src/basic/macro.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <assert.h>
   5 #include <errno.h>
   6 #include <inttypes.h>
   7 #include <stdbool.h>
   8 #include <sys/param.h>
   9 #include <sys/sysmacros.h>
  10 #include <sys/types.h>
  11
  12 #include "constants.h"
  13 #include "macro-fundamental.h"
  14
  15 /* Note: on GCC "no_sanitize_address" is a function attribute only, on llvm it may also be applied to global
  16  * variables. We define a specific macro which knows this. Note that on GCC we don't need this decorator so much, since
  17  * our primary use case for this attribute is registration structures placed in named ELF sections which shall not be
  18  * padded, but GCC doesn't pad those anyway if AddressSanitizer is enabled. */
  19 #if HAS_FEATURE_ADDRESS_SANITIZER && defined(__clang__)
  20 #define _variable_no_sanitize_address_ __attribute__((__no_sanitize_address__))
  21 #else
  22 #define _variable_no_sanitize_address_
  23 #endif
  24
  25 /* Apparently there's no has_feature() call defined to check for ubsan, hence let's define this
  26  * unconditionally on llvm */
  27 #if defined(__clang__)
  28 #define _function_no_sanitize_float_cast_overflow_ __attribute__((no_sanitize("float-cast-overflow")))
  29 #else
  30 #define _function_no_sanitize_float_cast_overflow_
  31 #endif
  32
  33 #if HAVE_WSTRINGOP_TRUNCATION
  34 #  define DISABLE_WARNING_STRINGOP_TRUNCATION                           \
  35         _Pragma("GCC diagnostic push");                                 \
  36         _Pragma("GCC diagnostic ignored \"-Wstringop-truncation\"")
  37 #else
  38 #  define DISABLE_WARNING_STRINGOP_TRUNCATION                           \
  39         _Pragma("GCC diagnostic push")
  40 #endif
  41
  42 /* test harness */
  43 #define EXIT_TEST_SKIP 77
  44
  45 /* builtins */
  46 #if __SIZEOF_INT__ == 4
  47 #define BUILTIN_FFS_U32(x) __builtin_ffs(x);
  48 #elif __SIZEOF_LONG__ == 4
  49 #define BUILTIN_FFS_U32(x) __builtin_ffsl(x);
  50 #else
  51 #error "neither int nor long are four bytes long?!?"
  52 #endif
  53
  54 static inline uint64_t u64_multiply_safe(uint64_t a, uint64_t b) {
  55         if (_unlikely_(a != 0 && b > (UINT64_MAX / a)))
  56                 return 0; /* overflow */
  57
  58         return a * b;
  59 }
  60
  61 /* align to next higher power-of-2 (except for: 0 => 0, overflow => 0) */
  62 static inline unsigned long ALIGN_POWER2(unsigned long u) {
  63
  64         /* Avoid subtraction overflow */
  65         if (u == 0)
  66                 return 0;
  67
  68         /* clz(0) is undefined */
  69         if (u == 1)
  70                 return 1;
  71
  72         /* left-shift overflow is undefined */
  73         if (__builtin_clzl(u - 1UL) < 1)
  74                 return 0;
  75
  76         return 1UL << (sizeof(u) * 8 - __builtin_clzl(u - 1UL));
  77 }
  78
  79 static inline size_t GREEDY_ALLOC_ROUND_UP(size_t l) {
  80         size_t m;
  81
  82         /* Round up allocation sizes a bit to some reasonable, likely larger value. This is supposed to be
  83          * used for cases which are likely called in an allocation loop of some form, i.e. that repetitively
  84          * grow stuff, for example strv_extend() and suchlike.
  85          *
  86          * Note the difference to GREEDY_REALLOC() here, as this helper operates on a single size value only,
  87          * and rounds up to next multiple of 2, needing no further counter.
  88          *
  89          * Note the benefits of direct ALIGN_POWER2() usage: type-safety for size_t, sane handling for very
  90          * small (i.e. <= 2) and safe handling for very large (i.e. > SSIZE_MAX) values. */
  91
  92         if (l <= 2)
  93                 return 2; /* Never allocate less than 2 of something.  */
  94
  95         m = ALIGN_POWER2(l);
  96         if (m == 0) /* overflow? */
  97                 return l;
  98
  99         return m;
 100 }
 101
 102 /*
 103  * container_of - cast a member of a structure out to the containing structure
 104  * @ptr: the pointer to the member.
 105  * @type: the type of the container struct this is embedded in.
 106  * @member: the name of the member within the struct.
