Index: usr.bin/diff3/diff3.1
===================================================================
--- usr.bin/diff3/diff3.1
+++ usr.bin/diff3/diff3.1
@@ -38,7 +38,11 @@
 .Nd 3-way differential file comparison
 .Sh SYNOPSIS
 .Nm diff3
-.Op Fl 3aEeXx
+.Op Fl 3aEeiXx
+.Op Fl Fl diff-program Ar program
+.Op Fl L | Fl Fl label Ar label1
+.Op Fl L | Fl Fl label Ar label2
+.Op Fl L | Fl Fl label Ar label3
 .Ar file1 file2 file3
 .Sh DESCRIPTION
 The
@@ -60,15 +64,16 @@
 .Pp
 The options are as follows:
 .Bl -tag -width "-E, -X"
-.It Fl 3
+.It Fl 3 , Fl Fl easy-only
 Produces an output script suitable for
 .Xr ed 1
 with changes
 specific only to
 .Ar file3 .
-.It Fl a
+.It Fl a , Fl Fl text
 Treat all files as ASCII.
-.It Fl E , X
+.It Fl E , Fl Fl show-overlap
+.It Fl X
 Similar to
 .Fl e
 and
@@ -77,7 +82,7 @@
 be noted with ==== in the normal listing) differently.
 The overlapping lines from both files will be inserted by the edit script,
 bracketed by "<<<<<<" and ">>>>>>" lines.
-.It Fl e
+.It Fl e , Fl Fl ed
 Produces output in a form suitable as an input script for the
 .Xr ed 1
 utility.
@@ -99,11 +104,27 @@
 It is useful for backing out changes specific to
 .Ar file2
 only.
-.It Fl x
+.It Fl i
+Appends 'w' and 'q'
+.Xr ed 1
+commands.
+.It Fl L , Fl Fl label
+Defines labels to print instead of file names
+.Ar file1 ,
+.Ar file2
+and
+.Ar file3 .
+.It Fl x, Fl Fl overlap-only
 Produces an output script suitable for
 .Xr ed 1
 with changes
 specific only to all three versions.
+.It Fl Fl diff-program Ar program
+Use
+.Ar program
+instead of the default
+.Xr diff 1
+to compare files.
 .El
 .Pp
 The
Index: usr.bin/diff3/diff3.c
===================================================================
--- usr.bin/diff3/diff3.c
+++ usr.bin/diff3/diff3.c
@@ -170,9 +170,9 @@
 static void
 usage(void)
 {
-	fprintf(stderr, "usage: diff3 [-3aAeEimTxX] [-L lable1] [-L label2] "
-	    "[ -L label3] file1 file2 file3\n");
-	exit (2);
+	fprintf(stderr, "usage: diff3 [-3aAeEimTxX] [-L label1] [-L label2] "
+	    "[-L label3] file1 file2 file3\n");
+	exit(2);
 }
 
 static int
@@ -186,7 +186,7 @@
 	f = fdopen(fd, "r");
 	if (f == NULL)
 		err(2, "fdopen");
-	for (i=0; (p = getchange(f)); i++) {
+	for (i = 0; (p = getchange(f)); i++) {
 		if (i >= szchanges - 1)
 			increase();
 		a = b = (int)strtoimax(p, &p, 10);
@@ -196,7 +196,7 @@
 		}
 		kind = *p++;
 		c = d = (int)strtoimax(p, &p, 10);
-		if (*p==',') {
+		if (*p == ',') {
 			p++;
 			d = (int)strtoimax(p, &p, 10);
 		}
@@ -212,8 +212,8 @@
 		(*dd)[i].new.to = d;
 	}
 	if (i) {
-		(*dd)[i].old.from = (*dd)[i-1].old.to;
-		(*dd)[i].new.from = (*dd)[i-1].new.to;
+		(*dd)[i].old.from = (*dd)[i - 1].old.to;
+		(*dd)[i].new.from = (*dd)[i - 1].new.to;
 	}
 	fclose(f);
 	return (i);
@@ -222,9 +222,9 @@
 static int
 diffexec(const char *diffprog, char **diffargv, int fd[])
 {
-	int pid, pd;
+	int pd;
 
