+ }
+ /*
+ * Calculate index into inode's block list of
+ * last direct and indirect blocks (if any)
+ * which we want to keep. Lastblock is -1 when
+ * the file is truncated to 0.
+ */
+ fs = oip->i_fs;
+ lastblock = lblkno(fs, length + fs->fs_bsize - 1) - 1;
+ lastiblock[SINGLE] = lastblock - NDADDR;
+ lastiblock[DOUBLE] = lastiblock[SINGLE] - NINDIR(fs);
+ lastiblock[TRIPLE] = lastiblock[DOUBLE] - NINDIR(fs) * NINDIR(fs);
+ nblocks = btodb(fs->fs_bsize);
+ /*
+ * Update size of file and block pointers
+ * on disk before we start freeing blocks.
+ * If we crash before free'ing blocks below,
+ * the blocks will be returned to the free list.
+ * lastiblock values are also normalized to -1
+ * for calls to indirtrunc below.
+ * (? fsck doesn't check validity of pointers in indirect blocks)
+ */
+ tip = *oip;
+ for (level = TRIPLE; level >= SINGLE; level--)
+ if (lastiblock[level] < 0) {
+ oip->i_ib[level] = 0;
+ lastiblock[level] = -1;
+ }
+ for (i = NDADDR - 1; i > lastblock; i--)
+ oip->i_db[i] = 0;
+ oip->i_size = length;
+ oip->i_flag |= ICHG|IUPD;
+ iupdat(oip, &time, &time, 1);
+ ip = &tip;