projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 1da177e4 LT |
2 | /* |
| 3 | * linux/fs/isofs/util.c | |
| 4 | */ | |
| 5 | ||
| e4a93be6 | 6 | #include <linux/time.h> |
| 94f2f715 | 7 | #include "isofs.h" |
| 1da177e4 LT |
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 | ||
| 34be4dbf | 19 | int iso_date(u8 *p, int flag) |
| 1da177e4 LT |
20 | { |
| 21 | int year, month, day, hour, minute, second, tz; | |
| e4a93be6 | 22 | int crtime; |
| 1da177e4 | 23 | |
| e4a93be6 | 24 | year = p[0]; |
| 1da177e4 LT |
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 { | |
| e4a93be6 | 36 | crtime = mktime64(year+1900, month, day, hour, minute, second); |
| 1da177e4 LT |
37 | |
| 38 | /* sign extend */ | |
| 39 | if (tz & 0x80) | |
| 40 | tz |= (-1 << 8); | |
| 41 | ||
| 42 | /* | |
| 43 | * The timezone offset is unreliable on some disks, | |
| 44 | * so we make a sanity check. In no case is it ever | |
| 45 | * more than 13 hours from GMT, which is 52*15min. | |
| 46 | * The time is always stored in localtime with the | |
| 47 | * timezone offset being what get added to GMT to | |
| 48 | * get to localtime. Thus we need to subtract the offset | |
| 49 | * to get to true GMT, which is what we store the time | |
| 50 | * as internally. On the local system, the user may set | |
| 51 | * their timezone any way they wish, of course, so GMT | |
| 52 | * gets converted back to localtime on the receiving | |
| 53 | * system. | |
| 54 | * | |
| 55 | * NOTE: mkisofs in versions prior to mkisofs-1.10 had | |
| 56 | * the sign wrong on the timezone offset. This has now | |
| 57 | * been corrected there too, but if you are getting screwy | |
| 58 | * results this may be the explanation. If enough people | |
| 59 | * complain, a user configuration option could be added | |
| 60 | * to add the timezone offset in with the wrong sign | |
| 61 | * for 'compatibility' with older discs, but I cannot see how | |
| 62 | * it will matter that much. | |
| 63 | * | |
| 64 | * Thanks to [email protected] (Volker Kuhlmann) | |
| 65 | * for pointing out the sign error. | |
| 66 | */ | |
| 67 | if (-52 <= tz && tz <= 52) | |
| 68 | crtime -= tz * 15 * 60; | |
| 69 | } | |
| 70 | return crtime; | |
| 71 | } |