topic Re: Unable set file limit from C-programm in Operating System - OpenVMS

Unable set file limit from C-programm

Dmitriy_21 — Fri, 17 Oct 2014 18:05:34 GMT

Hello experts

I am trying to set a file version limit from a C-program for a file (directory is the next step).

The value is remin the same "No version limit".

Can someone point me to a right direction?

I have attached source code for my test program.

This is a screen copy when i run my test program.

$ cc SETLIMIT.C
$ link SETLIMIT.OBJ
$ TESTSET="$DKA700:[DMITRIY]SETLIMIT.EXE"
$ testset file3.txt 3
$ dir /full file3.txt

Directory DKA700:[DMITRIY]

file3.txt;1 File ID: (13155,28,0)
Size: 0/0 Owner: [1,1]
Created: 17-OCT-2014 13:12:46.70
Revised: 17-OCT-2014 13:12:46.72 (1)
Expires: <None specified>
Backup: <No backup recorded>
Effective: <None specified>
Recording: <None specified>
Accessed: <None specified>
Attributes: <None specified>
Modified: <None specified>
Linkcount: 1
File organization: Sequential
Shelved state: Online
Caching attribute: Writethrough
File attributes: Allocation: 0, Extend: 0, Global buffer count: 0, No version limit
Record format: Variable length, maximum 0 bytes, longest 0 bytes
Record attributes: None
RMS attributes: None
Journaling enabled: None
File protection: System:RWED, Owner:RWED, Group:RE, World:
Access Cntrl List: None
Client attributes: None

Total of 1 file, 0/0 blocks.

Thanks

Dmitriy

Re: Unable set file limit from C-programm

H.Becker — Fri, 17 Oct 2014 19:16:56 GMT

According to the docs, almost all fields in xabfhc are output only, xab$w_lrl is the only exception. Did you search the web for some examples? I assume there are some.

Re: Unable set file limit from C-programm

Dmitriy_21 — Fri, 17 Oct 2014 19:45:33 GMT

H.Beker

Yes, did spend lot of time searching.

I have found that it is read-only, but can't find any straight reference how to set.

I come across this link http://compgroups.net/comp.os.vms/how-to-retrieve-and-set-default-file-version-limi/524495.

But it is incomplete specially without the referenced example (can't find uchar.c on the web anymore).

Re: Unable set file limit from C-programm

H.Becker — Fri, 17 Oct 2014 23:18:29 GMT

Google finds the FILE utility: http://www.decuslib.com/decus/vax88b1/meadows/file/file.c which seems accept /version_limit which in turn seems to set a file version limit. I admit I didn't try to compile the sources and test it, as it looks like VAX(C) code, which you may want to change for newer compilers and because "my VMS system" on the net is on the move.

Re: Unable set file limit from C-programm

Hoff — Fri, 17 Oct 2014 23:46:35 GMT

To set the file version limit under program control (and not via a subprocess that invokes the SET FILE /VERSION_LIMIT command), see the OpenVMS I/O Abuser's Reference Manual starting on page 46; specifically, see the QIO ACP interface and the IO$_MODIFY I/O function with the FIB$W_VERLIMIT itemcode. There aren't all that many IO$_MODIFY examples posted around the 'net, but see here, here and here as some starting points.

Re: Unable set file limit from C-programm

Steven Schweda — Sat, 18 Oct 2014 00:43:55 GMT

Re: Unable set file limit from C-programm

Hein van den Heuvel — Mon, 20 Oct 2014 17:41:00 GMT

As Steven indicates, there will be SYS$QIO examples on the web to help you.

But why bother? How often will this call be made?

Just call LIB$SPAWN to do the deed and move on.

Hein

Re: Unable set file limit from C-programm

Dmitriy_21 — Mon, 20 Oct 2014 21:31:27 GMT

Thank you for your response.

After changing my code to use sys$qiow, I still can't change the default limit setting.

All calls to IO system are finishing successfully.

I can't use LIB$SPAWN since I need to use this for many files.

Is anything in my code I am doing wrong?

Attached is the source code of my program and also the screen output.

To compile the code, header files will be needed from http://www.decuslib.com/decus/vax88b1/meadows/file.

