diff --git a/usr.bin/diff/diff.c b/usr.bin/diff/diff.c
index 9bf3f2ad79eb..b5fa12268bac 100644
--- a/usr.bin/diff/diff.c
+++ b/usr.bin/diff/diff.c
@@ -1,690 +1,698 @@
 /*	$OpenBSD: diff.c,v 1.67 2019/06/28 13:35:00 deraadt Exp $	*/
 
 /*
  * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *
  * Sponsored in part by the Defense Advanced Research Projects
  * Agency (DARPA) and Air Force Research Laboratory, Air Force
  * Materiel Command, USAF, under agreement number F39502-99-1-0512.
  */
 
 #include <sys/stat.h>
 
 #include <ctype.h>
 #include <err.h>
 #include <errno.h>
 #include <getopt.h>
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include "diff.h"
 #include "xmalloc.h"
 
 static const char diff_version[] = "FreeBSD diff 20260206";
 bool	 lflag, Nflag, Pflag, rflag, sflag, Tflag, cflag;
 bool	 ignore_file_case, suppress_common, color, noderef;
 static bool help = false;
 int	 diff_format, diff_context, diff_algorithm, status;
 bool	 diff_algorithm_set;
 int	 tabsize = 8, width = 130;
 static int	colorflag = COLORFLAG_NEVER;
 char	*start, *ifdefname, *diffargs, *label[2];
 char	*ignore_pats, *most_recent_pat;
 char	*group_format = NULL;
 const char	*add_code, *del_code;
 struct stat stb1, stb2;
 struct excludes *excludes_list;
 regex_t	 ignore_re, most_recent_re;
 
 static struct algorithm {
 	const char *name;
 	int id;
 } algorithms[] = {
 	{"stone", D_DIFFSTONE},
 	{"myers", D_DIFFMYERS},
 	{"patience", D_DIFFPATIENCE},
 	{NULL, D_DIFFNONE}
 };
 
 #define	OPTIONS	"0123456789A:aBbC:cdD:efF:HhI:iL:lnNPpqrS:sTtU:uwW:X:x:y"
 enum {
 	OPT_TSIZE = CHAR_MAX + 1,
 	OPT_STRIPCR,
 	OPT_IGN_FN_CASE,
 	OPT_NO_IGN_FN_CASE,
 	OPT_NORMAL,
 	OPT_HELP,
 	OPT_HORIZON_LINES,
 	OPT_CHANGED_GROUP_FORMAT,
 	OPT_SUPPRESS_COMMON,
 	OPT_COLOR,
 	OPT_NO_DEREFERENCE,
 	OPT_VERSION,
 };
 
 static struct option longopts[] = {
 	{ "algorithm",			required_argument,	0,	'A' },
 	{ "text",			no_argument,		0,	'a' },
 	{ "ignore-space-change",	no_argument,		0,	'b' },
 	{ "context",			optional_argument,	0,	'C' },
 	{ "ifdef",			required_argument,	0,	'D' },
 	{ "minimal",			no_argument,		0,	'd' },
 	{ "ed",				no_argument,		0,	'e' },
 	{ "forward-ed",			no_argument,		0,	'f' },
 	{ "show-function-line",		required_argument,	0,	'F' },
 	{ "speed-large-files",		no_argument,		NULL,	'H' },
 	{ "ignore-blank-lines",		no_argument,		0,	'B' },
 	{ "ignore-matching-lines",	required_argument,	0,	'I' },
 	{ "ignore-case",		no_argument,		0,	'i' },
 	{ "paginate",			no_argument,		NULL,	'l' },
 	{ "label",			required_argument,	0,	'L' },
 	{ "new-file",			no_argument,		0,	'N' },
 	{ "rcs",			no_argument,		0,	'n' },
 	{ "unidirectional-new-file",	no_argument,		0,	'P' },
 	{ "show-c-function",		no_argument,		0,	'p' },
 	{ "brief",			no_argument,		0,	'q' },
 	{ "recursive",			no_argument,		0,	'r' },
 	{ "report-identical-files",	no_argument,		0,	's' },
 	{ "starting-file",		required_argument,	0,	'S' },
 	{ "expand-tabs",		no_argument,		0,	't' },
 	{ "initial-tab",		no_argument,		0,	'T' },
 	{ "unified",			optional_argument,	0,	'U' },
 	{ "ignore-all-space",		no_argument,		0,	'w' },
 	{ "width",			required_argument,	0,	'W' },
 	{ "exclude",			required_argument,	0,	'x' },
 	{ "exclude-from",		required_argument,	0,	'X' },
 	{ "side-by-side",		no_argument,		NULL,	'y' },
 	{ "ignore-file-name-case",	no_argument,		NULL,	OPT_IGN_FN_CASE },
 	{ "help",			no_argument,		NULL,	OPT_HELP},
 	{ "horizon-lines",		required_argument,	NULL,	OPT_HORIZON_LINES },
 	{ "no-dereference",		no_argument,		NULL,	OPT_NO_DEREFERENCE},
 	{ "no-ignore-file-name-case",	no_argument,		NULL,	OPT_NO_IGN_FN_CASE },
 	{ "normal",			no_argument,		NULL,	OPT_NORMAL },
 	{ "strip-trailing-cr",		no_argument,		NULL,	OPT_STRIPCR },
 	{ "tabsize",			required_argument,	NULL,	OPT_TSIZE },
 	{ "changed-group-format",	required_argument,	NULL,	OPT_CHANGED_GROUP_FORMAT},
 	{ "suppress-common-lines",	no_argument,		NULL,	OPT_SUPPRESS_COMMON },
 	{ "color",			optional_argument,	NULL,	OPT_COLOR },
 	{ "version",			no_argument,		NULL,	OPT_VERSION},
 	{ NULL,				0,			0,	'\0'}
 };
 
