(Merge 3.1) Issue #11277: mmap.mmap() calls fcntl(fd, F_FULLFSYNC) on Mac OS X
to get around a mmap bug with sparse files. Patch written by Steffen Daode
Nurpmeso.
diff --git a/Doc/library/mmap.rst b/Doc/library/mmap.rst
index 125b34f..f036a60 100644
--- a/Doc/library/mmap.rst
+++ b/Doc/library/mmap.rst
@@ -94,6 +94,10 @@
defaults to 0. *offset* must be a multiple of the PAGESIZE or
ALLOCATIONGRANULARITY.
+ To ensure validity of the created memory mapping the file specified
+ by the descriptor *fileno* is internally automatically synchronized
+ with physical backing store on Mac OS X and OpenVMS.
+
This example shows a simple way of using :class:`mmap`::
import mmap
diff --git a/Misc/NEWS b/Misc/NEWS
index 0030bab..50f6aaf 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -70,6 +70,9 @@
Library
-------
+- Issue #11277: mmap.mmap() calls fcntl(fd, F_FULLFSYNC) on Mac OS X to get
+ around a mmap bug with sparse files. Patch written by Steffen Daode Nurpmeso.
+
- Issue #10761: Fix tarfile.extractall failure when symlinked files are
present. Initial patch by Scott Leerssen.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index e93acda..3078279 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -23,6 +23,9 @@
#ifndef MS_WINDOWS
#define UNIX
+# ifdef __APPLE__
+# include <fcntl.h>
+# endif
#endif
#ifdef MS_WINDOWS
@@ -1170,6 +1173,12 @@
"mmap invalid access parameter.");
}
+#ifdef __APPLE__
+ /* Issue #11277: fsync(2) is not enough on OS X - a special, OS X specific
+ fcntl(2) is necessary to force DISKSYNC and get around mmap(2) bug */
+ if (fd != -1)
+ (void)fcntl(fd, F_FULLFSYNC);
+#endif
#ifdef HAVE_FSTAT
# ifdef __VMS
/* on OpenVMS we must ensure that all bytes are written to the file */