Add -P arguments for dump(8) and restore(8) which allow the user to

use backup methods other than files and tapes.  The -P argument is
a normal sh(1) pipeline with either $DUMP_VOLUME or $RESTORE_VOLUME
defined in the environment, respectively.

For example, I can back up my home to three DVD+R[W]s as so:
Filesystem  1K-blocks     Used    Avail Capacity  Mounted on
/dev/ad0s2e  40028550 10093140 26733126    27%    /home
green# dump -0 -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /home

4 files changed, 84 insertions, 20 deletions

diff --git a/sbin/dump/dump.8 b/sbin/dump/dump.8
index 0e86ebe..fedf9a6 100644
--- a/sbin/dump/dump.8
+++ b/sbin/dump/dump.8
@@ -44,7 +44,7 @@
 .Op Fl C Ar cachesize
 .Op Fl D Ar dumpdates
 .Op Fl d Ar density
-.Op Fl f Ar file
+.Op Fl f Ar file | Fl P Ar pipecommand
 .Op Fl h Ar level
 .Op Fl s Ar feet
 .Op Fl T Ar date
@@ -190,6 +190,28 @@ program is
 .Pa /etc/rmt ;
 this can be overridden by the environment variable
 .Ev RMT .
+.It Fl P Ar pipecommand
+Use
+.Xr popen 3
+to execute the
+.Xr sh 1
+script string defined by
+.Ar pipecommand
+for the output device of each volume.
+This child pipeline's
+.Dv stdin
+.Pa ( /dev/fd/0 )
+is redirected from the
+.Nm
+output stream, and the environment variable
+.Ev DUMP_VOLUME
+is set to the current volume number being written.
+After every volume, the writer side of the pipe is closed and
+.Ar pipecommand
+is executed again.
+Subject to the media size specified by
+.Fl B ,
+each volume is written in this manner as if the output were a tape drive.
 .It Fl h Ar level
 Honor the user
 .Dq nodump
diff --git a/sbin/dump/dump.h b/sbin/dump/dump.h
index 08acb9e..75b33d5 100644
--- a/sbin/dump/dump.h
+++ b/sbin/dump/dump.h
@@ -56,6 +56,7 @@ char	*dumpinomap;	/* map of files to be dumped */
  */
 char	*disk;		/* name of the disk file */
 char	*tape;		/* name of the tape file */
+char	*popenout;	/* popen(3) per-"tape" command */
 char	*dumpdates;	/* name of the file containing dump date information*/
 char	*temp;		/* name of the file for doing rewrite of dumpdates */
 char	lastlevel;	/* dump level of previous dump */
diff --git a/sbin/dump/main.c b/sbin/dump/main.c
index baf8a25..09c27ab 100644
--- a/sbin/dump/main.c
+++ b/sbin/dump/main.c
@@ -110,9 +110,9 @@ main(int argc, char *argv[])
 	spcl.c_date = _time_to_time64(time(NULL));
 
 	tsize = 0;	/* Default later, based on 'c' option for cart tapes */
-	if ((tape = getenv("TAPE")) == NULL)
-		tape = _PATH_DEFTAPE;
 	dumpdates = _PATH_DUMPDATES;
+	popenout = NULL;
+	tape = NULL;
 	temp = _PATH_DTMP;
 	if (TP_BSIZE / DEV_BSIZE == 0 || TP_BSIZE % DEV_BSIZE != 0)
 		quit("TP_BSIZE must be a multiple of DEV_BSIZE\n");
@@ -123,7 +123,7 @@ main(int argc, char *argv[])
 
 	obsolete(&argc, &argv);
 	while ((ch = getopt(argc, argv,
-	    "0123456789aB:b:C:cD:d:f:h:LnSs:T:uWw")) != -1)
+	    "0123456789aB:b:C:cD:d:f:h:LnP:Ss:T:uWw")) != -1)
 		switch (ch) {
 		/* dump level */
 		case '0': case '1': case '2': case '3': case '4':
@@ -164,6 +164,9 @@ main(int argc, char *argv[])
 			break;
 
 		case 'f':		/* output file */
+			if (popenout != NULL)
+				errx(X_STARTUP, "You cannot use the P and f "
+				    "flags together.\n");
 			tape = optarg;
 			break;
 
@@ -179,6 +182,13 @@ main(int argc, char *argv[])
 			notify = 1;
 			break;
 