 static void checked_regcomp(char const *, regex_t *);
 static void usage(void) __dead2;
 static void conflicting_format(void) __dead2;
 static void push_excludes(char *);
 static void push_ignore_pats(char *);
 static void read_excludes_file(char *file);
 static void set_argstr(char **, char **);
 static char *splice(char *, char *);
 static bool do_color(void);
 
 int
 main(int argc, char **argv)
 {
-	const char *errstr = NULL;
-	char *ep, **oargv;
-	long  l;
-	int   ch, dflags, lastch, gotstdin, prevoptind, newarg;
+	const char *errstr;
+	char **oargv;
+	int ch, dflags, lastch, gotstdin, prevoptind, newarg;
 
 	oargv = argv;
 	gotstdin = 0;
 	dflags = 0;
 	lastch = '\0';
 	prevoptind = 1;
 	newarg = 1;
 	diff_context = 3;
 	diff_format = D_UNSET;
 	diff_algorithm = D_DIFFMYERS;
 	diff_algorithm_set = false;
 #define	FORMAT_MISMATCHED(type)	\
 	(diff_format != D_UNSET && diff_format != (type))
 	while ((ch = getopt_long(argc, argv, OPTIONS, longopts, NULL)) != -1) {
 		switch (ch) {
 		case '0': case '1': case '2': case '3': case '4':
 		case '5': case '6': case '7': case '8': case '9':
 			if (newarg)
 				usage();	/* disallow -[0-9]+ */
 			else if (lastch == 'c' || lastch == 'u')
 				diff_context = 0;
 			else if (!isdigit(lastch) || diff_context > INT_MAX / 10)
 				usage();
 			diff_context = (diff_context * 10) + (ch - '0');
 			break;
 		case 'A':
 			diff_algorithm = D_DIFFNONE;
 			for (struct algorithm *a = algorithms; a->name;a++) {
 				if(strcasecmp(optarg, a->name) == 0) {
 					diff_algorithm = a->id;
 					diff_algorithm_set = true;
 					break;
 				}
 			}
 
