util_bug.h 8.6 KB

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  1. /* Copyright (c) 2003-2004, Roger Dingledine
  2. * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
  3. * Copyright (c) 2007-2017, The Tor Project, Inc. */
  4. /* See LICENSE for licensing information */
  5. /**
  6. * \file util_bug.h
  7. *
  8. * \brief Macros to manage assertions, fatal and non-fatal.
  9. *
  10. * Guidelines: All the different kinds of assertion in this file are for
  11. * bug-checking only. Don't write code that can assert based on bad inputs.
  12. *
  13. * We provide two kinds of assertion here: "fatal" and "nonfatal". Use
  14. * nonfatal assertions for any bug you can reasonably recover from -- and
  15. * please, try to recover! Many severe bugs in Tor have been caused by using
  16. * a regular assertion when a nonfatal assertion would have been better.
  17. *
  18. * If you need to check a condition with a nonfatal assertion, AND recover
  19. * from that same condition, consider using the BUG() macro inside a
  20. * conditional. For example:
  21. *
  22. * <code>
  23. * // wrong -- use tor_assert_nonfatal() if you just want an assertion.
  24. * BUG(ptr == NULL);
  25. *
  26. * // okay, but needlessly verbose
  27. * tor_assert_nonfatal(ptr != NULL);
  28. * if (ptr == NULL) { ... }
  29. *
  30. * // this is how we do it:
  31. * if (BUG(ptr == NULL)) { ... }
  32. * </code>
  33. **/
  34. #ifndef TOR_UTIL_BUG_H
  35. #define TOR_UTIL_BUG_H
  36. #include "orconfig.h"
  37. #include "compat.h"
  38. #include "testsupport.h"
  39. /* Replace assert() with a variant that sends failures to the log before
  40. * calling assert() normally.
  41. */
  42. #ifdef NDEBUG
  43. /* Nobody should ever want to build with NDEBUG set. 99% of our asserts will
  44. * be outside the critical path anyway, so it's silly to disable bug-checking
  45. * throughout the entire program just because a few asserts are slowing you
  46. * down. Profile, optimize the critical path, and keep debugging on.
  47. *
  48. * And I'm not just saying that because some of our asserts check
  49. * security-critical properties.
  50. */
  51. #error "Sorry; we don't support building with NDEBUG."
  52. #endif
  53. /* Sometimes we don't want to use assertions during branch coverage tests; it
  54. * leads to tons of unreached branches which in reality are only assertions we
  55. * didn't hit. */
  56. #if defined(TOR_UNIT_TESTS) && defined(DISABLE_ASSERTS_IN_UNIT_TESTS)
  57. #define tor_assert(a) STMT_BEGIN \
  58. (void)(a); \
  59. STMT_END
  60. #else
  61. /** Like assert(3), but send assertion failures to the log as well as to
  62. * stderr. */
  63. #define tor_assert(expr) STMT_BEGIN \
  64. if (PREDICT_UNLIKELY(!(expr))) { \
  65. tor_assertion_failed_(SHORT_FILE__, __LINE__, __func__, #expr); \
  66. abort(); \
  67. } STMT_END
  68. #endif
  69. #define tor_assert_unreached() tor_assert(0)
  70. /* Non-fatal bug assertions. The "unreached" variants mean "this line should
  71. * never be reached." The "once" variants mean "Don't log a warning more than
  72. * once".
  73. *
  74. * The 'BUG' macro checks a boolean condition and logs an error message if it
  75. * is true. Example usage:
  76. * if (BUG(x == NULL))
  77. * return -1;
  78. */
  79. #ifdef __COVERITY__
  80. extern int bug_macro_deadcode_dummy__;
  81. #undef BUG
  82. // Coverity defines this in global headers; let's override it. This is a
  83. // magic coverity-only preprocessor thing.
  84. // We use this "deadcode_dummy__" trick to prevent coverity from
  85. // complaining about unreachable bug cases.
  86. #nodef BUG(x) ((x)?(__coverity_panic__(),1):(0+bug_macro_deadcode_dummy__))
  87. #endif
  88. #if defined(__COVERITY__) || defined(__clang_analyzer__)
  89. // We're running with a static analysis tool: let's treat even nonfatal
  90. // assertion failures as something that we need to avoid.
