C++/VB - CreateFile Fails - Second Execution On Same File

Hi All,

See code below. Why does the second call fail?

Do I misunderstand the MSDN documentation?

http://msdn.microsoft.com/en-us/library/aa363858(VS.85).aspx

TIA,

-Le Chaud Lapin-


int main (int argc, char *argv[], char *envp[])
{
// Please make sure the following file exists before running:
TCHAR szFilePath[] = "C:\\FOO.DOCX";

HANDLE h1 = CreateFile (
szFilePath,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);

HANDLE h2 = CreateFile (
szFilePath,
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);

DWORD dwError = GetLastError();

return 0;
}

  Uwe Sieber replied to Le Chaud Lapin

Because it is opened for writing and the second
call do not want to share write. With
work.

Uwe

  David Lowndes replied to Le Chaud Lapin

Because the first instance is opened for reading and writing, the
second one needs to allow the same sharing. i.e. it should be:

HANDLE h2 = CreateFile (
szFilePath,
GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);

You can test these usages of CreateFile using multiple instances of my
CFTest utility:
http://jddesign.co.uk/products/freeware/freeware_programs.htm#CFTest

Dave

  Uwe Sieber replied to David Lowndes

Here is mine :-)
http://www.uwe-sieber.de/files/CreateFileTest.zip


Uwe

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