 			if (diff_algorithm == D_DIFFNONE) {
-				printf("unknown algorithm: %s\n", optarg);
+				warnx("unknown algorithm: %s", optarg);
 				usage();
 			}
 			break;
 		case 'a':
 			dflags |= D_FORCEASCII;
 			break;
 		case 'b':
 			dflags |= D_FOLDBLANKS;
 			break;
 		case 'C':
 		case 'c':
 			if (FORMAT_MISMATCHED(D_CONTEXT))
 				conflicting_format();
 			cflag = true;
 			diff_format = D_CONTEXT;
 			if (optarg != NULL) {
-				l = strtol(optarg, &ep, 10);
-				if (*ep != '\0' || l < 0 || l >= INT_MAX)
+				diff_context = (int) strtonum(optarg,
+				    1, INT_MAX, &errstr);
+				if (errstr != NULL) {
+					warnx("context size is %s: %s",
+					    errstr, optarg);
 					usage();
-				diff_context = (int)l;
+				}
 			}
 			break;
 		case 'd':
 			dflags |= D_MINIMAL;
 			break;
 		case 'D':
 			if (FORMAT_MISMATCHED(D_IFDEF))
 				conflicting_format();
 			diff_format = D_IFDEF;
 			ifdefname = optarg;
 			break;
 		case 'e':
 			if (FORMAT_MISMATCHED(D_EDIT))
 				conflicting_format();
 			diff_format = D_EDIT;
 			break;
 		case 'f':
 			if (FORMAT_MISMATCHED(D_REVERSE))
 				conflicting_format();
 			diff_format = D_REVERSE;
 			break;
 		case 'H':
 			/* ignore but needed for compatibility with GNU diff */
 			break;
 		case 'h':
 			/* silently ignore for backwards compatibility */
 			break;
 		case 'B':
 			dflags |= D_SKIPBLANKLINES;
 			break;
 		case 'F':
 			if (dflags & D_PROTOTYPE)
 				conflicting_format();
 			dflags |= D_MATCHLAST;
 			most_recent_pat = xstrdup(optarg);
 			break;
 		case 'I':
 			push_ignore_pats(optarg);
 			break;
 		case 'i':
 			dflags |= D_IGNORECASE;
 			break;
 		case 'L':
 			if (label[0] == NULL)
 				label[0] = optarg;
 			else if (label[1] == NULL)
 				label[1] = optarg;
 			else
 				usage();
 			break;
 		case 'l':
 			dflags |= D_PAGINATION;
 			lflag = true;
 			break;
 		case 'N':
 			Nflag = true;
 			break;
 		case 'n':
 			if (FORMAT_MISMATCHED(D_NREVERSE))
 				conflicting_format();
 			diff_format = D_NREVERSE;
 			break;
 		case 'p':
 			if (dflags & D_MATCHLAST)
 				conflicting_format();
 			dflags |= D_PROTOTYPE;
 			break;
 		case 'P':
 			Pflag = true;
 			break;
 		case 'r':
 			rflag = true;
 			break;
 		case 'q':
 			if (FORMAT_MISMATCHED(D_BRIEF))
 				conflicting_format();
 			diff_format = D_BRIEF;
 			break;
 		case 'S':
 			start = optarg;
 			break;
 		case 's':
 			sflag = true;
 			break;
 		case 'T':
 			Tflag = true;
 			break;
 		case 't':
 			dflags |= D_EXPANDTABS;
 			break;
 		case 'U':
 		case 'u':
 			if (FORMAT_MISMATCHED(D_UNIFIED))
 				conflicting_format();
 			diff_format = D_UNIFIED;
 			if (optarg != NULL) {
-				l = strtol(optarg, &ep, 10);
-				if (*ep != '\0' || l < 0 || l >= INT_MAX)
+				diff_context = (int) strtonum(optarg,
+				    0, INT_MAX, &errstr);
+				if (errstr != NULL) {
+					warnx("context size is %s: %s",
+					    errstr, optarg);
 					usage();
-				diff_context = (int)l;
+				}
 			}
 			break;
 		case 'w':
 			dflags |= D_IGNOREBLANKS;
 			break;
 		case 'W':
 			width = (int) strtonum(optarg, 1, INT_MAX, &errstr);
-			if (errstr) {
-				warnx("Invalid argument for width");
+			if (errstr != NULL) {
+				warnx("width is %s: %s", errstr, optarg);
 				usage();
 			}
 			break;
 		case 'X':
 			read_excludes_file(optarg);
 			break;
 		case 'x':
 			push_excludes(optarg);
 			break;
 		case 'y':
 			if (FORMAT_MISMATCHED(D_SIDEBYSIDE))
 				conflicting_format();
 			diff_format = D_SIDEBYSIDE;
 			break;
 		case OPT_CHANGED_GROUP_FORMAT:
 			if (FORMAT_MISMATCHED(D_GFORMAT))
 				conflicting_format();
 			diff_format = D_GFORMAT;
 			group_format = optarg;
 			break;
 		case OPT_HELP:
 			help = true;
 			usage();
 			break;
 		case OPT_HORIZON_LINES:
 			break; /* XXX TODO for compatibility with GNU diff3 */
 		case OPT_IGN_FN_CASE:
 			ignore_file_case = true;
 			break;
 		case OPT_NO_IGN_FN_CASE:
 			ignore_file_case = false;
 			break;
 		case OPT_NORMAL:
 			if (FORMAT_MISMATCHED(D_NORMAL))
 				conflicting_format();
 			diff_format = D_NORMAL;
 			break;
 		case OPT_TSIZE:
 			tabsize = (int) strtonum(optarg, 1, INT_MAX, &errstr);
-			if (errstr) {
-				warnx("Invalid argument for tabsize");
+			if (errstr != NULL) {
+				warnx("tabsize is %s: %s", errstr, optarg);
 				usage();
 			}
 			break;
 		case OPT_STRIPCR:
 			dflags |= D_STRIPCR;
 			break;
 		case OPT_SUPPRESS_COMMON:
 			suppress_common = 1;
 			break;
 		case OPT_COLOR:
 			if (optarg == NULL || strncmp(optarg, "auto", 4) == 0)
 				colorflag = COLORFLAG_AUTO;
 			else if (strncmp(optarg, "always", 6) == 0)
 				colorflag = COLORFLAG_ALWAYS;
 			else if (strncmp(optarg, "never", 5) == 0)
 				colorflag = COLORFLAG_NEVER;
-			else
-				errx(2, "unsupported --color value '%s' (must be always, auto, or never)",
-					optarg);
+			else {
+				warnx("unsupported --color value "
+				    "(must be always, auto, or never): "
+				    "%s", optarg);
+				usage();
+			}
 			break;
 		case OPT_NO_DEREFERENCE:
 			noderef = true;
 			break;
 		case OPT_VERSION:
 			printf("%s\n", diff_version);
 			exit(0);
 		default:
 			usage();
 			break;
 		}
 		lastch = ch;
 		newarg = optind != prevoptind;
 		prevoptind = optind;
 	}
 	if (diff_format == D_UNSET && (dflags & D_PROTOTYPE) != 0)
 		diff_format = D_CONTEXT;
 	if (diff_format == D_UNSET)
 		diff_format = D_NORMAL;
 	argc -= optind;
 	argv += optind;
 
 	if (do_color()) {
 		char *p;
 		const char *env;
 
 		color = true;
 		add_code = "32";
 		del_code = "31";
 		env = getenv("DIFFCOLORS");
 		if (env != NULL && *env != '\0' && (p = strdup(env))) {
 			add_code = p;
 			strsep(&p, ":");
 			if (p != NULL)
 				del_code = p;
 		}
 	}
 
 #ifdef __OpenBSD__
 	if (pledge("stdio rpath tmppath", NULL) == -1)
 		err(2, "pledge");
 #endif
 
 	/*
 	 * Do sanity checks, fill in stb1 and stb2 and call the appropriate
 	 * driver routine.  Both drivers use the contents of stb1 and stb2.
 	 */
 	if (argc != 2)
 		usage();
 	checked_regcomp(ignore_pats, &ignore_re);
 	checked_regcomp(most_recent_pat, &most_recent_re);
 	if (strcmp(argv[0], "-") == 0) {
 		fstat(STDIN_FILENO, &stb1);
 		gotstdin = 1;
 	} else if (stat(argv[0], &stb1) != 0) {
 		if (!Nflag || errno != ENOENT)
 			err(2, "%s", argv[0]);
 		dflags |= D_EMPTY1;
 		memset(&stb1, 0, sizeof(struct stat));
 	}
 
 	if (strcmp(argv[1], "-") == 0) {
 		fstat(STDIN_FILENO, &stb2);
 		gotstdin = 1;
 	} else if (stat(argv[1], &stb2) != 0) {
 		if (!Nflag || errno != ENOENT)
 			err(2, "%s", argv[1]);
 		dflags |= D_EMPTY2;
 		memset(&stb2, 0, sizeof(stb2));
 		stb2.st_mode = stb1.st_mode;
 	}
 
 	if (dflags & D_EMPTY1 && dflags & D_EMPTY2){
 		warn("%s", argv[0]);
 		warn("%s", argv[1]);
 		exit(2);
 	}
 
