Index: Modules/mmapmodule.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Modules/mmapmodule.c,v
retrieving revision 2.43
diff -c -r2.43 mmapmodule.c
*** Modules/mmapmodule.c	7 Feb 2003 19:44:56 -0000	2.43
--- Modules/mmapmodule.c	23 Mar 2003 14:16:43 -0000
***************
*** 3,8 ****
--- 3,11 ----
   /  Hacked for Unix by AMK
   /  $Id: mmapmodule.c,v 2.43 2003/02/07 19:44:56 nnorwitz Exp $
  
+  / Modified to support mmap with offset - to map a 'window' fo a file
+  /   Author:  Yotam Medini  yotamm@mellanox.co.il
+  /
   / mmapmodule.cpp -- map a view of a file into memory
   /
   / todo: need permission flags, perhaps a 'chsize' analog
***************
*** 73,79 ****
  	PyObject_HEAD
  	char *	data;
  	size_t	size;
! 	size_t	pos;
  
  #ifdef MS_WINDOWS
  	HANDLE	map_handle;
--- 76,83 ----
  	PyObject_HEAD
  	char *	data;
  	size_t	size;
! 	size_t	pos;    /* relative to offset */
! 	size_t	offset; /* always 0 for MS_WINDOWS */
  
  #ifdef MS_WINDOWS
  	HANDLE	map_handle;
***************
*** 261,267 ****
  			if (i == len) {
  				return Py_BuildValue (
  					"l",
! 					(long) (p - self->data));
  			}
  		}
  		return Py_BuildValue ("l", (long) -1);
--- 265,271 ----
  			if (i == len) {
  				return Py_BuildValue (
  					"l",
!                                        (long)(self->offset + (p - self->data)));
  			}
  		}
  		return Py_BuildValue ("l", (long) -1);
***************
*** 453,459 ****
  	CHECK_VALID(NULL);
          if (!PyArg_ParseTuple(args, ":tell"))
  		return NULL;
! 	return (Py_BuildValue ("l", (long) self->pos) );
  }
  
  static PyObject *
--- 457,463 ----
  	CHECK_VALID(NULL);
          if (!PyArg_ParseTuple(args, ":tell"))
  		return NULL;
! 	return (Py_BuildValue ("l", (long) (self->offset + self->pos)) );
  }
  
  static PyObject *
***************
*** 499,504 ****
--- 503,509 ----
  		size_t where;
  		switch (how) {
  		case 0: /* relative to start */
+ 			dist -= self->offset;
  			if (dist < 0)
  				goto onoutofrange;
  			where = dist;
***************
*** 539,544 ****
--- 544,551 ----
  	    !is_writeable(self)) {
  		return NULL;
  	} else {
+ 		dest -= self->offset;
+ 		src  -= self->offset;
  		/* bounds check the values */
  		if (/* end of source after end of data?? */
  			((src+count) > self->size)
***************
*** 857,875 ****
  #endif
  	mmap_object *m_obj;
  	PyObject *map_size_obj = NULL;
  	int map_size;
  	int fd, flags = MAP_SHARED, prot = PROT_WRITE | PROT_READ;
  	access_mode access = ACCESS_DEFAULT;
  	char *keywords[] = {"fileno", "length", 
  			    "flags", "prot", 
! 			    "access", NULL};
  
! 	if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iO|iii", keywords, 
! 					 &fd, &map_size_obj, &flags, &prot, &access))
  		return NULL;
  	map_size = _GetMapSize(map_size_obj);
  	if (map_size < 0)
  		return NULL;
  
  	if ((access != ACCESS_DEFAULT) && 
  	    ((flags != MAP_SHARED) || ( prot != (PROT_WRITE | PROT_READ))))
--- 864,896 ----
  #endif
  	mmap_object *m_obj;
  	PyObject *map_size_obj = NULL;
+ 	PyObject *map_offset_obj = NULL;
  	int map_size;
  	int fd, flags = MAP_SHARED, prot = PROT_WRITE | PROT_READ;
  	access_mode access = ACCESS_DEFAULT;
+ 	off_t offset = 0;
  	char *keywords[] = {"fileno", "length", 
  			    "flags", "prot", 
! 			    "access", "offset", NULL};
  
! 	if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iO|iiiO", keywords, 
! 					 &fd, &map_size_obj, &flags, &prot, 
!                                          &access, &map_offset_obj))
  		return NULL;
  	map_size = _GetMapSize(map_size_obj);
  	if (map_size < 0)
  		return NULL;
+         if (map_offset_obj)
+         {
+ 		int tmp_offset = PyInt_AsLong(map_offset_obj);
+ 		if (tmp_offset < 0) {
+ 			if (!PyErr_Occurred())
+ 				PyErr_SetString(PyExc_ValueError,
+ 		    		    "offset must be a non-negative integer");
+ 			return NULL;
+ 		}
+ 		offset = (off_t) tmp_offset;
+         }
  
  	if ((access != ACCESS_DEFAULT) && 
  	    ((flags != MAP_SHARED) || ( prot != (PROT_WRITE | PROT_READ))))
***************
*** 897,903 ****
  	}
  