 107  */
 108 #define container_of(ptr, type, member) __container_of(UNIQ, (ptr), type, member)
 109 #define __container_of(uniq, ptr, type, member)                         \
 110         ({                                                              \
 111                 const typeof( ((type*)0)->member ) *UNIQ_T(A, uniq) = (ptr); \
 112                 (type*)( (char *)UNIQ_T(A, uniq) - offsetof(type, member) ); \
 113         })
 114
 115 #ifdef __COVERITY__
 116
 117 /* Use special definitions of assertion macros in order to prevent
 118  * false positives of ASSERT_SIDE_EFFECT on Coverity static analyzer
 119  * for uses of assert_se() and assert_return().
 120  *
 121  * These definitions make expression go through a (trivial) function
 122  * call to ensure they are not discarded. Also use ! or !! to ensure
 123  * the boolean expressions are seen as such.
 124  *
 125  * This technique has been described and recommended in:
 126  * https://community.synopsys.com/s/question/0D534000046Yuzb/suppressing-assertsideeffect-for-functions-that-allow-for-sideeffects
 127  */
 128
 129 extern void __coverity_panic__(void);
 130
 131 static inline void __coverity_check__(int condition) {
 132         if (!condition)
 133                 __coverity_panic__();
 134 }
 135
 136 static inline int __coverity_check_and_return__(int condition) {
 137         return condition;
 138 }
 139
 140 #define assert_message_se(expr, message) __coverity_check__(!!(expr))
 141
 142 #define assert_log(expr, message) __coverity_check_and_return__(!!(expr))
 143
 144 #else  /* ! __COVERITY__ */
 145
 146 #define assert_message_se(expr, message)                                \
 147         do {                                                            \
 148                 if (_unlikely_(!(expr)))                                \
 149                         log_assert_failed(message, PROJECT_FILE, __LINE__, __func__); \
 150         } while (false)
 151
 152 #define assert_log(expr, message) ((_likely_(expr))                     \
 153         ? (true)                                                        \
 154         : (log_assert_failed_return(message, PROJECT_FILE, __LINE__, __func__), false))
 155
 156 #endif  /* __COVERITY__ */
 157
 158 #define assert_se(expr) assert_message_se(expr, #expr)
 159
 160 /* We override the glibc assert() here. */
 161 #undef assert
 162 #ifdef NDEBUG
 163 #define assert(expr) ({ if (!(expr)) __builtin_unreachable(); })
 164 #else
 165 #define assert(expr) assert_message_se(expr, #expr)
 166 #endif
 167
 168 #define assert_not_reached()                                            \
 169         log_assert_failed_unreachable(PROJECT_FILE, __LINE__, __func__)
 170
 171 #define assert_return(expr, r)                                          \
 172         do {                                                            \
 173                 if (!assert_log(expr, #expr))                           \
 174                         return (r);                                     \
 175         } while (false)
 176
 177 #define assert_return_errno(expr, r, err)                               \
 178         do {                                                            \
 179                 if (!assert_log(expr, #expr)) {                         \
 180                         errno = err;                                    \
 181                         return (r);                                     \
 182                 }                                                       \
 183         } while (false)
 184
 185 #define return_with_errno(r, err)                     \
 186         do {                                          \
 187                 errno = abs(err);                     \
 188                 return r;                             \
 189         } while (false)
 190
 191 #define PTR_TO_INT(p) ((int) ((intptr_t) (p)))
 192 #define INT_TO_PTR(u) ((void *) ((intptr_t) (u)))
 193 #define PTR_TO_UINT(p) ((unsigned) ((uintptr_t) (p)))
 194 #define UINT_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 195
 196 #define PTR_TO_LONG(p) ((long) ((intptr_t) (p)))
 197 #define LONG_TO_PTR(u) ((void *) ((intptr_t) (u)))
 198 #define PTR_TO_ULONG(p) ((unsigned long) ((uintptr_t) (p)))
 199 #define ULONG_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 200
 201 #define PTR_TO_UINT8(p) ((uint8_t) ((uintptr_t) (p)))
 202 #define UINT8_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 203
 204 #define PTR_TO_INT32(p) ((int32_t) ((intptr_t) (p)))
 205 #define INT32_TO_PTR(u) ((void *) ((intptr_t) (u)))
 206 #define PTR_TO_UINT32(p) ((uint32_t) ((uintptr_t) (p)))
 207 #define UINT32_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 208
 209 #define PTR_TO_INT64(p) ((int64_t) ((intptr_t) (p)))
 210 #define INT64_TO_PTR(u) ((void *) ((intptr_t) (u)))
 211 #define PTR_TO_UINT64(p) ((uint64_t) ((uintptr_t) (p)))
 212 #define UINT64_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 213
 214 #define PTR_TO_SIZE(p) ((size_t) ((uintptr_t) (p)))
 215 #define SIZE_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 216
 217 #define CHAR_TO_STR(x) ((char[2]) { x, 0 })
 218
 219 #define char_array_0(x) x[sizeof(x)-1] = 0;
 220