+		case 'P':
+			if (tape != NULL)
+				errx(X_STARTUP, "You cannot use the P and f "
+				    "flags together.\n");
+			popenout = optarg;
+			break;
+
 		case 'S':               /* exit after estimating # of tapes */
 			just_estimate = 1;
 			break;
@@ -231,6 +241,10 @@ main(int argc, char *argv[])
 		    "You cannot use the T and u flags together.\n");
 		exit(X_STARTUP);
 	}
+	if (popenout) {
+		tape = "child pipeline process";
+	} else if (tape == NULL && (tape = getenv("TAPE")) == NULL)
+		tape = _PATH_DEFTAPE;
 	if (strcmp(tape, "-") == 0) {
 		pipeout++;
 		tape = "standard output";
@@ -316,8 +330,8 @@ main(int argc, char *argv[])
 				snapdump = 0;
 			}
 		} else if (snapdump == 0) {
-			msg("WARNING: %s%s\n",
-			    "should use -L when dumping live read-write ",
+			msg("WARNING: %s\n",
+			    "should use -L when dumping live read-write "
 			    "filesystems!");
 		} else {
 			char snapname[BUFSIZ], snapcmd[BUFSIZ];
@@ -562,8 +576,8 @@ usage(void)
 {
 	fprintf(stderr,
 		"usage: dump [-0123456789acLnSu] [-B records] [-b blocksize] [-C cachesize]\n"
-		"            [-D dumpdates] [-d density] [-f file] [-h level] [-s feet]\n"
-		"            [-T date] filesystem\n"
+		"            [-D dumpdates] [-d density] [-h level] [-s feet] [-T date]\n"
+		"            [-f file | -P pipecommand] filesystem\n"
 		"       dump -W | -w\n");
 	exit(X_STARTUP);
 }
diff --git a/sbin/dump/tape.c b/sbin/dump/tape.c
index 5437e05..490d3d9 100644
--- a/sbin/dump/tape.c
+++ b/sbin/dump/tape.c
@@ -67,6 +67,7 @@ extern	int ntrec;		/* blocking factor on tape */
 extern	int cartridge;
 extern	char *host;
 char	*nexttape;
+FILE	*popenfp = NULL;
 
 static	int atomic(ssize_t (*)(), int, char *, int);
 static	void doslave(int, int);
@@ -336,6 +337,12 @@ trewind(void)
 
 	msg("Closing %s\n", tape);
 
+	if (popenout) {
+		tapefd = -1;
+		(void)pclose(popenfp);
+		popenfp = NULL;
+		return;
+	}
 #ifdef RDUMP
 	if (host) {
 		rmtclose();
@@ -500,7 +507,6 @@ startnewtape(int top)
 	int	parentpid;
 	int	childpid;
 	int	status;
-	int	waitpid;
 	char	*p;
 	sig_t	interrupt_save;
 
@@ -530,9 +536,9 @@ restore_check_point:
 		msg("Tape: %d; parent process: %d child process %d\n",
 			tapeno+1, parentpid, childpid);
 #endif /* TDEBUG */
-		while ((waitpid = wait(&status)) != childpid)
-			msg("Parent %d waiting for child %d has another child %d return\n",
-				parentpid, childpid, waitpid);
+		if (waitpid(childpid, &status, 0) == -1)
+			msg("Waiting for child %d: %s\n", childpid,
+			    strerror(errno));
 		if (status & 0xFF) {
 			msg("Child %d returns LOB status %o\n",
 				childpid, status&0xFF);
@@ -589,20 +595,41 @@ restore_check_point:
 				nexttape = NULL;
 			msg("Dumping volume %d on %s\n", tapeno, tape);
 		}
+		if (pipeout) {
+			tapefd = STDOUT_FILENO;
+		} else if (popenout) {
+			char volno[sizeof("2147483647")];
+
+			(void)sprintf(volno, "%d", spcl.c_volume + 1);
+			if (setenv("DUMP_VOLUME", volno, 1) == -1) {
+				msg("Cannot set $DUMP_VOLUME.\n");
+				dumpabort(0);
+			}
+			popenfp = popen(popenout, "w");
+			if (popenfp == NULL) {
+				msg("Cannot open output pipeline \"%s\".\n",
+				    popenout);
+				dumpabort(0);
+			}
+			tapefd = fileno(popenfp);
+		} else {
 #ifdef RDUMP
-		while ((tapefd = (host ? rmtopen(tape, 2) :
-			pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
+			while ((tapefd = (host ? rmtopen(tape, 2) :
+				open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
 #else
-		while ((tapefd = (pipeout ? 1 :
-				  open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
+			while ((tapefd =
+			    open(tape, O_WRONLY|O_CREAT, 0666)) < 0)
 #endif
-		    {
-			msg("Cannot open output \"%s\".\n", tape);
-			if (!query("Do you want to retry the open?"))
-				dumpabort(0);
+			    {
+				msg("Cannot open output \"%s\".\n", tape);
+				if (!query("Do you want to retry the open?"))
+					dumpabort(0);
+			}
 		}
 
 		enslave();  /* Share open tape file descriptor with slaves */
+		if (popenout)
+			close(tapefd);	/* Give up our copy of it. */
 		signal(SIGINFO, infosch);
 
 		asize = 0;