🚀 go-pugleaf

"Colin B Maharaj" <noreply@myhost.com> wrote in message 
news:486bb9bd$1@newsgroups.borland.com...

>   if (hf == (HANDLE)0xffffffff)

Use the INVALID_HANDLE_VALUE macro instead:

    if (hf == INVALID_HANDLE_VALUE)

>      char *lpMsgBuf;
>      FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | 
> FORMAT_MESSAGE_FROM_SYSTEM,NULL,
>      GetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),(LPTSTR) 
> &lpMsgBuf,0,NULL);

The VCL has a SysErrorMessage() function that does that work for you:

    ShowMessage(SysErrorMessage(GetLastError()));

In any case, GetLastError() is returning ERROR_SHARING_VIOLATION (32, "The 
process cannot access the file because it is being used by another 
process.").  Which means your call to CreateFile() is not asking for enough 
sharing rights to allow it to succeed.

If you take your second call to FileOpen():

    int FileHandle2 = FileOpen(A, fmOpenRead | fmShareDenyNone);

And look at how FileOpen() is implemented in SysUtils.pas (if you have the 
VCL source code installed), you will see that it expands to the following 
CreateFile() call:

    ... = CreateFile(FileName, GENERIC_READ, FILE_SHARE_READ | 
FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);

Notice the extra FILE_SHARE_WRITE flag?  That is the key to making your code 
work.

Your first call to FileOpen() specifies the fmOpenReadWrite flag:

    int FileHandle = FileOpen(A, fmOpenReadWrite|fmShareDenyNone);

That expands to this:

    ... = CreateFile(FileName, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ 
| FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);

Since the file is writable, any subsequent opening of the file while the 
first handle is still active must specify the FILE_SHARE_WRITE flag or the 
opening fails.  That is why your second call to FileOpen() succeeds but your 
call to CreateFile() fails.


Gambit