Awesome detail. Thanks eryk. On Tue, 20 Sep 2016, 6:13 PM eryk sun <eryk...@gmail.com> wrote:
> On Mon, Sep 19, 2016 at 10:21 PM, Christopher Nilsson <ch...@slort.org> > wrote: > > > > That doesn't seem like a bug to me. GENERIC_WRITE represents several > > permissions mashed together, including FILE_WRITE and read control. > > > > Perhaps try with just FILE_WRITE on its own? > > For a file or directory, GENERIC_WRITE (0x80000000) gets mapped to > FILE_GENERIC_WRITE, which includes the following standard rights > (upper 16 bits): > > SYNCHRONIZE = 0x00100000 > READ_CONTROL = 0x00020000 > > and File-object specific rights (lower 16 bits): > > FILE_WRITE_ATTRIBUTES = 0x00000100 > FILE_WRITE_EA = 0x00000010 > FILE_APPEND_DATA = 0x00000004 > FILE_WRITE_DATA = 0x00000002 > > The relevant access right that's being denied in this case is SYNCHRONIZE. > > For example, SetCurrentDirectory uses a synchronous directory handle, > i.e. it calls NtOpenfile with desired access SYNCHRONIZE | > FILE_TRAVERSE and open option FILE_SYNCHRONOUS_IO_NONALERT. Similarly, > for listing a directory, FindFirstFile uses a synchronous handle with > SYNCHRONIZE | FILE_LIST_DIRECTORY access. > > The open option FILE_SYNCHRONOUS_IO_NONALERT is defined as follows: > > All operations on the file are performed synchronously. > Waits in the system that synchronize I/O queuing and > completion are not subject to alerts. This flag also > causes the I/O system to maintain the file-position > context. If this flag is set, the SYNCHRONIZE flag must > be set in the DesiredAccess parameter. > > For example, when FindFirstFile calls NtQueryDirectoryFile > (FileBothDirectoryInformation) to list the directory, the system call > sees the handle is opened for synchronous access, so it waits to > acquire the File object's Lock before calling the filesystem driver > (e.g. NTFS). Then it waits again to complete the request. > _______________________________________________ > python-win32 mailing list > python-win32@python.org > https://mail.python.org/mailman/listinfo/python-win32 >
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