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comparison: memory/build/replace_malloc.h
memory/build/replace_malloc.h
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| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 3 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 #ifndef replace_malloc_h | |
| 6 #define replace_malloc_h | |
| 7 | |
| 8 /* | |
| 9 * The replace_malloc facility allows an external library to replace or | |
| 10 * supplement the jemalloc implementation. | |
| 11 * | |
| 12 * The external library may be hooked by setting one of the following | |
| 13 * environment variables to the library path: | |
| 14 * - LD_PRELOAD on Linux, | |
| 15 * - DYLD_INSERT_LIBRARIES on OSX, | |
| 16 * - MOZ_REPLACE_MALLOC_LIB on Windows and Android. | |
| 17 * | |
| 18 * An initialization function is called before any malloc replacement | |
| 19 * function, and has the following declaration: | |
| 20 * | |
| 21 * void replace_init(const malloc_table_t *) | |
| 22 * | |
| 23 * The const malloc_table_t pointer given to that function is a table | |
| 24 * containing pointers to the original jemalloc implementation, so that | |
| 25 * replacement functions can call them back if they need to. The pointer | |
| 26 * itself can safely be kept around (no need to copy the table itself). | |
| 27 * | |
| 28 * The functions to be implemented in the external library are of the form: | |
| 29 * | |
| 30 * void *replace_malloc(size_t size) | |
| 31 * { | |
| 32 * // Fiddle with the size if necessary. | |
| 33 * // orig->malloc doesn't have to be called if the external library | |
| 34 * // provides its own allocator, but in this case it will have to | |
| 35 * // implement all functions. | |
| 36 * void *ptr = orig->malloc(size); | |
| 37 * // Do whatever you want with the ptr. | |
| 38 * return ptr; | |
| 39 * } | |
| 40 * | |
| 41 * where "orig" is the pointer obtained from replace_init. | |
| 42 * | |
| 43 * See malloc_decls.h for a list of functions that can be replaced this | |
| 44 * way. The implementations are all in the form: | |
| 45 * return_type replace_name(arguments [,...]) | |
| 46 * | |
| 47 * They don't all need to be provided. | |
| 48 * | |
| 49 * Building a replace-malloc library is like rocket science. It can end up | |
| 50 * with things blowing up, especially when trying to use complex types, and | |
| 51 * even more especially when these types come from XPCOM or other parts of the | |
| 52 * Mozilla codebase. | |
| 53 * It is recommended to add the following to a replace-malloc implementation's | |
| 54 * Makefile.in: | |
| 55 * MOZ_GLUE_LDFLAGS = # Don't link against mozglue | |
| 56 * WRAP_LDFLAGS = # Never wrap malloc function calls with -Wl,--wrap | |
| 57 * and the following to the implementation's moz.build: | |
| 58 * DISABLE_STL_WRAPPING = True # Avoid STL wrapping | |
| 59 * | |
| 60 * If your replace-malloc implementation lives under memory/replace, these | |
| 61 * are taken care of by memory/replace/defs.mk. | |
| 62 */ | |
| 63 | |
| 64 /* Implementing a replace-malloc library is incompatible with using mozalloc. */ | |
| 65 #define MOZ_NO_MOZALLOC 1 | |
| 66 | |
| 67 #include "mozilla/Types.h" | |
| 68 | |
| 69 MOZ_BEGIN_EXTERN_C | |
| 70 | |
| 71 #define MALLOC_DECL(name, return_type, ...) \ | |
| 72 typedef return_type(name ## _impl_t)(__VA_ARGS__); | |
| 73 | |
| 74 #include "malloc_decls.h" | |
| 75 | |
| 76 #define MALLOC_DECL(name, return_type, ...) \ | |
| 77 name ## _impl_t * name; | |
| 78 | |
| 79 typedef struct { | |
| 80 #include "malloc_decls.h" | |
| 81 } malloc_table_t; | |
| 82 | |
| 83 | |
| 84 /* MOZ_NO_REPLACE_FUNC_DECL and MOZ_REPLACE_WEAK are only defined in | |
| 85 * replace_malloc.c. Normally including this header will add function | |
| 86 * definitions. */ | |
| 87 #ifndef MOZ_NO_REPLACE_FUNC_DECL | |
| 88 | |
| 89 # ifndef MOZ_REPLACE_WEAK | |
| 90 # define MOZ_REPLACE_WEAK | |
| 91 # endif | |
| 92 | |
| 93 # define MALLOC_DECL(name, return_type, ...) \ | |
| 94 MOZ_EXPORT return_type replace_ ## name(__VA_ARGS__) MOZ_REPLACE_WEAK; | |
| 95 | |
| 96 # define MALLOC_FUNCS MALLOC_FUNCS_ALL | |
| 97 # include "malloc_decls.h" | |
| 98 | |
| 99 #endif /* MOZ_NO_REPLACE_FUNC_DECL */ | |
| 100 | |
| 101 /* | |
| 102 * posix_memalign, aligned_alloc, memalign and valloc all implement some | |
| 103 * kind of aligned memory allocation. For convenience, replace_posix_memalign, | |
| 104 * replace_aligned_alloc and replace_valloc can be automatically derived from | |
| 105 * memalign when MOZ_REPLACE_ONLY_MEMALIGN is defined before including this | |
| 106 * header. PAGE_SIZE also needs to be defined to the appropriate expression. | |
| 107 */ | |
| 108 #ifdef MOZ_REPLACE_ONLY_MEMALIGN | |
| 109 #include <errno.h> | |
| 110 | |
| 111 int replace_posix_memalign(void **ptr, size_t alignment, size_t size) | |
| 112 { | |
| 113 if (size == 0) { | |
| 114 *ptr = NULL; | |
| 115 return 0; | |
| 116 } | |
| 117 /* alignment must be a power of two and a multiple of sizeof(void *) */ | |
| 118 if (((alignment - 1) & alignment) != 0 || (alignment % sizeof(void *))) | |
| 119 return EINVAL; | |
| 120 *ptr = replace_memalign(alignment, size); | |
| 121 return *ptr ? 0 : ENOMEM; | |
| 122 } | |
| 123 | |
| 124 void *replace_aligned_alloc(size_t alignment, size_t size) | |
| 125 { | |
| 126 /* size should be a multiple of alignment */ | |
| 127 if (size % alignment) | |
| 128 return NULL; | |
| 129 return replace_memalign(alignment, size); | |
| 130 } | |
| 131 | |
| 132 void *replace_valloc(size_t size) | |
| 133 { | |
| 134 return replace_memalign(PAGE_SIZE, size); | |
| 135 } | |
| 136 #endif | |
| 137 | |
| 138 MOZ_END_EXTERN_C | |
| 139 | |
| 140 #endif /* replace_malloc_h */ |
