Isolate the pr(1) related code in its own source files

This keeps diffreg.c closer to what it is supposed to do:
diffing regular files.

It also allows my code to get a proper license

usr.bin/diff/Makefile

@@ -3,7 +3,7 @@
 .include <src.opts.mk>
 
 PROG=	diff
-SRCS=	diff.c diffdir.c diffreg.c xmalloc.c
+SRCS=	diff.c diffdir.c diffreg.c xmalloc.c pr.c
 
 HAS_TESTS=
 SUBDIR.${MK_TESTS}+= tests

usr.bin/diff/diffreg.c

@@ -70,11 +70,7 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/capsicum.h>
-#include <sys/procdesc.h>
 #include <sys/stat.h>
-#include <sys/types.h>
-#include <sys/event.h>
-#include <sys/wait.h>
 
 #include <capsicum_helpers.h>
 #include <ctype.h>
@@ -88,15 +84,11 @@ __FBSDID("$FreeBSD$");
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
-#include <limits.h>
-#include <signal.h>
 
+#include "pr.h"
 #include "diff.h"
 #include "xmalloc.h"
 
-#define _PATH_PR "/usr/bin/pr"
-
 /*
  * diff - compare two files.
  */
@@ -260,13 +252,9 @@ diffreg(char *file1, char *file2, int flags, int capsicum)
 {
 	FILE *f1, *f2;
 	int i, rval;
-	int	ostdout = -1;
+	struct pr *pr = NULL;
-	int pr_pd, kq;
-	struct kevent *e;
 	cap_rights_t rights_ro;
 
-	e = NULL;
-	kq = -1;
 	f1 = f2 = NULL;
 	rval = D_SAME;
 	anychange = 0;
@@ -324,52 +312,8 @@ diffreg(char *file1, char *file2, int flags, int capsicum)
 		goto closem;
 	}
 
-	if (lflag) {
+	if (lflag)
-		/* redirect stdout to pr */
+		pr = start_pr(file1, file2);
-		int	 pfd[2];
-		pid_t	pid;
-		char	*header;
-
-		xasprintf(&header, "%s %s %s", diffargs, file1, file2);
-		signal(SIGPIPE, SIG_IGN);
-		fflush(stdout);
-		rewind(stdout);
-		pipe(pfd);
-		switch ((pid = pdfork(&pr_pd, PD_CLOEXEC))) {
-		case -1:
-			status |= 2;
-			free(header);
-			err(2, "No more processes");
-		case 0:
-			/* child */
-			if (pfd[0] != STDIN_FILENO) {
-				dup2(pfd[0], STDIN_FILENO);
-				close(pfd[0]);
-			}
-			close(pfd[1]);
-			execl(_PATH_PR, _PATH_PR, "-h", header, (char *)0);
-			_exit(127);
-		default:
-
-			/* parent */
-			if (pfd[1] != STDOUT_FILENO) {
-				ostdout = dup(STDOUT_FILENO);
-				dup2(pfd[1], STDOUT_FILENO);
-				close(pfd[1]);
-			}
-			close(pfd[0]);
-			rewind(stdout);
-			free(header);
-			kq = kqueue();
-			if (kq == -1)
-				err(2, "kqueue");
-			e = xmalloc(sizeof(struct kevent));
-			EV_SET(e, pr_pd, EVFILT_PROCDESC, EV_ADD, NOTE_EXIT, 0,
-			    NULL);
-			if (kevent(kq, e, 1, NULL, 0, NULL) == -1)
-				err(2, "kevent");
-		}
-	}
 
