lib/assert/assert.h

   1 /*
   2  * Copyright (c) 2021  David Lamparter, for NetDEF, Inc.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 /* WARNING: this file is "special" in that it overrides the system-provided
  18  * assert.h by being on the include path before it.  That means it should
  19  * provide the functional equivalent.
  20  *
  21  * This is intentional because FRR extends assert() to write to the log and
  22  * add backtraces.  Overriding the entire file is the simplest and most
  23  * reliable way to get this to work;  there were problems previously with the
  24  * system assert.h getting included afterwards and redefining assert() back to
  25  * the system variant.
  26  */
  27
  28 #ifndef _FRR_ASSERT_H
  29 #define _FRR_ASSERT_H
  30
  31 #include "xref.h"
  32
  33 #ifdef __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 #ifndef __cplusplus
  38 /* C++ has this built-in, but C provides it in assert.h for >=C11.  Since we
  39  * replace assert.h entirely, we need to provide it here too.
  40  */
  41 #define static_assert _Static_assert
  42 #endif
  43
  44 struct xref_assert {
  45         struct xref xref;
  46
  47         const char *expr;
  48         const char *extra, *args;
  49 };
  50
  51 extern void _zlog_assert_failed(const struct xref_assert *xref,
  52                                 const char *extra, ...) PRINTFRR(2, 3)
  53         __attribute__((noreturn));
  54
  55 /* the "do { } while (expr_)" is there to get a warning for assignments inside
  56  * the assert expression aka "assert(x = 1)".  The (necessary) braces around
  57  * expr_ in the if () statement would suppress these warnings.  Since
  58  * _zlog_assert_failed() is noreturn, the while condition will never be
  59  * checked.
  60  */
  61 #define assert(expr_)                                                          \
  62         ({                                                                     \
  63                 static const struct xref_assert _xref __attribute__(           \
  64                         (used)) = {                                            \
  65                         .xref = XREF_INIT(XREFT_ASSERT, NULL, __func__),       \
  66                         .expr = #expr_,                                        \
  67                 };                                                             \
  68                 XREF_LINK(_xref.xref);                                         \
  69                 if (__builtin_expect((expr_) ? 0 : 1, 0))                      \
  70                         do {                                                   \
  71                                 _zlog_assert_failed(&_xref, NULL);             \
  72                         } while (expr_);                                       \
  73         })
  74
  75 #define assertf(expr_, extra_, ...)                                            \
  76         ({                                                                     \
  77                 static const struct xref_assert _xref __attribute__(           \
  78                         (used)) = {                                            \
  79                         .xref = XREF_INIT(XREFT_ASSERT, NULL, __func__),       \
  80                         .expr = #expr_,                                        \
  81                         .extra = extra_,                                       \
  82                         .args = #__VA_ARGS__,                                  \
  83                 };                                                             \
  84                 XREF_LINK(_xref.xref);                                         \
  85                 if (__builtin_expect((expr_) ? 0 : 1, 0))                      \
  86                         do {                                                   \
  87                                 _zlog_assert_failed(&_xref, extra_,            \
  88                                                     ##__VA_ARGS__);            \
  89                         } while (expr_);                                       \
  90         })
  91
  92 #define zassert assert
  93
  94 #ifdef __cplusplus
  95 }
  96 #endif
  97
  98 #endif /* _FRR_ASSERT_H */