src/common/macros.hpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   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 <common/compat/string.hpp>
  13
  14 #include <stddef.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17
  18 #include <type_traits>
  19
  20 /*
  21  * Takes a pointer x and transform it so we can use it to access members
  22  * without a function call. Here an example:
  23  *
  24  *    #define GET_SIZE(x) LTTNG_REF(x)->size
  25  *
  26  *    struct { int size; } s;
  27  *
  28  *    printf("size : %d\n", GET_SIZE(&s));
  29  *
  30  * For this example we can't use something like this for compatibility purpose
  31  * since this will fail:
  32  *
  33  *    #define GET_SIZE(x) x->size;
  34  *
  35  * This is mostly use for the compatibility layer of lttng-tools. See
  36  * poll/epoll for a good example. Since x can be on the stack or allocated
  37  * memory using malloc(), we must use generic accessors for compat in order to
  38  * *not* use a function to access members and not the variable name.
  39  */
  40 #define LTTNG_REF(x) ((typeof(*x) *)(x))
  41
  42 #ifdef NDEBUG
  43 /*
  44 * Force usage of the assertion condition to prevent unused variable warnings
  45 * when `assert()` are disabled by the `NDEBUG` definition.
  46 */
  47 # define LTTNG_ASSERT(_cond) ((void) sizeof((void) (_cond), 0))
  48 #else
  49 # include <assert.h>
  50 # define LTTNG_ASSERT(_cond) assert(_cond)
  51 #endif
  52
  53 /*
  54  * Memory allocation zeroed
  55  */
  56
  57 static inline
  58 void *zmalloc_internal(size_t size)
  59 {
  60         return calloc(1, size);
  61 }
  62
  63 template <typename T>
  64 struct can_malloc
  65 {
  66         static constexpr bool value = std::is_trivially_constructible<T>::value;
  67 };
  68
  69 /*
  70  * Malloc and zero-initialize an object of type T, asserting that T can be
  71  * safely malloc-ed (is trivially constructible).
  72  */
  73 template<typename T>
  74 T *zmalloc()
  75 {
  76         static_assert (can_malloc<T>::value, "type can be malloc'ed");
  77         return (T *) zmalloc_internal(sizeof(T));
  78 }
  79
  80 /*
  81  * Malloc and zero-initialize a buffer of size `size`, asserting that type T
  82  * can be safely malloc-ed (is trivially constructible).
  83  */
  84 template<typename T>
  85 T *zmalloc(size_t size)
  86 {
  87         static_assert (can_malloc<T>::value, "type can be malloc'ed");
  88         LTTNG_ASSERT(size >= sizeof(T));
  89         return (T *) zmalloc_internal(size);
  90 }
  91
  92 /*
  93  * Malloc and zero-initialize an array of `nmemb` elements of type T,
  94  * asserting that T can be safely malloc-ed (is trivially constructible).
  95  */
  96 template<typename T>
  97 T *calloc(size_t nmemb)
  98 {
  99         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 100         return (T *) zmalloc_internal(nmemb * sizeof(T));
 101 }
 102
 103 /*
 104  * Malloc an object of type T, asserting that T can be safely malloc-ed (is
 105  * trivially constructible).
 106  */
 107 template<typename T>
 108 T *malloc()
 109 {
 110         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 111         return (T *) malloc(sizeof(T));
 112 }
 113
 114 /*
 115  * Malloc a buffer of size `size`, asserting that type T can be safely
 116  * malloc-ed (is trivially constructible).
 117  */
 118 template<typename T>
 119 T *malloc(size_t size)
 120 {
 121         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 122         return (T *) malloc(size);
 123 }
 124
 125 /*
 126  * Prevent using `free` on types that are non-POD.
 127  *
 128  * Declare a delete prototype of free if the parameter type is not safe to free
 129  * (non-POD).
