src/basic/macro.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include "macro-fundamental.h" /* IWYU pragma: export */
   5
   6 #if !defined(HAS_FEATURE_MEMORY_SANITIZER)
   7 #  if defined(__has_feature)
   8 #    if __has_feature(memory_sanitizer)
   9 #      define HAS_FEATURE_MEMORY_SANITIZER 1
  10 #    endif
  11 #  endif
  12 #  if !defined(HAS_FEATURE_MEMORY_SANITIZER)
  13 #    define HAS_FEATURE_MEMORY_SANITIZER 0
  14 #  endif
  15 #endif
  16
  17 #if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
  18 #  ifdef __SANITIZE_ADDRESS__
  19 #      define HAS_FEATURE_ADDRESS_SANITIZER 1
  20 #  elif defined(__has_feature)
  21 #    if __has_feature(address_sanitizer)
  22 #      define HAS_FEATURE_ADDRESS_SANITIZER 1
  23 #    endif
  24 #  endif
  25 #  if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
  26 #    define HAS_FEATURE_ADDRESS_SANITIZER 0
  27 #  endif
  28 #endif
  29
  30 /* Note: on GCC "no_sanitize_address" is a function attribute only, on llvm it may also be applied to global
  31  * variables. We define a specific macro which knows this. Note that on GCC we don't need this decorator so much, since
  32  * our primary use case for this attribute is registration structures placed in named ELF sections which shall not be
  33  * padded, but GCC doesn't pad those anyway if AddressSanitizer is enabled. */
  34 #if HAS_FEATURE_ADDRESS_SANITIZER && defined(__clang__)
  35 #define _variable_no_sanitize_address_ __attribute__((__no_sanitize_address__))
  36 #else
  37 #define _variable_no_sanitize_address_
  38 #endif
  39
  40 /* Apparently there's no has_feature() call defined to check for ubsan, hence let's define this
  41  * unconditionally on llvm */
  42 #if defined(__clang__)
  43 #define _function_no_sanitize_float_cast_overflow_ __attribute__((no_sanitize("float-cast-overflow")))
  44 #else
  45 #define _function_no_sanitize_float_cast_overflow_
  46 #endif
  47
  48 /* test harness */
  49 #define EXIT_TEST_SKIP 77
  50
  51 static inline uint64_t u64_multiply_safe(uint64_t a, uint64_t b) {
  52         if (_unlikely_(a != 0 && b > (UINT64_MAX / a)))
  53                 return 0; /* overflow */
  54
  55         return a * b;
  56 }
  57
  58 /* align to next higher power-of-2 (except for: 0 => 0, overflow => 0) */
  59 static inline unsigned long ALIGN_POWER2(unsigned long u) {
  60
  61         /* Avoid subtraction overflow */
  62         if (u == 0)
  63                 return 0;
  64
  65         /* clz(0) is undefined */
  66         if (u == 1)
  67                 return 1;
  68
  69         /* left-shift overflow is undefined */
  70         if (__builtin_clzl(u - 1UL) < 1)
  71                 return 0;
  72
  73         return 1UL << (sizeof(u) * 8 - __builtin_clzl(u - 1UL));
  74 }
  75
  76 /*
  77  * container_of - cast a member of a structure out to the containing structure
  78  * @ptr: the pointer to the member.
  79  * @type: the type of the container struct this is embedded in.
  80  * @member: the name of the member within the struct.
  81  */
  82 #define container_of(ptr, type, member) __container_of(UNIQ, (ptr), type, member)
  83 #define __container_of(uniq, ptr, type, member)                         \
  84         ({                                                              \
  85                 const typeof( ((type*)0)->member ) *UNIQ_T(A, uniq) = (ptr); \
  86                 (type*)( (char *)UNIQ_T(A, uniq) - offsetof(type, member) ); \
  87         })
  88
  89 #define PTR_TO_INT(p) ((int) ((intptr_t) (p)))
  90 #define INT_TO_PTR(u) ((void *) ((intptr_t) (u)))
  91 #define PTR_TO_UINT(p) ((unsigned) ((uintptr_t) (p)))
  92 #define UINT_TO_PTR(u) ((void *) ((uintptr_t) (u)))
  93
  94 #define PTR_TO_LONG(p) ((long) ((intptr_t) (p)))
  95 #define LONG_TO_PTR(u) ((void *) ((intptr_t) (u)))
  96 #define PTR_TO_ULONG(p) ((unsigned long) ((uintptr_t) (p)))
  97 #define ULONG_TO_PTR(u) ((void *) ((uintptr_t) (u)))
  98
  99 #define PTR_TO_UINT8(p) ((uint8_t) ((uintptr_t) (p)))
 100 #define UINT8_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 101
 102 #define PTR_TO_INT32(p) ((int32_t) ((intptr_t) (p)))
 103 #define INT32_TO_PTR(u) ((void *) ((intptr_t) (u)))
 104 #define PTR_TO_UINT32(p) ((uint32_t) ((uintptr_t) (p)))
 105 #define UINT32_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 106
 107 #define PTR_TO_INT64(p) ((int64_t) ((intptr_t) (p)))
 108 #define INT64_TO_PTR(u) ((void *) ((intptr_t) (u)))
 109 #define PTR_TO_UINT64(p) ((uint64_t) ((uintptr_t) (p)))
 110 #define UINT64_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 111
 112 #define CHAR_TO_STR(x) ((char[2]) { x, 0 })
 113
 114 #define char_array_0(x) x[sizeof(x)-1] = 0;
 115
 116 /* Maximum buffer size needed for formatting an unsigned integer type as hex, including space for '0x'
 117  * prefix and trailing NUL suffix. */
 118 #define HEXADECIMAL_STR_MAX(type) (2 + sizeof(type) * 2 + 1)
 119
 120 /* Returns the number of chars needed to format variables of the specified type as a decimal string. Adds in
 121  * extra space for a negative '-' prefix for signed types. Includes space for the trailing NUL. */
 122 #define DECIMAL_STR_MAX(type)                                           \
 123         ((size_t) IS_SIGNED_INTEGER_TYPE(type) + 1U +                   \
 124             (sizeof(type) <= 1 ? 3U :                                   \
