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         /*
  67          * gcc versions before 5.0 lack some type traits defined in C++11.
  68          * Since in this instance we use the trait to prevent misuses
  69          * of malloc (and statically assert) and not to generate different
  70          * code based on this property, simply set value to true and allow
  71          * the code to compile. Anyone using a contemporary compiler will
  72          * catch the error.
  73          */
  74 #if __GNUG__ && __GNUC__ < 5
  75         static constexpr bool value = true;
  76 #else
  77         static constexpr bool value = std::is_trivially_constructible<T>::value;
  78 #endif
  79 };
  80
  81 /*
  82  * Malloc and zero-initialize an object of type T, asserting that T can be
  83  * safely malloc-ed (is trivially constructible).
  84  */
  85 template<typename T>
  86 T *zmalloc()
  87 {
  88         static_assert (can_malloc<T>::value, "type can be malloc'ed");
  89         return (T *) zmalloc_internal(sizeof(T));
  90 }
  91
  92 /*
  93  * Malloc and zero-initialize a buffer of size `size`, asserting that type T
  94  * can be safely malloc-ed (is trivially constructible).
  95  */
  96 template<typename T>
  97 T *zmalloc(size_t size)
  98 {
  99         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 100         LTTNG_ASSERT(size >= sizeof(T));
 101         return (T *) zmalloc_internal(size);
 102 }
 103
 104 /*
 105  * Malloc and zero-initialize an array of `nmemb` elements of type T,
 106  * asserting that T can be safely malloc-ed (is trivially constructible).
 107  */
 108 template<typename T>
 109 T *calloc(size_t nmemb)
 110 {
 111         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 112         return (T *) zmalloc_internal(nmemb * sizeof(T));
 113 }
 114
 115 /*
 116  * Malloc an object of type T, asserting that T can be safely malloc-ed (is
 117  * trivially constructible).
 118  */
 119 template<typename T>
 120 T *malloc()
 121 {
 122         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 123         return (T *) malloc(sizeof(T));
 124 }
 125
 126 /*
 127  * Malloc a buffer of size `size`, asserting that type T can be safely
 128  * malloc-ed (is trivially constructible).
 129  */
 130 template<typename T>
 131 T *malloc(size_t size)
 132 {
 133         static_assert (can_malloc<T>::value, "type can be malloc'ed");
 134         return (T *) malloc(size);
 135 }
 136
 137 /*
 138  * Prevent using `free` on types that are non-POD.
 139  *
 140  * Declare a delete prototype of free if the parameter type is not safe to free
 141  * (non-POD).
 142  *
 143  * If the parameter is a pointer to void, we can't check if what is pointed
 144  * to is safe to free or not, as we don't know what is pointed to.  Ideally,
 145  * all calls to free would be with a typed pointer, but there are too many
 146  * instances of passing a pointer to void to enforce that right now.  So allow
 147  * pointers to void, these will not be checked.
 148  */
 149
 150 template<typename T>
 151 struct can_free
 152 {
 153         /*
 154          * gcc versions before 5.0 lack some type traits defined in C++11.
 155          * Since in this instance we use the trait to prevent misuses
 156          * of free (and statically assert) and not to generate different
 157          * code based on this property, simply set value to true and allow
 158          * the code to compile. Anyone using a contemporary compiler will
 159          * catch the error.
 160          */
 161 #if __GNUG__ && __GNUC__ < 5
 162         static constexpr bool value = true;
 163 #else
 164         static constexpr bool value = std::is_trivially_destructible<T>::value || std::is_void<T>::value;
 165 #endif
 166 };
 167
 168 template<typename T, typename = typename std::enable_if<!can_free<T>::value>::type>
 169 void free(T *p) = delete;
 170
 171 template<typename T>
 172 struct can_memset
 173 {
 174         static constexpr bool value = std::is_pod<T>::value || std::is_void<T>::value;
 175 };
 176
 177 template <typename T, typename = typename std::enable_if<!can_memset<T>::value>::type>
 178 void *memset(T *s, int c, size_t n) = delete;
 179
 180 template<typename T>
 181 struct can_memcpy
 182 {
 183         /*
 184          * gcc versions before 5.0 lack some type traits defined in C++11.
 185          * Since in this instance we use the trait to prevent misuses
 186          * of memcpy (and statically assert) and not to generate different
 187          * code based on this property, simply set value to true and allow
 188          * the code to compile. Anyone using a contemporary compiler will
 189          * catch the error.
