1 /* 2 * linux/fs/isofs/util.c 3 */ 4 5 #include <linux/time.h> 6 #include "isofs.h" 7 8 /* 9 * We have to convert from a MM/DD/YY format to the Unix ctime format. 10 * We have to take into account leap years and all of that good stuff. 11 * Unfortunately, the kernel does not have the information on hand to 12 * take into account daylight savings time, but it shouldn't matter. 13 * The time stored should be localtime (with or without DST in effect), 14 * and the timezone offset should hold the offset required to get back 15 * to GMT. Thus we should always be correct. 16 */ 17 18 int iso_date(char * p, int flag) 19 { 20 int year, month, day, hour, minute, second, tz; 21 int crtime; 22 23 year = p[0]; 24 month = p[1]; 25 day = p[2]; 26 hour = p[3]; 27 minute = p[4]; 28 second = p[5]; 29 if (flag == 0) tz = p[6]; /* High sierra has no time zone */ 30 else tz = 0; 31 32 if (year < 0) { 33 crtime = 0; 34 } else { 35 crtime = mktime64(year+1900, month, day, hour, minute, second); 36 37 /* sign extend */ 38 if (tz & 0x80) 39 tz |= (-1 << 8); 40 41 /* 42 * The timezone offset is unreliable on some disks, 43 * so we make a sanity check. In no case is it ever 44 * more than 13 hours from GMT, which is 52*15min. 45 * The time is always stored in localtime with the 46 * timezone offset being what get added to GMT to 47 * get to localtime. Thus we need to subtract the offset 48 * to get to true GMT, which is what we store the time 49 * as internally. On the local system, the user may set 50 * their timezone any way they wish, of course, so GMT 51 * gets converted back to localtime on the receiving 52 * system. 53 * 54 * NOTE: mkisofs in versions prior to mkisofs-1.10 had 55 * the sign wrong on the timezone offset. This has now 56 * been corrected there too, but if you are getting screwy 57 * results this may be the explanation. If enough people 58 * complain, a user configuration option could be added 59 * to add the timezone offset in with the wrong sign 60 * for 'compatibility' with older discs, but I cannot see how 61 * it will matter that much. 62 * 63 * Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann) 64 * for pointing out the sign error. 65 */ 66 if (-52 <= tz && tz <= 52) 67 crtime -= tz * 15 * 60; 68 } 69 return crtime; 70 } 71