source/time/unix/timezone.cpp

   1 #include <unistd.h>
   2 #include <fcntl.h>
   3 #include "timestamp.h"
   4 #include "timezone.h"
   5 #include "utils.h"
   6
   7 using namespace std;
   8
   9 namespace {
  10
  11 long get_long(char *&ptr)
  12 {
  13         long result = 0;
  14         for(unsigned i=0; i<4; ++i)
  15                 result = (result<<8)+static_cast<unsigned char >(*ptr++);
  16         return result;
  17 }
  18
  19 }
  20
  21
  22 namespace Msp {
  23 namespace Time {
  24
  25 TimeZone TimeZone::platform_get_local_timezone()
  26 {
  27         int fd = open("/etc/localtime", O_RDONLY);
  28         if(fd!=-1)
  29         {
  30                 char hdr[44];
  31                 int len = read(fd, hdr, sizeof(hdr));
  32                 long gmtoff = -1;
  33                 string name;
  34                 if(len==44 && hdr[0]=='T' && hdr[1]=='Z' && hdr[2]=='i' && hdr[3]=='f')
  35                 {
  36                         char *ptr = hdr+20;
  37                         long isgmtcnt = get_long(ptr);
  38                         long isstdcnt = get_long(ptr);
  39                         long leapcnt = get_long(ptr);
  40                         long timecnt = get_long(ptr);
  41                         long typecnt = get_long(ptr);
  42                         long charcnt = get_long(ptr);
  43                         int size = timecnt*5+typecnt*6+isgmtcnt+isstdcnt+leapcnt*8+charcnt;
  44                         char *buf = new char[size];
  45                         len = read(fd, buf, size);
  46                         if(len==size)
  47                         {
  48                                 ptr = buf;
  49                                 int index = -1;
  50                                 time_t cur_time = Msp::Time::now().to_unixtime();
  51                                 for(int i=0; i<timecnt; ++i)
  52                                         if(get_long(ptr)<=cur_time)
  53                                                 index = i;
  54
  55                                 if(index>0)
  56                                         index = ptr[index];
  57                                 ptr += timecnt;
  58
  59                                 int abbrind = 0;
  60                                 for(int i=0; i<typecnt; ++i)
  61                                 {
  62                                         if((index>=0 && i==index) || (index<0 && !ptr[4] && gmtoff==-1))
  63                                         {
  64                                                 gmtoff = get_long(ptr);
  65                                                 ++ptr;
  66                                                 abbrind = *ptr++;
  67                                         }
  68                                         else
  69                                                 ptr += 6;
  70                                 }
  71
  72                                 name = ptr+abbrind;
  73                         }
  74                         delete[] buf;
  75                 }
  76                 close(fd);
  77
  78                 if(gmtoff!=-1)
  79                         return TimeZone(gmtoff/60, name);
  80         }
  81         return TimeZone();
  82 }
  83
  84 } // namespace Time
  85 } // namespace Msp