v4.19.13 snapshot.
diff --git a/fs/isofs/util.c b/fs/isofs/util.c
new file mode 100644
index 0000000..e88dba7
--- /dev/null
+++ b/fs/isofs/util.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/isofs/util.c
+ */
+
+#include <linux/time.h>
+#include "isofs.h"
+
+/*
+ * We have to convert from a MM/DD/YY format to the Unix ctime format.
+ * We have to take into account leap years and all of that good stuff.
+ * Unfortunately, the kernel does not have the information on hand to
+ * take into account daylight savings time, but it shouldn't matter.
+ * The time stored should be localtime (with or without DST in effect),
+ * and the timezone offset should hold the offset required to get back
+ * to GMT. Thus we should always be correct.
+ */
+
+int iso_date(u8 *p, int flag)
+{
+ int year, month, day, hour, minute, second, tz;
+ int crtime;
+
+ year = p[0];
+ month = p[1];
+ day = p[2];
+ hour = p[3];
+ minute = p[4];
+ second = p[5];
+ if (flag == 0) tz = p[6]; /* High sierra has no time zone */
+ else tz = 0;
+
+ if (year < 0) {
+ crtime = 0;
+ } else {
+ crtime = mktime64(year+1900, month, day, hour, minute, second);
+
+ /* sign extend */
+ if (tz & 0x80)
+ tz |= (-1 << 8);
+
+ /*
+ * The timezone offset is unreliable on some disks,
+ * so we make a sanity check. In no case is it ever
+ * more than 13 hours from GMT, which is 52*15min.
+ * The time is always stored in localtime with the
+ * timezone offset being what get added to GMT to
+ * get to localtime. Thus we need to subtract the offset
+ * to get to true GMT, which is what we store the time
+ * as internally. On the local system, the user may set
+ * their timezone any way they wish, of course, so GMT
+ * gets converted back to localtime on the receiving
+ * system.
+ *
+ * NOTE: mkisofs in versions prior to mkisofs-1.10 had
+ * the sign wrong on the timezone offset. This has now
+ * been corrected there too, but if you are getting screwy
+ * results this may be the explanation. If enough people
+ * complain, a user configuration option could be added
+ * to add the timezone offset in with the wrong sign
+ * for 'compatibility' with older discs, but I cannot see how
+ * it will matter that much.
+ *
+ * Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann)
+ * for pointing out the sign error.
+ */
+ if (-52 <= tz && tz <= 52)
+ crtime -= tz * 15 * 60;
+ }
+ return crtime;
+}