[PATCH] add offset argument to mmap

[Christopher Li]

I am surprised to find out the mmap module in python always
mmap from offset 0. So I just hack up some patch to allow it
accept offset arguments.

So here it is.

Chris
Add optional offset argument to mmap module.

Test on linux with Python 2.4.
The windows code is totally untested.

Signed-Off-by: Christopher Li <py****@chrisli .org>

Index: Modules/mmapmodule.c
=============== =============== =============== =============== =======
--- Modules.orig/mmapmodule.c 2004-05-19 10:39:08.000000 000 -0400
+++ Modules/mmapmodule.c 2005-05-26 10:01:51.000000 000 -0400
@@ -853,14 +853,17 @@
mmap_object *m_obj;
PyObject *map_size_obj = NULL;
int map_size;
+ unsigned long offset = 0;
int fd, flags = MAP_SHARED, prot = PROT_WRITE | PROT_READ;
access_mode access = ACCESS_DEFAULT;
char *keywords[] = {"fileno", "length",
"flags", "prot",
- "access", NULL};
+ "access", "offset",
+ NULL};

- if (!PyArg_ParseTu pleAndKeywords( args, kwdict, "iO|iii", keywords,
- &fd, &map_size_ob j, &flags, &prot, &access))
+ if (!PyArg_ParseTu pleAndKeywords( args, kwdict, "iO|iiil", keywords,
+ &fd, &map_size_ob j, &flags, &prot,
+ &access, &offset))
return NULL;
map_size = _GetMapSize(map _size_obj);
if (map_size < 0)
@@ -910,7 +913,7 @@
m_obj->fd = fd;
m_obj->data = mmap(NULL, map_size,
prot, flags,
- fd, 0);
+ fd, offset);
if (m_obj->data == (char *)-1) {
m_obj->data = NULL;
Py_DECREF(m_obj );
@@ -929,6 +932,7 @@
mmap_object *m_obj;
PyObject *map_size_obj = NULL;
int map_size;
+ unsigned long offset = 0;
char *tagname = "";
DWORD dwErr = 0;
int fileno;
@@ -939,9 +943,9 @@
"tagname",
"access", NULL };

- if (!PyArg_ParseTu pleAndKeywords( args, kwdict, "iO|zi", keywords,
+ if (!PyArg_ParseTu pleAndKeywords( args, kwdict, "iO|zil", keywords,
&fileno, &map_size_ob j,
- &tagname, &access)) {
+ &tagname, &access, &offset)) {
return NULL;
}

@@ -1040,8 +1044,8 @@
if (m_obj->map_handle != NULL) {
m_obj->data = (char *) MapViewOfFile (m_obj->map_handle,
dwDesiredAccess ,
- 0,
- 0,
+ offset>>32,
+ (unsigned int)offset,
0);
if (m_obj->data != NULL) {
return ((PyObject *) m_obj);