# /* * Copyright 1975 Bell Telephone Laboratories Inc */ #include "param.h" #include "inode.h" #include "user.h" #include "buf.h" #include "systm.h" /* * Bmap defines the structure of file system storage * by returning the physical block number on a device given the * inode and the logical block number in a file. */ bmap(ip, bn) struct inode *ip; int bn; { register *bp, *bap, nb; int *nbp, d, i; d = ip->i_dev; if(bn & 0174000) { u.u_error = EFBIG; return(0); } #ifdef CONTIG if(ip->i_mode&ICONT) { if(bn >= ip->i_addr[1]) return(0); else return(ip->i_addr[0]+bn); } #endif if((ip->i_mode&ILARG) == 0) { /* * small file algorithm */ if((bn & ~7) != 0) { /* * convert small to large */ if ((bp = alloc(d)) == NULL) return(NULL); bap = bp->b_addr; for(i=0; i<8; i++) { *bap++ = ip->i_addr[i]; ip->i_addr[i] = 0; } ip->i_addr[0] = bp->b_blkno; bdwrite(bp); ip->i_mode =| ILARG; goto large; } nb = ip->i_addr[bn]; if(nb == 0 && (bp = alloc(d)) != NULL) { bdwrite(bp); nb = bp->b_blkno; ip->i_addr[bn] = nb; ip->i_flag =| IUPD; } return(nb); } /* * large file algorithm */ large: i = bn>>8; if((nb=ip->i_addr[i]) == 0) { ip->i_flag =| IUPD; if ((bp = alloc(d)) == NULL) return(NULL); ip->i_addr[i] = bp->b_blkno; } else bp = bread(d, nb); bap = bp->b_addr; /* * normal indirect fetch */ i = bn & 0377; if((nb=bap[i]) == 0 && (nbp = alloc(d)) != NULL) { nb = nbp->b_blkno; bap[i] = nb; bdwrite(nbp); bdwrite(bp); } else brelse(bp); return(nb); } /* * Pass back c to the user at his location u_base; * update u_base, u_count, and u_offset. Return -1 * on the last character of the user's read. * u_base is in the user address space unless u_segflg is set. */ passc(c) char c; { if(subyte(u.u_base, c) < 0) { u.u_error = EFAULT; return(-1); } u.u_count--; if(++u.u_offset[1] == 0) u.u_offset[0]++; u.u_base++; return(u.u_count == 0? -1: 0); } /* * Pick up and return the next character from the user's * write call at location u_base; * update u_base, u_count, and u_offset. Return -1 * when u_count is exhausted. u_base is in the user's * address space unless u_segflg is set. */ cpass() { register c; if(u.u_count == 0) return(-1); if((c=fubyte(u.u_base)) < 0) { u.u_error = EFAULT; return(-1); } u.u_count--; if(++u.u_offset[1] == 0) u.u_offset[0]++; u.u_base++; return(c&0377); } /* * copy count words from from to to. */ bcopy(from, to, count) int *from, *to; { register *a, *b, c; a = from; b = to; c = count; do *b++ = *a++; while(--c); }