BSD 4 release

[unix-history] / usr / src / cmd / sdb / old.c

static  char sccsid[] = "@(#)old.c 4.1 10/9/80";
/*
* sdb - a symbolic debugger for UNIX.
*/

/*
* This file contains support routines for older versions of the system.
*/

#ifndef VMUNIX
/*
* These routines are used only if the system
* doesn't have virtual memory.  They
* are used only to read the symbol table, which
* is simply kept in VM on VMUNIX.
*/
#include <pagsiz.h>
#include "bio.h"

bread(brs, buff, nbytes)
struct brbuf *brs; char *buff; {
       register int k, nb;

       if (nbytes > 0) {
               for (nb=nbytes; nb>0; nb--) {
                       if (brs->nr == 0) {
                               brs->nr = read(brs->fd, brs->next=brs->b, BSIZE);
                               brs->nl = 0;
                               if (brs->nr < 0) return(-1);
                               if (brs->nr == 0) return(nbytes-nb);
                               }
                       *buff++ = *brs->next++;
                       brs->nr--;
                       brs->nl++;
                       }
               }
       else {
               nbytes = -nbytes;
               for (nb=nbytes; nb>0; nb--) {
                       if (brs->nl == 0) {
                               if ((k=tell(brs->fd)) >= BSIZE + brs->nr) {
                                       lseek(brs->fd, (long) -(BSIZE + brs->nr), 1);
                                       brs->nl = read(brs->fd, brs->b, BSIZE);
                               } else {
                                       lseek(brs->fd, 0L, 0);
                                       k = k - brs->nr;
                                       if (k < 0) k = 0;
                                       brs->nl = read(brs->fd, brs->b, k);
                               }
                               if (brs->nl == 0) return(nbytes-nb);
                               brs->next = brs->b + brs->nl;
                               brs->nr = 0;
                               }
                       *--buff = *--brs->next;
                       brs->nr++;
                       brs->nl--;
                       }
               }
       return(nbytes);
       }

blseek(brs, offset, flag) 
struct brbuf *brs; long offset; {
       brs->nl = 0;
       brs->nr = 0;
       return(lseek(brs->fd,offset,flag));
       }

binit(brs)
struct brbuf *brs; {
       brs->nl = brs->nr = 0;
}

long
tell(fildes) {
       return(lseek(fildes, 0L, 1));
}
#endif