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 <memory>
  19 #include <pthread.h>
  20 #include <type_traits>
  21
  22 /*
  23  * Takes a pointer x and transform it so we can use it to access members
  24  * without a function call. Here an example:
  25  *
  26  *    #define GET_SIZE(x) LTTNG_REF(x)->size
  27  *
  28  *    struct { int size; } s;
  29  *
  30  *    printf("size : %d\n", GET_SIZE(&s));
  31  *
  32  * For this example we can't use something like this for compatibility purpose
  33  * since this will fail:
  34  *
  35  *    #define GET_SIZE(x) x->size;
  36  *
  37  * This is mostly use for the compatibility layer of lttng-tools. See
  38  * poll/epoll for a good example. Since x can be on the stack or allocated
  39  * memory using malloc(), we must use generic accessors for compat in order to
  40  * *not* use a function to access members and not the variable name.
  41  */
  42 #define LTTNG_REF(x) ((typeof(*x) *)(x))
  43
  44 #ifdef NDEBUG
  45 /*
  46 * Force usage of the assertion condition to prevent unused variable warnings
  47 * when `assert()` are disabled by the `NDEBUG` definition.
  48 */
  49 # define LTTNG_ASSERT(_cond) ((void) sizeof((void) (_cond), 0))
  50 #else
  51 # include <assert.h>
  52 # define LTTNG_ASSERT(_cond) assert(_cond)
  53 #endif
  54
  55 /*
  56  * Memory allocation zeroed
  57  */
  58
  59 static inline
  60 void *zmalloc_internal(size_t size)
  61 {
  62         return calloc(1, size);
  63 }
  64
  65 template <typename T>
  66 struct can_malloc
  67 {
  68         /*
  69          * gcc versions before 5.0 lack some type traits defined in C++11.
  70          * Since in this instance we use the trait to prevent misuses
  71          * of malloc (and statically assert) and not to generate different
  72          * code based on this property, simply set value to true and allow
  73          * the code to compile. Anyone using a contemporary compiler will
  74          * catch the error.
  75          */
  76 #if __GNUG__ && __GNUC__ < 5
  77         static constexpr bool value = true;
  78 #else
  79         static constexpr bool value = std::is_trivially_constructible<T>::value;
  80 #endif
  81 };
  82
  83 /*
  84  * Malloc and zero-initialize an object of type T, asserting that T can be
  85  * safely malloc-ed (is trivially constructible).
  86  */
  87 template<typename T>
  88 T *zmalloc()
  89 {
  90         static_assert (can_malloc<T>::value, "type can be malloc'ed");
  91         return (T *) zmalloc_internal(sizeof(T));
  92 }
  93
  94 /*
  95  * Malloc and zero-initialize a buffer of size `size`, asserting that type T
  96  * can be safely malloc-ed (is trivially constructible).
  97  */
  98 template<typename T>
  99 T *zmalloc(size_t size)
 100 {
 101         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 102         LTTNG_ASSERT(size >= sizeof(T));
 103         return (T *) zmalloc_internal(size);
 104 }
 105
 106 /*
 107  * Malloc and zero-initialize an array of `nmemb` elements of type T,
 108  * asserting that T can be safely malloc-ed (is trivially constructible).
 109  */
 110 template<typename T>
 111 T *calloc(size_t nmemb)
 112 {
 113         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 114         return (T *) zmalloc_internal(nmemb * sizeof(T));
 115 }
 116
 117 /*
 118  * Malloc an object of type T, asserting that T can be safely malloc-ed (is
 119  * trivially constructible).
 120  */
 121 template<typename T>
 122 T *malloc()
 123 {
 124         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 125         return (T *) malloc(sizeof(T));
 126 }
 127
 128 /*
 129  * Malloc a buffer of size `size`, asserting that type T can be safely
 130  * malloc-ed (is trivially constructible).
 131  */
 132 template<typename T>
 133 T *malloc(size_t size)
 134 {
 135         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 136         return (T *) malloc(size);
 137 }
 138
 139 /*
 140  * Prevent using `free` on types that are non-POD.
 141  *
 142  * Declare a delete prototype of free if the parameter type is not safe to free
 143  * (non-POD).
 144  *
 145  * If the parameter is a pointer to void, we can't check if what is pointed
 146  * to is safe to free or not, as we don't know what is pointed to.  Ideally,
 147  * all calls to free would be with a typed pointer, but there are too many
 148  * instances of passing a pointer to void to enforce that right now.  So allow
 149  * pointers to void, these will not be checked.
 150  */
 151
 152 template<typename T>
 153 struct can_free
 154 {
 155         /*
 156          * gcc versions before 5.0 lack some type traits defined in C++11.
 157          * Since in this instance we use the trait to prevent misuses
 158          * of free (and statically assert) and not to generate different
 159          * code based on this property, simply set value to true and allow
 160          * the code to compile. Anyone using a contemporary compiler will
 161          * catch the error.
 162          */
 163 #if __GNUG__ && __GNUC__ < 5
 164         static constexpr bool value = true;
 165 #else
 166         static constexpr bool value = std::is_trivially_destructible<T>::value || std::is_void<T>::value;
 167 #endif
 168 };
 169
 170 template<typename T, typename = typename std::enable_if<!can_free<T>::value>::type>
 171 void free(T *p) = delete;
 172
 173 template<typename T>
 174 struct can_memset
 175 {
 176         static constexpr bool value = std::is_pod<T>::value || std::is_void<T>::value;
 177 };
 178
 179 template <typename T, typename = typename std::enable_if<!can_memset<T>::value>::type>
 180 void *memset(T *s, int c, size_t n) = delete;
 181
 182 template<typename T>
 183 struct can_memcpy
 184 {
 185         /*
 186          * gcc versions before 5.0 lack some type traits defined in C++11.
