Fix a number of long-standing restore bugs in tape.c, mainly relating

to multi-volume restores:
 - In findinode(), keep a copy of header->c_type so that we don't
   exit the do-while loop until we have processed the current header.
   Exiting too early leaves curfile.ino set to 0, which confuses
   the logic in createfiles(), so multi-volume restores with the
   'x' command don't work if you follow the instructions and supply
   the tapes in reverse order.  This appears to have been broken
   by CSRG revision 5.33 tape.c (Oct 1992).
 - The logic in getvol() for deciding how many records to skip after
   the volume header was confused; sometimes it would skip too few
   records and sometimes too many, leading to "resync restore"
   warnings and missing files. Skip to the next header only when
   the current action is not `USING'. Work around a dump bug that
   sets c_count incorrectly in the volume header of the first tape.
   Some of the problems here date back to at least 1991.
 - Back out revision 1.23. This appeared to avoid warnings about
   missing files in the 'rN' verification case, but it made the
   problems with the 'x' command worse by stopping getvol() from
   even attempting to find the first inode number on the newly
   inserted tape. The bug it addressed is fixed by correcting the
   skipping logic as described above.
 - Save the value of `tpblksread' in case the wrong volume is
   supplied, because it is incremented each time we read a volume
   header. We already saved `blksread' for the same reson.

1 files changed, 19 insertions, 18 deletions

diff --git a/sbin/restore/tape.c b/sbin/restore/tape.c
index cbb93e5..560c437 100644
--- a/sbin/restore/tape.c
+++ b/sbin/restore/tape.c
@@ -297,7 +297,7 @@ void
 getvol(nextvol)
 	long nextvol;
 {
-	long newvol, savecnt, wantnext, i;
+	long newvol, savecnt, savetpcnt, i;
 	union u_spcl tmpspcl;
 #	define tmpbuf tmpspcl.s_spcl
 	char buf[TP_BSIZE];
@@ -318,16 +318,15 @@ getvol(nextvol)
 		goto gethdr;
 	}
 	savecnt = blksread;
+	savetpcnt = tpblksread;
 again:
+	tpblksread = savetpcnt;
 	if (pipein)
 		done(1); /* pipes do not get a second chance */
-	if (command == 'R' || command == 'r' || curfile.action != SKIP) {
+	if (command == 'R' || command == 'r' || curfile.action != SKIP)
 		newvol = nextvol;
-		wantnext = 1;
-	} else {
+	else
 		newvol = 0;
-		wantnext = 0;
-	}
 	while (newvol <= 0) {
 		if (tapesread == 0) {
 			fprintf(stderr, "%s%s%s%s%s",
@@ -424,10 +423,16 @@ gethdr:
 	dprintf(stdout, "read %ld recs, tape starts with %ld\n",
 		tpblksread, tmpbuf.c_firstrec);
  	if (tmpbuf.c_type == TS_TAPE && (tmpbuf.c_flags & DR_NEWHEADER)) {
- 		if (!wantnext) {
+ 		if (curfile.action != USING) {
  			tpblksread = tmpbuf.c_firstrec;
- 			for (i = tmpbuf.c_count; i > 0; i--)
- 				readtape(buf);
+			/*
+			 * XXX Dump incorrectly sets c_count to 1 in the
+			 * volume header of the first tape, so ignore
+			 * c_count when volno == 1.
+			 */
+			if (volno != 1)
+				for (i = tmpbuf.c_count; i > 0; i--)
+					readtape(buf);
  		} else if (tmpbuf.c_firstrec > 0 &&
 			   tmpbuf.c_firstrec < tpblksread - 1) {
 			/*
@@ -440,17 +445,11 @@ gethdr:
  				readtape(buf);
  		}
  	}
-	if (curfile.action == USING  || curfile.action == SKIP) {
+	if (curfile.action == USING) {
 		if (volno == 1)
 			panic("active file into volume 1\n");
 		return;
 	}
-	/*
-	 * Skip up to the beginning of the next record
-	 */
-	if (tmpbuf.c_type == TS_TAPE && (tmpbuf.c_flags & DR_NEWHEADER))
-		for (i = tmpbuf.c_count; i > 0; i--)
-			readtape(buf);
 	(void) gethead(&spcl);
 	findinode(&spcl);
 	if (gettingfile) {
@@ -1222,6 +1221,7 @@ findinode(header)
 	static long skipcnt = 0;
 	long i;
 	char buf[TP_BSIZE];
+	int htype;
 
 	curfile.name = "<name unknown>";
 	curfile.action = UNKNOWN;
@@ -1234,7 +1234,8 @@ findinode(header)
 			    _time32_to_time(header->c_date) != dumpdate)
 				skipcnt++;
 		}
-		switch (header->c_type) {
+		htype = header->c_type;
+		switch (htype) {
 
 		case TS_ADDR:
 			/*
@@ -1274,7 +1275,7 @@ findinode(header)
 			/* NOTREACHED */
 
 		}
-	} while (header->c_type == TS_ADDR);
+	} while (htype == TS_ADDR);
 	if (skipcnt > 0)
 		fprintf(stderr, "resync restore, skipped %ld blocks\n",
 		    skipcnt);