+ assert(off <= r->sz); assert(want <= r->sz - off);
+ n = read_sectors(pos, r->buf + off*SECTORSZ, want);
+ return (n);
+}
+
+static ssize_t recovery_read_buffer(struct recoverybuf *r,
+ secaddr pos, secaddr want)
+{
+ secaddr diff, pp, nn;
+ ssize_t n;
+
+#ifdef DEBUG
+ progress_clear(&progress);
+ show_recovery_buffer_map(r, "begin(%"PRIuSEC", %"PRIuSEC")", pos, want);
+#endif
+
+ if (pos < r->pos) {
+ diff = r->pos - pos;
+ if (r->start + diff >= r->sz) {
+ r->pos = pos; r->start = r->end = 0;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "cleared; shift up by %"PRIuSEC"", diff);
+#endif
+ } else {
+ if (r->end + diff > r->sz) r->end = r->sz - diff;
+ rearrange_sectors(r, r->start + diff, r->start, r->end - r->start);
+ r->pos -= diff; r->start += diff; r->end += diff;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "shifted up by %"PRIuSEC"", diff);
+#endif
+ }
+ } else if (pos > r->pos + r->end) {
+ r->pos = pos; r->start = r->end = 0;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "cleared; beyond previous region");
+#endif
+ } else if (pos + want > r->pos + r->sz) {
+ diff = (pos + want) - (r->pos + r->sz);
+ if (r->end <= diff) {
+ r->pos = pos; r->start = r->end = 0;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "cleared; shift down by %"PRIuSEC"", diff);
+#endif
+ } else {
+ if (r->start < diff) r->start = diff;
+ rearrange_sectors(r, r->start - diff, r->start, r->end - r->start);
+ r->pos += diff; r->start -= diff; r->end -= diff;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "shifted down by %"PRIuSEC"", diff);
+#endif
+ }
+ }
+
+ if (pos < r->pos + r->start) {
+ pp = pos - r->pos; nn = r->start - pp;
+#ifdef DEBUG
+ printf(";; read low (%"PRIuSEC"@%"PRIuSEC", %"PRIuSEC")", pos, pp, nn);
+ fflush(stdout);
+#endif
+ n = recovery_read_sectors(r, pos, pp, nn);
+#ifdef DEBUG
+ printf(" -> %zd\n", n);
+#endif
+ if (n != nn) {
+ if (n >= 0 && n > want) n = want;
+ goto end;
+ }
+ r->start = pp;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "joined new region");
+#endif
+ }
+
+ if (pos + want > r->pos + r->end) {
+ pp = r->end; nn = (pos + want) - (r->pos + r->end);
+#ifdef DEBUG
+ printf(";; read high (%"PRIuSEC"@%"PRIuSEC", %"PRIuSEC")",
+ r->pos + pp, pp, nn);
+ fflush(stdout);
+#endif
+ n = recovery_read_sectors(r, r->pos + pp, pp, nn);
+#ifdef DEBUG
+ printf(" -> %zd\n", n);
+#endif
+ if (n > 0) {
+ r->end += n;
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "joined new region");
+#endif
+ }
+ }
+
+ n = r->pos + r->end - pos;
+ if (!n && want) n = -1;
+ else if (n > want) n = want;
+
+end:
+#ifdef DEBUG
+ show_recovery_buffer_map(r, "done; return %zd", n);
+#endif
+ return (n);
+}
+
+static ssize_t recovery_read_multiple(struct recoverybuf *r,
+ secaddr pos, secaddr want)
+{
+ ssize_t n;
+ secaddr skip, want0 = want;
+
+ while (want > r->sz) {
+ skip = want - r->sz;
+ n = recovery_read_buffer(r, pos + skip, r->sz);
+ if (n < r->sz) return (skip + (n >= 0 ? n : 0));
+ want -= r->sz;
+ }
+ n = recovery_read_buffer(r, pos, want);
+ if (n < 0 || n < want) return (n);
+ return (want0);
+}
+
+static ssize_t recovery_read(struct recoverybuf *r,
+ secaddr pos, secaddr want)
+{
+ secaddr lo = pos, hi = pos + want, span;
+ ssize_t n;
+
+ if (hi < r->good_lo || lo > r->good_hi) {
+ n = recovery_read_multiple(r, lo, hi - lo);
+ if (n > 0) { r->good_lo = lo; r->good_hi = lo + n; }
+ return (n);
+ }
+
+ if (hi > r->good_hi) {
+ span = hi - r->good_hi;
+ n = recovery_read_multiple(r, r->good_hi, span);
+ if (n > 0) r->good_hi += n;
+ if (n < 0 || n < span) return (r->good_hi - lo);
+ }
+
+ if (lo < r->good_lo) {
+ span = r->good_lo - lo;
+ n = recovery_read_multiple(r, lo, span);
+ if (n == span) r->good_lo = lo;
+ else return (n);
+ }
+
+ n = r->good_hi - pos; if (n > want) n = want;
+ if (!n) { errno = EIO; n = -1; }
+ return (n);
+}
+
+static double clear_factor = 1.5;
+static secaddr clear_min = 1, clear_max = SECLIMIT;
+static double step_factor = 2.0;
+static secaddr step_min = 1, step_max = 0;
+
+static secaddr run_length_wanted(secaddr pos, secaddr badlen, secaddr end)
+{
+ secaddr want;
+
+ want = clear_factor*badlen;
+ if (want < clear_min) want = clear_min;
+ if (want > end - pos) want = end - pos;
+ if (clear_max && want > clear_max) want = clear_max;
+ return (want);
+}
+
+static void report_bad_blocks_progress(secaddr bad_hi, int err)
+ { bad_err = err; report_progress(bad_hi); }
+
+static ssize_t find_good_sector(secaddr *pos_inout, secaddr end,
+ unsigned char *buf, secaddr sz)
+{
+ secaddr pos = *pos_inout, bad_lo, bad_hi, good, step, want;
+ struct recoverybuf r;
+ ssize_t n;
+
+ bad_start = pos; bad_err = errno;
+ badblock_progress.render = render_badblock_progress;
+ progress_additem(&progress, &badblock_progress);
+
+ r.buf = buf; r.sz = sz; r.pos = r.start = r.end = 0;
+ r.good_lo = r.good_hi = 0;
+
+ want = sz; if (want > end - pos) want = end - pos;
+ for (retry = 0; retry < max_retries; retry++) {
+ report_bad_blocks_progress(pos, errno);
+ n = recovery_read(&r, pos, want);
+#ifdef DEBUG
+ progress_clear(&progress);
+ printf(";; [retry] try reading %"PRIuSEC" .. %"PRIuSEC" -> %zd\n",
+ pos, pos + want, n);
+#endif
+ if (n > 0) {
+ progress_clear(&progress);
+ moan("sector %"PRIuSEC" read ok after retry", pos);
+ progress_removeitem(&progress, &badblock_progress);
+ progress_update(&progress);
+ return (n);
+ }