source/time/timezone.cpp

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