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/*
* linux/fs/isofs/util.c
*
* The special functions in the file are numbered according to the section
* of the iso 9660 standard in which they are described. isonum_733 will
* convert numbers according to section 7.3.3, etc.
*
* isofs special functions. This file was lifted in its entirety from
* the 386BSD iso9660 filesystem, by Pace Willisson <pace@blitz.com>.
*/
#include <linux/time.h>
int
isonum_711 (char * p)
{
return (*p & 0xff);
}
int
isonum_712 (char * p)
{
int val;
val = *p;
if (val & 0x80)
val |= 0xffffff00;
return (val);
}
int
isonum_721 (char * p)
{
return ((p[0] & 0xff) | ((p[1] & 0xff) << 8));
}
int
isonum_722 (char * p)
{
return (((p[0] & 0xff) << 8) | (p[1] & 0xff));
}
int
isonum_723 (char * p)
{
#if 0
if (p[0] != p[3] || p[1] != p[2]) {
fprintf (stderr, "invalid format 7.2.3 number\n");
exit (1);
}
#endif
return (isonum_721 (p));
}
int
isonum_731 (char * p)
{
return ((p[0] & 0xff)
| ((p[1] & 0xff) << 8)
| ((p[2] & 0xff) << 16)
| ((p[3] & 0xff) << 24));
}
int
isonum_732 (char * p)
{
return (((p[0] & 0xff) << 24)
| ((p[1] & 0xff) << 16)
| ((p[2] & 0xff) << 8)
| (p[3] & 0xff));
}
int
isonum_733 (char * p)
{
#if 0
int i;
for (i = 0; i < 4; i++) {
if (p[i] != p[7-i]) {
fprintf (stderr, "bad format 7.3.3 number\n");
exit (1);
}
}
#endif
return (isonum_731 (p));
}
/*
* 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};
extern struct timezone sys_tz;
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;
if (sys_tz.tz_dsttime)
crtime -= 3600;
/* 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 explaination. 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;
}
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