 221 #define sizeof_field(struct_type, member) sizeof(((struct_type *) 0)->member)
 222 #define endoffsetof_field(struct_type, member) (offsetof(struct_type, member) + sizeof_field(struct_type, member))
 223
 224 /* Maximum buffer size needed for formatting an unsigned integer type as hex, including space for '0x'
 225  * prefix and trailing NUL suffix. */
 226 #define HEXADECIMAL_STR_MAX(type) (2 + sizeof(type) * 2 + 1)
 227
 228 /* Returns the number of chars needed to format variables of the specified type as a decimal string. Adds in
 229  * extra space for a negative '-' prefix for signed types. Includes space for the trailing NUL. */
 230 #define DECIMAL_STR_MAX(type)                                           \
 231         ((size_t) IS_SIGNED_INTEGER_TYPE(type) + 1U +                   \
 232             (sizeof(type) <= 1 ? 3U :                                   \
 233              sizeof(type) <= 2 ? 5U :                                   \
 234              sizeof(type) <= 4 ? 10U :                                  \
 235              sizeof(type) <= 8 ? (IS_SIGNED_INTEGER_TYPE(type) ? 19U : 20U) : sizeof(int[-2*(sizeof(type) > 8)])))
 236
 237 /* Returns the number of chars needed to format the specified integer value. It's hence more specific than
 238  * DECIMAL_STR_MAX() which answers the same question for all possible values of the specified type. Does
 239  * *not* include space for a trailing NUL. (If you wonder why we special case _x_ == 0 here: it's to trick
 240  * out gcc's -Wtype-limits, which would complain on comparing an unsigned type with < 0, otherwise. By
 241  * special-casing == 0 here first, we can use <= 0 instead of < 0 to trick out gcc.) */
 242 #define DECIMAL_STR_WIDTH(x)                                      \
 243         ({                                                        \
 244                 typeof(x) _x_ = (x);                              \
 245                 size_t ans;                                       \
 246                 if (_x_ == 0)                                     \
 247                         ans = 1;                                  \
 248                 else {                                            \
 249                         ans = _x_ <= 0 ? 2 : 1;                   \
 250                         while ((_x_ /= 10) != 0)                  \
 251                                 ans++;                            \
 252                 }                                                 \
 253                 ans;                                              \
 254         })
 255
 256 #define SWAP_TWO(x, y) do {                        \
 257                 typeof(x) _t = (x);                \
 258                 (x) = (y);                         \
 259                 (y) = (_t);                        \
 260         } while (false)
 261
 262 #define STRV_MAKE(...) ((char**) ((const char*[]) { __VA_ARGS__, NULL }))
 263 #define STRV_MAKE_EMPTY ((char*[1]) { NULL })
 264 #define STRV_MAKE_CONST(...) ((const char* const*) ((const char*[]) { __VA_ARGS__, NULL }))
 265
 266 /* Pointers range from NULL to POINTER_MAX */
 267 #define POINTER_MAX ((void*) UINTPTR_MAX)
 268
 269 /* Iterates through a specified list of pointers. Accepts NULL pointers, but uses POINTER_MAX as internal marker for EOL. */
 270 #define FOREACH_POINTER(p, x, ...)                                                       \
 271         for (typeof(p) *_l = (typeof(p)[]) { ({ p = x; }), ##__VA_ARGS__, POINTER_MAX }; \
 272              p != (typeof(p)) POINTER_MAX;                                               \
 273              p = *(++_l))
 274
 275 #define _FOREACH_ARRAY(i, array, num, m, end)                           \
 276         for (typeof(array[0]) *i = (array), *end = ({                   \
 277                                 typeof(num) m = (num);                  \
 278                                 (i && m > 0) ? i + m : NULL;            \
 279                         }); end && i < end; i++)
 280
 281 #define FOREACH_ARRAY(i, array, num)                                    \
 282         _FOREACH_ARRAY(i, array, num, UNIQ_T(m, UNIQ), UNIQ_T(end, UNIQ))
 283
 284 #define _DEFINE_TRIVIAL_REF_FUNC(type, name, scope)             \
 285         scope type *name##_ref(type *p) {                       \
 286                 if (!p)                                         \
 287                         return NULL;                            \
 288                                                                 \
 289                 /* For type check. */                           \
 290                 unsigned *q = &p->n_ref;                        \
 291                 assert(*q > 0);                                 \
 292                 assert_se(*q < UINT_MAX);                       \
 293                                                                 \
 294                 (*q)++;                                         \
 295                 return p;                                       \
 296         }
 297
 298 #define _DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func, scope) \
 299         scope type *name##_unref(type *p) {                      \
 300                 if (!p)                                          \
