FIGURE 1
                                  FID_TEST.C
	 
#include stdio			    /* standard I/O */
#include rms			    /* loads RMS control block definitions */
#include fiddef			    /* loads FID structure definition */
#include dvidef			    /* loads $GETDVI definitions */
#include descrip		    /* loads VMS descriptor definitions */

#define DEV_NAME "FILE_DEV"	    /* logical for disk device */
#define FILE_NAME "TEST.DAT"	    /* name for file in header record */
#define TEST_REC "This is a test"   /* text of test record */

/* some convenient VMS type definitions */
typedef unsigned char BYTE;
typedef unsigned short WORD;

/* define RMS structures as types */
typedef struct FAB RMS_FAB;
typedef struct RAB RMS_RAB;
typedef struct NAM RMS_NAM;
typedef struct fiddef VMS_FID;

/* define item list type */
typedef struct vms_itemlist_3 {
    WORD buf_len;
    WORD code;
    unsigned buffer;
    WORD *ret_len;
    } VMS_ITEMLIST_3;

/* define IOSB type */
typedef struct vms_iosb {
    WORD code;
    WORD length;
    unsigned info;
    } VMS_IOSB;


/****** variable declarations ******/

/* the RMS control blocks */
static RMS_FAB fab;
static RMS_NAM nam;
static RMS_RAB rab;

/* buffer for reading back the test record */
static char read_buf[256];

/* saved FID and device info */
static VMS_FID sav_fid;
static char sav_dvi[NAM$C_DVI];

/* $GETDVI data declarations */
static VMS_ITEMLIST_3 dvi_itm[2];	/* item list */
static VMS_IOSB dvi_iosb;		/* IOSB */
static WORD dvi_len;			/* return length */
static char dvi_str[64];		/* returned physical device name */
static $DESCRIPTOR(dev_d, DEV_NAME);	/* device logical name */

/* descriptor and buffer for returned file name */
static char fname_buf[256];
static $DESCRIPTOR(fname_d, fname_buf);
static WORD fname_len;

main()
{
int sys_stat;


/****** CREATE A PERMANENT TEMPORARY FILE *******/

/* set up item list for SYS$GETDVI and get physical name of device */
dvi_itm[0].code = DVI$_DEVNAM;
dvi_itm[0].buf_len = sizeof(dvi_str);
dvi_itm[0].buffer = &dvi_str;
dvi_itm[0].ret_len = &dvi_len;
dvi_itm[1].code = dvi_itm[1].buf_len = 0;

sys_stat = sys$getdviw (
               0,	    /* efn */
               0,	    /* channel */
               &dev_d,	    /* device name */
               &dvi_itm,    /* item list */
               &dvi_iosb,   /* IOSB */
               0,	    /* AST address */
               0,	    /* AST param */
               0);	    /* null argument */
if (!(sys_stat & 1)) {sys$exit(sys_stat);}
if (!(dvi_iosb.code & 1)) {sys$exit(dvi_iosb.code);}

/* cleanup and sanity check of device name length */
/* the trailing colon MUST be removed */
	 if ((dvi_len > 15)
	|| (dvi_len == 0))
    sys$exit(0);
if (dvi_str[dvi_len - 1] = ':')
    dvi_len -= 1;

/* set up FAB block */
fab = cc$rms_fab;			/* initialize the FAB */
fab.fab$l_nam = &nam;			/* link to NAM block */
fab.fab$l_fop = FAB$M_TMP		/* specify temporary file */
		| FAB$M_NAM;		/* and NAM block input */
fab.fab$b_fac = FAB$M_PUT;		/* write access */
fab.fab$l_fna = FILE_NAME;		/* specify file name */
fab.fab$b_fns = strlen(FILE_NAME);

