exception. Assignment to an \constant{ACCESS_WRITE} memory map
affects both memory and the underlying file. Assignment to an
\constant{ACCESS_COPY} memory map affects memory but does not update
-the underlying file.
+the underlying file. \versionchanged[To map anonymous memory,
+-1 should be passed as the fileno along with the length]{2.5}
\begin{funcdesc}{mmap}{fileno, length\optional{, tagname\optional{, access}}}
\strong{(Windows version)} Maps \var{length} bytes from the file
#include <string.h>
#include <sys/types.h>
+/* maybe define MAP_ANON in terms of MAP_ANONYMOUS */
+#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
+# define MAP_ANONYMOUS MAP_ANON
+#endif
+
static PyObject *mmap_module_error;
typedef enum
PyObject *map_size_obj = NULL;
int map_size;
int fd, flags = MAP_SHARED, prot = PROT_WRITE | PROT_READ;
+ int devzero = -1;
int access = (int)ACCESS_DEFAULT;
static const char *keywords[] = {"fileno", "length",
"flags", "prot",
m_obj->data = NULL;
m_obj->size = (size_t) map_size;
m_obj->pos = (size_t) 0;
- m_obj->fd = dup(fd);
- if (m_obj->fd == -1) {
- Py_DECREF(m_obj);
- PyErr_SetFromErrno(mmap_module_error);
- return NULL;
+ if (fd == -1) {
+ m_obj->fd = -1;
+ /* Assume the caller wants to map anonymous memory.
+ This is the same behaviour as Windows. mmap.mmap(-1, size)
+ on both Windows and Unix map anonymous memory.
+ */
+#ifdef MAP_ANONYMOUS
+ /* BSD way to map anonymous memory */
+ flags |= MAP_ANONYMOUS;
+#else
+ /* SVR4 method to map anonymous memory is to open /dev/zero */
+ fd = devzero = open("/dev/zero", O_RDWR);
+ if (devzero == -1) {
+ Py_DECREF(m_obj);
+ PyErr_SetFromErrno(mmap_module_error);
+ return NULL;
+ }
+#endif
+ } else {
+ m_obj->fd = dup(fd);
+ if (m_obj->fd == -1) {
+ Py_DECREF(m_obj);
+ PyErr_SetFromErrno(mmap_module_error);
+ return NULL;
+ }
}
+
m_obj->data = mmap(NULL, map_size,
prot, flags,
fd, 0);
+
+ if (devzero != -1) {
+ close(devzero);
+ }
+
if (m_obj->data == (char *)-1) {
m_obj->data = NULL;
Py_DECREF(m_obj);
if (map_size < 0)
return NULL;
- /* if an actual filename has been specified */
- if (fileno != 0) {
+ /* assume -1 and 0 both mean invalid filedescriptor
+ to 'anonymously' map memory.
+ XXX: fileno == 0 is a valid fd, but was accepted prior to 2.5.
+ XXX: Should this code be added?
+ if (fileno == 0)
+ PyErr_Warn(PyExc_DeprecationWarning,
+ "don't use 0 for anonymous memory");
+ */
+ if (fileno != -1 && fileno != 0) {
fh = (HANDLE)_get_osfhandle(fileno);
if (fh==(HANDLE)-1) {
PyErr_SetFromErrno(mmap_module_error);
PyDict_SetItemString (dict, "MAP_EXECUTABLE",
PyInt_FromLong(MAP_EXECUTABLE) );
#endif
-#ifdef MAP_ANON
- PyDict_SetItemString (dict, "MAP_ANON", PyInt_FromLong(MAP_ANON) );
+#ifdef MAP_ANONYMOUS
+ PyDict_SetItemString (dict, "MAP_ANON", PyInt_FromLong(MAP_ANONYMOUS) );
PyDict_SetItemString (dict, "MAP_ANONYMOUS",
- PyInt_FromLong(MAP_ANON) );
+ PyInt_FromLong(MAP_ANONYMOUS) );
#endif
PyDict_SetItemString (dict, "PAGESIZE",