src/common/macros.h

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #ifndef _MACROS_H
  10 #define _MACROS_H
  11
  12 #include <stdlib.h>
  13 #include <stddef.h>
  14 #include <string.h>
  15 #include <common/compat/string.h>
  16
  17 /*
  18  * Takes a pointer x and transform it so we can use it to access members
  19  * without a function call. Here an example:
  20  *
  21  *    #define GET_SIZE(x) LTTNG_REF(x)->size
  22  *
  23  *    struct { int size; } s;
  24  *
  25  *    printf("size : %d\n", GET_SIZE(&s));
  26  *
  27  * For this example we can't use something like this for compatibility purpose
  28  * since this will fail:
  29  *
  30  *    #define GET_SIZE(x) x->size;
  31  *
  32  * This is mostly use for the compatibility layer of lttng-tools. See
  33  * poll/epoll for a good example. Since x can be on the stack or allocated
  34  * memory using malloc(), we must use generic accessors for compat in order to
  35  * *not* use a function to access members and not the variable name.
  36  */
  37 #define LTTNG_REF(x) ((typeof(*x) *)(x))
  38
  39 /*
  40  * Memory allocation zeroed
  41  */
  42 static inline
  43 void *zmalloc(size_t len)
  44 {
  45         return calloc(1, len);
  46 }
  47
  48 #ifndef ARRAY_SIZE
  49 #define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
  50 #endif
  51
  52 #ifndef container_of
  53 #define container_of(ptr, type, member)                                 \
  54         ({                                                              \
  55                 const typeof(((type *)NULL)->member) * __ptr = (ptr);   \
  56                 (type *)((char *)__ptr - offsetof(type, member));       \
  57         })
  58 #endif
  59
  60
  61 /*
  62  * The min and max macros are not needed in C++ (std::min and std::max are
  63  * preferred) and they conflict with some C++ header file. Don't define them
  64  * when compiling C++ source.
  65  */
  66 #ifndef __cplusplus
  67
  68 # ifndef max
  69 #  define max(a, b) ((a) > (b) ? (a) : (b))
  70 # endif
  71
  72 # ifndef min
  73 #  define min(a, b) ((a) < (b) ? (a) : (b))
  74 # endif
  75
  76 # ifndef max_t
  77 #  define max_t(type, a, b)     max((type) a, (type) b)
  78 # endif
  79
  80 # ifndef min_t
  81 #  define min_t(type, a, b)     min((type) a, (type) b)
  82 # endif
  83
  84 #endif
  85
  86 #ifndef LTTNG_PACKED
  87 #define LTTNG_PACKED __attribute__((__packed__))
  88 #endif
  89
  90 #ifndef LTTNG_NO_SANITIZE_ADDRESS
  91 #if defined(__clang__) || defined (__GNUC__)
  92 #define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
  93 #else
  94 #define LTTNG_NO_SANITIZE_ADDRESS
  95 #endif
  96 #endif
  97
  98 #define is_signed(type) (((type) -1) < (type) 1)
  99
 100 #define member_sizeof(type, field)      sizeof(((type *) 0)->field)
 101
 102 #define ASSERT_LOCKED(lock) LTTNG_ASSERT(pthread_mutex_trylock(&lock))
 103
 104 /*
 105  * lttng_strncpy returns 0 on success, or nonzero on failure.
 106  * It checks that the @src string fits into @dst_len before performing
 107  * the copy. On failure, no copy has been performed.
 108  *
 109  * dst_len includes the string's trailing NULL.
 110  */
 111 static inline
 112 int lttng_strncpy(char *dst, const char *src, size_t dst_len)
 113 {
 114         if (lttng_strnlen(src, dst_len) >= dst_len) {
 115                 /* Fail since copying would result in truncation. */
 116                 return -1;
 117         }
 118         strcpy(dst, src);
 119         return 0;
 120 }
 121
 122 #ifdef NDEBUG
 123 /*
 124 * Force usage of the assertion condition to prevent unused variable warnings
 125 * when `assert()` are disabled by the `NDEBUG` definition.
 126 */
 127 # define LTTNG_ASSERT(_cond) ((void) sizeof((void) (_cond), 0))
 128 #else
 129 # include <assert.h>
 130 # define LTTNG_ASSERT(_cond) assert(_cond)
 131 #endif
 132
 133 #endif /* _MACROS_H */