From: Hein van den Heuvel [hein_netscape@eps.zko.dec.com]
Sent: Wednesday, December 03, 2003 4:26 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: How do you modify RMS file attributes when using ofstream
I/O ?



Stuart wrote:

> cheers guys,
>
> We've sorted it now.  Used lib$spawn to carry out 'set file/attributes'
> commands on the files after they have been created.

Great. No problem if you do it once an hour and have the resources.
If spawning is too expensive / difficult / slow, then you may want to
consider a subroutine. Now SET FILE is not callable. There are 3
ways to code this up, and I will provide examples for each as they are all
tricky.
1) The more or less documented ACP QIO to change RECATTR in the file header.
2) A simple RMS 'trick' with normal calls for sequential files only. Easy
enough.
3) Using the undocumented RMS SYS$MODIFY call.


> The problem came around because a fortran application used to view the
> files(created in C++ using ofstream) was allocating memory for a line length
> buffer to that of the rms file attribute 'longest line bytes', which was set
> to 0 therefore not reading anything out of the file.

You may want to check out the usage of the logical name DECC$DEFAULT_LRL

Eamples below.... [hey... it's almost Xmass time ;-) ]

Hein.



U$1:[HEIN.EXAMPLES]LRL_MODIFY.C;1

/*
** lrl_modify.c         Hein van den Heuvel, December 2003
**
**      Template program to set RMS LRL attributes for RMS files.
**      This is done as a side effect of temporarely changing the file
**      attributes in memory to fixed-length through sys$modify.
**      Usage: Define as external DCL command and pass filespec as param.
**      Have fun.
*/


#include <rms>
#include <rmedef>
#include <stdio>
#include <stdlib>

int set_lrl (char *filename, int lrl)
{
struct FAB      fab;
struct XABFHC   fhc;
size_t          strlen();
int             stat, rfm, mrs, sys$open(), sys$close(), sys$modify();

fab = cc$rms_fab;
fhc = cc$rms_xabfhc;
fab.fab$b_fac = FAB$M_PUT | FAB$M_TRN;
fab.fab$l_fna = filename;
fab.fab$b_fns = strlen( filename );
fab.fab$l_xab = (void *) &fhc;

stat = sys$open ( &fab );
if (!(stat&1)) return stat;
if (lrl > 32767) return RMS$_RSZ;
mrs = fab.fab$w_mrs;
rfm = fab.fab$b_rfm;
fab.fab$l_ctx = RME$C_SETRFM;
fab.fab$v_esc = 1;
fab.fab$w_mrs = lrl;
fab.fab$b_rfm = FAB$C_FIX;
stat = sys$modify ( &fab );
if (stat & 1) {
  fab.fab$w_mrs = mrs;
  fab.fab$b_rfm = rfm;
  stat = sys$modify ( &fab );
  }
if (stat&1) stat = sys$close(&fab);
return stat;
}

main (int argc, char *argv[])
{
if (argc < 3) {
  printf ("Usage: %s <filename> <new-larger-lrl>\n", argv[0]);
  return 1;
  }
return set_lrl ( argv[1], atoi(argv[2]) );
}

U$1:[HEIN.EXAMPLES]LRL_QIO.C;1

/*
** lrl_qio.c            Hein van den Heuvel, December 2003
**
**      Template program to set RMS LRL attribute for RMS files.
**      This is done using an ACP QIO.
**      Usage: Define as external DCL command and pass filespec as param.
**      Have fun.
*/


#include <rms>
#include atrdef
#include fibdef
/*  fdhdef and fatdef live in lib.mlb and SYS$LIB_C.TLB */
#include iodef
#include stdio
#include stdlib
#include string
#define FAT$W_RSIZE 1

int set_lrl (char *filename, int lrl)
{
struct fibdef fib;
size_t          strlen();
int             stat, channel, sys$open(), sys$close(), sys$qiow();

    union {
     char fill[ATR$S_RECATTR];
     short word[5];}fat;        /* fake it, as fat.h not always present */
    short iosb[4];
    struct { long count; void *address; } fibdes;
    struct atrdef atr[2];

struct FAB      fab;
struct NAM      nam;

