lib/compiler.h

   1 /*
   2  * Copyright (c) 2015-2017  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 #ifndef _FRR_COMPILER_H
  18 #define _FRR_COMPILER_H
  19
  20 #ifdef __cplusplus
  21 extern "C" {
  22 #endif
  23
  24 /* function attributes, use like
  25  *   void prototype(void) __attribute__((_CONSTRUCTOR(100)));
  26  */
  27 #if defined(__clang__)
  28 #if __clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 5)
  29 #  define _RET_NONNULL    , returns_nonnull
  30 #endif
  31 #if __has_attribute(fallthrough)
  32 #  define _FALLTHROUGH __attribute__((fallthrough));
  33 #endif
  34 # define _CONSTRUCTOR(x)  constructor(x)
  35 # define _DEPRECATED(x) deprecated(x)
  36 #elif defined(__GNUC__)
  37 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 9)
  38 #  define _RET_NONNULL    , returns_nonnull
  39 #endif
  40 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
  41 #  define _CONSTRUCTOR(x) constructor(x)
  42 #  define _DESTRUCTOR(x)  destructor(x)
  43 #  define _ALLOC_SIZE(x)  alloc_size(x)
  44 #endif
  45 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
  46 #  define _DEPRECATED(x) deprecated(x)
  47 #endif
  48 #if __GNUC__ >= 7
  49 #  define _FALLTHROUGH __attribute__((fallthrough));
  50 #endif
  51 #endif
  52
  53 #ifdef __sun
  54 /* Solaris doesn't do constructor priorities due to linker restrictions */
  55 #undef _CONSTRUCTOR
  56 #undef _DESTRUCTOR
  57 #endif
  58
  59 /* fallback versions */
  60 #ifndef _RET_NONNULL
  61 # define _RET_NONNULL
  62 #endif
  63 #ifndef _CONSTRUCTOR
  64 # define _CONSTRUCTOR(x) constructor
  65 #endif
  66 #ifndef _DESTRUCTOR
  67 # define _DESTRUCTOR(x) destructor
  68 #endif
  69 #ifndef _ALLOC_SIZE
  70 # define _ALLOC_SIZE(x)
  71 #endif
  72 #ifndef _FALLTHROUGH
  73 #define _FALLTHROUGH
  74 #endif
  75 #ifndef _DEPRECATED
  76 #define _DEPRECATED(x) deprecated
  77 #endif
  78
  79 /* pure = function does not modify memory & return value is the same if
  80  * memory hasn't changed (=> allows compiler to optimize)
  81  *
  82  * Mostly autodetected by the compiler if function body is available (i.e.
  83  * static inline functions in headers).  Since that implies it should only be
  84  * used in headers for non-inline functions, the "extern" is included here.
  85  */
  86 #define ext_pure        extern __attribute__((pure))
  87
  88 /* for helper functions defined inside macros */
  89 #define macro_inline    static inline __attribute__((unused))
  90 #define macro_pure      static inline __attribute__((unused, pure))
  91
  92 /*
  93  * for warnings on macros, put in the macro content like this:
  94  *   #define MACRO BLA CPP_WARN("MACRO has been deprecated")
  95  */
  96 #define CPP_STR(X) #X
  97
  98 #if defined(__ICC)
  99 #define CPP_NOTICE(text) _Pragma(CPP_STR(message __FILE__ ": " text))
 100 #define CPP_WARN(text) CPP_NOTICE(text)
 101
 102 #elif (defined(__GNUC__)                                                       \
 103        && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))           \
 104         || (defined(__clang__)                                                 \
 105             && (__clang_major__ >= 4                                           \
 106                 || (__clang_major__ == 3 && __clang_minor__ >= 5)))
 107 #define CPP_WARN(text) _Pragma(CPP_STR(GCC warning text))
 108 #define CPP_NOTICE(text) _Pragma(CPP_STR(message text))
 109
 110 #else
 111 #define CPP_WARN(text)
 112 #define CPP_NOTICE(text)
 113 #endif
 114
 115 /* MAX / MIN are not commonly defined, but useful */
 116 /* note: glibc sys/param.h has #define MIN(a,b) (((a)<(b))?(a):(b)) */
 117 #ifdef MAX
 118 #undef MAX
 119 #endif
 120 #define MAX(a, b)                                                              \
 121         ({                                                                     \
 122                 typeof(a) _max_a = (a);                                        \
 123                 typeof(b) _max_b = (b);                                        \
 124                 _max_a > _max_b ? _max_a : _max_b;                             \
 125         })
 126 #ifdef MIN
 127 #undef MIN
 128 #endif
 129 #define MIN(a, b)                                                              \
 130         ({                                                                     \
 131                 typeof(a) _min_a = (a);                                        \
 132                 typeof(b) _min_b = (b);                                        \
 133                 _min_a < _min_b ? _min_a : _min_b;                             \
 134         })
 135
 136 #ifndef offsetof
 137 #ifdef __compiler_offsetof
 138 #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE,MEMBER)
 139 #else
 140 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 141 #endif
 142 #endif
 143
 144 /* this variant of container_of() retains 'const' on pointers without needing
 145  * to be told to do so.  The following will all work without warning:
 146  *
 147  * struct member *p;
 148  * const struct member *cp;
 149  *
 150  * const struct cont *x = container_of(cp, struct cont, member);
 151  * const struct cont *x = container_of(cp, const struct cont, member);
 152  * const struct cont *x = container_of(p,  struct cont, member);
 153  * const struct cont *x = container_of(p,  const struct cont, member);
 154  * struct cont *x       = container_of(p,  struct cont, member);
 155  *
 156  * but the following will generate warnings about stripping const:
 157  *
 158  * struct cont *x       = container_of(cp, struct cont, member);
 159  * struct cont *x       = container_of(cp, const struct cont, member);
 160  * struct cont *x       = container_of(p,  const struct cont, member);
 161  */
 162 #ifdef container_of
 163 #undef container_of
 164 #endif
 165 #define container_of(ptr, type, member)                                        \
 166         (__builtin_choose_expr(                                                \
 167                 __builtin_types_compatible_p(typeof(&((type *)0)->member),     \
 168                         typeof(ptr))                                           \
 169                     ||  __builtin_types_compatible_p(void *, typeof(ptr)),     \
 170                 ({                                                             \
 171                         typeof(((type *)0)->member) *__mptr = (void *)(ptr);   \
 172                         (type *)((char *)__mptr - offsetof(type, member));     \
 173                 }),                                                            \
 174                 ({                                                             \
 175                         typeof(((const type *)0)->member) *__mptr = (ptr);     \
 176                         (const type *)((const char *)__mptr -                  \
 177                                         offsetof(type, member));               \
 178                 })                                                             \
 179         ))
 180
 181 #define container_of_null(ptr, type, member)                                   \
 182         ({                                                                     \
 183                 typeof(ptr) _tmp = (ptr);                                      \
 184                 _tmp ? container_of(_tmp, type, member) : NULL;                \
 185         })
 186
 187 #define array_size(ar) (sizeof(ar) / sizeof(ar[0]))
 188
 189 #ifdef __cplusplus
 190 }
 191 #endif
 192
 193 #endif /* _FRR_COMPILER_H */