Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 68K/cpm68k_pgms/sdbas/CRE.C

/* SDB - relation creation routines */



#include "sdbio.h"



/* db_rcreate(rname) - begin the creation of a new relation */

struct relation *db_rcreate(rname)

  char *rname;

{

    struct relation *rptr;



    /* allocate the relation structure */

    if ((rptr = calloc(1,sizeof(struct relation))) == NULL)

#ifdef CPM68K

        return ((struct relation *) ((long int)db_nerror(INSMEM)));

#else

        return (db_nerror(INSMEM));

#endif

    /* initialize the relation structure */

    strncpy(rptr->rl_name,rname,RNSIZE);

    rptr->rl_tcnt = 0;

    rptr->rl_tmax = 0;

    rptr->rl_data = 512;

    rptr->rl_size = 1;

    rptr->rl_header.hd_attrs[0].at_name[0] = 0;



    /* return the new relation structure pointer */

    return (rptr);

}



/* db_rcheader - create the relation header */

int db_rcheader(rptr)

  struct relation *rptr;

{

    char rname[RNSIZE+1],filename[RNSIZE+13];



    /* initialize the relation file header */

    db_cvbytes(rptr->rl_tcnt,rptr->rl_header.hd_tcnt);

    db_cvbytes(rptr->rl_tmax,rptr->rl_header.hd_tmax);

    db_cvbytes(rptr->rl_data,rptr->rl_header.hd_data);

    db_cvbytes(rptr->rl_size,rptr->rl_header.hd_size);



    /* create the relation file name */

    strncpy(rname,rptr->rl_name,RNSIZE); rname[RNSIZE] = 0;

    sprintf(filename,"%s.sdb",rname);



    /* create the relation file */

#ifdef CPM68K

    if ((rptr->rl_fd = creatb(filename,0)) == -1) {

#else

    if ((rptr->rl_fd = creat(filename,0)) == -1) {

#endif

        free(rptr);

        return (db_ferror(RELCRE));

    }



    /* write the header to the relation file */

    if (write(rptr->rl_fd,&rptr->rl_header,512) != 512) {

        close(rptr->rl_fd);

        free(rptr);

        return (db_ferror(BADHDR));

    }



    /* return successfully */

    return (TRUE);

}



/* db_rctuples - create the relation tuples */

int db_rctuples(rptr,tcnt)

  struct relation *rptr; unsigned int tcnt;

{

    unsigned int i;

    char *tbuf;



    /* store the number of tuples */

    rptr->rl_tmax = tcnt;



    /* allocate a tuple buffer */

    if ((tbuf = calloc(1,rptr->rl_size)) == NULL)

        return (db_ferror(INSMEM));



    /* write null tuples into the file */

    for (i = 0; i < tcnt; i++)

        if (write(rptr->rl_fd,tbuf,rptr->rl_size) != rptr->rl_size) {

            free(tbuf);

            return (db_ferror(INSBLK));

        }



    /* free the tuple buffer */

    free(tbuf);



    /* return successfully */

    return (TRUE);

}



/* db_rcdone(rptr) - finish the creation of a new relation */

int db_rcdone(rptr)

  struct relation *rptr;

{

    /* initialize the relation file header */

    db_cvbytes(rptr->rl_tcnt,rptr->rl_header.hd_tcnt);

    db_cvbytes(rptr->rl_tmax,rptr->rl_header.hd_tmax);



    /* write the header to the relation file */

    lseek(rptr->rl_fd,0L,0);

    if (write(rptr->rl_fd,&rptr->rl_header,512) != 512) {

        close(rptr->rl_fd);

        free(rptr);

        return (db_ferror(BADHDR));

    }



   /* close the relation file */

    close(rptr->rl_fd);



    /* free the relation structure */

    free(rptr);



    /* return successfully */

    return (TRUE);

}



/* db_rcattr(rptr,aname,type,size) - add an attribute to relation being created */

int db_rcattr(rptr,aname,type,size)

  struct relation *rptr; char *aname; int type,size;

{

    int i;



    /* look for attribute name */

    for (i = 0; i < NATTRS; i++)

        if (rptr->rl_header.hd_attrs[i].at_name[0] == 0)

            break;

        else if (db_sncmp(aname,rptr->rl_header.hd_attrs[i].at_name,ANSIZE) == 0)

            return (db_ferror(DUPATT));



    /* check for too many attributes */

    if (i == NATTRS)

        return (db_ferror(MAXATT));



    /* store the new attribute */

    strncpy(rptr->rl_header.hd_attrs[i].at_name,aname,ANSIZE);

    rptr->rl_header.hd_attrs[i].at_type = type;

    rptr->rl_header.hd_attrs[i].at_size = size;



    /* terminate the attribute table */

    if (++i != NATTRS)

        rptr->rl_header.hd_attrs[i].at_name[0] = 0;



    /* update the tuple size */

    rptr->rl_size += size;



    /* return successfully */

    return (TRUE);

}