Implement seekability for disk devices (not just regular files).

Also, fix pos_out() to do the same checks pos_in() did.

Done for:	jdp, luigi, the good of the world

3 files changed, 13 insertions, 11 deletions

diff --git a/bin/dd/dd.c b/bin/dd/dd.c
index b817b00..b6e0ebb 100644
--- a/bin/dd/dd.c
+++ b/bin/dd/dd.c
@@ -46,11 +46,12 @@ static char const copyright[] =
 static char sccsid[] = "@(#)dd.c	8.5 (Berkeley) 4/2/94";
 #endif
 static const char rcsid[] =
-	"$Id: dd.c,v 1.16 1999/04/25 21:13:33 imp Exp $";
+	"$Id: dd.c,v 1.18 1999/06/20 14:58:51 green Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
 #include <sys/stat.h>
+#include <sys/diskslice.h>
 #include <sys/mtio.h>
 
 #include <ctype.h>
@@ -224,10 +225,14 @@ getfdtype(io)
 	IO *io;
 {
 	struct mtget mt;
+	struct diskslices ds;
 	struct stat sb;
 
 	if (fstat(io->fd, &sb))
 		err(1, "%s", io->name);
+	if ((S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode)) &&
+	    ioctl(io->fd, DIOCGSLICEINFO, &ds) != -1)
+		io->flags |= ISDISK;
 	if (S_ISCHR(sb.st_mode))
 		io->flags |= ioctl(io->fd, MTIOCGET, &mt) ? ISCHR : ISTAPE;
 	else if (lseek(io->fd, (off_t)0, SEEK_CUR) == -1 && errno == ESPIPE)
diff --git a/bin/dd/dd.h b/bin/dd/dd.h
index bc3fd60..9344d3d 100644
--- a/bin/dd/dd.h
+++ b/bin/dd/dd.h
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)dd.h	8.3 (Berkeley) 4/2/94
- *	$Id: dd.h,v 1.8 1998/02/11 02:23:31 asami Exp $
+ *	$Id: dd.h,v 1.10 1999/06/20 14:58:51 green Exp $
  */
 
 /* Input/output stream state. */
@@ -49,7 +49,8 @@ typedef struct {
 #define	ISCHR		0x01		/* character device (warn on short) */
 #define	ISPIPE		0x02		/* pipe (not truncatable) */
 #define	ISTAPE		0x04		/* tape (not seekable) */
-#define	NOREAD		0x08		/* not readable */
+#define	ISDISK		0x08		/* disk (valid to seek on) */
+#define	NOREAD		0x10		/* not readable */
 	u_int	flags;
 
 	char 	*name;			/* name */
diff --git a/bin/dd/position.c b/bin/dd/position.c
index 7bab913..ae5191f 100644
--- a/bin/dd/position.c
+++ b/bin/dd/position.c
@@ -40,7 +40,7 @@
 static char sccsid[] = "@(#)position.c	8.3 (Berkeley) 4/2/94";
 #endif
 static const char rcsid[] =
-	"$Id: position.c,v 1.8 1998/05/13 07:33:54 charnier Exp $";
+	"$Id: position.c,v 1.10 1999/06/20 14:58:55 green Exp $";
 #endif /* not lint */
 
 #include <sys/types.h>
@@ -66,7 +66,7 @@ pos_in()
 	off_t cnt;
 
 	/* If not a character, pipe or tape device, try to seek on it. */
-	if (!(in.flags & (ISCHR|ISPIPE|ISTAPE))) {
+	if (!(in.flags & (ISCHR|ISPIPE|ISTAPE)) || in.flags & ISDISK) {
 		if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1)
 			err(1, "%s", in.name);
 		return;
@@ -121,12 +121,8 @@ pos_out()
 	off_t cnt;
 	ssize_t n;
 
-	/*
-	 * If not a tape, try seeking on the file.  Seeking on a pipe is
-	 * going to fail, but don't protect the user -- they shouldn't
-	 * have specified the seek operand.
-	 */
-	if (!(out.flags & ISTAPE)) {
+	/* If not a character, pipe or tape device, try to seek on it. */
+	if (!(out.flags & (ISCHR|ISPIPE|ISTAPE)) || out.flags & ISDISK) {
 		if (lseek(out.fd, out.offset * out.dbsz, SEEK_SET) == -1)
 			err(1, "%s", out.name);
 		return;