 125              sizeof(type) <= 2 ? 5U :                                   \
 126              sizeof(type) <= 4 ? 10U :                                  \
 127              sizeof(type) <= 8 ? (IS_SIGNED_INTEGER_TYPE(type) ? 19U : 20U) : sizeof(int[-2*(sizeof(type) > 8)])))
 128
 129 /* Returns the number of chars needed to format the specified integer value. It's hence more specific than
 130  * DECIMAL_STR_MAX() which answers the same question for all possible values of the specified type. Does
 131  * *not* include space for a trailing NUL. (If you wonder why we special case _x_ == 0 here: it's to trick
 132  * out gcc's -Wtype-limits, which would complain on comparing an unsigned type with < 0, otherwise. By
 133  * special-casing == 0 here first, we can use <= 0 instead of < 0 to trick out gcc.) */
 134 #define DECIMAL_STR_WIDTH(x)                                      \
 135         ({                                                        \
 136                 typeof(x) _x_ = (x);                              \
 137                 size_t ans;                                       \
 138                 if (_x_ == 0)                                     \
 139                         ans = 1;                                  \
 140                 else {                                            \
 141                         ans = _x_ <= 0 ? 2 : 1;                   \
 142                         while ((_x_ /= 10) != 0)                  \
 143                                 ans++;                            \
 144                 }                                                 \
 145                 ans;                                              \
 146         })
 147
 148 #define SWAP_TWO(x, y) do {                        \
 149                 typeof(x) _t = (x);                \
 150                 (x) = (y);                         \
 151                 (y) = (_t);                        \
 152         } while (false)
 153
 154 #define STRV_MAKE(...) ((char**) ((const char*[]) { __VA_ARGS__, NULL }))
 155 #define STRV_MAKE_EMPTY ((char*[1]) { NULL })
 156 #define STRV_MAKE_CONST(...) ((const char* const*) ((const char*[]) { __VA_ARGS__, NULL }))
 157
 158 /* Pointers range from NULL to POINTER_MAX */
 159 #define POINTER_MAX ((void*) UINTPTR_MAX)
 160
 161 /* A macro to force copying of a variable from memory. This is useful whenever we want to read something from
 162  * memory and want to make sure the compiler won't optimize away the destination variable for us. It's not
 163  * supposed to be a full CPU memory barrier, i.e. CPU is still allowed to reorder the reads, but it is not
 164  * allowed to remove our local copies of the variables. We want this to work for unaligned memory, hence
 165  * memcpy() is great for our purposes. */
 166 #define READ_NOW(x)                                                     \
 167         ({                                                              \
 168                 typeof(x) _copy;                                        \
 169                 memcpy(&_copy, &(x), sizeof(_copy));                    \
 170                 asm volatile ("" : : : "memory");                       \
 171                 _copy;                                                  \
 172         })
 173
 174 #define saturate_add(x, y, limit)                                       \
 175         ({                                                              \
 176                 typeof(limit) _x = (x);                                 \
 177                 typeof(limit) _y = (y);                                 \
 178                 _x > (limit) || _y >= (limit) - _x ? (limit) : _x + _y; \
 179         })
 180
 181 static inline size_t size_add(size_t x, size_t y) {
 182         return saturate_add(x, y, SIZE_MAX);
 183 }
 184
 185 /* A little helper for subtracting 1 off a pointer in a safe UB-free way. This is intended to be used for
 186  * loops that count down from a high pointer until some base. A naive loop would implement this like this:
 187  *
 188  * for (p = end-1; p >= base; p--) …
 189  *
 190  * But this is not safe because p before the base is UB in C. With this macro the loop becomes this instead:
 191  *
 192  * for (p = PTR_SUB1(end, base); p; p = PTR_SUB1(p, base)) …
 193  *
 194  * And is free from UB! */
 195 #define PTR_SUB1(p, base)                                \
 196         ({                                               \
 197                 typeof(p) _q = (p);                      \
 198                 _q && _q > (base) ? &_q[-1] : NULL;      \
 199         })
 200
 201 /* Iterate through each argument passed. All must be the same type as 'entry' or must be implicitly
 202  * convertible. The iteration variable 'entry' must already be defined. */
 203 #define FOREACH_ARGUMENT(entry, ...)                                     \
 204         _FOREACH_ARGUMENT(entry, UNIQ_T(_entries_, UNIQ), UNIQ_T(_current_, UNIQ), UNIQ_T(_va_sentinel_, UNIQ), ##__VA_ARGS__)
 205 #define _FOREACH_ARGUMENT(entry, _entries_, _current_, _va_sentinel_, ...)      \
 206         for (typeof(entry) _va_sentinel_[1] = {}, _entries_[] = { __VA_ARGS__ __VA_OPT__(,) _va_sentinel_[0] }, *_current_ = _entries_; \
 207              ((long)(_current_ - _entries_) < (long)(ELEMENTSOF(_entries_) - 1)) && ({ entry = *_current_; true; }); \
 208              _current_++)