 	if (stb1.st_mode == 0)
 		stb1.st_mode = stb2.st_mode;
 
 	if (gotstdin && (S_ISDIR(stb1.st_mode) || S_ISDIR(stb2.st_mode)))
 		errx(2, "can't compare - to a directory");
 	set_argstr(oargv, argv);
 	if (S_ISDIR(stb1.st_mode) && S_ISDIR(stb2.st_mode)) {
 		if (diff_format == D_IFDEF)
 			errx(2, "-D option not supported with directories");
 		diffdir(argv[0], argv[1], dflags);
 	} else {
 		if (S_ISDIR(stb1.st_mode)) {
 			argv[0] = splice(argv[0], argv[1]);
 			if (stat(argv[0], &stb1) == -1)
 				err(2, "%s", argv[0]);
 		}
 		if (S_ISDIR(stb2.st_mode)) {
 			argv[1] = splice(argv[1], argv[0]);
 			if (stat(argv[1], &stb2) == -1)
 				err(2, "%s", argv[1]);
 		}
 		print_status(diffreg(argv[0], argv[1], dflags, 1), argv[0],
 		    argv[1], "");
 	}
 	if (fflush(stdout) != 0)
 		err(2, "stdout");
 	exit(status);
 }
 
 static void
 checked_regcomp(char const *pattern, regex_t *comp)
 {
 	char buf[BUFSIZ];
 	int error;
 
 	if (pattern == NULL)
 		return;
 
 	error = regcomp(comp, pattern, REG_NEWLINE | REG_EXTENDED);
 	if (error != 0) {
 		regerror(error, comp, buf, sizeof(buf));
 		if (*pattern != '\0')
 			errx(2, "%s: %s", pattern, buf);
 		else
 			errx(2, "%s", buf);
 	}
 }
 
 static void
 set_argstr(char **av, char **ave)
 {
 	size_t argsize;
 	char **ap;
 
 	argsize = 4 + *ave - *av + 1;
 	diffargs = xmalloc(argsize);
 	strlcpy(diffargs, "diff", argsize);
 	for (ap = av + 1; ap < ave; ap++) {
 		if (strcmp(*ap, "--") != 0) {
 			strlcat(diffargs, " ", argsize);
 			strlcat(diffargs, *ap, argsize);
 		}
 	}
 }
 
 /*
  * Read in an excludes file and push each line.
  */
 static void
 read_excludes_file(char *file)
 {
 	FILE *fp;
 	char *pattern = NULL;
 	size_t blen = 0;
 	ssize_t len;
 
 	if (strcmp(file, "-") == 0)
 		fp = stdin;
 	else if ((fp = fopen(file, "r")) == NULL)
 		err(2, "%s", file);
 	while ((len = getline(&pattern, &blen, fp)) >= 0) {
 		if ((len > 0) && (pattern[len - 1] == '\n'))
 			pattern[len - 1] = '\0';
 		push_excludes(pattern);
 		/* we allocate a new string per line */
 		pattern = NULL;
 		blen = 0;
 	}
 	free(pattern);
 	if (strcmp(file, "-") != 0)
 		fclose(fp);
 }
 
 /*
  * Push a pattern onto the excludes list.
  */
 static void
 push_excludes(char *pattern)
 {
 	struct excludes *entry;
 
 	entry = xmalloc(sizeof(*entry));
 	entry->pattern = pattern;
 	entry->next = excludes_list;
 	excludes_list = entry;
 }
 
 static void
 push_ignore_pats(char *pattern)
 {
 	size_t len;
 
 	if (ignore_pats == NULL)
 		ignore_pats = xstrdup(pattern);
 	else {
 		/* old + "|" + new + NUL */
 		len = strlen(ignore_pats) + strlen(pattern) + 2;
 		ignore_pats = xreallocarray(ignore_pats, 1, len);
 		strlcat(ignore_pats, "|", len);
 		strlcat(ignore_pats, pattern, len);
 	}
 }
 
 void
 print_status(int val, char *path1, char *path2, const char *entry)
 {
 	if (label[0] != NULL)
 		path1 = label[0];
 	if (label[1] != NULL)
 		path2 = label[1];
 
 	switch (val) {
 	case D_BINARY:
 		printf("Binary files %s%s and %s%s differ\n",
 		    path1, entry, path2, entry);
 		break;
 	case D_DIFFER:
 		if (diff_format == D_BRIEF)
 			printf("Files %s%s and %s%s differ\n",
 			    path1, entry, path2, entry);
 		break;
 	case D_SAME:
 		if (sflag)
 			printf("Files %s%s and %s%s are identical\n",
 			    path1, entry, path2, entry);
 		break;
 	case D_MISMATCH1:
 		printf("File %s%s is a directory while file %s%s is a regular file\n",
 		    path1, entry, path2, entry);
 		break;
 	case D_MISMATCH2:
 		printf("File %s%s is a regular file while file %s%s is a directory\n",
 		    path1, entry, path2, entry);
 		break;
 	case D_SKIPPED1:
 		printf("File %s%s is not a regular file or directory and was skipped\n",
 		    path1, entry);
 		break;
 	case D_SKIPPED2:
 		printf("File %s%s is not a regular file or directory and was skipped\n",
 		    path2, entry);
 		break;
 	case D_ERROR:
 		break;
 	}
 }
 
