This replaces functionality in "lint" that checked every function with a non-void return is handled. We cannot use GCC's functionality for this, since a "(void)" cast is not sufficient to turn it off, and besides, we want this to be the default for everything. --- check_all_func_returns.c | 88 ++++++++++++++++++++++++++++++++++++++++ check_list.h | 3 ++ 2 files changed, 91 insertions(+) create mode 100644 check_all_func_returns.c diff --git a/check_all_func_returns.c b/check_all_func_returns.c new file mode 100644 index 00000000..f9d77449 --- /dev/null +++ b/check_all_func_returns.c @@ -0,0 +1,88 @@ +/* + * Copyright 2018 Joyent, Inc. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt + */ + +/* + * Like lint of old, check that every return value from every function is used. + * Casting to (void) will silence this check. + */ + +#include "smatch.h" +#include "smatch_slist.h" + +static void check_func_return(struct expression *expr) +{ + struct symbol *sym = get_real_base_type(get_type(expr->fn)); + const char *func = expr_to_str(expr->fn); + struct statement *stmt; + + if (sym == NULL) { + sm_error("unknown type for func '%s'", func); + return; + } + + if (expr->type != EXPR_CALL) { + sm_error("func '%s' is not a call site", func); + return; + } + + /* + * There is never any need to check these returns. + */ + if (strcmp(func, "memcpy") == 0 || + strcmp(func, "memmove") == 0 || + strcmp(func, "memset") == 0) + return; + + /* + * Closer to a policy here, but there seems very few cases where it's + * useful to check the return value of the standard printf() family + * outputting to stdout or stderr. + */ + if (strcmp(func, "printf") == 0 || strcmp(func, "vprintf") == 0) + return; + + if (strcmp(func, "fprintf") == 0 || strcmp(func, "vfprintf")) { + const char *arg0 = expr_to_str(get_argument_from_call_expr(expr->args, 0)); + + if (arg0 != NULL && + (strcmp(arg0, "(&__iob[1])") == 0 || + strcmp(arg0, "(&__iob[2])") == 0)) + return; + } + + /* + * Either we got the return type already (direct call), + * or we need to go one further (function pointer call) + */ + if (sym == &void_ctype || (sym->type == SYM_FN && + get_real_base_type(sym) == &void_ctype)) + return; + + stmt = last_ptr_list((struct ptr_list *)big_statement_stack); + + if (stmt->type == STMT_EXPRESSION && stmt->expression == expr) + sm_error("unchecked function return '%s'", expr_to_str(expr->fn)); +} + +void check_all_func_returns(int id) +{ + if (option_project != PROJ_ILLUMOS_KERNEL && + option_project != PROJ_ILLUMOS_USER) + return; + + add_hook(&check_func_return, FUNCTION_CALL_HOOK); +} diff --git a/check_list.h b/check_list.h index 564bd1c2..cc3ce853 100644 --- a/check_list.h +++ b/check_list.h @@ -198,6 +198,9 @@ CK(check_wine_WtoA) CK(check_arm64_tagged) +/* illumos specific */ +CK(check_all_func_returns) + #include "check_list_local.h" CK(register_scope) -- 2.17.1
