Defer printing of the per-file diff header until after the regexp

"ignore" processing has finished.  This way we only print the header
for files that have diffs.  The new behavior matches GNU diff (which
is where the -I flag comes from).  OK otto@ espie@

1 files changed, 14 insertions, 12 deletions

diff --git a/usr.bin/diff/diffreg.c b/usr.bin/diff/diffreg.c
index eaf587e52fd..35633e249a7 100644
--- a/usr.bin/diff/diffreg.c
+++ b/usr.bin/diff/diffreg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: diffreg.c,v 1.64 2006/02/22 07:26:08 otto Exp $	*/
+/*	$OpenBSD: diffreg.c,v 1.65 2007/02/22 01:44:36 millert Exp $	*/
 
 /*
  * Copyright (C) Caldera International Inc.  2001-2002.
@@ -65,7 +65,7 @@
  */
 
 #ifndef lint
-static const char rcsid[] = "$OpenBSD: diffreg.c,v 1.64 2006/02/22 07:26:08 otto Exp $";
+static const char rcsid[] = "$OpenBSD: diffreg.c,v 1.65 2007/02/22 01:44:36 millert Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -201,7 +201,7 @@ static int lastline;
 static int lastmatchline;
 
 static FILE *opentemp(const char *);
-static void output(char *, FILE *, char *, FILE *);
+static void output(char *, FILE *, char *, FILE *, int);
 static void check(char *, FILE *, char *, FILE *);
 static void range(int, int, char *);
 static void uni_range(int, int);
@@ -212,7 +212,7 @@ static void prune(void);
 static void equiv(struct line *, int, struct line *, int, int *);
 static void unravel(int);
 static void unsort(struct line *, int, int *);
-static void change(char *, FILE *, char *, FILE *, int, int, int, int);
+static void change(char *, FILE *, char *, FILE *, int, int, int, int, int);
 static void sort(struct line *, int);
 static void print_header(const char *, const char *);
 static int  ignoreline(char *);
@@ -405,8 +405,7 @@ diffreg(char *ofile1, char *ofile2, int flags)
 			rewind(stdout);
 			free(header);
 		}
-	} else if (flags & D_HEADER)
-		printf("%s %s %s\n", diffargs, file1, file2);
+	}
 	prepare(0, f1, stb1.st_size);
 	prepare(1, f2, stb2.st_size);
 	prune();
@@ -437,7 +436,7 @@ diffreg(char *ofile1, char *ofile2, int flags)
 	ixold = erealloc(ixold, (len[0] + 2) * sizeof(long));
 	ixnew = erealloc(ixnew, (len[1] + 2) * sizeof(long));
 	check(file1, f1, file2, f2);
-	output(file1, f1, file2, f2);
+	output(file1, f1, file2, f2, (flags & D_HEADER));
 	if (ostdout != -1) {
 		int wstatus;
 
@@ -898,7 +897,7 @@ skipline(FILE *f)
 }
 
 static void
-output(char *file1, FILE *f1, char *file2, FILE *f2)
+output(char *file1, FILE *f1, char *file2, FILE *f2, int flags)
 {
 	int m, i0, i1, j0, j1;
 
@@ -917,7 +916,7 @@ output(char *file1, FILE *f1, char *file2, FILE *f2)
 				i1++;
 			j1 = J[i1 + 1] - 1;
 			J[i1] = j1;
-			change(file1, f1, file2, f2, i0, i1, j0, j1);
+			change(file1, f1, file2, f2, i0, i1, j0, j1, flags);
 		}
 	} else {
 		for (i0 = m; i0 >= 1; i0 = i1 - 1) {
@@ -929,11 +928,11 @@ output(char *file1, FILE *f1, char *file2, FILE *f2)
 				i1--;
 			j1 = J[i1 - 1] + 1;
 			J[i1] = j1;
-			change(file1, f1, file2, f2, i1, i0, j1, j0);
+			change(file1, f1, file2, f2, i1, i0, j1, j0, flags);
 		}
 	}
 	if (m == 0)
-		change(file1, f1, file2, f2, 1, 0, 1, len[1]);
+		change(file1, f1, file2, f2, 1, 0, 1, len[1], flags);
 	if (format == D_IFDEF) {
 		for (;;) {
 #define	c i0
@@ -1003,7 +1002,8 @@ ignoreline(char *line)
  * lines missing from the to file.
  */
 static void
-change(char *file1, FILE *f1, char *file2, FILE *f2, int a, int b, int c, int d)
+change(char *file1, FILE *f1, char *file2, FILE *f2, int a, int b, int c, int d,
+    int flags)
 {
 	static size_t max_context = 64;
 	int i;
@@ -1037,6 +1037,8 @@ restart:
 		return;
 	}
 proceed:
+	if (flags & D_HEADER)
+		printf("%s %s %s\n", diffargs, file1, file2);
 	if (format == D_CONTEXT || format == D_UNIFIED) {
 		/*
 		 * Allocate change records as needed.