-	switch (pid = pdfork(&pd, PD_CLOEXEC)) {
+	switch (pdfork(&pd, PD_CLOEXEC)) {
 	case 0:
 		close(fd[0]);
 		if (dup2(fd[1], STDOUT_FILENO) == -1)
@@ -396,7 +396,7 @@
 		printf("%da\n", rold->from - 1);
 	else {
 		printf("%d", rold->from);
-		if (rold->to > rold->from+1)
+		if (rold->to > rold->from + 1)
 			printf(",%d", rold->to - 1);
 		printf("c\n");
 	}
@@ -433,7 +433,7 @@
 		if ((line = get_line(fp[i], &j)) == NULL)
 			errx(EXIT_FAILURE, "logic error");
 		if (pr != NULL)
-			printf("%s%s", Tflag == 1? "\t" : pr, line);
+			printf("%s%s", Tflag == 1 ? "\t" : pr, line);
 		cline[i]++;
 	}
 	return ((int) n);
@@ -455,11 +455,13 @@
 	skip(0, r1->from, NULL);
 	skip(1, r2->from, NULL);
 	nchar = 0;
-	for (nline=0; nline < r1->to - r1->from; nline++) {
+	for (nline = 0; nline < r1->to - r1->from; nline++) {
 		do {
 			c = getc(fp[0]);
 			d = getc(fp[1]);
-			if (c == -1 || d== -1)
+			if (c == -1 && d == -1)
+				break;
+			if (c == -1 || d == -1)
 				errx(EXIT_FAILURE, "logic error");
 			nchar++;
 			if (c != d) {
@@ -480,6 +482,7 @@
 	for (i = 0; i < 2; i++)
 		(void)fseek(fp[i], (long)-nchar, SEEK_CUR);
 }
+
 /*
  * collect an editing script for later regurgitation
  */
@@ -512,7 +515,7 @@
 		if (!oflag || !overlap[n]) {
 			prange(&de[n].old);
 		} else {
-			printf("%da\n", de[n].old.to -1);
+			printf("%da\n", de[n].old.to - 1);
 			if (Aflag) {
 				printf("%s\n", f2mark);
 				fseek(fp[1], de[n].old.from, SEEK_SET);
@@ -527,11 +530,19 @@
 			printf("=======\n");
 		}
 		fseek(fp[2], (long)de[n].new.from, SEEK_SET);
-		for (k = de[n].new.to - de[n].new.from; k > 0; k-= j) {
+		for (k = de[n].new.to - de[n].new.from; k > 0; k -= j) {
+			size_t r;
+
 			j = k > BUFSIZ ? BUFSIZ : k;
-			if (fread(block, 1, j, fp[2]) != j)
+			r = fread(block, 1, j, fp[2]);
+			if (r == 0) {
+				if (feof(fp[2]))
+					break;
 				errx(2, "logic error");
-			fwrite(block, 1, j, stdout);
+			}
+			if (r != j)
+				j = r;
+			(void)fwrite(block, 1, j, stdout);
 		}
 		if (!oflag || !overlap[n])
 			printf(".\n");
@@ -557,22 +568,22 @@
 	newsz = szchanges == 0 ? 64 : 2 * szchanges;
 	incr = newsz - szchanges;
 
-	p = realloc(d13, newsz * sizeof(struct diff));
+	p = reallocarray(d13, newsz, sizeof(struct diff));
 	if (p == NULL)
 		err(1, NULL);
 	memset(p + szchanges, 0, incr * sizeof(struct diff));
 	d13 = p;
-	p = realloc(d23, newsz * sizeof(struct diff));
+	p = reallocarray(d23, newsz, sizeof(struct diff));
 	if (p == NULL)
 		err(1, NULL);
 	memset(p + szchanges, 0, incr * sizeof(struct diff));
 	d23 = p;
-	p = realloc(de, newsz * sizeof(struct diff));
+	p = reallocarray(de, newsz, sizeof(struct diff));
 	if (p == NULL)
 		err(1, NULL);
 	memset(p + szchanges, 0, incr * sizeof(struct diff));
 	de = p;
-	q = realloc(overlap, newsz * sizeof(char));
+	q = reallocarray(overlap, newsz, sizeof(char));
 	if (q == NULL)
 		err(1, NULL);
 	memset(q + szchanges, 0, incr * sizeof(char));
@@ -750,7 +761,7 @@
 		for (i = 0; i < nke; i++) {
 			status = e[i].data;
 			if (WIFEXITED(status) && WEXITSTATUS(status) >= 2)
-				errx(2, "diff exited abormally");
+				errx(2, "diff exited abnormally");
 			else if (WIFSIGNALED(status))
 				errx(2, "diff killed by signal %d",
 				    WTERMSIG(status));