lib/assert/assert.h

   1 // SPDX-License-Identifier: ISC
   2 /*
   3  * Copyright (c) 2021  David Lamparter, for NetDEF, Inc.
   4  */
   5
   6 /* WARNING: this file is "special" in that it overrides the system-provided
   7  * assert.h by being on the include path before it.  That means it should
   8  * provide the functional equivalent.
   9  *
  10  * This is intentional because FRR extends assert() to write to the log and
  11  * add backtraces.  Overriding the entire file is the simplest and most
  12  * reliable way to get this to work;  there were problems previously with the
  13  * system assert.h getting included afterwards and redefining assert() back to
  14  * the system variant.
  15  */
  16
  17 #ifndef _FRR_ASSERT_H
  18 #define _FRR_ASSERT_H
  19
  20 #include "xref.h"
  21
  22 #ifdef __cplusplus
  23 extern "C" {
  24 #endif
  25
  26 #ifndef __cplusplus
  27 /* C++ has this built-in, but C provides it in assert.h for >=C11.  Since we
  28  * replace assert.h entirely, we need to provide it here too.
  29  */
  30 #define static_assert _Static_assert
  31 #endif
  32
  33 struct xref_assert {
  34         struct xref xref;
  35
  36         const char *expr;
  37         const char *extra, *args;
  38 };
  39
  40 extern void _zlog_assert_failed(const struct xref_assert *xref,
  41                                 const char *extra, ...) PRINTFRR(2, 3)
  42         __attribute__((noreturn));
  43
  44 /* the "do { } while (expr_)" is there to get a warning for assignments inside
  45  * the assert expression aka "assert(x = 1)".  The (necessary) braces around
  46  * expr_ in the if () statement would suppress these warnings.  Since
  47  * _zlog_assert_failed() is noreturn, the while condition will never be
  48  * checked.
  49  */
  50 #define assert(expr_)                                                          \
  51         ({                                                                     \
  52                 static const struct xref_assert _xref __attribute__(           \
  53                         (used)) = {                                            \
  54                         .xref = XREF_INIT(XREFT_ASSERT, NULL, __func__),       \
  55                         .expr = #expr_,                                        \
  56                 };                                                             \
  57                 XREF_LINK(_xref.xref);                                         \
  58                 if (__builtin_expect((expr_) ? 0 : 1, 0))                      \
  59                         do {                                                   \
  60                                 _zlog_assert_failed(&_xref, NULL);             \
  61                         } while (expr_);                                       \
  62         })
  63
  64 #define assertf(expr_, extra_, ...)                                            \
  65         ({                                                                     \
  66                 static const struct xref_assert _xref __attribute__(           \
  67                         (used)) = {                                            \
  68                         .xref = XREF_INIT(XREFT_ASSERT, NULL, __func__),       \
  69                         .expr = #expr_,                                        \
  70                         .extra = extra_,                                       \
  71                         .args = #__VA_ARGS__,                                  \
  72                 };                                                             \
  73                 XREF_LINK(_xref.xref);                                         \
  74                 if (__builtin_expect((expr_) ? 0 : 1, 0))                      \
  75                         do {                                                   \
  76                                 _zlog_assert_failed(&_xref, extra_,            \
  77                                                     ##__VA_ARGS__);            \
  78                         } while (expr_);                                       \
  79         })
  80
  81 #define zassert assert
  82
  83 #ifdef __cplusplus
  84 }
  85 #endif
  86
  87 #endif /* _FRR_ASSERT_H */