Issue 327: tar should accept zero-sized exclude files with -X

Key problem:  We were using archive_read_format_raw() to read
the exclude file which does not accept empty files.
Enabling archive_read_format_empty() and reworking the
end-of-input handling fixed this.

Also add a test for this case to prevent it from regressing.

libarchive/archive_match.c

@@ -580,6 +580,7 @@ add_pattern_from_file(struct archive_match *a, struct match_list *mlist,
 		return (ARCHIVE_FATAL);
 	}
 	r = archive_read_support_format_raw(ar);
+	r = archive_read_support_format_empty(ar);
 	if (r != ARCHIVE_OK) {
 		archive_copy_error(&(a->archive), ar);
 		archive_read_free(ar);
@@ -596,9 +597,13 @@ add_pattern_from_file(struct archive_match *a, struct match_list *mlist,
 	}
 	r = archive_read_next_header(ar, &ae);
 	if (r != ARCHIVE_OK) {
-		archive_copy_error(&(a->archive), ar);
 		archive_read_free(ar);
-		return (r);
+		if (r == ARCHIVE_EOF) {
+			return (ARCHIVE_OK);
+		} else {
+			archive_copy_error(&(a->archive), ar);
+			return (r);
+		}
 	}
 
 	archive_string_init(&as);

tar/test/test_option_X_upper.c

@@ -142,4 +142,18 @@ DEFINE_TEST(test_option_X_upper)
 	assertEmptyFile("test.out");
 	assertEmptyFile("test.err");
 	assertChdir("..");
+
+	/* Test 8: with empty exclusions file */
+	assertMakeDir("test8", 0755);
+	assertChdir("test8");
+	assertMakeFile("exclusions", 0644, "");
+	assertEqualInt(0,
+	    systemf("%s -xf ../archive.tar -X exclusions >test.out 2>test.err", testprog));
+	assertFileContents("file1", 5, "file1");
+	assertFileContents("file2", 5, "file2");
+	assertFileContents("file3a", 6, "file3a");
+	assertFileContents("file4a", 6, "file4a");
+	assertEmptyFile("test.out");
+	assertEmptyFile("test.err");
+	assertChdir("..");
 }