Re: IFS open() and existing files not truncating

You have to tell it that you want it to truncate an existing file!

To make it truncate an existing file, change this line:

     c                   eval      oflag = O_CREAT+O_WRONLY + O_CODEPAGE

to:
     c                   eval      oflag = O_CREAT + O_WRONLY + O_CODEPAGE
                                           + O_TRUNC

And, if you don't already have a constant defining O_TRUNC, it should
look like this:

     D*                                            Truncate File to 0 bytes
     D O_TRUNC         C                   64



On Tue, 14 May 2002, Robin Coles wrote:

> While the IFS code is under discussion, I'm writing a program to create
> a file on the IFS for emailing, and have shamelessly plagiarised Scott's
> code, which works fine, but....
>
> If I open the file as:
>      c                   eval      oflag = O_CREAT+O_WRONLY + O_CODEPAGE
>
>      ** set mode to All
>
>      c                   eval      omode = S_IRWXU + S_IRWXG + S_IRWXO
>
>      c                   eval      fd = open(p_filename: oflag: omode:
>      c                                      CP_ASCII)
>
> I was expecting the file to be created if it didn't exist, and
> completely overwritten if it did.
>
> I ran it once and the file was created OK.  I inserted 2 extra lines
> using EDTF and ran it again, and it's effectively updated the existing
> lines (it writes a timestamp so I know I'm not going completely mad) and
> left the manually inserted lines there.
>
> Is this correct?  If so, I'll add an unlink() but I didn't think that
> would be needed.
>