  91. #define ALL_BUGS_ARE_FATAL
  92. #endif
  93. #ifdef ALL_BUGS_ARE_FATAL
  94. #define tor_assert_nonfatal_unreached() tor_assert(0)
  95. #define tor_assert_nonfatal(cond) tor_assert((cond))
  96. #define tor_assert_nonfatal_unreached_once() tor_assert(0)
  97. #define tor_assert_nonfatal_once(cond) tor_assert((cond))
  98. #define BUG(cond) \
  99. (PREDICT_UNLIKELY(cond) ? \
  100. (tor_assertion_failed_(SHORT_FILE__,__LINE__,__func__,"!("#cond")"), \
  101. abort(), 1) \
  102. : 0)
  103. #elif defined(TOR_UNIT_TESTS) && defined(DISABLE_ASSERTS_IN_UNIT_TESTS)
  104. #define tor_assert_nonfatal_unreached() STMT_NIL
  105. #define tor_assert_nonfatal(cond) ((void)(cond))
  106. #define tor_assert_nonfatal_unreached_once() STMT_NIL
  107. #define tor_assert_nonfatal_once(cond) ((void)(cond))
  108. #define BUG(cond) (PREDICT_UNLIKELY(cond) ? 1 : 0)
  109. #else /* Normal case, !ALL_BUGS_ARE_FATAL, !DISABLE_ASSERTS_IN_UNIT_TESTS */
  110. #define tor_assert_nonfatal_unreached() STMT_BEGIN \
  111. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, NULL, 0); \
  112. STMT_END
  113. #define tor_assert_nonfatal(cond) STMT_BEGIN \
  114. if (PREDICT_UNLIKELY(!(cond))) { \
  115. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, #cond, 0); \
  116. } \
  117. STMT_END
  118. #define tor_assert_nonfatal_unreached_once() STMT_BEGIN \
  119. static int warning_logged__ = 0; \
  120. if (!warning_logged__) { \
  121. warning_logged__ = 1; \
  122. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, NULL, 1); \
  123. } \
  124. STMT_END
  125. #define tor_assert_nonfatal_once(cond) STMT_BEGIN \
  126. static int warning_logged__ = 0; \
  127. if (!warning_logged__ && PREDICT_UNLIKELY(!(cond))) { \
  128. warning_logged__ = 1; \
  129. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, #cond, 1); \
  130. } \
  131. STMT_END
  132. #define BUG(cond) \
  133. (PREDICT_UNLIKELY(cond) ? \
  134. (tor_bug_occurred_(SHORT_FILE__,__LINE__,__func__,"!("#cond")",0), 1) \
  135. : 0)
  136. #endif
  137. #ifdef __GNUC__
  138. #define IF_BUG_ONCE__(cond,var) \
  139. if (( { \
  140. static int var = 0; \
  141. int bool_result = (cond); \
  142. if (PREDICT_UNLIKELY(bool_result) && !var) { \
  143. var = 1; \
  144. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, \
  145. "!("#cond")", 1); \
  146. } \
  147. PREDICT_UNLIKELY(bool_result); } ))
  148. #else
  149. #define IF_BUG_ONCE__(cond,var) \
  150. static int var = 0; \
  151. if (PREDICT_UNLIKELY(cond) ? \
  152. (var ? 1 : \
  153. (var=1, \
  154. tor_bug_occurred_(SHORT_FILE__, __LINE__, __func__, \
  155. "!("#cond")", 1), \
  156. 1)) \
  157. : 0)
  158. #endif
  159. #define IF_BUG_ONCE_VARNAME_(a) \
  160. warning_logged_on_ ## a ## __
  161. #define IF_BUG_ONCE_VARNAME__(a) \
  162. IF_BUG_ONCE_VARNAME_(a)
  163. /** This macro behaves as 'if (bug(x))', except that it only logs its
  164. * warning once, no matter how many times it triggers.
  165. */
  166. #define IF_BUG_ONCE(cond) \
  167. IF_BUG_ONCE__((cond), \
  168. IF_BUG_ONCE_VARNAME__(__LINE__))
  169. /** Define this if you want Tor to crash when any problem comes up,
  170. * so you can get a coredump and track things down. */
  171. // #define tor_fragile_assert() tor_assert_unreached(0)
  172. #define tor_fragile_assert() tor_assert_nonfatal_unreached_once()
  173. void tor_assertion_failed_(const char *fname, unsigned int line,
  174. const char *func, const char *expr);
  175. void tor_bug_occurred_(const char *fname, unsigned int line,
  176. const char *func, const char *expr,
  177. int once);
  178. #ifdef TOR_UNIT_TESTS
  179. void tor_capture_bugs_(int n);
  180. void tor_end_capture_bugs_(void);
  181. const struct smartlist_t *tor_get_captured_bug_log_(void);
  182. void tor_set_failed_assertion_callback(void (*fn)(void));
  183. #endif
  184. #endif