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_field_array_element_type_is_supported -
  63  *
  64  * Adds a compilation assertion that array and sequence fields declared by the
  65  * user are of an integral type.
  66  */
  67 #define lttng_ust_field_array_element_type_is_supported(type, item) \
  68                 lttng_ust_static_assert(lttng_ust_is_integer_type(type), \
  69                         "Non-integer type `" #item "` not supported as element of LTTNG_UST_FIELD_ARRAY or LTTNG_UST_FIELD_SEQUENCE", \
  70                         Non_integer_type__##item##__not_supported_as_element_of_LTTNG_UST_FIELD_ARRAY_or_LTTNG_UST_FIELD_SEQUENCE)
  71
  72
  73 /**
  74  * lttng_ust_runtime_bug_on - check condition at runtime
  75  * @condition: the condition which should be false.
  76  *
  77  * If the condition is true, a BUG will be triggered at runtime.
  78  */
  79 #define lttng_ust_runtime_bug_on(condition)                             \
  80         do {                                                            \
  81                 if (caa_unlikely(condition)) {                          \
  82                         fprintf(stderr,                                 \
  83                                 "LTTng BUG in file %s, line %d.\n",     \
  84                                 __FILE__, __LINE__);                    \
  85                         exit(EXIT_FAILURE);                             \
  86                 }                                                       \
  87         } while (0)
  88
  89
  90 /**
  91  * lttng_ust_build_bug_on - check condition at build
  92  * @condition: the condition which should be false.
  93  *
  94  * If the condition is true, the compiler will generate a build error.
  95  */
  96 #define lttng_ust_build_bug_on(condition)                       \
  97         ((void) sizeof(char[-!!(condition)]))
  98
  99
 100 /**
 101  * lttng_ust_build_runtime_bug_on - check condition at build (if constant) or runtime
 102  * @condition: the condition which should be false.
 103  *
 104  * If the condition is a constant and true, the compiler will generate a build
 105  * error. If the condition is not constant, a BUG will be triggered at runtime
 106  * if the condition is ever true. If the condition is constant and false, no
 107  * code is emitted.
 108  */
 109 #define lttng_ust_build_runtime_bug_on(condition)               \
 110         do {                                                    \
 111                 if (__builtin_constant_p(condition))            \
 112                         lttng_ust_build_bug_on(condition);      \
 113                 else                                            \
 114                         lttng_ust_runtime_bug_on(condition);    \
 115         } while (0)
 116
 117
 118 /**
 119  * lttng_ust_offset_align - Calculate the offset needed to align an object on
 120  *                its natural alignment towards higher addresses.
 121  * @align_drift:  object offset from an "alignment"-aligned address.
 122  * @alignment:    natural object alignment. Must be non-zero, power of 2.
 123  *
 124  * Returns the offset that must be added to align towards higher
 125  * addresses.
 126  */
 127 #define lttng_ust_offset_align(align_drift, alignment)                         \
 128         ({                                                                     \
 129                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 130                                    || ((alignment) & ((alignment) - 1)));      \
 131                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
 132         })
 133
 134
 135 /**
 136  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
 137  *                object on its natural alignment towards lower 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 subtracted to align towards lower addresses.
 142  */
 143 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
 144         ({                                                                     \
 145                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 146                                    || ((alignment) & ((alignment) - 1)));      \
 147                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
 148         })
 149
 150 #endif /* _LTTNG_UST_UTILS_H */