fab = cc$rms_fab;
nam = cc$rms_nam;
fab.fab$b_fac = FAB$M_PUT | FAB$M_TRN;
fab.fab$l_fna = filename;
fab.fab$b_fns = strlen( filename );
fab.fab$b_fac = FAB$M_GET | FAB$M_PUT;
fab.fab$l_fop = FAB$M_UFO;
fab.fab$l_nam = &nam;
fab.fab$l_fna = filename;
fab.fab$b_fns = strlen( filename );
memset (&fib, 0, sizeof(fib));

if (lrl > 32767) return RMS$_RSZ;
stat = sys$open ( &fab );
if (!(stat&1)) return stat;
channel = fab.fab$l_stv;

    fibdes.count = sizeof(fib);
    fibdes.address = &fib;

    fib.fib$l_acctl  = ( FIB$M_WRITE );
    fib.fib$w_fid_num = nam.nam$w_fid[0];
    fib.fib$w_fid_seq = nam.nam$w_fid[1];
    fib.fib$w_fid_rvn = nam.nam$w_fid[2];

    /*
    ** Need to get record attributes first to set new rsize
    */
    atr[0].atr$w_type  = ATR$C_RECATTR;
    atr[0].atr$w_size  = ATR$S_RECATTR;
    atr[0].atr$l_addr  = &fat;
    atr[1].atr$w_type  = 0;
    atr[1].atr$w_size  = 0;

/*  Get the file's current attributes */

    stat = sys$qiow(0,channel,IO$_ACCESS,iosb,0,0,&fibdes,0,0,0,&atr,0);
    if (stat & 1) stat = iosb[0];
    if (!(stat & 1)) return stat;

    fat.word[FAT$W_RSIZE] = lrl; /* $FATDEF in LIB.MLB */
    stat = sys$qiow(0,channel,IO$_MODIFY,iosb,0,0,&fibdes,0,0,0,&atr,0);
    if (stat & 1) stat = iosb[0];
    if (!(stat & 1)) return stat;
    return sys$qiow(0,channel,IO$_DEACCESS,iosb,0,0,&fibdes,0,0,0,0,0);
}

main (int argc, char *argv[])
{
if (argc < 3) {
  printf ("Usage: %s <filename> <new-larger-lrl>\n", argv[0]);
  return 1;
  }
return set_lrl ( argv[1], atoi(argv[2]) );
}


U$1:[HEIN.EXAMPLES]LRL_TRUNCATE.C;1



/*
** lrl_truncate.c               Hein van den Heuvel, December 2003
**
**      Template program to incease RMS LRL attribute for sequential files.
**      This is done by temporarely appending a record with size LRL and
**      truncating the file at the insertion point to remove that record.
**      Usage: Define as external DCL command and pass filespec as param.
**      Have fun.
*/


#include <rms>
#include <stdio>
#include <stdlib>

int set_lrl (char *filename, int lrl)
{
struct FAB      fab;
struct RAB      rab;
struct XABFHC   fhc;
size_t          strlen();
int             stat, sys$display(), sys$open(), sys$close(),
                sys$put(), sys$connect(), sys$truncate();

fab = cc$rms_fab;
rab = cc$rms_rab;
fhc = cc$rms_xabfhc;
fab.fab$b_fac = FAB$M_PUT | FAB$M_TRN;
fab.fab$l_fna = filename;
fab.fab$b_fns = strlen( filename );
fab.fab$l_xab = (void *) &fhc;
rab.rab$l_fab = &fab;
rab.rab$l_rbf = (void *) malloc ( lrl ); /* sys$put will test for succes */
rab.rab$w_rsz = lrl;
rab.rab$l_rop = RAB$M_EOF;

stat = sys$open ( &fab );
if (!(stat&1)) return stat;
if (fab.fab$b_org!=FAB$C_SEQ) return RMS$_ORG;
if (fhc.xab$w_lrl > lrl || lrl > 32767) return RMS$_RSZ;
stat = sys$connect (&rab);      /* sys$put will test for succes */
stat = sys$put (&rab);          /* append record with length LRL, giving RFA */
if (!(stat&1)) return stat;     /* returns RMS$_RBF if malloc failed */
free ( rab.rab$l_rbf );
rab.rab$b_rac = RAB$C_RFA;
stat = sys$truncate (&rab);     /* remove that helper record */
if (stat&1) stat = sys$close(&fab);
return stat;
}

main (int argc, char *argv[])
{
if (argc < 3) {
  printf ("Usage: %s <filename> <new-larger-lrl>\n", argv[0]);
  return 1;
  }
return set_lrl ( argv[1], atoi(argv[2]) );
}

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