From 513eba4411f9c6f8b09375734fdaafc49a962eae Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Wed, 16 Feb 2022 23:37:50 +0000
Subject: [PATCH] dvd-sector-copy.c: Add machinery for installing pretend bad
 sectors.

For testing the recovery algorithm(s).
---
 dvd-sector-copy.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/dvd-sector-copy.c b/dvd-sector-copy.c
index c6bad44..28a4943 100644
--- a/dvd-sector-copy.c
+++ b/dvd-sector-copy.c
@@ -32,6 +32,12 @@
 #define ISDIGIT(ch) CTYPE_HACK(isdigit, ch)
 #define ISSPACE(ch) CTYPE_HACK(isspace, ch)
 
+#ifdef DEBUG
+#  define D(x) x
+#else
+#  define D(x)
+#endif
+
 #define N(v) (sizeof(v)/sizeof((v)[0]))
 
 #define SECTORSZ 2048
@@ -390,9 +396,51 @@ static int dvdfd = -1, outfd = -1;
 static dvd_file_t *vob;
 static const char *mapfile; static FILE *mapfp;
 
+struct badblock { secaddr start, end; };
+DEFVEC(badblock_v, struct badblock);
+static badblock_v badblocks = VEC_INIT;
+
+static int compare_badblock(const void *a, const void *b)
+{
+  const struct badblock *ba = a, *bb = b;
+
+  if (ba->start < bb->start) return (-1);
+  else if (ba->start > bb->start) return (+1);
+
+  if (ba->end < bb->end) return (-1);
+  else if (ba->end > bb->end) return (+1);
+
+  return (0);
+}
+
 static ssize_t read_sectors(secaddr pos, void *buf, secaddr want)
 {
   ssize_t n;
+  size_t lo, mid, hi;
+  struct badblock *bad, *best;
+
+  best = 0; lo = 0; hi = badblocks.n;
+#ifdef DEBUG
+  clear_progress();
+  printf(";; searching badblocks for %"PRIuSEC" .. %"PRIuSEC"\n",
+	 pos, pos + want);
+#endif
+  while (lo < hi) {
+    mid = lo + (hi - lo)/2; bad = &badblocks.v[mid];
+#ifdef DEBUG
+    printf(";;   try %zu (%"PRIuSEC" .. %"PRIuSEC")... ",
+	   mid, bad->start, bad->end);
+#endif
+    if (pos < bad->start) { D( printf("high\n"); ) best = bad; hi = mid; }
+    else if (pos >= bad->end) { D( printf("low\n"); ) lo = mid + 1; }
+    else { D( printf("match!\n"); ) errno = EIO; return (-1); }
+  }
+#ifdef DEBUG
+  if (best)
+    printf(";;   next is %"PRIuSEC" .. %"PRIuSEC"\n",
+	   best->start, best->end);
+#endif
+  if (best && pos + want > best->start) want = best->start - pos;
 
 again:
   if (vob)
@@ -651,6 +699,7 @@ int main(int argc, char *argv[])
   secaddr start, end, last;
   const struct event *ev;
   const char *device, *outfile;
+  struct badblock *bad;
   int opt, blksz;
   unsigned n;
   size_t i;
@@ -699,6 +748,25 @@ int main(int argc, char *argv[])
 	if (ferror(fp))
 	  bail_syserr(errno, "failed to read ranges file `%s'", optarg);
 	break;
+      case 'X':
+	fp = fopen(optarg, "r");
+	if (!fp)
+	  bail_syserr(errno, "failed to open bad-blocks file `%s'", optarg);
+	i = 0; last = -1;
+	for (;;) {
+	  BUF_REWIND(&buf); if (read_line(fp, &buf)) break;
+	  p = buf.p; i++;
+	  while (ISSPACE(*p)) p++;
+	  if (!*p || *p == '#') continue;
+	  if (parse_range(p, 0, &start, &end) ||
+	      (last <= SECLIMIT && start < last))
+	    bail("bad range `%s' at `%s' line %zu", buf.p, optarg, i);
+	  if (start < end)
+	    { VEC_PUSH(bad, &badblocks); bad->start = start; bad->end = end; }
+	}
+	if (ferror(fp))
+	  bail_syserr(errno, "failed to read bad-blocks file `%s'", optarg);
+	break;
       case 'b':
 	if (mapfile) bail("can't have multiple map files");
 	mapfile = optarg;
@@ -721,6 +789,17 @@ int main(int argc, char *argv[])
 
   device = argv[optind]; outfile = argv[optind + 1];
 
+  if (badblocks.n) {
+    qsort(badblocks.v, badblocks.n, sizeof(struct badblock),
+	  compare_badblock);
+#ifdef DEBUG
+    printf(";; fake bad blocks:\n");
+    for (i = 0; i < badblocks.n; i++)
+      printf(";;\t%8"PRIuSEC" .. %"PRIuSEC"\n",
+	     badblocks.v[i].start, badblocks.v[i].end);
+#endif
+  }
+
   dvdfd = open(device, O_RDONLY);
   if (dvdfd < 0)
     bail_syserr(errno, "failed to open device `%s'", device);
-- 
2.11.0