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-rw-r--r--fs/isofs/util.c83
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diff --git a/fs/isofs/util.c b/fs/isofs/util.c
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1/*
2 * linux/fs/isofs/util.c
3 */
4
5#include <linux/time.h>
6#include <linux/fs.h>
7#include <linux/iso_fs.h>
8
9/*
10 * We have to convert from a MM/DD/YY format to the Unix ctime format.
11 * We have to take into account leap years and all of that good stuff.
12 * Unfortunately, the kernel does not have the information on hand to
13 * take into account daylight savings time, but it shouldn't matter.
14 * The time stored should be localtime (with or without DST in effect),
15 * and the timezone offset should hold the offset required to get back
16 * to GMT. Thus we should always be correct.
17 */
18
19int iso_date(char * p, int flag)
20{
21 int year, month, day, hour, minute, second, tz;
22 int crtime, days, i;
23
24 year = p[0] - 70;
25 month = p[1];
26 day = p[2];
27 hour = p[3];
28 minute = p[4];
29 second = p[5];
30 if (flag == 0) tz = p[6]; /* High sierra has no time zone */
31 else tz = 0;
32
33 if (year < 0) {
34 crtime = 0;
35 } else {
36 int monlen[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
37
38 days = year * 365;
39 if (year > 2)
40 days += (year+1) / 4;
41 for (i = 1; i < month; i++)
42 days += monlen[i-1];
43 if (((year+2) % 4) == 0 && month > 2)
44 days++;
45 days += day - 1;
46 crtime = ((((days * 24) + hour) * 60 + minute) * 60)
47 + second;
48
49 /* sign extend */
50 if (tz & 0x80)
51 tz |= (-1 << 8);
52
53 /*
54 * The timezone offset is unreliable on some disks,
55 * so we make a sanity check. In no case is it ever
56 * more than 13 hours from GMT, which is 52*15min.
57 * The time is always stored in localtime with the
58 * timezone offset being what get added to GMT to
59 * get to localtime. Thus we need to subtract the offset
60 * to get to true GMT, which is what we store the time
61 * as internally. On the local system, the user may set
62 * their timezone any way they wish, of course, so GMT
63 * gets converted back to localtime on the receiving
64 * system.
65 *
66 * NOTE: mkisofs in versions prior to mkisofs-1.10 had
67 * the sign wrong on the timezone offset. This has now
68 * been corrected there too, but if you are getting screwy
69 * results this may be the explanation. If enough people
70 * complain, a user configuration option could be added
71 * to add the timezone offset in with the wrong sign
72 * for 'compatibility' with older discs, but I cannot see how
73 * it will matter that much.
74 *
75 * Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann)
76 * for pointing out the sign error.
77 */
78 if (-52 <= tz && tz <= 52)
79 crtime -= tz * 15 * 60;
80 }
81 return crtime;
82}
83