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