1 files changed, 133 insertions, 0 deletions
diff --git a/memory/build/replace_malloc.h b/memory/build/replace_malloc.h
new file mode 100644
index 000000000..a61744f60
--- /dev/null
+++ b/memory/build/replace_malloc.h
@@ -0,0 +1,133 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef replace_malloc_h
+#define replace_malloc_h
+
+/*
+ * The replace_malloc facility allows an external library to replace or
+ * supplement the jemalloc implementation.
+ *
+ * The external library may be hooked by setting one of the following
+ * environment variables to the library path:
+ *   - LD_PRELOAD on Linux,
+ *   - DYLD_INSERT_LIBRARIES on OSX,
+ *   - MOZ_REPLACE_MALLOC_LIB on Windows and Android.
+ *
+ * An initialization function is called before any malloc replacement
+ * function, and has the following declaration:
+ *
+ *   void replace_init(const malloc_table_t *)
+ *
+ * The const malloc_table_t pointer given to that function is a table
+ * containing pointers to the original jemalloc implementation, so that
+ * replacement functions can call them back if they need to. The pointer
+ * itself can safely be kept around (no need to copy the table itself).
+ *
+ * The functions to be implemented in the external library are of the form:
+ *
+ *   void *replace_malloc(size_t size)
+ *   {
+ *     // Fiddle with the size if necessary.
+ *     // orig->malloc doesn't have to be called if the external library
+ *     // provides its own allocator, but in this case it will have to
+ *     // implement all functions.
+ *     void *ptr = orig->malloc(size);
+ *     // Do whatever you want with the ptr.
+ *     return ptr;
+ *   }
+ *
+ * where "orig" is the pointer obtained from replace_init.
+ *
+ * See malloc_decls.h for a list of functions that can be replaced this
+ * way. The implementations are all in the form:
+ *   return_type replace_name(arguments [,...])
+ *
+ * They don't all need to be provided.
+ *
+ * Building a replace-malloc library is like rocket science. It can end up
+ * with things blowing up, especially when trying to use complex types, and
+ * even more especially when these types come from XPCOM or other parts of the
+ * Mozilla codebase.
+ * It is recommended to add the following to a replace-malloc implementation's
+ * moz.build:
+ *   DISABLE_STL_WRAPPING = True # Avoid STL wrapping
+ *
+ * If your replace-malloc implementation lives under memory/replace, these
+ * are taken care of by memory/replace/defs.mk.
+ */
+
+#ifdef replace_malloc_bridge_h
+#error Do not include replace_malloc_bridge.h before replace_malloc.h. \
+  In fact, you only need the latter.
+#endif
+
+#define REPLACE_MALLOC_IMPL
+
+#include "replace_malloc_bridge.h"
+
+/* Implementing a replace-malloc library is incompatible with using mozalloc. */
+#define MOZ_NO_MOZALLOC 1
+
+#include "mozilla/Types.h"
+
+MOZ_BEGIN_EXTERN_C
+
+/* MOZ_NO_REPLACE_FUNC_DECL and MOZ_REPLACE_WEAK are only defined in
+ * replace_malloc.c. Normally including this header will add function
+ * definitions. */
+#ifndef MOZ_NO_REPLACE_FUNC_DECL
+
+#  ifndef MOZ_REPLACE_WEAK
+#    define MOZ_REPLACE_WEAK
+#  endif
+
+#  define MALLOC_DECL(name, return_type, ...) \
+    MOZ_EXPORT return_type replace_ ## name(__VA_ARGS__) MOZ_REPLACE_WEAK;
+
+#  define MALLOC_FUNCS MALLOC_FUNCS_ALL
+#  include "malloc_decls.h"
+
+#endif /* MOZ_NO_REPLACE_FUNC_DECL */
+
+/*
+ * posix_memalign, aligned_alloc, memalign and valloc all implement some
+ * kind of aligned memory allocation. For convenience, replace_posix_memalign,
+ * replace_aligned_alloc and replace_valloc can be automatically derived from
+ * memalign when MOZ_REPLACE_ONLY_MEMALIGN is defined before including this
+ * header. PAGE_SIZE also needs to be defined to the appropriate expression.
+ */
+#ifdef MOZ_REPLACE_ONLY_MEMALIGN
+#include <errno.h>
+
+int replace_posix_memalign(void **ptr, size_t alignment, size_t size)
+{
+  if (size == 0) {
+    *ptr = NULL;
+    return 0;
+  }
+  /* alignment must be a power of two and a multiple of sizeof(void *) */
+  if (((alignment - 1) & alignment) != 0 || (alignment % sizeof(void *)))
+    return EINVAL;
+  *ptr = replace_memalign(alignment, size);
+  return *ptr ? 0 : ENOMEM;
+}
+
+void *replace_aligned_alloc(size_t alignment, size_t size)
+{
+  /* size should be a multiple of alignment */
+  if (size % alignment)
+    return NULL;
+  return replace_memalign(alignment, size);
+}
+
+void *replace_valloc(size_t size)
+{
+  return replace_memalign(PAGE_SIZE, size);
+}
+#endif
+
+MOZ_END_EXTERN_C
+
+#endif /* replace_malloc_h */