5 files changed, 137 insertions, 3 deletions

diff --git a/usr.bin/diff3/diff3.1 b/usr.bin/diff3/diff3.1
index f0fd481c75f1..6968af44bfbd 100644
--- a/usr.bin/diff3/diff3.1
+++ b/usr.bin/diff3/diff3.1
@@ -38,7 +38,7 @@
 .Nd 3-way differential file comparison
 .Sh SYNOPSIS
 .Nm diff3
-.Op Fl 3AaEeiTXx
+.Op Fl 3AaEeimTXx
 .Op Fl Fl diff-program Ar program
 .Op Fl Fl strip-trailing-cr
 .Op Fl L | Fl Fl label Ar label1
@@ -117,6 +117,8 @@ Defines labels to print instead of file names
 .Ar file2
 and
 .Ar file3 .
+.It Fl m, Fl Fl merge
+Merge output instead of generating ed script.
 .It Fl T, Fl Fl initial-tab
 In the normal listing,
 use a tab instead of two spaces
diff --git a/usr.bin/diff3/diff3.c b/usr.bin/diff3/diff3.c
index 5df6357065fc..629e23288875 100644
--- a/usr.bin/diff3/diff3.c
+++ b/usr.bin/diff3/diff3.c
@@ -153,6 +153,7 @@ static void prange(struct range *, bool);
 static void repos(int);
 static void edscript(int) __dead2;
 static void Ascript(int) __dead2;
+static void mergescript(int) __dead2;
 static void increase(void);
 static void usage(void) __dead2;
 static void printrange(FILE *, struct range *);
@@ -389,7 +390,9 @@ merge(int m1, int m2)
 		}
 	}
 
-	if (Aflag)
+	if (mflag)
+		mergescript(j);
+	else if (Aflag)
 		Ascript(j);
 	else if (eflag)
 		edscript(j);
@@ -687,6 +690,86 @@ Ascript(int n)
 	exit(overlapcnt > 0);
 }
 
+/*
+ * Output the merged file directly (don't generate an ed script). When
+ * regurgitating diffs we need to walk forward through the file and print any
+ * inbetween lines.
+ */
+static void
+mergescript(int i)
+{
+	struct range r;
+	int n;
+
+	r.from = 1;
+	r.to = 1;
+
+	for (n = 1; n < i+1; n++) {
+		/* print any lines leading up to here */
+		r.to = de[n].old.from;
+		printrange(fp[0], &r);
+
+		if (de[n].type == DIFF_TYPE2) {
+			printf("%s %s\n", oldmark, f2mark);
+			printrange(fp[1], &de[n].old);
+			printf("=======\n");
+			printrange(fp[2], &de[n].new);
+			printf("%s %s\n", newmark, f3mark);
+		} else if (de[n].type == DIFF_TYPE3) {
+			if (!oflag || !overlap[n]) {
+				printrange(fp[2], &de[n].new);
+			} else {
+
+				printf("%s %s\n", oldmark, f1mark);
+				printrange(fp[0], &de[n].old);
+
+				printf("%s %s\n", orgmark, f2mark);
+				if (de[n].old.from == de[n].old.to) {
+					struct range or;
+					or.from = de[n].old.from -1;
+					or.to = de[n].new.to;
+					printrange(fp[1], &or);
+				} else
+					printrange(fp[1], &de[n].old);
+
+				printf("=======\n");
+
+				printrange(fp[2], &de[n].new);
+				printf("%s %s\n", newmark, f3mark);
+			}
+		}
+
+		if (de[n].old.from == de[n].old.to)
+			r.from = de[n].new.to;
+		else
+			r.from = de[n].old.to;
+	}
+	/*
+	 * Print from the final range to the end of 'myfile'. Any deletions or
+	 * additions to this file should have been handled by now.
+	 *
+	 * If the ranges are the same we need to rewind a line.
+	 * If the new range is 0 length (from == to), we need to use the old
+	 * range.
+	 */
+	if ((de[n-1].old.from == de[n-1].new.from) &&
+		(de[n-1].old.to == de[n-1].new.to))
+		r.from--;
+	else if (de[n-1].new.from == de[n-1].new.to)
+		r.from = de[n-1].old.from;
+
+	/*
+	 * If the range is a 3 way merge then we need to skip a line in the
+	 * trailing output.
+	 */
+	if (de[n-1].type == DIFF_TYPE3)
+		r.from++;
+
+	r.to = INT_MAX;
+	printrange(fp[0], &r);
+	exit(overlapcnt > 0);
+}
+
 static void
 increase(void)
 {
diff --git a/usr.bin/diff3/tests/Makefile b/usr.bin/diff3/tests/Makefile
index fc69dea260e8..0785e78aaee3 100644
--- a/usr.bin/diff3/tests/Makefile
+++ b/usr.bin/diff3/tests/Makefile
@@ -22,6 +22,7 @@ ${PACKAGE}FILES+=	\
 	8.out \
 	9.out \
 	long-ed.out \
-	long-A.out
+	long-A.out \
+	long-merge.out \
 