 static void
 usage(void)
 {
 	(void)fprintf(help ? stdout : stderr,
 	    "usage: diff [-aBbdilpTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
 	    "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
 	    "            [-I pattern] [-F pattern] [-L label] file1 file2\n"
 	    "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
 	    "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
 	    "            [-F pattern] -C number file1 file2\n"
 	    "       diff [-aBbdiltw] [-I pattern] [--ignore-case] [--no-ignore-case]\n"
 	    "            [--normal] [--strip-trailing-cr] [--tabsize] -D string file1 file2\n"
 	    "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
 	    "            [--no-ignore-case] [--normal] [--tabsize] [--strip-trailing-cr]\n"
 	    "            [-F pattern] -U number file1 file2\n"
 	    "       diff [-aBbdilNPprsTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
 	    "            [--no-ignore-case] [--normal] [--tabsize] [-I pattern] [-L label]\n"
 	    "            [-F pattern] [-S name] [-X file] [-x pattern] dir1 dir2\n"
 	    "       diff [-aBbditwW] [--expand-tabs] [--ignore-all-space]\n"
 	    "            [--ignore-blank-lines] [--ignore-case] [--minimal]\n"
 	    "            [--no-ignore-file-name-case] [--strip-trailing-cr]\n"
 	    "            [--suppress-common-lines] [--tabsize] [--text] [--width]\n"
 	    "            -y | --side-by-side file1 file2\n"
 	    "       diff [--help] [--version]\n");
 
 	if (help)
 		exit(0);
 	else
 		exit(2);
 }
 
 static void
 conflicting_format(void)
 {
 
 	fprintf(stderr, "error: conflicting output format options.\n");
 	usage();
 }
 
 static bool
 do_color(void)
 {
 	const char *p, *p2;
 
 	switch (colorflag) {
 	case COLORFLAG_AUTO:
 		p = getenv("CLICOLOR");
 		p2 = getenv("COLORTERM");
 		if ((p != NULL && *p != '\0') || (p2 != NULL && *p2 != '\0'))
 			return isatty(STDOUT_FILENO);
 		break;
 	case COLORFLAG_ALWAYS:
 		return (true);
 	case COLORFLAG_NEVER:
 		return (false);
 	}
 
 	return (false);
 }
 
 static char *
 splice(char *dir, char *path)
 {
 	char *tail, *buf;
 	size_t dirlen;
 
 	dirlen = strlen(dir);
 	while (dirlen != 0 && dir[dirlen - 1] == '/')
 	    dirlen--;
 	if ((tail = strrchr(path, '/')) == NULL)
 		tail = path;
 	else
 		tail++;
 	xasprintf(&buf, "%.*s/%s", (int)dirlen, dir, tail);
 	return (buf);
 }
diff --git a/usr.bin/diff/tests/diff_test.sh b/usr.bin/diff/tests/diff_test.sh
index 0d3acf50edf9..3afd12355a80 100755
--- a/usr.bin/diff/tests/diff_test.sh
+++ b/usr.bin/diff/tests/diff_test.sh
@@ -1,492 +1,506 @@
 
 atf_test_case simple
 atf_test_case unified
 atf_test_case header
 atf_test_case header_ns
 atf_test_case ifdef
 atf_test_case group_format
 atf_test_case side_by_side
 atf_test_case side_by_side_tabbed
 atf_test_case brief_format
 atf_test_case b230049
 atf_test_case stripcr_o
 atf_test_case b252515
 atf_test_case b278988
 atf_test_case Bflag
 atf_test_case Nflag
 atf_test_case tabsize
 atf_test_case conflicting_format
 atf_test_case label
 atf_test_case report_identical
 atf_test_case non_regular_file
 atf_test_case binary
 atf_test_case functionname
 atf_test_case noderef
 atf_test_case ignorecase
 atf_test_case dirloop
-atf_test_case bigc
-atf_test_case bigu
+atf_test_case crange
+atf_test_case urange
 atf_test_case prleak
 atf_test_case same
 
 simple_body()
 {
 	atf_check -o file:$(atf_get_srcdir)/simple.out -s eq:1 \
 		diff "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_e.out -s eq:1 \
 		diff -e "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_u.out -s eq:1 \
 		diff -u -L input1 -L input2 "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_n.out -s eq:1 \
 		diff -n "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input2.in"
 
 	atf_check -o inline:"Files $(atf_get_srcdir)/input1.in and $(atf_get_srcdir)/input2.in differ\n" -s eq:1 \
 		diff -q "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input2.in"
 
 	atf_check \
 		diff -q "$(atf_get_srcdir)/input1.in" "$(atf_get_srcdir)/input1.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_i.out -s eq:1 \
 		diff -i "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_w.out -s eq:1 \
 		diff -w "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_b.out -s eq:1 \
 		diff -b "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 
 	atf_check -o file:$(atf_get_srcdir)/simple_p.out -s eq:1 \
 		diff --label input_c1.in --label input_c2.in -p "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 }
 
 unified_body()
 {
 	atf_check -o file:$(atf_get_srcdir)/unified_p.out -s eq:1 \
 		diff -up -L input_c1.in -L input_c2.in  "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 	atf_check -o file:$(atf_get_srcdir)/unified_9999.out -s eq:1 \
 		diff -u9999 -L input_c1.in -L input_c2.in "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 }
 
 b230049_body()
 {
 	printf 'a\nb\r\nc\n' > b230049_a.in
 	printf 'a\r\nb\r\nc\r\n' > b230049_b.in
 	atf_check -o empty -s eq:0 \
 		diff -up --strip-trailing-cr -L b230049_a.in -L b230049_b.in \
 		    b230049_a.in b230049_b.in
 }
 
 stripcr_o_body()
 {
 	printf 'a\nX\nc\n' > stripcr_o_X.in
 	printf 'a\r\nY\r\nc\r\n' > stripcr_o_Y.in
 	atf_check -o "file:$(atf_get_srcdir)/strip_o.out" -s eq:1 \
 		diff -L1 -L2 -u --strip-trailing-cr stripcr_o_X.in stripcr_o_Y.in
 }
 
