Opening an Existing Block File

typedef struct {            /* sequential file header */
     size_t recsize;        /* record size */
} shdr_t;

typedef struct {            /* sequential file control structure */
     shdr_t shdr;           /* file header */
     BLKFILE *bp;           /* block file pointer */
} seq_t;
seq_t sb[SOPEN_MAX];       /* sequential file control structure table */

seq_t *sp = sb[0];

/* open sequential file */
sp->bp = bopen(filename, "r+", sizeof(shdr_t), (size_t)1, (size_t)0);
if (sp->bp == NULL);
     /* error */
}
/* read file header to get record size */
rs = bgeth(sp->bp, (void *)&sp->shdr);
if (rs == -1) {
     /* error */
}
/* set up buffering */
rs = bsetvbuf(sp->bp, NULL, sp->shdr.recsize, SBUFCNT);
if (rs != 0) {
     /* error */
}