 	if (capsicum) {
 		cap_rights_init(&rights_ro, CAP_READ, CAP_FSTAT, CAP_SEEK);
@@ -443,26 +387,8 @@ diffreg(char *file1, char *file2, int flags, int capsicum)
 	ixnew = xreallocarray(ixnew, len[1] + 2, sizeof(*ixnew));
 	check(f1, f2, flags);
 	output(file1, f1, file2, f2, flags);
-	if (ostdout != -1 && e != NULL) {
+	if (pr != NULL)
-		/* close the pipe to pr and restore stdout */
+		stop_pr(pr);
-		int wstatus;
-
-		fflush(stdout);
-		if (ostdout != STDOUT_FILENO) {
-			close(STDOUT_FILENO);
-			dup2(ostdout, STDOUT_FILENO);
-			close(ostdout);
-		}
-		if (kevent(kq, NULL, 0, e, 1, NULL) == -1)
-			err(2, "kevent");
-		wstatus = e[0].data;
-		close(kq);
-		if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0)
-			errx(2, "pr exited abnormally");
-		else if (WIFSIGNALED(wstatus))
-			errx(2, "pr killed by signal %d",
-			    WTERMSIG(wstatus));
-	}
 
 closem:
 	if (anychange) {

usr.bin/diff/pr.c

@@ -0,0 +1,124 @@
+/*-
+ * Copyright (c) 2017 Baptiste Daroussin <bapt@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer
+ *    in this position and unchanged.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/procdesc.h>
+#include <sys/wait.h>
+
+#include <err.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "pr.h"
+#include "diff.h"
+#include "xmalloc.h"
+
+#define _PATH_PR "/usr/bin/pr"
+
+struct pr *
+start_pr(char *file1, char *file2)
+{
+	int pfd[2];
+	int pr_pd;
+	pid_t pid;
+	char *header;
+	struct pr *pr;
+
+	pr = xcalloc(1, sizeof(*pr));
+
+	xasprintf(&header, "%s %s %s", diffargs, file1, file2);
+	signal(SIGPIPE, SIG_IGN);
+	fflush(stdout);
+	rewind(stdout);
+	pipe(pfd);
+	switch ((pid = pdfork(&pr_pd, PD_CLOEXEC))) {
+	case -1:
+		status |= 2;
+		free(header);
+		err(2, "No more processes");
+	case 0:
+		/* child */
+		if (pfd[0] != STDIN_FILENO) {
+			dup2(pfd[0], STDIN_FILENO);
+			close(pfd[0]);
+		}
+		close(pfd[1]);
+		execl(_PATH_PR, _PATH_PR, "-h", header, (char *)0);
+		_exit(127);
+	default:
+
+		/* parent */
+		if (pfd[1] != STDOUT_FILENO) {
+			pr->ostdout = dup(STDOUT_FILENO);
+			dup2(pfd[1], STDOUT_FILENO);
+			close(pfd[1]);
+			close(pfd[1]);
+			}
+			close(pfd[0]);
+			rewind(stdout);
+			free(header);
+			pr->kq = kqueue();
+			if (pr->kq == -1)
+				err(2, "kqueue");
+			pr->e = xmalloc(sizeof(struct kevent));
+			EV_SET(pr->e, pr_pd, EVFILT_PROCDESC, EV_ADD, NOTE_EXIT, 0,
+			    NULL);
+			if (kevent(pr->kq, pr->e, 1, NULL, 0, NULL) == -1)
+				err(2, "kevent");
+	}
+	return (pr);
+}
+
+/* close the pipe to pr and restore stdout */
+void
+stop_pr(struct pr *pr)
+{
+	int wstatus;
+
+	if (pr == NULL)
+		return;
+
+	fflush(stdout);
+	if (pr->ostdout != STDOUT_FILENO) {
+		close(STDOUT_FILENO);
+		dup2(pr->ostdout, STDOUT_FILENO);
+		close(pr->ostdout);
+	}
+	if (kevent(pr->kq, NULL, 0, pr->e, 1, NULL) == -1)
+		err(2, "kevent");
+	wstatus = pr->e[0].data;
+	close(pr->kq);
+	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0)
+		errx(2, "pr exited abnormally");
+	else if (WIFSIGNALED(wstatus))
+		errx(2, "pr killed by signal %d",
+		    WTERMSIG(wstatus));
+}

usr.bin/diff/pr.h

@@ -0,0 +1,38 @@
+/*-
+ * Copyright (c) 2017 Baptiste Daroussin <bapt@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer
+ *    in this position and unchanged.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/event.h>
+
+struct pr {
+	int ostdout;
+	int kq;
+	struct kevent *e;
+};
+
+struct pr *start_pr(char *file1, char *file2);
+void stop_pr(struct pr *);