| 1 | /* subr_xxx.c 4.9 81/11/20 */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/conf.h" |
| 6 | #include "../h/inode.h" |
| 7 | #include "../h/dir.h" |
| 8 | #include "../h/user.h" |
| 9 | #include "../h/buf.h" |
| 10 | #include "../h/proc.h" |
| 11 | |
| 12 | /* |
| 13 | * Bmap defines the structure of file system storage |
| 14 | * by returning the physical block number on a device given the |
| 15 | * inode and the logical block number in a file. |
| 16 | * When convenient, it also leaves the physical |
| 17 | * block number of the next block of the file in rablock |
| 18 | * for use in read-ahead. |
| 19 | */ |
| 20 | daddr_t |
| 21 | bmap(ip, bn, rwflg) |
| 22 | register struct inode *ip; |
| 23 | daddr_t bn; |
| 24 | { |
| 25 | register i; |
| 26 | struct buf *bp, *nbp; |
| 27 | int j, sh; |
| 28 | daddr_t nb, *bap; |
| 29 | dev_t dev; |
| 30 | |
| 31 | if(bn < 0) { |
| 32 | u.u_error = EFBIG; |
| 33 | return((daddr_t)0); |
| 34 | } |
| 35 | dev = ip->i_dev; |
| 36 | rablock = 0; |
| 37 | |
| 38 | /* |
| 39 | * blocks 0..NADDR-4 are direct blocks |
| 40 | */ |
| 41 | if(bn < NADDR-3) { |
| 42 | i = bn; |
| 43 | nb = ip->i_un.i_addr[i]; |
| 44 | if(nb == 0) { |
| 45 | if(rwflg==B_READ || (bp = alloc(dev))==NULL) |
| 46 | return((daddr_t)-1); |
| 47 | nb = dbtofsb(bp->b_blkno); |
| 48 | if ((ip->i_mode&IFMT) == IFDIR) |
| 49 | /* |
| 50 | * Write directory blocks synchronously |
| 51 | * so they never appear with garbage in |
| 52 | * them on the disk. |
| 53 | */ |
| 54 | bwrite(bp); |
| 55 | else |
| 56 | bdwrite(bp); |
| 57 | ip->i_un.i_addr[i] = nb; |
| 58 | ip->i_flag |= IUPD|ICHG; |
| 59 | } |
| 60 | if(i < NADDR-4) |
| 61 | rablock = ip->i_un.i_addr[i+1]; |
| 62 | return(nb); |
| 63 | } |
| 64 | |
| 65 | /* |
| 66 | * addresses NADDR-3, NADDR-2, and NADDR-1 |
| 67 | * have single, double, triple indirect blocks. |
| 68 | * the first step is to determine |
| 69 | * how many levels of indirection. |
| 70 | */ |
| 71 | sh = 0; |
| 72 | nb = 1; |
| 73 | bn -= NADDR-3; |
| 74 | for(j=3; j>0; j--) { |
| 75 | sh += NSHIFT; |
| 76 | nb <<= NSHIFT; |
| 77 | if(bn < nb) |
| 78 | break; |
| 79 | bn -= nb; |
| 80 | } |
| 81 | if(j == 0) { |
| 82 | u.u_error = EFBIG; |
| 83 | return((daddr_t)0); |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * fetch the first indirect block |
| 88 | */ |
| 89 | nb = ip->i_un.i_addr[NADDR-j]; |
| 90 | if(nb == 0) { |
| 91 | if(rwflg==B_READ || (bp = alloc(dev))==NULL) |
| 92 | return((daddr_t)-1); |
| 93 | nb = dbtofsb(bp->b_blkno); |
| 94 | /* |
| 95 | * Write synchronously so that indirect blocks |
| 96 | * never point at garbage. |
| 97 | */ |
| 98 | bwrite(bp); |
| 99 | ip->i_un.i_addr[NADDR-j] = nb; |
| 100 | ip->i_flag |= IUPD|ICHG; |
| 101 | } |
| 102 | |
| 103 | /* |
| 104 | * fetch through the indirect blocks |
| 105 | */ |
| 106 | for(; j<=3; j++) { |
| 107 | bp = bread(dev, nb); |
| 108 | if(bp->b_flags & B_ERROR) { |
| 109 | brelse(bp); |
| 110 | return((daddr_t)0); |
| 111 | } |
| 112 | bap = bp->b_un.b_daddr; |
| 113 | sh -= NSHIFT; |
| 114 | i = (bn>>sh) & NMASK; |
| 115 | nb = bap[i]; |
| 116 | if(nb == 0) { |