 190          */
 191 #if __GNUG__ && __GNUC__ < 5
 192         static constexpr bool value = true;
 193 #else
 194         static constexpr bool value = std::is_trivially_copyable<T>::value;
 195 #endif
 196 };
 197
 198 template <typename T, typename U,
 199                 typename = typename std::enable_if<!can_memcpy<T>::value>::type,
 200                 typename = typename std::enable_if<!can_memcpy<U>::value>::type>
 201 void *memcpy(T *d, const U *s, size_t n) = delete;
 202
 203 template<typename T>
 204 struct can_memmove
 205 {
 206         /*
 207          * gcc versions before 5.0 lack some type traits defined in C++11.
 208          * Since in this instance we use the trait to prevent misuses
 209          * of memmove (and statically assert) and not to generate different
 210          * code based on this property, simply set value to true and allow
 211          * the code to compile. Anyone using a contemporary compiler will
 212          * catch the error.
 213          */
 214 #if __GNUG__ && __GNUC__ < 5
 215         static constexpr bool value = true;
 216 #else
 217         static constexpr bool value = std::is_trivially_copyable<T>::value;
 218 #endif
 219 };
 220
 221 template <typename T, typename U,
 222                 typename = typename std::enable_if<!can_memmove<T>::value>::type,
 223                 typename = typename std::enable_if<!can_memmove<U>::value>::type>
 224 void *memmove(T *d, const U *s, size_t n) = delete;
 225
 226 #ifndef ARRAY_SIZE
 227 #define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
 228 #endif
 229
 230 #ifndef container_of
 231 #define container_of(ptr, type, member)                                 \
 232         ({                                                              \
 233                 const typeof(((type *)NULL)->member) * __ptr = (ptr);   \
 234                 (type *)((char *)__ptr - offsetof(type, member));       \
 235         })
 236 #endif
 237
 238 #ifndef LTTNG_PACKED
 239 #define LTTNG_PACKED __attribute__((__packed__))
 240 #endif
 241
 242 #ifndef LTTNG_NO_SANITIZE_ADDRESS
 243 #if defined(__clang__) || defined (__GNUC__)
 244 #define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
 245 #else
 246 #define LTTNG_NO_SANITIZE_ADDRESS
 247 #endif
 248 #endif
 249
 250 #define member_sizeof(type, field)      sizeof(((type *) 0)->field)
 251
 252 #define ASSERT_LOCKED(lock) LTTNG_ASSERT(pthread_mutex_trylock(&lock))
 253 #define ASSERT_RCU_READ_LOCKED(lock) LTTNG_ASSERT(rcu_read_ongoing())
 254
 255 /* Attribute suitable to tag functions as having printf()-like arguments. */
 256 #define ATTR_FORMAT_PRINTF(_string_index, _first_to_check) \
 257         __attribute__((format(printf, _string_index, _first_to_check)))
 258
 259 /* Attribute suitable to tag functions as having strftime()-like arguments. */
 260 #define ATTR_FORMAT_STRFTIME(_string_index) \
 261         __attribute__((format(strftime, _string_index, 0)))
 262
 263 /* Macros used to ignore specific compiler diagnostics. */
 264
 265 #define DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
 266 #define DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
 267
 268 #if defined(__clang__)
 269   /* Clang */
 270 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
 271 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 272         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 273 # define DIAGNOSTIC_IGNORE_LOGICAL_OP
 274 #else
 275   /* GCC */
 276 # define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT \
 277         _Pragma("GCC diagnostic ignored \"-Wsuggest-attribute=format\"")
 278 # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
 279         _Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
 280 # define DIAGNOSTIC_IGNORE_LOGICAL_OP \
 281         _Pragma("GCC diagnostic ignored \"-Wlogical-op\"")
 282 #endif
 283
 284 /* Used to make specific C++ functions to C code. */
 285 #ifdef __cplusplus
 286 #define C_LINKAGE extern "C"
 287 #else
 288 #define C_LINKAGE
 289 #endif
 290
 291 /*
 292  * lttng_strncpy returns 0 on success, or nonzero on failure.
 293  * It checks that the @src string fits into @dst_len before performing
 294  * the copy. On failure, no copy has been performed.
 295  *
 296  * Assumes that 'src' is null-terminated.
 297  *
 298  * dst_len includes the string's trailing NULL.
 299  */
 300 static inline
 301 int lttng_strncpy(char *dst, const char *src, size_t dst_len)
 302 {
 303         if (strlen(src) >= dst_len) {
 304                 /* Fail since copying would result in truncation. */
 305                 return -1;
 306         }
 307         strcpy(dst, src);
 308         return 0;
 309 }
 310
 311 #endif /* _MACROS_H */