dd: add status=progress support

This reports the current status on a single line every second, mirroring
similar functionality in GNU dd, and carefully interacts with SIGINFO.

PR:		229615
Submitted by:	Thomas Hurst <tom@hur.st> (modified for style(9) nits by me)
MFC after:	1 week

bin/dd/args.c

@@ -306,6 +306,8 @@ f_status(char *arg)
 		ddflags |= C_NOINFO;
 	else if (strcmp(arg, "noxfer") == 0)
 		ddflags |= C_NOXFER;
+	else if (strcmp(arg, "progress") == 0)
+		ddflags |= C_PROGRESS;
 	else
 		errx(1, "unknown status %s", arg);
 }

bin/dd/dd.1

@@ -32,7 +32,7 @@
 .\"     @(#)dd.1	8.2 (Berkeley) 1/13/94
 .\" $FreeBSD$
 .\"
-.Dd April 2, 2017
+.Dd August 8, 2018
 .Dt DD 1
 .Os
 .Sh NAME
@@ -164,12 +164,14 @@ bytes per second.
 Where
 .Cm value
 is one of the symbols from the following list.
-.Bl -tag -width "noxfer"
+.Bl -tag -width "progress"
 .It Cm noxfer
 Do not print the transfer statistics as the last line of status output.
 .It Cm none
 Do not print the status output.
 Error messages are shown; informational messages are not.
+.It Cm progress
+Print basic transfer statistics once per second.
 .El
 .It Cm conv Ns = Ns Ar value Ns Op , Ns Ar value ...
 Where

bin/dd/dd.c

@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/disklabel.h>
 #include <sys/filio.h>
 #include <sys/mtio.h>
+#include <sys/time.h>
 
 #include <assert.h>
 #include <capsicum_helpers.h>
@@ -89,6 +90,7 @@ const	u_char *ctab;		/* conversion table */
 char	fill_char;		/* Character to fill with if defined */
 size_t	speed = 0;		/* maximum speed, in bytes per second */
 volatile sig_atomic_t need_summary;
+volatile sig_atomic_t need_progress;
 
 int
 main(int argc __unused, char *argv[])
@@ -102,6 +104,7 @@ main(int argc __unused, char *argv[])
 		err(1, "unable to enter capability mode");
 
 	(void)signal(SIGINFO, siginfo_handler);
+	(void)signal(SIGALRM, sigalrm_handler);
 	(void)signal(SIGINT, terminate);
 
 	atexit(summary);
@@ -281,6 +284,14 @@ setup(void)
 		ctab = casetab;
 	}
 
+	if ((ddflags & C_PROGRESS)) {
+		struct itimerval timer = {
+			.it_interval = { .tv_sec = 1, .tv_usec = 0 },
+			.it_value = { .tv_sec = 1, .tv_usec = 0 },
+		};
+		setitimer(ITIMER_REAL, &timer, NULL);
+	}
+
 	if (clock_gettime(CLOCK_MONOTONIC, &st.start))
 		err(1, "clock_gettime");
 }
@@ -461,6 +472,9 @@ dd_in(void)
 		if (need_summary) {
 			summary();
 		}
+		if (need_progress) {
+			progress();
+		}
 	}
 }
 

bin/dd/dd.h

@@ -100,5 +100,6 @@ typedef struct {
 #define	C_STATUS	0x08000000
 #define	C_NOXFER	0x10000000
 #define	C_NOINFO	0x20000000
+#define	C_PROGRESS	0x40000000
 
 #define	C_PARITY	(C_PAREVEN | C_PARODD | C_PARNONE | C_PARSET)

bin/dd/extern.h

@@ -46,7 +46,9 @@ void pos_in(void);
 void pos_out(void);
 double secs_elapsed(void);
 void summary(void);
+void progress(void);
 void siginfo_handler(int);
+void sigalrm_handler(int);
 void terminate(int);
 void unblock(void);
 void unblock_close(void);
@@ -66,3 +68,4 @@ extern const u_char a2ibm_32V[], a2ibm_POSIX[];
 extern u_char casetab[];
 extern char fill_char;
 extern volatile sig_atomic_t need_summary;
+extern volatile sig_atomic_t need_progress;

bin/dd/misc.c

@@ -56,6 +56,8 @@ __FBSDID("$FreeBSD$");
 #include "dd.h"
 #include "extern.h"
 
+static int need_newline;
+
 double
 secs_elapsed(void)
 {
@@ -83,6 +85,9 @@ summary(void)
 	if (ddflags & C_NOINFO)
 		return;
 
+	if (need_newline && !need_summary)
+		fprintf(stderr, "\n");
+
 	secs = secs_elapsed();
 
 	(void)fprintf(stderr,
@@ -102,6 +107,28 @@ summary(void)
 	need_summary = 0;
 }
 
+void
+progress(void)
+{
+	double secs;
+	static int lastlen;
+	int len;
+
+	secs = secs_elapsed();
+	len = fprintf(stderr,
+	    "\r%ju bytes transferred in %.0f secs (%.0f bytes/sec)",
+	    st.bytes, secs, st.bytes / secs);
+
+	if (len > 0) {
+		if (len < lastlen)
+			(void)fprintf(stderr, "%*s", len - lastlen, "");
+		lastlen = len;
+	}
+
+	need_newline = 1;
+	need_progress = 0;
+}
+
 /* ARGSUSED */
 void
 siginfo_handler(int signo __unused)
@@ -110,6 +137,14 @@ siginfo_handler(int signo __unused)
 	need_summary = 1;
 }
 
+/* ARGSUSED */
+void
+sigalrm_handler(int signo __unused)
+{
+
+	need_progress = 1;
+}
+
 /* ARGSUSED */
 void
 terminate(int sig)