memory: add uv_replace_allocator

With uv_replace_allocator, it's possible to override the default
memory allocator's malloc and free calls with functions of the user's
choosing. This allows libuv to interoperate with projects requiring a
custom memory allocator.

Internally, all calls to malloc and free have been replaced with
uv__malloc and uv__free, respectively. The uv__malloc and uv__free
functions call malloc and free unless they have been overridden by a
previous call to uv_replace_allocator.

As part of this change, the special aligned memory allocations
performed in src/win/fs-event.c have been replaced with standard
allocations. The 4-byte alignment being requested in this file was
unnecessary, since standard allocators already guarantee at least an
8-byte alignment.

PR-URL: https://github.com/libuv/libuv/pull/231
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

1 files changed, 21 insertions, 1 deletions

diff --git a/docs/src/misc.rst b/docs/src/misc.rst
index c096fd09..aa3ab6ab 100644
--- a/docs/src/misc.rst
+++ b/docs/src/misc.rst
@@ -15,6 +15,16 @@ Data types
 
     Buffer data type.
 
+.. c:type:: uv_malloc_func
+
+    Function pointer type for the malloc override used by
+    :c:func:`uv_replace_allocator`.
+
+.. c:type:: uv_free_func
+
+    Function pointer type for the free override used by
+    :c:func:`uv_replace_allocator`.
+
 .. c:type:: uv_file
 
     Cross platform representation of a file handle.
@@ -26,7 +36,7 @@ Data types
 .. c:type:: uv_os_fd_t
 
     Abstract representation of a file descriptor. On Unix systems this is a
-    `typedef` of `int` and on Windows fa `HANDLE`.
+    `typedef` of `int` and on Windows a `HANDLE`.
 
 .. c:type:: uv_rusage_t
 
@@ -115,6 +125,16 @@ API
     Returns the libuv version number as a string. For non-release versions
     "-pre" is appended, so the version number could be "1.2.3-pre".
 
+.. c:function:: int uv_replace_allocator(uv_malloc_func malloc_func, uv_free_func free_func)
+
+    .. versionadded:: 1.5.0
+
+    Override the use of the standard library's malloc and free functions for
+    memory allocation. If used, this function must be called before any
+    other libuv function is called. On success, it returns 0. If called more
+    than once, the replacement request is ignored and the function returns
+    ``UV_EINVAL``.
+
 .. c:function:: uv_buf_t uv_buf_init(char* base, unsigned int len)
 
     Constructor for :c:type:`uv_buf_t`.