 .include <bsd.test.mk>
diff --git a/usr.bin/diff3/tests/diff3_test.sh b/usr.bin/diff3/tests/diff3_test.sh
index 8df84b0d8ff2..c30f258128af 100755
--- a/usr.bin/diff3/tests/diff3_test.sh
+++ b/usr.bin/diff3/tests/diff3_test.sh
@@ -4,6 +4,7 @@ atf_test_case diff3
 atf_test_case diff3_lesssimple
 atf_test_case diff3_ed
 atf_test_case diff3_A
+atf_test_case diff3_merge
 
 diff3_body()
 {
@@ -56,10 +57,22 @@ diff3_A_body()
 		diff3 -A -L long-m.txt -L long-o.txt -L long-y.txt $(atf_get_srcdir)/long-m.txt $(atf_get_srcdir)/long-o.txt $(atf_get_srcdir)/long-y.txt
 }
 
+
+diff3_merge_body()
+{
+	atf_check -s exit:1 -o file:$(atf_get_srcdir)/9.out \
+		diff3 -m -L 1 -L 2 -L 3 $(atf_get_srcdir)/1.txt $(atf_get_srcdir)/2.txt $(atf_get_srcdir)/3.txt
+	atf_check -s exit:1 -o file:$(atf_get_srcdir)/tao-merge.out \
+		diff3 -m -L lao.txt -L tzu.txt -L tao.txt $(atf_get_srcdir)/lao.txt $(atf_get_srcdir)/tzu.txt $(atf_get_srcdir)/tao.txt
+	atf_check -s exit:1 -o file:$(atf_get_srcdir)/long-merge.out \
+		diff3 -m -L long-m.txt -L long-o.txt -L long-y.txt $(atf_get_srcdir)/long-m.txt $(atf_get_srcdir)/long-o.txt $(atf_get_srcdir)/long-y.txt
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case diff3
 #	atf_add_test_case diff3_lesssimple
 	atf_add_test_case diff3_ed
 	atf_add_test_case diff3_A
+	atf_add_test_case diff3_merge
 }
diff --git a/usr.bin/diff3/tests/long-merge.out b/usr.bin/diff3/tests/long-merge.out
new file mode 100644
index 000000000000..5139a48fa429
--- /dev/null
+++ b/usr.bin/diff3/tests/long-merge.out
@@ -0,0 +1,35 @@
+This is a long file
+These lines are the same in all three files
+These lines are the same in all three files
+This line is different in mine, not better
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+This line is different in yours, much butter
+These lines are the same in all three files
+These lines are the same in all three files
+<<<<<<< long-o.txt
+This line is different in yours and mine, but the same
+=======
+This line is different in yours and mine, the same is in both
+>>>>>>> long-y.txt
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+<<<<<<< long-m.txt
+This line is different in yours and mine, best change in mine
+||||||| long-o.txt
+This line is different in yours and mine, but the different in each
+=======
+This line is different in yours and mine, but the best in yours
+>>>>>>> long-y.txt
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files
+These lines are the same in all three files