include/lttng/ust-utils.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _LTTNG_UST_UTILS_H
   8 #define _LTTNG_UST_UTILS_H
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <urcu/compiler.h>
  13
  14 /* For lttng_ust_is_integer_type */
  15 #if defined (__cplusplus)
  16 #include <type_traits>
  17 #endif
  18
  19
  20 /**
  21  * lttng_ust_stringify - convert a literal value to a C string
  22  */
  23 #define __lttng_ust_stringify1(x)       #x
  24 #define lttng_ust_stringify(x)  __lttng_ust_stringify1(x)
  25
  26 /**
  27  * lttng_ust_is_signed_type - check if type is signed
  28  *
  29  * Returns true if the type of @type is signed.
  30  */
  31 #if defined(__cplusplus)
  32 #define lttng_ust_is_signed_type(type)  (std::is_signed<type>::value)
  33 #else
  34 #define lttng_ust_is_signed_type(type)  ((type) -1 < (type) 1)
  35 #endif
  36
  37
  38 /**
  39  * lttng_ust_is_integer_type - check if type is an integer
  40  *
  41  * Returns true if the type of @type is an integer.
  42  */
  43 #if defined(__cplusplus)
  44 #define lttng_ust_is_integer_type(type) (std::is_integral<type>::value)
  45 #else
  46 #define lttng_ust_is_integer_type(type) \
  47                 (__builtin_types_compatible_p(type, _Bool) || \
  48                 __builtin_types_compatible_p(type, char) || \
  49                 __builtin_types_compatible_p(type, signed char) || \
  50                 __builtin_types_compatible_p(type, unsigned char) || \
  51                 __builtin_types_compatible_p(type, short) || \
  52                 __builtin_types_compatible_p(type, unsigned short) || \
  53                 __builtin_types_compatible_p(type, int) || \
  54                 __builtin_types_compatible_p(type, unsigned int) || \
  55                 __builtin_types_compatible_p(type, long) || \
  56                 __builtin_types_compatible_p(type, unsigned long) || \
  57                 __builtin_types_compatible_p(type, long long) || \
  58                 __builtin_types_compatible_p(type, unsigned long long))
  59 #endif
  60
  61 /**
  62  * lttng_ust_is_pointer_type - check if type is a pointer
  63  *
  64  * Returns true if the type of @type is a pointer.
  65  *
  66  * Note: The C implementation of lttng_ust_is_pointer_type uses pointer
  67  * arithmetic, which does not work on opaque pointer types.
  68  */
  69 #if defined(__cplusplus)
  70 #define lttng_ust_is_pointer_type(type) (std::is_pointer<type>::value)
  71 #else
  72 /* The difference between two pointers is an integer. */
  73 #define lttng_ust_is_pointer_type(type) \
  74         (lttng_ust_is_integer_type(typeof(((type)1 - (type)1))) && !lttng_ust_is_integer_type(type))
  75 #endif
  76
  77
  78 /**
  79  * lttng_ust_field_array_element_type_is_supported -
  80  *
  81  * Adds a compilation assertion that array and sequence fields declared by the
  82  * user are of an integral or pointer type.
  83  */
  84 #define lttng_ust_field_array_element_type_is_supported(type, item) \
  85                 lttng_ust_static_assert(lttng_ust_is_integer_type(type) || lttng_ust_is_pointer_type(type), \
  86                         "Non-integer, non-pointer type `" #item "` not supported as element of LTTNG_UST_FIELD_ARRAY or LTTNG_UST_FIELD_SEQUENCE", \
  87                         Non_integer_type__##item##__not_supported_as_element_of_LTTNG_UST_FIELD_ARRAY_or_LTTNG_UST_FIELD_SEQUENCE)
  88
  89
  90 /**
  91  * lttng_ust_runtime_bug_on - check condition at runtime
  92  * @condition: the condition which should be false.
  93  *
  94  * If the condition is true, a BUG will be triggered at runtime.
  95  */
  96 #define lttng_ust_runtime_bug_on(condition)                             \
  97         do {                                                            \
  98                 if (caa_unlikely(condition)) {                          \
  99                         fprintf(stderr,                                 \
 100                                 "LTTng BUG in file %s, line %d.\n",     \
 101                                 __FILE__, __LINE__);                    \
 102                         exit(EXIT_FAILURE);                             \
 103                 }                                                       \
 104         } while (0)
 105
 106
 107 /**
 108  * lttng_ust_build_bug_on - check condition at build
 109  * @condition: the condition which should be false.
 110  *
 111  * If the condition is true, the compiler will generate a build error.
 112  */
 113 #define lttng_ust_build_bug_on(condition)                       \
 114         ((void) sizeof(char[-!!(condition)]))
 115
 116
 117 /**
 118  * lttng_ust_build_runtime_bug_on - check condition at build (if constant) or runtime
 119  * @condition: the condition which should be false.
 120  *
 121  * If the condition is a constant and true, the compiler will generate a build
 122  * error. If the condition is not constant, a BUG will be triggered at runtime
 123  * if the condition is ever true. If the condition is constant and false, no
 124  * code is emitted.
 125  */
 126 #define lttng_ust_build_runtime_bug_on(condition)               \
 127         do {                                                    \
 128                 if (__builtin_constant_p(condition))            \
 129                         lttng_ust_build_bug_on(condition);      \
 130                 else                                            \
 131                         lttng_ust_runtime_bug_on(condition);    \
 132         } while (0)
 133
 134
 135 /**
 136  * lttng_ust_offset_align - Calculate the offset needed to align an object on
 137  *                its natural alignment towards higher addresses.
 138  * @align_drift:  object offset from an "alignment"-aligned address.
 139  * @alignment:    natural object alignment. Must be non-zero, power of 2.
 140  *
 141  * Returns the offset that must be added to align towards higher
 142  * addresses.
 143  */
 144 #define lttng_ust_offset_align(align_drift, alignment)                         \
 145         ({                                                                     \
 146                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 147                                    || ((alignment) & ((alignment) - 1)));      \
 148                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
 149         })
 150
 151
 152 /**
 153  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
 154  *                object on its natural alignment towards lower addresses.
 155  * @align_drift:  object offset from an "alignment"-aligned address.
 156  * @alignment:    natural object alignment. Must be non-zero, power of 2.
 157  *
 158  * Returns the offset that must be subtracted to align towards lower addresses.
 159  */
 160 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
 161         ({                                                                     \
 162                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 163                                    || ((alignment) & ((alignment) - 1)));      \
 164                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
 165         })
 166
 167 #endif /* _LTTNG_UST_UTILS_H */