 b252515_body()
 {
 	printf 'a b\n' > b252515_a.in
 	printf 'a  b\n' > b252515_b.in
 	atf_check -o empty -s eq:0 \
 		diff -qw b252515_a.in b252515_b.in
 }
 
 b278988_body()
 {
 	printf 'a\nb\nn' > b278988.a.in
 	printf 'a\n\nb\nn' > b278988.b.in
 	atf_check -o empty -s eq:0 \
 		diff -Bw b278988.a.in b278988.b.in
 }
 
 header_body()
 {
 	export TZ=UTC
 	: > empty
 	echo hello > hello
 	touch -d 2015-04-03T01:02:03 empty
 	touch -d 2016-12-22T11:22:33 hello
 	atf_check -o "file:$(atf_get_srcdir)/header.out" -s eq:1 \
 		diff -u empty hello
 }
 
 header_ns_body()
 {
 	export TZ=UTC
 	: > empty
 	echo hello > hello
 	touch -d 2015-04-03T01:02:03.123456789 empty
 	touch -d 2016-12-22T11:22:33.987654321 hello
 	atf_check -o "file:$(atf_get_srcdir)/header_ns.out" -s eq:1 \
 		diff -u empty hello
 }
 
 ifdef_body()
 {
 	atf_check -o file:$(atf_get_srcdir)/ifdef.out -s eq:1 \
 		diff -D PLOP "$(atf_get_srcdir)/input_c1.in" \
 		"$(atf_get_srcdir)/input_c2.in"
 }
 
 group_format_body()
 {
 	atf_check -o file:$(atf_get_srcdir)/group-format.out -s eq:1 \
 		diff --changed-group-format='<<<<<<< (local)
 %<=======
 %>>>>>>>> (stock)
 ' "$(atf_get_srcdir)/input_c1.in" "$(atf_get_srcdir)/input_c2.in"
 }
 
 side_by_side_body()
 {
 	atf_check -o save:A printf "A\nB\nC\n"
 	atf_check -o save:B printf "D\nB\nE\n"
 
 	exp_output=$(printf "A[[:space:]]+|[[:space:]]+D\nB[[:space:]]+B\nC[[:space:]]+|[[:space:]]+E")
 	exp_output_suppressed=$(printf "A[[:space:]]+|[[:space:]]+D\nC[[:space:]]+|[[:space:]]+E")
 
 	atf_check -o match:"$exp_output" -s exit:1 \
 	    diff --side-by-side A B
 	atf_check -o match:"$exp_output" -s exit:1 \
 	    diff -y A B
 	atf_check -o match:"$exp_output_suppressed" -s exit:1 \
 	    diff -y --suppress-common-lines A B
 	atf_check -o match:"$exp_output_suppressed" -s exit:1 \
 	    diff -W 65 -y --suppress-common-lines A B
 }
 
 side_by_side_tabbed_body()
 {
 	file_a=$(atf_get_srcdir)/side_by_side_tabbed_a.in
 	file_b=$(atf_get_srcdir)/side_by_side_tabbed_b.in
 
 	atf_check -o save:diffout -s not-exit:0 \
 	    diff -y ${file_a} ${file_b}
 	atf_check -o save:diffout_expanded -s not-exit:0 \
 	    diff -yt ${file_a} ${file_b}
 
 	atf_check -o not-empty grep -Ee 'file A.+file B' diffout
 	atf_check -o not-empty grep -Ee 'file A.+file B' diffout_expanded
 
 	atf_check -o not-empty grep -Ee 'tabs.+tabs' diffout
 	atf_check -o not-empty grep -Ee 'tabs.+tabs' diffout_expanded
 }
 
 brief_format_body()
 {
 	atf_check mkdir A B
 
 	atf_check -x "echo 1 > A/test-file"
 	atf_check -x "echo 2 > B/test-file"
 
 	atf_check cp -Rf A C
 	atf_check cp -Rf A D
 
 	atf_check -x "echo 3 > D/another-test-file"
 
 	atf_check \
 	    -s exit:1 \
 	    -o inline:"Files A/test-file and B/test-file differ\n" \
 	    diff -rq A B
 
 	atf_check diff -rq A C
 
 	atf_check \
 	    -s exit:1 \
 	    -o inline:"Only in D: another-test-file\n" \
 	    diff -rq A D
 
 	atf_check \
 	    -s exit:1 \
 	    -o inline:"Files A/another-test-file and D/another-test-file differ\n" \
 	    diff -Nrq A D
 }
 
 Bflag_body()
 {
 	atf_check -x 'printf "A\nB\n" > A'
 	atf_check -x 'printf "A\n\nB\n" > B'
 	atf_check -x 'printf "A\n \nB\n" > C'
 	atf_check -x 'printf "A\nC\nB\n" > D'
 	atf_check -x 'printf "A\nB\nC\nD\nE\nF\nG\nH" > E'
 	atf_check -x 'printf "A\n\nB\nC\nD\nE\nF\nX\nH" > F'
 
 	atf_check -s exit:0 -o inline:"" diff -B A B
 	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_C.out" diff -B A C
 	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_D.out" diff -B A D
 	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_F.out" diff -B E F
 }
 