 130  *
 131  * If the parameter is a pointer to void, we can't check if what is pointed
 132  * to is safe to free or not, as we don't know what is pointed to.  Ideally,
 133  * all calls to free would be with a typed pointer, but there are too many
 134  * instances of passing a pointer to void to enforce that right now.  So allow
 135  * pointers to void, these will not be checked.
 136  */
 137
 138 template<typename T>
 139 struct is_pod_or_void
 140 {
 141         static constexpr bool value = std::is_pod<T>::value || std::is_void<T>::value;
 142 };
 143
 144 template<typename T, typename = typename std::enable_if<!is_pod_or_void<T>::value>::type>
 145 void free(T *p) = delete;
 146
 147 #ifndef ARRAY_SIZE
 148 #define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
 149 #endif
 150
 151 #ifndef container_of
 152 #define container_of(ptr, type, member)                                 \
 153         ({                                                              \
 154                 const typeof(((type *)NULL)->member) * __ptr = (ptr);   \
 155                 (type *)((char *)__ptr - offsetof(type, member));       \
 156         })
 157 #endif
 158
 159 #ifndef LTTNG_PACKED
 160 #define LTTNG_PACKED __attribute__((__packed__))
 161 #endif
 162
 163 #ifndef LTTNG_NO_SANITIZE_ADDRESS
 164 #if defined(__clang__) || defined (__GNUC__)
 165 #define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
 166 #else
 167 #define LTTNG_NO_SANITIZE_ADDRESS
 168 #endif
 169 #endif
 170
 171 #define member_sizeof(type, field)      sizeof(((type *) 0)->field)
 172
 173 #define ASSERT_LOCKED(lock) LTTNG_ASSERT(pthread_mutex_trylock(&lock))
 174 #define ASSERT_RCU_READ_LOCKED(lock) LTTNG_ASSERT(rcu_read_ongoing())
 175
 176 /* Attribute suitable to tag functions as having printf()-like arguments. */
 177 #define ATTR_FORMAT_PRINTF(_string_index, _first_to_check) \
 178         __attribute__((format(printf, _string_index, _first_to_check)))
 179
 180 /* Attribute suitable to tag functions as having strftime()-like arguments. */
 181 #define ATTR_FORMAT_STRFTIME(_string_index) \
 182         __attribute__((format(strftime, _string_index, 0)))
 183
 184 /* Macros used to ignore specific compiler diagnostics. */
 185
 186 #define DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
 187 #define DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
 188
 189 #if defined(__clang__)
 190   /* Clang */
 191 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
 192 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 193         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 194 # define DIAGNOSTIC_IGNORE_LOGICAL_OP
 195 #else
 196   /* GCC */
 197 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT \
 198         _Pragma("GCC diagnostic ignored \"-Wsuggest-attribute=format\"")
 199 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 200         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 201 # define DIAGNOSTIC_IGNORE_LOGICAL_OP \
 202         _Pragma("GCC diagnostic ignored \"-Wlogical-op\"")
 203 #endif
 204
 205 /* Used to make specific C++ functions to C code. */
 206 #ifdef __cplusplus
 207 #define C_LINKAGE extern "C"
 208 #else
 209 #define C_LINKAGE
 210 #endif
 211
 212 /*
 213  * lttng_strncpy returns 0 on success, or nonzero on failure.
 214  * It checks that the @src string fits into @dst_len before performing
 215  * the copy. On failure, no copy has been performed.
 216  *
 217  * Assumes that 'src' is null-terminated.
 218  *
 219  * dst_len includes the string's trailing NULL.
 220  */
 221 static inline
 222 int lttng_strncpy(char *dst, const char *src, size_t dst_len)
 223 {
 224         if (strlen(src) >= dst_len) {
 225                 /* Fail since copying would result in truncation. */
 226                 return -1;
 227         }
 228         strcpy(dst, src);
 229         return 0;
 230 }
 231
 232 #endif /* _MACROS_H */