goto_label->ident->name);
 313                 }
 314                 nullify_path();
 315                 return;
 316         case STMT_NONE:
 317                 return;
 318         case STMT_ASM:
 319                 __split_expr(stmt->asm_string);
 320                 //__split_expr(stmt->asm_outputs);
 321                 //__split_expr(stmt->asm_inputs);
 322                 //__split_expr(stmt->asm_clobbers);
 323                 return;
 324         case STMT_CONTEXT:
 325                 return;
 326         case STMT_RANGE:
 327                 __split_expr(stmt->range_expression);
 328                 __split_expr(stmt->range_low);
 329                 __split_expr(stmt->range_high);
 330                 return;
 331         }
 332 }
 333
 334 static void split_expr_list(struct expression_list *expr_list)
 335 {
 336         struct expression *expr;
 337         FOR_EACH_PTR(expr_list, expr) {
 338                 __split_expr(expr);
 339         } END_FOR_EACH_PTR(expr);
 340 }
 341
 342
 343 static void split_sym(struct symbol *sym)
 344 {
 345         if (!sym)
 346                 return;
 347         if (!(sym->namespace & NS_SYMBOL))
 348                 return;
 349
 350         __pass_to_client(sym, SYM_HOOK);
 351         split_statements(sym->stmt);
 352         __split_expr(sym->array_size);
 353         split_symlist(sym->arguments);
 354         split_symlist(sym->symbol_list);
 355         split_statements(sym->inline_stmt);
 356         split_symlist(sym->inline_symbol_list);
 357         __split_expr(sym->initializer);
 358 }
 359
 360 static void split_symlist(struct symbol_list *sym_list)
 361 {
 362         struct symbol *sym;
 363
 364         FOR_EACH_PTR(sym_list, sym) {
 365                 split_sym(sym);
 366         } END_FOR_EACH_PTR(sym);
 367 }
 368
 369 static void split_functions(struct symbol_list *sym_list)
 370 {
 371         struct symbol *sym;
 372
 373         FOR_EACH_PTR(sym_list, sym) {
 374                 struct symbol *base_type;
 375                 base_type = get_base_type(sym);
 376                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 377                         if (base_type->stmt)
 378                                 line_func_start = base_type->stmt->pos.line;
 379                         if (sym->ident)
 380                                 cur_func = sym->ident->name;
 381                         __smatch_lineno = sym->pos.line;
 382                         SM_DEBUG("new function:  %s\n", cur_func);
 383                         __pass_to_client(sym, FUNC_DEF_HOOK);
 384                         __unnullify_path();
 385                         split_statements(base_type->stmt);
 386                         __pass_to_client(sym, END_FUNC_HOOK);
 387                         cur_func = NULL;
 388                         line_func_start = 0;
 389                         clear_all_states();
 390
 391                 } else {
 392                         __pass_to_client(sym, BASE_HOOK);
 393                 }
 394         } END_FOR_EACH_PTR(sym);
 395         __pass_to_client_no_data(END_FILE_HOOK);
 396 }
 397
 398 void smatch (int argc, char **argv)
 399 {
 400
 401         struct string_list *filelist = NULL;
 402         struct symbol_list *sym_list;
 403
 404         if (argc < 2) {
 405                 printf("Usage:  smatch [--debug] <filename.c>\n");
 406                 exit(1);
 407         }
 408         sparse_initialize(argc, argv, &filelist);
 409         FOR_EACH_PTR_NOTAG(filelist, filename) {
 410                 sym_list = __sparse(filename);
 411                 split_functions(sym_list);
 412         } END_FOR_EACH_PTR_NOTAG(filename);
 413 }