 Nflag_body()
 {
 	atf_check -x 'printf "foo" > A'
 
 	atf_check -s exit:1 -o ignore -e ignore diff -N A NOFILE 
 	atf_check -s exit:1 -o ignore -e ignore diff -N NOFILE A 
 	atf_check -s exit:2 -o ignore -e ignore diff -N NOFILE1 NOFILE2 
 }
 
 tabsize_body()
 {
 	printf "\tA\n" > A
 	printf "\tB\n" > B
 
 	atf_check -s exit:1 \
 	    -o inline:"1c1\n<  A\n---\n>  B\n" \
 	    diff -t --tabsize 1 A B
 }
 
 conflicting_format_body()
 {
 	printf "\tA\n" > A
 	printf "\tB\n" > B
 
 	atf_check -s exit:2 -e ignore diff -c -u A B
 	atf_check -s exit:2 -e ignore diff -e -f A B
 	atf_check -s exit:2 -e ignore diff -y -q A B
 	atf_check -s exit:2 -e ignore diff -q -u A B
 	atf_check -s exit:2 -e ignore diff -q -c A B
 	atf_check -s exit:2 -e ignore diff --normal -c A B
 	atf_check -s exit:2 -e ignore diff -c --normal A B
 
 	atf_check -s exit:1 -o ignore -e ignore diff -u -u A B
 	atf_check -s exit:1 -o ignore -e ignore diff -e -e A B
 	atf_check -s exit:1 -o ignore -e ignore diff -y -y A B
 	atf_check -s exit:1 -o ignore -e ignore diff -q -q A B
 	atf_check -s exit:1 -o ignore -e ignore diff -c -c A B
 	atf_check -s exit:1 -o ignore -e ignore diff --normal --normal A B
 }
 
 label_body()
 {
 	printf "\tA\n" > A
 
 	atf_check -o inline:"Files hello and world are identical\n" \
 		-s exit:0 diff --label hello --label world -s A A
 
 	atf_check -o inline:"Binary files hello and world differ\n" \
 		-s exit:1 diff --label hello --label world `which diff` `which ls`
 }
 
 report_identical_head()
 {
 	atf_set "require.user" unprivileged
 }
 report_identical_body()
 {
 	printf "\tA\n" > A
 	printf "\tB\n" > B
 	atf_check -s exit:0 -o match:"are identical" \
 		  diff -s A A
 	atf_check -s exit:1 -o not-match:"are identical" \
 		  diff -s A B
 	chmod -r B
 	atf_check -s exit:2 -e inline:"diff: B: Permission denied\n" \
 		-o empty diff -s A B
 }
 
 non_regular_file_body()
 {
 	printf "\tA\n" > A
 	mkfifo B
 	printf "\tA\n" > B &
 
 	atf_check diff A B
 	printf "\tB\n" > B &
 	atf_check -s exit:1 \
 		-o inline:"--- A\n+++ B\n@@ -1 +1 @@\n-\tA\n+\tB\n" \
 		diff --label A --label B -u A B
 }
 
 binary_body()
 {
 	# the NUL byte has to be after at least BUFSIZ bytes to trick asciifile()
 	yes 012345678901234567890123456789012345678901234567890 | head -n 174 > A
 	cp A B
 	printf '\n\0\n' >> A
 	printf '\nx\n' >> B
 
 	atf_check -o inline:"Binary files A and B differ\n" -s exit:1 diff A B
 	atf_check -o inline:"176c\nx\n.\n" -s exit:1 diff -ae A B
 }
 
 functionname_body()
 {
 	atf_check -o file:$(atf_get_srcdir)/functionname_c.out -s exit:1 \
 		diff -u -p -L functionname.in -L functionname_c.in \
 		"$(atf_get_srcdir)/functionname.in" "$(atf_get_srcdir)/functionname_c.in"
 
 	atf_check -o file:$(atf_get_srcdir)/functionname_objcm.out -s exit:1 \
 		diff -u -p -L functionname.in -L functionname_objcm.in \
 		"$(atf_get_srcdir)/functionname.in" "$(atf_get_srcdir)/functionname_objcm.in"
 
 	atf_check -o file:$(atf_get_srcdir)/functionname_objcclassm.out -s exit:1 \
 		diff -u -p -L functionname.in -L functionname_objcclassm.in \
 		"$(atf_get_srcdir)/functionname.in" "$(atf_get_srcdir)/functionname_objcclassm.in"
 }
 
 noderef_body()
 {
 	atf_check mkdir A B
 
 	atf_check -x "echo 1 > A/test-file"
 	atf_check -x "echo 1 > test-file"
 	atf_check -x "echo 1 > test-file2"
 
 	atf_check ln -s $(pwd)/test-file B/test-file
 
 	atf_check -o empty -s exit:0 diff -r A B
 	atf_check -o inline:"File A/test-file is a file while file B/test-file is a symbolic link\n" \
 		-s exit:1 diff -r --no-dereference A B
 
 	# both test files are now the same symbolic link
 	atf_check rm A/test-file
 
 	atf_check ln -s $(pwd)/test-file A/test-file
 	atf_check -o empty -s exit:0 diff -r A B
 	atf_check -o empty -s exit:0 diff -r --no-dereference A B
 
 	# make test files different symbolic links, but same contents
 	atf_check unlink A/test-file
 	atf_check ln -s $(pwd)/test-file2 A/test-file
 
 	atf_check -o empty -s exit:0 diff -r A B
 	atf_check -o inline:"Symbolic links A/test-file and B/test-file differ\n" -s exit:1 diff -r --no-dereference A B
 }
 
 ignorecase_body()
 {
 	atf_check mkdir A
 	atf_check mkdir B
 
 	atf_check -x "echo hello > A/foo"
 	atf_check -x "echo hello > B/FOO"
 
 	atf_check -o empty -s exit:0 diff -u -r --ignore-file-name-case A B
 }
 
 dirloop_head()
 {
 	atf_set "timeout" "10"
 }
 dirloop_body()
 {
 	atf_check mkdir -p a/foo/bar
 	atf_check ln -s .. a/foo/bar/up
 	atf_check cp -a a b
 	atf_check \
 	    -e match:"a/foo/bar/up: Directory loop detected" \
 	    -e match:"b/foo/bar/up: Directory loop detected" \
 	    diff -r a b
 	atf_check rm [ab]/foo/bar/up
 	atf_check mkdir -p b/foo/bar
 	atf_check ln -s foo a/baz
 	atf_check ln -s foo b/baz
 	atf_check diff -r a b
 }
 
