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 #include <sstream>
  10 #include <iomanip>
  11 #ifdef WIN32
  12 #include <windows.h>
  13 #else
  14 #include <fcntl.h>
  15 #endif
  16 #include "../core/except.h"
  17 #include "timestamp.h"
  18 #include "timezone.h"
  19 #include "units.h"
  20 #include "utils.h"
  21
  22 using namespace std;
  23
  24 namespace {
  25
  26 using Msp::Time::TimeZone;
  27
  28 #ifndef WIN32
  29 long get_long(char *&ptr)
  30 {
  31         long result = 0;
  32         for(unsigned i=0; i<4; ++i)
  33                 result = (result<<8)+static_cast<unsigned char >(*ptr++);
  34         return result;
  35 }
  36 #endif
  37
  38 TimeZone get_local_timezone()
  39 {
  40 #ifdef WIN32
  41         TIME_ZONE_INFORMATION tzinfo;
  42         DWORD dst = GetTimeZoneInformation(&tzinfo);
  43         if(dst==TIME_ZONE_ID_INVALID)
  44                 throw Msp::SystemError("Failed to get time zone information", GetLastError());
  45
  46         int offset = tzinfo.Bias;
  47         if(dst==TIME_ZONE_ID_STANDARD)
  48                 offset += tzinfo.StandardBias;
  49         else if(dst==TIME_ZONE_ID_DAYLIGHT)
  50                 offset += tzinfo.DaylightBias;
  51
  52         return TimeZone(offset);
  53 #else
  54         int fd = open("/etc/localtime", O_RDONLY);
  55         if(fd>=-1)
  56         {
  57                 char hdr[44];
  58                 int len = read(fd, hdr, sizeof(hdr));
  59                 long gmtoff = -1;
  60                 string name;
  61                 if(len==44 && hdr[0]=='T' && hdr[1]=='Z' && hdr[2]=='i' && hdr[3]=='f')
  62                 {
  63                         char *ptr = hdr+20;
  64                         long isgmtcnt = get_long(ptr);
  65                         long isstdcnt = get_long(ptr);
  66                         long leapcnt = get_long(ptr);
  67                         long timecnt = get_long(ptr);
  68                         long typecnt = get_long(ptr);
  69                         long charcnt = get_long(ptr);
  70                         int size = timecnt*5+typecnt*6+isgmtcnt+isstdcnt+leapcnt*8+charcnt;
  71                         char buf[size];
  72                         len = read(fd, buf, size);
  73                         if(len==size)
  74                         {
  75                                 ptr = buf;
  76                                 int index = -1;
  77                                 time_t cur_time = Msp::Time::now().to_unixtime();
  78                                 for(int i=0; i<timecnt; ++i)
  79                                         if(get_long(ptr)<=cur_time)
  80                                                 index = i;
  81
  82                                 if(index>0)
  83                                         index = ptr[index];
  84                                 ptr += timecnt;
  85
  86                                 int abbrind = 0;
  87                                 for(int i=0; i<typecnt; ++i)
  88                                 {
  89                                         if((index>=0 && i==index) || (index<0 && !ptr[4] && gmtoff==-1))
  90                                         {
  91                                                 gmtoff = get_long(ptr);
  92                                                 ++ptr;
  93                                                 abbrind = *ptr++;
  94                                         }
  95                                         else
  96                                                 ptr += 6;
  97                                 }
  98
  99                                 name = ptr+abbrind;
 100                         }
 101                 }
 102                 close(fd);
 103
 104                 if(gmtoff!=-1)
 105                         return TimeZone(gmtoff/60, name);
 106         }
 107         return TimeZone();
 108 #endif
 109 }
 110
 111 }
 112
 113 namespace Msp {
 114 namespace Time {
 115
 116 TimeZone::TimeZone():
 117         name("UTC")
 118 { }
 119
 120 TimeZone::TimeZone(int minutes):
 121         offset(minutes*min)
 122 {
 123         if(minutes)
 124         {
 125                 ostringstream ss;
 126                 ss.fill('0');
 127                 int m = abs(minutes);
 128                 ss<<"UTC"<<(minutes<0 ? '-' : '+')<<m/60;
 129                 if(m%60)
 130                         ss<<':'<<setw(2)<<m%60;
 131         }
 132         else
 133                 name = "UTC";
 134 }
 135
 136 TimeZone::TimeZone(int minutes, const string &n):
 137         name(n),
 138         offset(minutes*min)
 139 { }
 140
 141 const TimeZone &TimeZone::utc()
 142 {
 143         static TimeZone tz(0);
 144         return tz;
 145 }
 146
 147 const TimeZone &TimeZone::local()
 148 {
 149         static TimeZone tz = get_local_timezone();
 150         return tz;
 151 }
 152
 153 } // namespace Time
 154 } // namespace Msp