source/time/timezone.cpp

   1 /* $Id$
   2
   3 This file is part of libmspcore
   4 Copyright © 2008-2009  Mikko Rasa, Mikkosoft Productions
   5 Distributed under the LGPL
   6 */
   7
   8 #include <cstdlib>
   9 #ifdef WIN32
  10 #include <windows.h>
  11 #else
  12 #include <fcntl.h>
  13 #endif
  14 #include <msp/core/systemerror.h>
  15 #include <msp/strings/format.h>
  16 #include "timestamp.h"
  17 #include "timezone.h"
  18 #include "units.h"
  19 #include "utils.h"
  20
  21 using namespace std;
  22
  23 namespace {
  24
  25 using Msp::Time::TimeZone;
  26
  27 #ifndef WIN32
  28 long get_long(char *&ptr)
  29 {
  30         long result = 0;
  31         for(unsigned i=0; i<4; ++i)
  32                 result = (result<<8)+static_cast<unsigned char >(*ptr++);
  33         return result;
  34 }
  35 #endif
  36
  37 TimeZone get_local_timezone()
  38 {
  39 #ifdef WIN32
  40         TIME_ZONE_INFORMATION tzinfo;
  41         DWORD dst = GetTimeZoneInformation(&tzinfo);
  42         if(dst==TIME_ZONE_ID_INVALID)
  43                 throw Msp::system_error("GetTimeZoneInformation");
  44
  45         int offset = tzinfo.Bias;
  46         if(dst==TIME_ZONE_ID_STANDARD)
  47                 offset += tzinfo.StandardBias;
  48         else if(dst==TIME_ZONE_ID_DAYLIGHT)
  49                 offset += tzinfo.DaylightBias;
  50
  51         return TimeZone(offset);
  52 #else
  53         int fd = open("/etc/localtime", O_RDONLY);
  54         if(fd!=-1)
  55         {
  56                 char hdr[44];
  57                 int len = read(fd, hdr, sizeof(hdr));
  58                 long gmtoff = -1;
  59                 string name;
  60                 if(len==44 && hdr[0]=='T' && hdr[1]=='Z' && hdr[2]=='i' && hdr[3]=='f')
  61                 {
  62                         char *ptr = hdr+20;
  63                         long isgmtcnt = get_long(ptr);
  64                         long isstdcnt = get_long(ptr);
  65                         long leapcnt = get_long(ptr);
  66                         long timecnt = get_long(ptr);
  67                         long typecnt = get_long(ptr);
  68                         long charcnt = get_long(ptr);
  69                         int size = timecnt*5+typecnt*6+isgmtcnt+isstdcnt+leapcnt*8+charcnt;
  70                         char buf[size];
  71                         len = read(fd, buf, size);
  72                         if(len==size)
  73                         {
  74                                 ptr = buf;
  75                                 int index = -1;
  76                                 time_t cur_time = Msp::Time::now().to_unixtime();
  77                                 for(int i=0; i<timecnt; ++i)
  78                                         if(get_long(ptr)<=cur_time)
  79                                                 index = i;
  80
  81                                 if(index>0)
  82                                         index = ptr[index];
  83                                 ptr += timecnt;
  84
  85                                 int abbrind = 0;
  86                                 for(int i=0; i<typecnt; ++i)
  87                                 {
  88                                         if((index>=0 && i==index) || (index<0 && !ptr[4] && gmtoff==-1))
  89                                         {
  90                                                 gmtoff = get_long(ptr);
  91                                                 ++ptr;
  92                                                 abbrind = *ptr++;
  93                                         }
  94                                         else
  95                                                 ptr += 6;
  96                                 }
  97
  98                                 name = ptr+abbrind;
  99                         }
 100                 }
 101                 close(fd);
 102
 103                 if(gmtoff!=-1)
 104                         return TimeZone(gmtoff/60, name);
 105         }
 106         return TimeZone();
 107 #endif
 108 }
 109
 110 }
 111
 112 namespace Msp {
 113 namespace Time {
 114
 115 TimeZone::TimeZone():
 116         name("UTC")
 117 { }
 118
 119 TimeZone::TimeZone(int minutes):
 120         offset(minutes*min)
 121 {
 122         if(minutes)
 123         {
 124                 int m = abs(minutes);
 125                 name = format("UTC%c%d", (minutes<0 ? '-' : '+'), m/60);
 126                 if(m%60)
 127                         name += format(":%02d", m%60);
 128         }
 129         else
 130                 name = "UTC";
 131 }
 132
 133 TimeZone::TimeZone(int minutes, const string &n):
 134         name(n),
 135         offset(minutes*min)
 136 { }
 137
 138 const TimeZone &TimeZone::utc()
 139 {
 140         static TimeZone tz(0);
 141         return tz;
 142 }
 143
 144 const TimeZone &TimeZone::local()
 145 {
 146         static TimeZone tz = get_local_timezone();
 147         return tz;
 148 }
 149
 150 } // namespace Time
 151 } // namespace Msp