[Python-checkins] cpython (2.7): (Merge 3.1) Issue #11277: mmap.mmap() calls fcntl(fd, F_FULLFSYNC) on Mac OS X

[victor.stinner]

http://hg.python.org/cpython/rev/618c3e971e80
changeset:   69796:618c3e971e80
branch:      2.7
parent:      69774:a13310c045b0
user:        Victor Stinner <victor.stinner at haypocalc.com>
date:        Tue May 03 14:36:36 2011 +0200
summary:
  (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.

files:
  Doc/library/mmap.rst |  4 ++++
  Misc/NEWS            |  3 +++
  Modules/mmapmodule.c |  9 +++++++++
  3 files changed, 16 insertions(+), 0 deletions(-)


diff --git a/Doc/library/mmap.rst b/Doc/library/mmap.rst
--- 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
--- 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
--- 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 */

-- 
Repository URL: http://hg.python.org/cpython