1 /* 2 * Copyright 2018 Joyent, Inc. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 2 7 * of the License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt 16 */ 17 18 /* 19 * Like lint of old, check that every return value from every function is used. 20 * Casting to (void) will silence this check. 21 */ 22 23 #include "smatch.h" 24 #include "smatch_slist.h" 25 26 static void check_func_return(struct expression *expr) 27 { 28 struct symbol *sym = get_real_base_type(get_type(expr->fn)); 29 const char *func = expr_to_str(expr->fn); 30 struct statement *stmt; 31 32 if (sym == NULL) { 33 sm_error("unknown type for func '%s'", func); 34 return; 35 } 36 37 if (expr->type != EXPR_CALL) { 38 sm_error("func '%s' is not a call site", func); 39 return; 40 } 41 42 /* 43 * There is never any need to check these returns. 44 */ 45 if (strcmp(func, "memcpy") == 0 || 46 strcmp(func, "memmove") == 0 || 47 strcmp(func, "memset") == 0) 48 return; 49 50 /* 51 * Closer to a policy here, but there seems very few cases where it's 52 * useful to check the return value of the standard printf() family 53 * outputting to stdout or stderr. 54 */ 55 if (strcmp(func, "printf") == 0 || strcmp(func, "vprintf") == 0) 56 return; 57 58 if (strcmp(func, "fprintf") == 0 || strcmp(func, "vfprintf")) { 59 const char *arg0 = expr_to_str(get_argument_from_call_expr(expr->args, 0)); 60 61 if (arg0 != NULL && 62 (strcmp(arg0, "(&__iob[1])") == 0 || 63 strcmp(arg0, "(&__iob[2])") == 0)) 64 return; 65 } 66 67 /* 68 * Either we got the return type already (direct call), 69 * or we need to go one further (function pointer call) 70 */ 71 if (sym == &void_ctype || (sym->type == SYM_FN && 72 get_real_base_type(sym) == &void_ctype)) 73 return; 74 75 stmt = last_ptr_list((struct ptr_list *)big_statement_stack); 76 77 if (stmt && stmt->type == STMT_EXPRESSION && stmt->expression == expr) 78 sm_error("unchecked function return '%s'", expr_to_str(expr->fn)); 79 } 80 81 void check_all_func_returns(int id) 82 { 83 if (option_project != PROJ_ILLUMOS_KERNEL && 84 option_project != PROJ_ILLUMOS_USER) 85 return; 86 87 add_hook(&check_func_return, FUNCTION_CALL_HOOK); 88 }