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 #if defined(__cplusplus)
  67 #define lttng_ust_is_pointer_type(type) (std::is_pointer<type>::value)
  68 #else
  69 /* The difference between two pointers is an integer. */
  70 #define lttng_ust_is_pointer_type(type) \
  71         (lttng_ust_is_integer_type(typeof(((type)1 - (type)1))) && !lttng_ust_is_integer_type(type))
  72 #endif
  73
  74
  75 /**
  76  * lttng_ust_field_array_element_type_is_supported -
  77  *
  78  * Adds a compilation assertion that array and sequence fields declared by the
  79  * user are of an integral or pointer type.
  80  */
  81 #define lttng_ust_field_array_element_type_is_supported(type, item) \
  82                 lttng_ust_static_assert(lttng_ust_is_integer_type(type) || lttng_ust_is_pointer_type(type), \
  83                         "Non-integer, non-pointer type `" #item "` not supported as element of LTTNG_UST_FIELD_ARRAY or LTTNG_UST_FIELD_SEQUENCE", \
  84                         Non_integer_type__##item##__not_supported_as_element_of_LTTNG_UST_FIELD_ARRAY_or_LTTNG_UST_FIELD_SEQUENCE)
  85
  86
  87 /**
  88  * lttng_ust_runtime_bug_on - check condition at runtime
  89  * @condition: the condition which should be false.
  90  *
  91  * If the condition is true, a BUG will be triggered at runtime.
  92  */
  93 #define lttng_ust_runtime_bug_on(condition)                             \
  94         do {                                                            \
  95                 if (caa_unlikely(condition)) {                          \
  96                         fprintf(stderr,                                 \
  97                                 "LTTng BUG in file %s, line %d.\n",     \
  98                                 __FILE__, __LINE__);                    \
  99                         exit(EXIT_FAILURE);                             \
 100                 }                                                       \
 101         } while (0)
 102
 103
 104 /**
 105  * lttng_ust_build_bug_on - check condition at build
 106  * @condition: the condition which should be false.
 107  *
 108  * If the condition is true, the compiler will generate a build error.
 109  */
 110 #define lttng_ust_build_bug_on(condition)                       \
 111         ((void) sizeof(char[-!!(condition)]))
 112
 113
 114 /**
 115  * lttng_ust_build_runtime_bug_on - check condition at build (if constant) or runtime
 116  * @condition: the condition which should be false.
 117  *
 118  * If the condition is a constant and true, the compiler will generate a build
 119  * error. If the condition is not constant, a BUG will be triggered at runtime
 120  * if the condition is ever true. If the condition is constant and false, no
 121  * code is emitted.
 122  */
 123 #define lttng_ust_build_runtime_bug_on(condition)               \
 124         do {                                                    \
 125                 if (__builtin_constant_p(condition))            \
 126                         lttng_ust_build_bug_on(condition);      \
 127                 else                                            \
 128                         lttng_ust_runtime_bug_on(condition);    \
 129         } while (0)
 130
 131
 132 /**
 133  * lttng_ust_offset_align - Calculate the offset needed to align an object on
 134  *                its natural alignment towards higher addresses.
 135  * @align_drift:  object offset from an "alignment"-aligned address.
 136  * @alignment:    natural object alignment. Must be non-zero, power of 2.
 137  *
 138  * Returns the offset that must be added to align towards higher
 139  * addresses.
 140  */
 141 #define lttng_ust_offset_align(align_drift, alignment)                         \
 142         ({                                                                     \
 143                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 144                                    || ((alignment) & ((alignment) - 1)));      \
 145                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
 146         })
 147
 148
 149 /**
 150  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
 151  *                object on its natural alignment towards lower addresses.
 152  * @align_drift:  object offset from an "alignment"-aligned address.
 153  * @alignment:    natural object alignment. Must be non-zero, power of 2.
 154  *
 155  * Returns the offset that must be subtracted to align towards lower addresses.
 156  */
 157 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
 158         ({                                                                     \
 159                 lttng_ust_build_runtime_bug_on((alignment) == 0                \
 160                                    || ((alignment) & ((alignment) - 1)));      \
 161                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
 162         })
 163
 164 #endif /* _LTTNG_UST_UTILS_H */