+ byte *rbuf, *wbuf, *msg;
+ sh_off_t rstart, wstart, w_bucket_start;
+ int roff, woff, rsize, l;
+ struct obuck_header *rhdr, *whdr;
+
+ rbuf = xmalloc(obuck_shake_buflen);
+ wbuf = xmalloc(obuck_shake_buflen);
+ rstart = wstart = 0;
+ roff = woff = rsize = 0;
+
+ /* We need to be the only accessor, all the object ID's are becoming invalid */
+ obuck_lock_write();
+
+ for(;;)
+ {
+ bucket_start = rstart + roff;
+ w_bucket_start = wstart + woff;
+ if (rsize - roff < OBUCK_ALIGN)
+ goto reread;
+ rhdr = (struct obuck_header *)(rbuf + roff);
+ if (rhdr->magic != OBUCK_MAGIC ||
+ rhdr->oid != OBUCK_OID_DELETED && rhdr->oid != (oid_t)(bucket_start >> OBUCK_SHIFT))
+ {
+ msg = "header mismatch";
+ goto broken;
+ }
+ l = (sizeof(struct obuck_header) + rhdr->length + 4 + OBUCK_ALIGN - 1) & ~(OBUCK_ALIGN-1);
+ if (l > obuck_shake_buflen)
+ {
+ if (rhdr->oid != OBUCK_OID_DELETED)
+ {
+ msg = "bucket longer than ShakeBufSize";
+ goto broken;
+ }
+ rstart = bucket_start + l;
+ roff = 0;
+ rsize = 0;
+ goto reread;
+ }
+ if (rsize - roff < l)
+ goto reread;
+ if (GET_U32(rbuf + roff + l - 4) != OBUCK_TRAILER)
+ {
+ msg = "missing trailer";
+ goto broken;
+ }
+ if (rhdr->oid != OBUCK_OID_DELETED)
+ {
+ if (kibitz(rhdr, w_bucket_start >> OBUCK_SHIFT, (byte *)(rhdr+1)))
+ {
+ if (bucket_start == w_bucket_start)
+ {
+ /* No copying needed now nor ever in the past, hence woff==0 */
+ wstart += l;
+ }
+ else
+ {
+ if (obuck_shake_buflen - woff < l)
+ {
+ if (sh_pwrite(obuck_fd, wbuf, woff, wstart) != woff)
+ die("obuck_shakedown write failed: %m");
+ wstart += woff;
+ woff = 0;
+ }
+ whdr = (struct obuck_header *)(wbuf+woff);
+ memcpy(whdr, rhdr, l);
+ whdr->oid = w_bucket_start >> OBUCK_SHIFT;
+ woff += l;
+ }
+ }
+ }
+ else
+ kibitz(rhdr, OBUCK_OID_DELETED, NULL);
+ roff += l;
+ continue;
+
+ reread:
+ if (roff)
+ {
+ memmove(rbuf, rbuf+roff, rsize-roff);
+ rsize -= roff;
+ rstart += roff;
+ roff = 0;
+ }
+ l = sh_pread(obuck_fd, rbuf+rsize, obuck_shake_buflen-rsize, rstart+rsize);
+ if (l < 0)
+ die("obuck_shakedown read error: %m");
+ if (!l)
+ {
+ if (!rsize)
+ break;
+ msg = "unexpected EOF";
+ goto broken;
+ }
+ rsize += l;
+ }
+ if (woff)
+ {
+ if (sh_pwrite(obuck_fd, wbuf, woff, wstart) != woff)
+ die("obuck_shakedown write failed: %m");
+ wstart += woff;
+ }
+ sh_ftruncate(obuck_fd, wstart);
+