-bigc_head()
+crange_head()
 {
-	atf_set "descr" "Context diff with very large context"
+	atf_set "descr" "Context diff context length range"
 }
-bigc_body()
+crange_body()
 {
-	echo $'x\na\ny' >a
-	echo $'x\nb\ny' >b
-	atf_check -s exit:2 -e ignore diff -C$(((1<<31)-1)) a b
-	atf_check -s exit:1 -o match:'--- 1,3 ---' \
-	    diff -C$(((1<<31)-2)) a b
-	atf_check -s exit:1 -o match:'--- 1,3 ---' \
-	    diff -Astone -C$(((1<<31)-2)) a b
+	echo $'x\nx\na\ny\ny' >a
+	echo $'x\nx\nb\ny\ny' >b
+	atf_check -s exit:2 -e match:'too small' \
+	    diff -C-1 a b
+	atf_check -s exit:2 -e match:'too small' \
+	    diff -C0 a b
+	atf_check -s exit:1 -o match:'--- 2,4 ---' \
+	    diff -C1 a b
+	atf_check -s exit:1 -o match:'--- 2,4 ---' \
+	    diff -Astone -C1 a b
+	atf_check -s exit:2 -e match:'too large' \
+	    diff -C$((1<<31)) a b
+	atf_check -s exit:1 -o match:'--- 1,5 ---' \
+	    diff -C$(((1<<31)-1)) a b
+	atf_check -s exit:1 -o match:'--- 1,5 ---' \
+	    diff -Astone -C$(((1<<31)-1)) a b
 }
 
-bigu_head()
+urange_head()
 {
-	atf_set "descr" "Unified diff with very large context"
+	atf_set "descr" "Unified diff context length range"
 }
-bigu_body()
+urange_body()
 {
-	echo $'x\na\ny' >a
-	echo $'x\nb\ny' >b
-	atf_check -s exit:2 -e ignore diff -U$(((1<<31)-1)) a b
-	atf_check -s exit:1 -o match:'^@@ -1,3 \+1,3 @@$' \
-	    diff -U$(((1<<31)-2)) a b
-	atf_check -s exit:1 -o match:'^@@ -1,3 \+1,3 @@$' \
-	    diff -Astone -U$(((1<<31)-2)) a b
+	echo $'x\nx\na\ny\ny' >a
+	echo $'x\nx\nb\ny\ny' >b
+	atf_check -s exit:2 -e match:'too small' \
+	    diff -U-1 a b
+	atf_check -s exit:1 -o match:'^@@ -3 \+3 @@$' \
+	    diff -U0 a b
+	atf_check -s exit:2 -e match:'too large' \
+	    diff -U$((1<<31)) a b
+	atf_check -s exit:1 -o match:'^@@ -1,5 \+1,5 @@$' \
+	    diff -U$(((1<<31)-1)) a b
+	atf_check -s exit:1 -o match:'^@@ -1,5 \+1,5 @@$' \
+	    diff -Astone -U$(((1<<31)-1)) a b
 }
 
 prleak_head()
 {
 	atf_set "descr" "Verify that pagination does not leak resources"
 }
 prleak_body()
 {
 	local n=32
 	mkdir a b
 	for hi in $(jot -w%02x $n 0) ; do
 		mkdir a/$hi b/$hi
 		for lo in $(jot -w%02x $n 0) ; do
 			echo "$hi$lo" >a/$hi/$lo
 			echo "$hi$lo" >b/$hi/$lo
 		done
 	done
 	ulimit -n 1000
 	ulimit -u 1000
 	atf_check diff -rul a b
 	atf_check diff -Astone -rul a b
 }
 
 same_head()
 {
 	atf_set "descr" "Don't diff a file or directory with itself"
 }
 same_body()
 {
 	local n=256
 	mkdir a
 	for hi in $(jot -w%02x $n 0) ; do
 		mkdir a/$hi
 		for lo in $(jot -w%02x $n 0) ; do
 			echo "$hi$lo" >a/$hi/$lo
 		done
 	done
 	ln -s a b
 	atf_check timeout 1s diff -rqs a b
 }
 
 atf_init_test_cases()
 {
 	atf_add_test_case simple
 	atf_add_test_case unified
 	atf_add_test_case header
 	atf_add_test_case header_ns
 	atf_add_test_case ifdef
 	atf_add_test_case group_format
 	atf_add_test_case side_by_side
 	atf_add_test_case side_by_side_tabbed
 	atf_add_test_case brief_format
 	atf_add_test_case b230049
 	atf_add_test_case stripcr_o
 	atf_add_test_case b252515
 	atf_add_test_case b278988
 	atf_add_test_case Bflag
 	atf_add_test_case Nflag
 	atf_add_test_case tabsize
 	atf_add_test_case conflicting_format
 	atf_add_test_case label
 	atf_add_test_case report_identical
 	atf_add_test_case non_regular_file
 	atf_add_test_case binary
 	atf_add_test_case functionname
 	atf_add_test_case noderef
 	atf_add_test_case ignorecase
 	atf_add_test_case dirloop
-	atf_add_test_case bigc
-	atf_add_test_case bigu
+	atf_add_test_case crange
+	atf_add_test_case urange
 	atf_add_test_case prleak
 	atf_add_test_case same
 }