The Tor Browser: mfbt/Types.h@97036ab72558

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

     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/. */

     7 /* mfbt foundational types and macros. */

     9 #ifndef mozilla_Types_h

    10 #define mozilla_Types_h

    12 /*

    13  * This header must be valid C and C++, includable by code embedding either

    14  * SpiderMonkey or Gecko.

    15  */

    17 /* Expose all <stdint.h> types and size_t. */

    18 #include <stddef.h>

    19 #include <stdint.h>

    21 /* Implement compiler and linker macros needed for APIs. */

    23 /*

    24  * MOZ_EXPORT is used to declare and define a symbol or type which is externally

    25  * visible to users of the current library.  It encapsulates various decorations

    26  * needed to properly export the method's symbol.

    27  *

    28  *   api.h:

    29  *     extern MOZ_EXPORT int MeaningOfLife(void);

    30  *     extern MOZ_EXPORT int LuggageCombination;

    31  *

    32  *   api.c:

    33  *     int MeaningOfLife(void) { return 42; }

    34  *     int LuggageCombination = 12345;

    35  *

    36  * If you are merely sharing a method across files, just use plain |extern|.

    37  * These macros are designed for use by library interfaces -- not for normal

    38  * methods or data used cross-file.

    39  */

    40 #if defined(WIN32)

    41 #  define MOZ_EXPORT   __declspec(dllexport)

    42 #else /* Unix */

    43 #  ifdef HAVE_VISIBILITY_ATTRIBUTE

    44 #    define MOZ_EXPORT       __attribute__((visibility("default")))

    45 #  elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)

    46 #    define MOZ_EXPORT      __global

    47 #  else

    48 #    define MOZ_EXPORT /* nothing */

    49 #  endif

    50 #endif

    53 /*

    54  * Whereas implementers use MOZ_EXPORT to declare and define library symbols,

    55  * users use MOZ_IMPORT_API and MOZ_IMPORT_DATA to access them.  Most often the

    56  * implementer of the library will expose an API macro which expands to either

    57  * the export or import version of the macro, depending upon the compilation

    58  * mode.

    59  */

    60 #ifdef _WIN32

    61 #  if defined(__MWERKS__)

    62 #    define MOZ_IMPORT_API /* nothing */

    63 #  else

    64 #    define MOZ_IMPORT_API __declspec(dllimport)

    65 #  endif

    66 #else

    67 #  define MOZ_IMPORT_API MOZ_EXPORT

    68 #endif

    70 #if defined(_WIN32) && !defined(__MWERKS__)

    71 #  define MOZ_IMPORT_DATA  __declspec(dllimport)

    72 #else

    73 #  define MOZ_IMPORT_DATA  MOZ_EXPORT

    74 #endif

    76 /*

    77  * Consistent with the above comment, the MFBT_API and MFBT_DATA macros expose

    78  * export mfbt declarations when building mfbt, and they expose import mfbt

    79  * declarations when using mfbt.

    80  */

    81 #if defined(IMPL_MFBT)

    82 #  define MFBT_API     MOZ_EXPORT

    83 #  define MFBT_DATA    MOZ_EXPORT

    84 #else

    85   /*

    86    * On linux mozglue is linked in the program and we link libxul.so with

    87    * -z,defs. Normally that causes the linker to reject undefined references in

    88    * libxul.so, but as a loophole it allows undefined references to weak

    89    * symbols. We add the weak attribute to the import version of the MFBT API

    90    * macros to exploit this.

    91    */

    92 #  if defined(MOZ_GLUE_IN_PROGRAM)

    93 #    define MFBT_API   __attribute__((weak)) MOZ_IMPORT_API

    94 #    define MFBT_DATA  __attribute__((weak)) MOZ_IMPORT_DATA

    95 #  else

    96 #    define MFBT_API   MOZ_IMPORT_API

    97 #    define MFBT_DATA  MOZ_IMPORT_DATA

    98 #  endif

    99 #endif

   101 /*

   102  * C symbols in C++ code must be declared immediately within |extern "C"|

   103  * blocks.  However, in C code, they need not be declared specially.  This

   104  * difference is abstracted behind the MOZ_BEGIN_EXTERN_C and MOZ_END_EXTERN_C

   105  * macros, so that the user need not know whether he is being used in C or C++

   106  * code.

   107  *

   108  *   MOZ_BEGIN_EXTERN_C

   109  *

   110  *   extern MOZ_EXPORT int MostRandomNumber(void);

   111  *   ...other declarations...

   112  *

   113  *   MOZ_END_EXTERN_C

   114  *

   115  * This said, it is preferable to just use |extern "C"| in C++ header files for

   116  * its greater clarity.

   117  */

   118 #ifdef __cplusplus

   119 #  define MOZ_BEGIN_EXTERN_C    extern "C" {

   120 #  define MOZ_END_EXTERN_C      }

   121 #else

   122 #  define MOZ_BEGIN_EXTERN_C

   123 #  define MOZ_END_EXTERN_C

   124 #endif

   126 /*

   127  * GCC's typeof is available when decltype is not.

   128  */

   129 #if defined(__GNUC__) && defined(__cplusplus) && \

   130   !defined(__GXX_EXPERIMENTAL_CXX0X__) && __cplusplus < 201103L

   131 #  define decltype __typeof__

   132 #endif

   134 #endif /* mozilla_Types_h */

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mfbt/Types.h@97036ab72558

mfbt/Types.h