  #ifdef HAVE_FSTAT
! 	if (fstat(fd, &st) == 0 && (size_t)map_size > st.st_size) {
  		PyErr_SetString(PyExc_ValueError, 
  				"mmap length is greater than file size");
  		return NULL;
--- 918,927 ----
  	}
  
  #ifdef HAVE_FSTAT
! 	if (fstat(fd, &st) == 0 && 
!             !S_ISCHR(st.st_mode) && 
!             offset + (size_t)map_size > st.st_size) 
!         {
  		PyErr_SetString(PyExc_ValueError, 
  				"mmap length is greater than file size");
  		return NULL;
***************
*** 907,916 ****
  	if (m_obj == NULL) {return NULL;}
  	m_obj->size = (size_t) map_size;
  	m_obj->pos = (size_t) 0;
  	m_obj->fd = fd;
  	m_obj->data = mmap(NULL, map_size, 
  			   prot, flags,
! 			   fd, 0);
  	if (m_obj->data == (char *)-1) {
  		Py_DECREF(m_obj);
  		PyErr_SetFromErrno(mmap_module_error);
--- 931,941 ----
  	if (m_obj == NULL) {return NULL;}
  	m_obj->size = (size_t) map_size;
  	m_obj->pos = (size_t) 0;
+ 	m_obj->offset = offset;
  	m_obj->fd = fd;
  	m_obj->data = mmap(NULL, map_size, 
  			   prot, flags,
! 			   fd, offset);
  	if (m_obj->data == (char *)-1) {
  		Py_DECREF(m_obj);
  		PyErr_SetFromErrno(mmap_module_error);
***************
*** 986,991 ****
--- 1011,1017 ----
  	m_obj->file_handle = INVALID_HANDLE_VALUE;
  	m_obj->map_handle = INVALID_HANDLE_VALUE;
  	m_obj->tagname = NULL;
+ 	m_obj->offset = 0;
  
  	if (fh) {
  		/* It is necessary to duplicate the handle, so the
Index: Lib/test/test_mmap.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/test/test_mmap.py,v
retrieving revision 1.30
diff -c -r1.30 test_mmap.py
*** Lib/test/test_mmap.py	13 Jan 2003 21:38:45 -0000	1.30
--- Lib/test/test_mmap.py	23 Mar 2003 14:16:44 -0000
***************
*** 267,272 ****
--- 267,283 ----
              else:
                  verify(0, "Incompatible parameters should raise ValueError.")
              f.close()
+ 
+             # Try invalid offset
+             f = open(TESTFN, "r+b")
+             for offset in [-2, -1, None]:
+                 try:
+                     m = mmap.mmap(f.fileno(), mapsize, offset=offset)
+                 except (ValueError, TypeError):
+                     pass
+                 else:
+                     verify(0, "Invalid offset should raise ValueError.")
+             f.close()
      finally:
          try:
              os.unlink(TESTFN)
Index: Doc/lib/libmmap.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libmmap.tex,v
retrieving revision 1.8
diff -c -r1.8 libmmap.tex
*** Doc/lib/libmmap.tex	3 Dec 2001 18:27:22 -0000	1.8
--- Doc/lib/libmmap.tex	23 Mar 2003 14:16:44 -0000
***************
*** 57,63 ****
  \end{funcdesc}
  
  \begin{funcdescni}{mmap}{fileno, length\optional{, flags\optional{,
!                          prot\optional{, access}}}}
    \strong{(\UNIX{} version)} Maps \var{length} bytes from the file
    specified by the file descriptor \var{fileno}, and returns a mmap
    object.
--- 57,63 ----
  \end{funcdesc}
  
  \begin{funcdescni}{mmap}{fileno, length\optional{, flags\optional{,
!                          prot\optional{, access\optional{, offset}}}}
    \strong{(\UNIX{} version)} Maps \var{length} bytes from the file
    specified by the file descriptor \var{fileno}, and returns a mmap
    object.
***************
*** 78,83 ****
--- 78,88 ----
    as an optional keyword parameter.  It is an error to specify both
    \var{flags}, \var{prot} and \var{access}.  See the description of
    \var{access} above for information on how to use this parameter.
+ 
+   \var{offset} may be specified as a non-negative integer offset.
+   mmap references will be relative to the offset from the beginning
+   of the file.
+ \versionchanged[The offset parameter was added]{2.3}
  \end{funcdescni}