1 files changed, 83 insertions, 0 deletions

diff --git a/fs/isofs/util.c b/fs/isofs/util.c
new file mode 100644
index 000000000000..3f6d9c1ac95a
--- /dev/null
+++ b/fs/isofs/util.c
@@ -0,0 +1,83 @@
+/*
+ *  linux/fs/isofs/util.c
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/iso_fs.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(char * p, int flag)
+{
+        int year, month, day, hour, minute, second, tz;
+        int crtime, days, i;
+
+        year = p[0] - 70;
+        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 {
+                int monlen[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
+
+                days = year * 365;
+                if (year > 2)
+                        days += (year+1) / 4;
+                for (i = 1; i < month; i++)
+                        days += monlen[i-1];
+                if (((year+2) % 4) == 0 && month > 2)
+                        days++;
+                days += day - 1;
+                crtime = ((((days * 24) + hour) * 60 + minute) * 60)
+                        + 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;
+}               
+