Implement -j for cvs diff, allowing tag:date based diffs (normally date-based

diffs are against the head branch only).

MFC after:	1 week

contrib/cvs/src/diff.c

@@ -50,6 +50,7 @@ static void diff_mark_errors PROTO((int err));
 static char *diff_rev1, *diff_rev2;
 /* Command line dates, from -D option.  Malloc'd.  */
 static char *diff_date1, *diff_date2;
+static char *diff_join1, *diff_join2;
 static char *use_rev1, *use_rev2;
 static int have_rev1_label, have_rev2_label;
 
@@ -223,10 +224,12 @@ diff (argc, argv)
     diff_rev2 = NULL;
     diff_date1 = NULL;
     diff_date2 = NULL;
+    diff_join1 = NULL;
+    diff_join2 = NULL;
 
     optind = 0;
     while ((c = getopt_long (argc, argv,
-	       "+abcdefhilnpstuwy0123456789BHNRTC:D:F:I:L:U:V:W:k:r:",
+	       "+abcdefhilnpstuwy0123456789BHNRTC:D:F:I:L:U:V:W:k:r:j:",
 			     longopts, &option_index)) != -1)
     {
 	switch (c)
@@ -286,6 +289,27 @@ diff (argc, argv)
 		    free (options);
 		options = RCS_check_kflag (optarg);
 		break;
+	    case 'j':
+		{
+		    char *ptr;
+		    char *cpy = strdup(optarg);
+
+		    if ((ptr = strchr(optarg, ':')) != NULL)
+			*ptr++ = 0;
+		    if (diff_rev2 != NULL || diff_date2 != NULL)
+			error (1, 0,
+			   "no more than two revisions/dates can be specified");
+		    if (diff_rev1 != NULL || diff_date1 != NULL) {
+			diff_join2 = cpy;
+			diff_rev2 = optarg;
+			diff_date2 = ptr ? Make_Date(ptr) : NULL;
+		    } else {
+			diff_join1 = cpy;
+			diff_rev1 = optarg;
+			diff_date1 = ptr ? Make_Date(ptr) : NULL;
+		    }
+		}
+		break;
 	    case 'r':
 		if (diff_rev2 != NULL || diff_date2 != NULL)
 		    error (1, 0,
@@ -334,13 +358,18 @@ diff (argc, argv)
 	send_option_string (opts);
 	if (options[0] != '\0')
 	    send_arg (options);
-	if (diff_rev1)
+	if (diff_join1)
+	    option_with_arg ("-j", diff_join1);
+	else if (diff_rev1)
 	    option_with_arg ("-r", diff_rev1);
-	if (diff_date1)
+	else if (diff_date1)
 	    client_senddate (diff_date1);
-	if (diff_rev2)
+
+	if (diff_join2)
+	    option_with_arg ("-j", diff_join2);
+	else if (diff_rev2)
 	    option_with_arg ("-r", diff_rev2);
-	if (diff_date2)
+	else if (diff_date2)
 	    client_senddate (diff_date2);
 
 	/* Send the current files unless diffing two revs from the archive */
@@ -353,12 +382,9 @@ diff (argc, argv)
 
 	send_to_server ("diff\012", 0);
         err = get_responses_and_close ();
-	free (options);
+    } else
-	options = NULL;
-	return (err);
-    }
 #endif
-
+    {
 	if (diff_rev1 != NULL)
 	    tag_check_valid (diff_rev1, argc, argv, local, 0, "");
 	if (diff_rev2 != NULL)
@@ -375,6 +401,7 @@ diff (argc, argv)
 			       diff_dirleaveproc, NULL, argc, argv, local,
 			       which, 0, 1, (char *) NULL, 1);
 
+    }
     /* clean up */
     free (options);
     options = NULL;
@@ -383,6 +410,10 @@ diff (argc, argv)
 	free (diff_date1);
     if (diff_date2 != NULL)
 	free (diff_date2);
+    if (diff_join1 != NULL)
+	free (diff_join1);
+    if (diff_join2 != NULL)
+	free (diff_join2);
 
     return (err);
 }
@@ -432,7 +463,7 @@ diff_fileproc (callerdat, finfo)
 		int exists;
 
 		exists = 0;
-		/* special handling for TAG_HEAD */
+		/* special handling for TAG_HEAD XXX */
 		if (diff_rev1 && strcmp (diff_rev1, TAG_HEAD) == 0)
 		{
 		    char *head =
@@ -840,7 +871,7 @@ diff_file_nodiff (finfo, vers, empty_file)
 
     if (diff_rev1 || diff_date1)
     {
-	/* special handling for TAG_HEAD */
+	/* special handling for TAG_HEAD XXX */
 	if (diff_rev1 && strcmp (diff_rev1, TAG_HEAD) == 0)
 	    use_rev1 = ((vers->vn_rcs == NULL || vers->srcfile == NULL)
 			? NULL
@@ -855,7 +886,7 @@ diff_file_nodiff (finfo, vers, empty_file)
     }
     if (diff_rev2 || diff_date2)
     {
-	/* special handling for TAG_HEAD */
+	/* special handling for TAG_HEAD XXX */
 	if (diff_rev2 && strcmp (diff_rev2, TAG_HEAD) == 0)
 	    use_rev2 = ((vers->vn_rcs == NULL || vers->srcfile == NULL)
 			? NULL