xpcom/base/nscore.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nscore_h___
   8 #define nscore_h___
   9
  10 /* Definitions of functions and operators that allocate memory. */
  11 #if !defined(NS_NO_XPCOM) && !defined(MOZ_NO_MOZALLOC)
  12 #  include "mozilla/mozalloc.h"
  13 #endif
  14
  15 /**
  16  * Incorporate the integer data types which XPCOM uses.
  17  */
  18 #include <stddef.h>  // IWYU pragma: export
  19 #include <stdint.h>  // IWYU pragma: export
  20
  21 #include "mozilla/HelperMacros.h"  // IWYU pragma: export
  22 #include "mozilla/RefCountType.h"
  23
  24 /* Core XPCOM declarations. */
  25
  26 /*----------------------------------------------------------------------*/
  27 /* Import/export defines */
  28
  29 #ifdef HAVE_VISIBILITY_HIDDEN_ATTRIBUTE
  30 #  define NS_VISIBILITY_HIDDEN __attribute__((visibility("hidden")))
  31 #else
  32 #  define NS_VISIBILITY_HIDDEN
  33 #endif
  34
  35 #if defined(HAVE_VISIBILITY_ATTRIBUTE)
  36 #  define NS_VISIBILITY_DEFAULT __attribute__((visibility("default")))
  37 #elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
  38 #  define NS_VISIBILITY_DEFAULT __global
  39 #else
  40 #  define NS_VISIBILITY_DEFAULT
  41 #endif
  42
  43 #define NS_HIDDEN_(type) NS_VISIBILITY_HIDDEN type
  44 #define NS_EXTERNAL_VIS_(type) NS_VISIBILITY_DEFAULT type
  45
  46 #define NS_HIDDEN NS_VISIBILITY_HIDDEN
  47 #define NS_EXTERNAL_VIS NS_VISIBILITY_DEFAULT
  48
  49 /**
  50  * Mark a function as using a potentially non-standard function calling
  51  * convention.  This can be used on functions that are called very
  52  * frequently, to reduce the overhead of the function call.  It is still worth
  53  * using the macro for C++ functions which take no parameters since it allows
  54  * passing |this| in a register.
  55  *
  56  *  - Do not use this on any scriptable interface method since xptcall won't be
  57  *    aware of the different calling convention.
  58  *  - This must appear on the declaration, not the definition.
  59  *  - Adding this to a public function _will_ break binary compatibility.
  60  *  - This may be used on virtual functions but you must ensure it is applied
  61  *    to all implementations - the compiler will _not_ warn but it will crash.
  62  *  - This has no effect for functions which take a variable number of
  63  *    arguments.
  64  *  - __fastcall on windows should not be applied to class
  65  *    constructors/destructors - use the NS_CONSTRUCTOR_FASTCALL macro for
  66  *    constructors/destructors.
  67  *
  68  * Examples: int NS_FASTCALL func1(char *foo);
  69  *           NS_HIDDEN_(int) NS_FASTCALL func2(char *foo);
  70  */
  71
  72 #if defined(__i386__) && defined(__GNUC__)
  73 #  define NS_FASTCALL __attribute__((regparm(3), stdcall))
  74 #  define NS_CONSTRUCTOR_FASTCALL __attribute__((regparm(3), stdcall))
  75 #elif defined(XP_WIN) && !defined(_WIN64)
  76 #  define NS_FASTCALL __fastcall
  77 #  define NS_CONSTRUCTOR_FASTCALL
  78 #else
  79 #  define NS_FASTCALL
  80 #  define NS_CONSTRUCTOR_FASTCALL
  81 #endif
  82
  83 /**
  84  * Various API modifiers.
  85  *
  86  * - NS_IMETHOD/NS_IMETHOD_: use for in-class declarations and definitions.
  87  * - NS_IMETHODIMP/NS_IMETHODIMP_: use for out-of-class definitions.
  88  * - NS_METHOD_: usually used in conjunction with NS_CALLBACK_. Best avoided.
  89  * - NS_CALLBACK_: used in some legacy situations. Best avoided.
  90  */
  91
  92 #ifdef XP_WIN
  93
  94 #  define NS_IMPORT __declspec(dllimport)
  95 #  define NS_IMPORT_(type) __declspec(dllimport) type __stdcall
  96 #  define NS_EXPORT __declspec(dllexport)
  97 #  define NS_EXPORT_(type) __declspec(dllexport) type __stdcall
  98 #  define NS_IMETHOD_(type) virtual type __stdcall
  99 #  define NS_IMETHODIMP_(type) type __stdcall
 100 #  define NS_METHOD_(type) type __stdcall
 101 #  define NS_CALLBACK_(_type, _name) _type(__stdcall* _name)
 102 #  ifndef _WIN64
 103 // Win64 has only one calling convention.  __stdcall will be ignored by the
 104 // compiler.
