From: Fuehrer@seabase.com (Gary Fuehrer) Subject: mmap(,,,MAP_PRIVATE,,) bug and fix 13 Aug 1997 17:58:36 -0700 Approved: cygnus.gnu-win32@cygnus.com Distribution: cygnus Message-ID: <6CC63E2E4FC1D011A2A700609716117A266F05.cygnus.gnu-win32@seawolf> Mime-Version: 1.0 Content-Type: text/plain Original-To: "'gnu-win32@cygnus.com'" X-Priority: 3 X-Mailer: Internet Mail Service (5.0.1458.49) Original-Sender: owner-gnu-win32@cygnus.com The B18 implementation of mmap() fails when MAP_PRIVATE is used. The problem is caused because of this pair of lines in mmap.cc: DWORD access = (prot & PROT_WRITE) ? FILE_MAP_WRITE : FILE_MAP_READ; access |= (flags & MAP_PRIVATE) ? FILE_MAP_COPY : 0; When MAP_PRIVATE is set, then "access" = "FILE_MAP_READ/WRITE | MAP_PRIVATE". When "access" is subsequently passed to MapViewOfFile(), it fails. The Microsoft documentation for MapViewOfFile() states the following concerning the access parameter: "This parameter can be one of the following values:...". So, the failure is because of trying to use more than one of the access types at the same time. Fix: Change the above lines of code to the following (only the second line is different): DWORD access = (prot & PROT_WRITE) ? FILE_MAP_WRITE : FILE_MAP_READ; if (flags & MAP_PRIVATE) access = FILE_MAP_COPY; I've tested this change and it seems to work correctly. Will this fix make it in for B19? Gary - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request@cygnus.com" with one line of text: "help".