/* set up NAM block */
nam = cc$rms_nam;			/* initialize NAM block */

/* the nam$t_dvi field is a counted string: the first byte is the */
/* length of the device name string, which starts with the second byte */
memcpy(&nam.nam$t_dvi[1], dvi_str,	/* specify dev name */
	    dvi_len);
nam.nam$t_dvi[0] = dvi_len;		/* and length */

/* set up RAB block */
rab = cc$rms_rab;			/* initialize RAB block */
rab.rab$l_fab = &fab;			/* link to FAB */
rab.rab$l_rbf = TEST_REC;		/* point to test record */
rab.rab$w_rsz = strlen(TEST_REC);	/* test record size */

/* create the file */
sys_stat = SYS$CREATE(&fab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

/* display the file information */
printf("The file was created on %15s with FID %d,%d,%d\n",
	    &nam.nam$t_dvi[1], nam.nam$w_fid[0],
	    nam.nam$w_fid[1], nam.nam$w_fid[2]);

/* save the FID and DVI information */
memcpy(&sav_fid, &nam.nam$w_fid, sizeof(sav_fid));
memcpy(&sav_dvi, &nam.nam$t_dvi, sizeof(sav_dvi));

/* connect the record stream */
sys_stat = SYS$CONNECT(&rab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

/* write the test record */
sys_stat = SYS$PUT(&rab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

/* close the file */
sys_stat = SYS$CLOSE(&fab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}



/********* OPEN THE FILE FOR READ ACCESS *******/

/* get and display the file name */
dev_d.dsc$a_pointer = &sav_dvi[1];
dev_d.dsc$w_length = sav_dvi[0];
sys_stat = LIB$FID_TO_NAME(&dev_d, &sav_fid, &fname_d, &fname_len);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}
fname_buf[fname_len] = '\0';
printf("The returned file name is %s\n", fname_buf);

/* set up FAB block */
fab = cc$rms_fab;		/* initialize */
fab.fab$l_fop = FAB$M_NAM;	/* specify NAM block input */
fab.fab$l_nam = &nam;		/* link in NAM block */
fab.fab$b_fac = FAB$M_GET;	/* read access */

/* set up NAM block */
nam = cc$rms_nam;		/* initialize */
/* set up saved device and FID information */
memcpy(&nam.nam$w_fid, &sav_fid, sizeof(nam.nam$w_fid));
memcpy(&nam.nam$t_dvi, &sav_dvi, sizeof(nam.nam$t_dvi));

/* set up the RAB block */
rab = cc$rms_rab;			    /* initialize the RAB */
rab.rab$l_fab = &fab;			    /* link to FAB */
rab.rab$l_ubf = read_buf;		    /* point to read buffer */
rab.rab$w_usz = sizeof(read_buf) - 1;	    /* allow for terminating '\0' */

/* open the file */
sys_stat = SYS$OPEN(&fab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

/* connect the record stream */
sys_stat = SYS$CONNECT(&rab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

/* read a record */
sys_stat = SYS$GET(&rab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

read_buf[rab.rab$w_rsz] = '\0';		    /* terminate the string */
printf("The record returned is: %s\n", read_buf);

/* close the file */
sys_stat = SYS$CLOSE(&fab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}


/******* DELETE THE FILE WITH THE $ERASE FUNCTION ******/

/* set up FAB block */
fab = cc$rms_fab;		/* initialize */
fab.fab$l_fop = FAB$M_NAM;	/* specify NAM block input */
fab.fab$l_nam = &nam;		/* link in NAM block */

/* set up NAM block */
nam = cc$rms_nam;		/* initialize */
/* set up saved device and FID information */
memcpy(&nam.nam$w_fid, &sav_fid, sizeof(nam.nam$w_fid));
memcpy(&nam.nam$t_dvi, &sav_dvi, sizeof(nam.nam$t_dvi));

/* delete the file */
sys_stat = SYS$ERASE(&fab, NULL, NULL);
if (!(sys_stat & 1)) {sys$exit(sys_stat);}

}