source/time/timezone.cpp

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