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97 lines
3.3 KiB
C
97 lines
3.3 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef replace_malloc_h
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#define replace_malloc_h
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// The replace_malloc facility allows an external library to replace or
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// supplement the jemalloc implementation.
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//
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// The external library may be hooked by setting one of the following
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// environment variables to the library path:
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// - LD_PRELOAD on Linux,
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// - DYLD_INSERT_LIBRARIES on OSX,
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// - MOZ_REPLACE_MALLOC_LIB on Windows and Android.
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//
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// An initialization function is called before any malloc replacement
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// function, and has the following declaration:
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//
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// void replace_init(const malloc_table_t *)
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//
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// The const malloc_table_t pointer given to that function is a table
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// containing pointers to the original jemalloc implementation, so that
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// replacement functions can call them back if they need to. The pointer
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// itself can safely be kept around (no need to copy the table itself).
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//
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// The functions to be implemented in the external library are of the form:
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//
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// void *replace_malloc(size_t size)
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// {
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// // Fiddle with the size if necessary.
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// // orig->malloc doesn't have to be called if the external library
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// // provides its own allocator, but in this case it will have to
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// // implement all functions.
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// void *ptr = orig->malloc(size);
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// // Do whatever you want with the ptr.
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// return ptr;
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// }
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//
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// where "orig" is the pointer obtained from replace_init.
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//
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// See malloc_decls.h for a list of functions that can be replaced this
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// way. The implementations are all in the form:
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// return_type replace_name(arguments [,...])
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//
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// They don't all need to be provided.
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//
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// Building a replace-malloc library is like rocket science. It can end up
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// with things blowing up, especially when trying to use complex types, and
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// even more especially when these types come from XPCOM or other parts of the
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// Mozilla codebase.
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// It is recommended to add the following to a replace-malloc implementation's
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// moz.build:
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// DISABLE_STL_WRAPPING = True # Avoid STL wrapping
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//
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// If your replace-malloc implementation lives under memory/replace, these
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// are taken care of by memory/replace/defs.mk.
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#ifdef replace_malloc_bridge_h
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#error Do not include replace_malloc_bridge.h before replace_malloc.h. \
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In fact, you only need the latter.
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#endif
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#define REPLACE_MALLOC_IMPL
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#include "replace_malloc_bridge.h"
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// Implementing a replace-malloc library is incompatible with using mozalloc.
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#define MOZ_NO_MOZALLOC 1
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#include "mozilla/Types.h"
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MOZ_BEGIN_EXTERN_C
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// MOZ_NO_REPLACE_FUNC_DECL and MOZ_REPLACE_WEAK are only defined in
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// replace_malloc.c. Normally including this header will add function
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// definitions.
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#ifndef MOZ_NO_REPLACE_FUNC_DECL
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#ifndef MOZ_REPLACE_WEAK
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#define MOZ_REPLACE_WEAK
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#endif
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#define MALLOC_DECL(name, return_type, ...) \
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MOZ_EXPORT return_type replace_##name(__VA_ARGS__) MOZ_REPLACE_WEAK;
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#define MALLOC_FUNCS MALLOC_FUNCS_ALL
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#include "malloc_decls.h"
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#endif // MOZ_NO_REPLACE_FUNC_DECL
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MOZ_END_EXTERN_C
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#endif // replace_malloc_h
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