| 117 | if(rwflg==B_READ || (nbp = alloc(dev))==NULL) { |
| 118 | brelse(bp); |
| 119 | return((daddr_t)-1); |
| 120 | } |
| 121 | nb = dbtofsb(nbp->b_blkno); |
| 122 | if (j < 3 || (ip->i_mode&IFMT) == IFDIR) |
| 123 | /* |
| 124 | * Write synchronously so indirect blocks |
| 125 | * never point at garbage and blocks |
| 126 | * in directories never contain garbage. |
| 127 | */ |
| 128 | bwrite(nbp); |
| 129 | else |
| 130 | bdwrite(nbp); |
| 131 | bap[i] = nb; |
| 132 | bdwrite(bp); |
| 133 | } else |
| 134 | brelse(bp); |
| 135 | } |
| 136 | |
| 137 | /* |
| 138 | * calculate read-ahead. |
| 139 | */ |
| 140 | if(i < NINDIR-1) |
| 141 | rablock = bap[i+1]; |
| 142 | return(nb); |
| 143 | } |
| 144 | |
| 145 | /* |
| 146 | * Pass back c to the user at his location u_base; |
| 147 | * update u_base, u_count, and u_offset. Return -1 |
| 148 | * on the last character of the user's read. |
| 149 | * u_base is in the user address space unless u_segflg is set. |
| 150 | */ |
| 151 | passc(c) |
| 152 | register c; |
| 153 | { |
| 154 | register id; |
| 155 | |
| 156 | if((id = u.u_segflg) == 1) |
| 157 | *u.u_base = c; |
| 158 | else |
| 159 | if(id?suibyte(u.u_base, c):subyte(u.u_base, c) < 0) { |
| 160 | u.u_error = EFAULT; |
| 161 | return(-1); |
| 162 | } |
| 163 | u.u_count--; |
| 164 | u.u_offset++; |
| 165 | u.u_base++; |
| 166 | return(u.u_count == 0? -1: 0); |
| 167 | } |
| 168 | |
| 169 | #include "ct.h" |
| 170 | #if NCT > 0 |
| 171 | /* |
| 172 | * Pick up and return the next character from the user's |
| 173 | * write call at location u_base; |
| 174 | * update u_base, u_count, and u_offset. Return -1 |
| 175 | * when u_count is exhausted. u_base is in the user's |
| 176 | * address space unless u_segflg is set. |
| 177 | */ |
| 178 | cpass() |
| 179 | { |
| 180 | register c, id; |
| 181 | |
| 182 | if(u.u_count == 0) |
| 183 | return(-1); |
| 184 | if((id = u.u_segflg) == 1) |
| 185 | c = *u.u_base; |
| 186 | else |
| 187 | if((c = id==0?fubyte(u.u_base):fuibyte(u.u_base)) < 0) { |
| 188 | u.u_error = EFAULT; |
| 189 | return(-1); |
| 190 | } |
| 191 | u.u_count--; |
| 192 | u.u_offset++; |
| 193 | u.u_base++; |
| 194 | return(c&0377); |
| 195 | } |
| 196 | #endif |
| 197 | |
| 198 | /* |
| 199 | * Routine which sets a user error; placed in |
| 200 | * illegal entries in the bdevsw and cdevsw tables. |
| 201 | */ |
| 202 | nodev() |
| 203 | { |
| 204 | |
| 205 | u.u_error = ENODEV; |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * Null routine; placed in insignificant entries |
| 210 | * in the bdevsw and cdevsw tables. |
| 211 | */ |
| 212 | nulldev() |
| 213 | { |
| 214 | |
| 215 | } |
| 216 | |
| 217 | imin(a, b) |
| 218 | { |
| 219 | |
| 220 | return (a < b ? a : b); |
| 221 | } |
| 222 | |
| 223 | imax(a, b) |
| 224 | { |
| 225 | |
| 226 | return (a > b ? a : b); |
| 227 | } |
| 228 | |
| 229 | struct proc * |
| 230 | pfind(pid) |
| 231 | int pid; |
| 232 | { |
| 233 | register struct proc *p; |
| 234 | |
| 235 | for (p = &proc[pidhash[PIDHASH(pid)]]; p != &proc[0]; p = &proc[p->p_idhash]) |
| 236 | if (p->p_pid == pid) |
| 237 | return (p); |
| 238 | return ((struct proc *)0); |
| 239 | } |