 301                         return NULL;                             \
 302                                                                  \
 303                 assert(p->n_ref > 0);                            \
 304                 p->n_ref--;                                      \
 305                 if (p->n_ref > 0)                                \
 306                         return NULL;                             \
 307                                                                  \
 308                 return free_func(p);                             \
 309         }
 310
 311 #define DEFINE_TRIVIAL_REF_FUNC(type, name)     \
 312         _DEFINE_TRIVIAL_REF_FUNC(type, name,)
 313 #define DEFINE_PRIVATE_TRIVIAL_REF_FUNC(type, name)     \
 314         _DEFINE_TRIVIAL_REF_FUNC(type, name, static)
 315 #define DEFINE_PUBLIC_TRIVIAL_REF_FUNC(type, name)      \
 316         _DEFINE_TRIVIAL_REF_FUNC(type, name, _public_)
 317
 318 #define DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func)        \
 319         _DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func,)
 320 #define DEFINE_PRIVATE_TRIVIAL_UNREF_FUNC(type, name, free_func)        \
 321         _DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func, static)
 322 #define DEFINE_PUBLIC_TRIVIAL_UNREF_FUNC(type, name, free_func)         \
 323         _DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func, _public_)
 324
 325 #define DEFINE_TRIVIAL_REF_UNREF_FUNC(type, name, free_func)    \
 326         DEFINE_TRIVIAL_REF_FUNC(type, name);                    \
 327         DEFINE_TRIVIAL_UNREF_FUNC(type, name, free_func);
 328
 329 #define DEFINE_PRIVATE_TRIVIAL_REF_UNREF_FUNC(type, name, free_func)    \
 330         DEFINE_PRIVATE_TRIVIAL_REF_FUNC(type, name);                    \
 331         DEFINE_PRIVATE_TRIVIAL_UNREF_FUNC(type, name, free_func);
 332
 333 #define DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(type, name, free_func)    \
 334         DEFINE_PUBLIC_TRIVIAL_REF_FUNC(type, name);                    \
 335         DEFINE_PUBLIC_TRIVIAL_UNREF_FUNC(type, name, free_func);
 336
 337 /* A macro to force copying of a variable from memory. This is useful whenever we want to read something from
 338  * memory and want to make sure the compiler won't optimize away the destination variable for us. It's not
 339  * supposed to be a full CPU memory barrier, i.e. CPU is still allowed to reorder the reads, but it is not
 340  * allowed to remove our local copies of the variables. We want this to work for unaligned memory, hence
 341  * memcpy() is great for our purposes. */
 342 #define READ_NOW(x)                                                     \
 343         ({                                                              \
 344                 typeof(x) _copy;                                        \
 345                 memcpy(&_copy, &(x), sizeof(_copy));                    \
 346                 asm volatile ("" : : : "memory");                       \
 347                 _copy;                                                  \
 348         })
 349
 350 #define saturate_add(x, y, limit)                                       \
 351         ({                                                              \
 352                 typeof(limit) _x = (x);                                 \
 353                 typeof(limit) _y = (y);                                 \
 354                 _x > (limit) || _y >= (limit) - _x ? (limit) : _x + _y; \
 355         })
 356
 357 static inline size_t size_add(size_t x, size_t y) {
 358         return saturate_add(x, y, SIZE_MAX);
 359 }
 360
 361 typedef struct {
 362         int _empty[0];
 363 } dummy_t;
 364
 365 assert_cc(sizeof(dummy_t) == 0);
 366
 367 /* A little helper for subtracting 1 off a pointer in a safe UB-free way. This is intended to be used for
 368  * loops that count down from a high pointer until some base. A naive loop would implement this like this:
 369  *
 370  * for (p = end-1; p >= base; p--) …
 371  *
 372  * But this is not safe because p before the base is UB in C. With this macro the loop becomes this instead:
 373  *
 374  * for (p = PTR_SUB1(end, base); p; p = PTR_SUB1(p, base)) …
 375  *
 376  * And is free from UB! */
 377 #define PTR_SUB1(p, base)                                \
 378         ({                                               \
 379                 typeof(p) _q = (p);                      \
 380                 _q && _q > (base) ? &_q[-1] : NULL;      \
 381         })
 382
 383 /* Iterate through each variadic arg. All must be the same type as 'entry' or must be implicitly
 384  * convertible. The iteration variable 'entry' must already be defined. */
 385 #define VA_ARGS_FOREACH(entry, ...)                                     \
 386         _VA_ARGS_FOREACH(entry, UNIQ_T(_entries_, UNIQ), UNIQ_T(_current_, UNIQ), ##__VA_ARGS__)
 387 #define _VA_ARGS_FOREACH(entry, _entries_, _current_, ...)         \
 388         for (typeof(entry) _entries_[] = { __VA_ARGS__ }, *_current_ = _entries_; \
 389              ((long)(_current_ - _entries_) < (long)ELEMENTSOF(_entries_)) && ({ entry = *_current_; true; }); \
 390              _current_++)
 391
 392 #include "log.h"