 105 #    define NS_STDCALL __stdcall
 106 #    define NS_HAVE_STDCALL
 107 #  else
 108 #    define NS_STDCALL
 109 #  endif
 110 #  define NS_FROZENCALL __cdecl
 111
 112 #else
 113
 114 #  define NS_IMPORT NS_EXTERNAL_VIS
 115 #  define NS_IMPORT_(type) NS_EXTERNAL_VIS_(type)
 116 #  define NS_EXPORT NS_EXTERNAL_VIS
 117 #  define NS_EXPORT_(type) NS_EXTERNAL_VIS_(type)
 118 #  define NS_IMETHOD_(type) virtual type
 119 #  define NS_IMETHODIMP_(type) type
 120 #  define NS_METHOD_(type) type
 121 #  define NS_CALLBACK_(_type, _name) _type(*_name)
 122 #  define NS_STDCALL
 123 #  define NS_FROZENCALL
 124
 125 #endif
 126
 127 #define NS_IMETHOD NS_IMETHOD_(nsresult)
 128 #define NS_IMETHODIMP NS_IMETHODIMP_(nsresult)
 129
 130 /**
 131  * Import/Export macros for XPCOM APIs
 132  */
 133
 134 #define EXPORT_XPCOM_API(type) type
 135 #define IMPORT_XPCOM_API(type) type
 136 #define GLUE_XPCOM_API(type) type
 137
 138 #ifdef __cplusplus
 139 #  define NS_EXTERN_C extern "C"
 140 #else
 141 #  define NS_EXTERN_C
 142 #endif
 143
 144 #define XPCOM_API(type) NS_EXTERN_C type
 145
 146 /* If a program allocates memory for the lifetime of the app, it doesn't make
 147  * sense to touch memory pages and free that memory at shutdown,
 148  * unless we are running leak stats.
 149  *
 150  * Note that we're also setting this for code coverage and pgo profile
 151  * generation, because both of those require atexit hooks, which won't fire
 152  * if we're using _exit. Bug 1555974 covers improving this.
 153  *
 154  */
 155 #ifndef NS_FREE_PERMANENT_DATA
 156 #  if defined(NS_BUILD_REFCNT_LOGGING) || defined(MOZ_VALGRIND) ||            \
 157       defined(MOZ_ASAN) || defined(MOZ_TSAN) || defined(MOZ_CODE_COVERAGE) || \
 158       defined(MOZ_PROFILE_GENERATE) || defined(JS_STRUCTURED_SPEW)
 159 #    define NS_FREE_PERMANENT_DATA
 160 #  endif
 161 #endif
 162
 163 /**
 164  * NS_NO_VTABLE is emitted by xpidl in interface declarations whenever
 165  * xpidl can determine that the interface can't contain a constructor.
 166  * This results in some space savings and possible runtime savings -
 167  * see bug 49416.  We undefine it first, as xpidl-generated headers
 168  * define it for IDL uses that don't include this file.
 169  */
 170 #ifdef NS_NO_VTABLE
 171 #  undef NS_NO_VTABLE
 172 #endif
 173 #if defined(_MSC_VER)
 174 #  define NS_NO_VTABLE __declspec(novtable)
 175 #else
 176 #  define NS_NO_VTABLE
 177 #endif
 178
 179 /**
 180  * Generic XPCOM result data type
 181  */
 182 #include "nsError.h"  // IWYU pragma: export
 183
 184 typedef MozRefCountType nsrefcnt;
 185
 186 namespace mozilla {
 187 // Extensions to the mozilla::Result type for handling of nsresult values.
 188 //
 189 // Note that these specializations need to be defined before Result.h is
 190 // included, or we run into explicit specialization after instantiation errors,
 191 // especially if Result.h is used in multiple sources in a unified compile.
 192
 193 namespace detail {
 194 // When used as an error value, nsresult should never be NS_OK.
 195 // This specialization allows us to pack Result<Ok, nsresult> into a
 196 // nsresult-sized value.
 197 template <typename T>
 198 struct UnusedZero;
 199 template <>
 200 struct UnusedZero<nsresult> {
 201   using StorageType = nsresult;
 202
 203   static constexpr bool value = true;
 204   static constexpr StorageType nullValue = NS_OK;
 205
 206   static constexpr void AssertValid(StorageType aValue) {}
 207   static constexpr const nsresult& Inspect(const StorageType& aValue) {
 208     return aValue;
 209   }
 210   static constexpr nsresult Unwrap(StorageType aValue) { return aValue; }
 211   static constexpr StorageType Store(nsresult aValue) { return aValue; }
 212 };
 213 }  // namespace detail
 214
 215 template <typename T>
 216 class GenericErrorResult;
 217 template <>
 218 class GenericErrorResult<nsresult>;
 219
 220 struct Ok;
 221 template <typename V, typename E>
 222 class Result;
 223
 224 // Allow MOZ_TRY to handle `nsresult` values.
 225 template <typename E = nsresult>
 226 inline Result<Ok, E> ToResult(nsresult aValue);
 227 }  // namespace mozilla
 228
 229 /*
 230  * Use these macros to do 64bit safe pointer conversions.
 231  */
 232
 233 #define NS_PTR_TO_INT32(x) ((int32_t)(intptr_t)(x))
 234 #define NS_PTR_TO_UINT32(x) ((uint32_t)(intptr_t)(x))
 235 #define NS_INT32_TO_PTR(x) ((void*)(intptr_t)(x))
 236
 237 /*
 238  * If we're being linked as standalone glue, we don't want a dynamic
 239  * dependency on NSPR libs, so we skip the debug thread-safety
 240  * checks, and we cannot use the THREADSAFE_ISUPPORTS macros.
 241  */
 242 #if defined(XPCOM_GLUE) && !defined(XPCOM_GLUE_USE_NSPR)
 243 #  define XPCOM_GLUE_AVOID_NSPR
 244 #endif
 245
 246 /*
 247  * SEH exception macros.
 248  */
 249 #ifdef HAVE_SEH_EXCEPTIONS
 250 #  define MOZ_SEH_TRY __try
 251 #  define MOZ_SEH_EXCEPT(expr) __except (expr)
 252 #else
 253 #  define MOZ_SEH_TRY if (true)
 254 #  define MOZ_SEH_EXCEPT(expr) else
 255 #endif
 256
 257 #endif /* nscore_h___ */