Re: IFS open() and existing files not truncating

[Scott Klement <klemscot@xxxxxxxxxxxx>]

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.
>