/* Copyright (c) 2003-2004, Roger Dingledine * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. * Copyright (c) 2007-2019, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** * \file util_bug.h * * \brief Macros to manage assertions, fatal and non-fatal. * * Guidelines: All the different kinds of assertion in this file are for * bug-checking only. Don't write code that can assert based on bad inputs. * * We provide two kinds of assertion here: "fatal" and "nonfatal". Use * nonfatal assertions for any bug you can reasonably recover from -- and * please, try to recover! Many severe bugs in Tor have been caused by using * a regular assertion when a nonfatal assertion would have been better. * * If you need to check a condition with a nonfatal assertion, AND recover * from that same condition, consider using the BUG() macro inside a * conditional. For example: * * * // wrong -- use tor_assert_nonfatal() if you just want an assertion. * BUG(ptr == NULL); * * // okay, but needlessly verbose * tor_assert_nonfatal(ptr != NULL); * if (ptr == NULL) { ... } * * // this is how we do it: * if (BUG(ptr == NULL)) { ... } * **/ #ifndef TOR_UTIL_BUG_H #define TOR_UTIL_BUG_H #include "orconfig.h" #include "lib/cc/compat_compiler.h" #include "lib/log/log.h" #include "lib/testsupport/testsupport.h" /* Replace assert() with a variant that sends failures to the log before * calling assert() normally. */ #ifdef NDEBUG /* Nobody should ever want to build with NDEBUG set. 99% of our asserts will * be outside the critical path anyway, so it's silly to disable bug-checking * throughout the entire program just because a few asserts are slowing you * down. Profile, optimize the critical path, and keep debugging on. * * And I'm not just saying that because some of our asserts check * security-critical properties. */ #error "Sorry; we don't support building with NDEBUG." #endif /* defined(NDEBUG) */ #if defined(TOR_UNIT_TESTS) && defined(__GNUC__) /* We define this GCC macro as a replacement for PREDICT_UNLIKELY() in this * header, so that in our unit test builds, we'll get compiler warnings about * stuff like tor_assert(n = 5). * * The key here is that (e) is wrapped in exactly one layer of parentheses, * and then passed right to a conditional. If you do anything else to the * expression here, or introduce any more parentheses, the compiler won't * help you. * * We only do this for the unit-test build case because it interferes with * the likely-branch labeling. Note below that in the other case, we define * these macros to just be synonyms for PREDICT_(UN)LIKELY. */ #define ASSERT_PREDICT_UNLIKELY_(e) \ ( { \ int tor__assert_tmp_value__; \ if (e) \ tor__assert_tmp_value__ = 1; \ else \ tor__assert_tmp_value__ = 0; \ tor__assert_tmp_value__; \ } ) #define ASSERT_PREDICT_LIKELY_(e) ASSERT_PREDICT_UNLIKELY_(e) #else #define ASSERT_PREDICT_UNLIKELY_(e) PREDICT_UNLIKELY(e) #define ASSERT_PREDICT_LIKELY_(e) PREDICT_LIKELY(e) #endif /* Sometimes we don't want to use assertions during branch coverage tests; it * leads to tons of unreached branches which in reality are only assertions we * didn't hit. */ #if defined(TOR_UNIT_TESTS) && defined(DISABLE_ASSERTS_IN_UNIT_TESTS) #define tor_assert(a) STMT_BEGIN \ (void)(a); \ STMT_END #else /** Like assert(3), but send assertion failures to the log as well as to * stderr. */ #define tor_assert(expr) STMT_BEGIN \ if (ASSERT_PREDICT_LIKELY_(expr)) { \ } else { \ tor_assertion_failed_(SHORT_FILE__, __LINE__, __func__, #expr); \ tor_abort_(); \ } STMT_END #endif /* defined(TOR_UNIT_TESTS) && defined(DISABLE_ASSERTS_IN_UNIT_TESTS) */ #define tor_assert_unreached() \ STMT_BEGIN { \ tor_assertion_failed_(SHORT_FILE__, __LINE__, __func__, \ "line should be unreached"); \ tor_abort_(); \ } STMT_END /* Non-fatal bug assertions. The "unreached" variants mean "this line should * never be reached." The "once" variants mean "Don't log a warning more than * once". * * The 'BUG' macro checks a boolean condition and logs an error message if it * is true. Example usage: * if (BUG(x == NULL)) * return -1; */ #ifdef __COVERITY__ #undef BUG // Coverity defines this in global headers; let's override it. This is a // magic coverity-only preprocessor thing. #nodef BUG(x) (x) #endif /* defined(__COVERITY__) */ #if defined(__COVERITY__) || defined(__clang_analyzer__) // We're running with a static analysis tool: let's treat even nonfatal // assertion failures as something that we need to avoid. #define ALL_BUGS_ARE_FATAL #endif #ifdef ALL_BUGS_ARE_FATAL #define tor_assert_nonfatal_unreached() tor_assert(0) #define tor_assert_nonfatal(cond) tor_assert((cond)) #define tor_assert_nonfatal_unreached_once() tor_assert(0) #define tor_assert_nonfatal_once(cond) tor_assert((cond)) #define BUG(cond) \ (ASSERT_PREDICT_UNLIKELY_(cond) ? \ (tor_assertion_failed_(SHORT_FILE__,__LINE__,__func__,"!("#cond")"), \ tor_abort_(), 1) \ : 0) #elif defined(TOR_UNIT_TESTS) && defined(DISABLE_ASSERTS_IN_UNIT_TESTS) #define tor_assert_nonfatal_unreached() STMT_NIL #define tor_assert_nonfatal(cond) ((void)(cond)) #define tor_assert_nonfatal_unreached_once() STMT_NIL #define tor_assert_nonfatal_once(cond) ((void)(cond)) #define BUG(cond) (ASSERT_PREDICT_UNLIKELY_(cond) ? 1 : 0) #else /* Normal case, !ALL_BUGS_ARE_FATAL, !DISABLE_ASSERTS_IN_UNIT_TESTS */ #define tor_assert_nonfatal_unreached() STMT_BEGIN \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, NULL, 0); \ STMT_END #define tor_assert_nonfatal(cond) STMT_BEGIN \ if (ASSERT_PREDICT_LIKELY_(cond)) { \ } else { \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, #cond, 0); \ } \ STMT_END #define tor_assert_nonfatal_unreached_once() STMT_BEGIN \ static int warning_logged__ = 0; \ if (!warning_logged__) { \ warning_logged__ = 1; \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, NULL, 1); \ } \ STMT_END #define tor_assert_nonfatal_once(cond) STMT_BEGIN \ static int warning_logged__ = 0; \ if (ASSERT_PREDICT_LIKELY_(cond)) { \ } else if (!warning_logged__) { \ warning_logged__ = 1; \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, #cond, 1); \ } \ STMT_END #define BUG(cond) \ (ASSERT_PREDICT_UNLIKELY_(cond) ? \ (tor_bug_occurred_(SHORT_FILE__,__LINE__,__func__,"!("#cond")",0), 1) \ : 0) #endif /* defined(ALL_BUGS_ARE_FATAL) || ... */ #ifdef __GNUC__ #define IF_BUG_ONCE__(cond,var) \ if (( { \ static int var = 0; \ int bool_result = !!(cond); \ if (bool_result && !var) { \ var = 1; \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, \ "!("#cond")", 1); \ } \ bool_result; } )) #else /* !(defined(__GNUC__)) */ #define IF_BUG_ONCE__(cond,var) \ static int var = 0; \ if ((cond) ? \ (var ? 1 : \ (var=1, \ tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, \ "!("#cond")", 1), \ 1)) \ : 0) #endif /* defined(__GNUC__) */ #define IF_BUG_ONCE_VARNAME_(a) \ warning_logged_on_ ## a ## __ #define IF_BUG_ONCE_VARNAME__(a) \ IF_BUG_ONCE_VARNAME_(a) /** This macro behaves as 'if (bug(x))', except that it only logs its * warning once, no matter how many times it triggers. */ #define IF_BUG_ONCE(cond) \ IF_BUG_ONCE__(ASSERT_PREDICT_UNLIKELY_(cond), \ IF_BUG_ONCE_VARNAME__(__LINE__)) /** Define this if you want Tor to crash when any problem comes up, * so you can get a coredump and track things down. */ // #define tor_fragile_assert() tor_assert_unreached(0) #define tor_fragile_assert() tor_assert_nonfatal_unreached_once() void tor_assertion_failed_(const char *fname, unsigned int line, const char *func, const char *expr); void tor_bug_occurred_(const char *fname, unsigned int line, const char *func, const char *expr, int once); void tor_abort_(void) ATTR_NORETURN; #ifdef _WIN32 #define SHORT_FILE__ (tor_fix_source_file(__FILE__)) const char *tor_fix_source_file(const char *fname); #else #define SHORT_FILE__ (__FILE__) #define tor_fix_source_file(s) (s) #endif /* defined(_WIN32) */ #ifdef TOR_UNIT_TESTS void tor_capture_bugs_(int n); void tor_end_capture_bugs_(void); const struct smartlist_t *tor_get_captured_bug_log_(void); void tor_set_failed_assertion_callback(void (*fn)(void)); #endif /* defined(TOR_UNIT_TESTS) */ #endif /* !defined(TOR_UTIL_BUG_H) */