 187          * Since in this instance we use the trait to prevent misuses
 188          * of memcpy (and statically assert) and not to generate different
 189          * code based on this property, simply set value to true and allow
 190          * the code to compile. Anyone using a contemporary compiler will
 191          * catch the error.
 192          */
 193 #if __GNUG__ && __GNUC__ < 5
 194         static constexpr bool value = true;
 195 #else
 196         static constexpr bool value = std::is_trivially_copyable<T>::value;
 197 #endif
 198 };
 199
 200 template <typename T, typename U,
 201                 typename = typename std::enable_if<!can_memcpy<T>::value>::type,
 202                 typename = typename std::enable_if<!can_memcpy<U>::value>::type>
 203 void *memcpy(T *d, const U *s, size_t n) = delete;
 204
 205 template<typename T>
 206 struct can_memmove
 207 {
 208         /*
 209          * gcc versions before 5.0 lack some type traits defined in C++11.
 210          * Since in this instance we use the trait to prevent misuses
 211          * of memmove (and statically assert) and not to generate different
 212          * code based on this property, simply set value to true and allow
 213          * the code to compile. Anyone using a contemporary compiler will
 214          * catch the error.
 215          */
 216 #if __GNUG__ && __GNUC__ < 5
 217         static constexpr bool value = true;
 218 #else
 219         static constexpr bool value = std::is_trivially_copyable<T>::value;
 220 #endif
 221 };
 222
 223 template <typename T, typename U,
 224                 typename = typename std::enable_if<!can_memmove<T>::value>::type,
 225                 typename = typename std::enable_if<!can_memmove<U>::value>::type>
 226 void *memmove(T *d, const U *s, size_t n) = delete;
 227
 228 #ifndef ARRAY_SIZE
 229 #define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
 230 #endif
 231
 232 #ifndef LTTNG_PACKED
 233 #define LTTNG_PACKED __attribute__((__packed__))
 234 #endif
 235
 236 #ifndef LTTNG_NO_SANITIZE_ADDRESS
 237 #if defined(__clang__) || defined (__GNUC__)
 238 #define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
 239 #else
 240 #define LTTNG_NO_SANITIZE_ADDRESS
 241 #endif
 242 #endif
 243
 244 #define member_sizeof(type, field)      sizeof(((type *) 0)->field)
 245
 246 #define ASSERT_LOCKED(lock) LTTNG_ASSERT(pthread_mutex_trylock(&lock))
 247 #define ASSERT_RCU_READ_LOCKED(lock) LTTNG_ASSERT(rcu_read_ongoing())
 248
 249 /* Attribute suitable to tag functions as having printf()-like arguments. */
 250 #define ATTR_FORMAT_PRINTF(_string_index, _first_to_check) \
 251         __attribute__((format(printf, _string_index, _first_to_check)))
 252
 253 /* Attribute suitable to tag functions as having strftime()-like arguments. */
 254 #define ATTR_FORMAT_STRFTIME(_string_index) \
 255         __attribute__((format(strftime, _string_index, 0)))
 256
 257 /* Macros used to ignore specific compiler diagnostics. */
 258
 259 #define DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
 260 #define DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
 261
 262 #if defined(__clang__)
 263   /* Clang */
 264 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
 265 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 266         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 267 # define DIAGNOSTIC_IGNORE_LOGICAL_OP
 268 # define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
 269 # define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 270         _Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
 271 #else
 272   /* GCC */
 273 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT \
 274         _Pragma("GCC diagnostic ignored \"-Wsuggest-attribute=format\"")
 275 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 276         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 277 # define DIAGNOSTIC_IGNORE_LOGICAL_OP \
 278         _Pragma("GCC diagnostic ignored \"-Wlogical-op\"")
 279 # define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES \
 280         _Pragma("GCC diagnostic ignored \"-Wduplicated-branches\"")
 281 # define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF \
 282         _Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
 283 #endif
 284
 285 /* Used to make specific C++ functions to C code. */
 286 #ifdef __cplusplus
 287 #define C_LINKAGE extern "C"
 288 #else
 289 #define C_LINKAGE
 290 #endif
 291
 292 /*
 293  * lttng_strncpy returns 0 on success, or nonzero on failure.
 294  * It checks that the @src string fits into @dst_len before performing
 295  * the copy. On failure, no copy has been performed.
 296  *
 297  * Assumes that 'src' is null-terminated.
 298  *
 299  * dst_len includes the string's trailing NULL.
 300  */
 301 static inline
 302 int lttng_strncpy(char *dst, const char *src, size_t dst_len)
 303 {
 304         if (strlen(src) >= dst_len) {
 305                 /* Fail since copying would result in truncation. */
 306                 return -1;
 307         }
 308         strcpy(dst, src);
 309         return 0;
 310 }
 311
 312 namespace lttng {
 313 namespace utils {
 314 template <class Parent, class Member>
 315 Parent *container_of(const Member *member, const Member Parent::*ptr_to_member)
 316 {
 317         const Parent *dummy_parent = nullptr;
 318         auto *offset_of_member = reinterpret_cast<const char *>(&(dummy_parent->*ptr_to_member));
 319         auto address_of_parent = reinterpret_cast<const char *>(member) - offset_of_member;
 320
 321         return reinterpret_cast<Parent *>(address_of_parent);
 322 }
 323 } /* namespace utils */
 324 } /* namespace lttng */
 325
 326 #endif /* _MACROS_H */