Thanks

Dmitriy

Re: Unable set file limit from C-programm

Hein van den Heuvel — Tue, 21 Oct 2014 11:10:53 GMT

[editted - the dog ate my homework on first submission]

>> To compile the code, header files will be needed from http://www.decuslib.com/decus/vax88b1/meadows/file.

That may be part of the problem.

Just compile with: cc SET_VERLIMIT.C+sys$library:sys$lib_c.tlb

To make that work, fix up FATDEF -> FAT, fchdef -> FCH, ATRDEF -> atrdef. FAT$S_FATDEF -> ATR$S_RECATTR

remove fjndef, and the second set of moves into fid and did.

fwiw... the printing of the FID is not correct for ID > 65K. Need to show FID[2] or add in NMX

>> I can't use LIB$SPAWN since I need to use this for many files.

I used to think that way. I was wrong. Your time is infinitely more valuable than some execution overhead except for a few rare cases

See attached.

It works for me now.

Hein

Re: Unable set file limit from C-programm

H.Becker — Tue, 21 Oct 2014 08:45:55 GMT

This works for me, with the VMS supplied header files:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define __NEW_STARLET 1
#include <descrip.h>
#include <fabdef.h>
#include <fibdef.h>
#include <iodef.h>
#include <iosbdef.h>
#include <namdef.h>
#include <starlet.h>
#include <ssdef.h>

static int setverlimit(char *filename, unsigned short limit) {
    static FABDEF fab;
    static NAMDEF nam;
    static FIBDEF fib;
    static struct dsc$descriptor FibDesc = { sizeof fib, DSC$K_DTYPE_Z,
            DSC$K_CLASS_S, (char *) &fib };
    static struct dsc$descriptor_s DevDesc = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_S,
            &nam.nam$t_dvi[1] };
    static struct dsc$descriptor_s FileName = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_S,
            0};

    char EName[NAM$C_MAXRSS];
    unsigned short int DevChan;
    IOSB iosb;

    int i, status;

    fab = cc$rms_fab;
    fab.fab$l_fna = filename;
    fab.fab$b_fns = strlen(filename);
    fab.fab$l_nam = &nam;
    nam = cc$rms_nam;
    nam.nam$l_esa = EName;
    nam.nam$b_ess = sizeof(EName);

    status = sys$parse(&fab);
    if (!(status & 1))
        return status;

    status = sys$search(&fab);
    if (!(status & 1))
        return status;

    DevDesc.dsc$w_length = nam.nam$t_dvi[0];
    status = sys$assign(&DevDesc, &DevChan, 0, 0);
    if (!(status & 1))
        return status;

    FileName.dsc$a_pointer = nam.nam$l_name;
    FileName.dsc$w_length = nam.nam$b_name+nam.nam$b_type+nam.nam$b_ver;

    for (i = 0; i < 3; i++)
        fib.fib$w_fid[i] = nam.nam$w_fid[i];
    for (i = 0; i < 3; i++)
        fib.fib$w_did[i] = nam.nam$w_did[i];

    fib.fib$w_verlimit = limit;
    status = sys$qiow(0, DevChan, IO$_MODIFY, &iosb, 0, 0, &FibDesc,
            (__int64)&FileName, 0, 0, 0, 0);
    if (status & 1)
        status = iosb.iosb$w_status;
    if (!(status & 1))
        return status;
    
    status = sys$dassgn(DevChan);
    return status;
}

int main(int argc, char *argv[]) {
    int status = SS$_INSFARG;
    if (argc > 2) {
        unsigned int limit;
        sscanf (argv[2], "%u", &limit);
        if (limit > 32767)
            limit = 0;
        status = setverlimit(argv[1],(unsigned short)limit);
    }
    exit (status);
}

Re: Unable set file limit from C-programm

Hein van den Heuvel — Tue, 21 Oct 2014 11:19:14 GMT

Hartmut wrote...

if (status & 1)
        status = iosb.iosb$w_status;
    if (!(status & 1))
        return status;

That's exactly the one of the many changes I was going to make. Verbatim

All those stupid fancy - shmancey (sp?) macros serve nothing other then obfusicate the core code itself.

3 potential calls to DASSGN when one is always executed? Bletch.

I left it to make it easier to compare before-after for the OP.

Cheers,

Hein

Re: Unable set file limit from C-programm

Dmitriy_21 — Tue, 21 Oct 2014 15:19:18 GMT

Thanks every one for your help!

With appropriate headers program is working as excpected.