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[libs/core.git] / 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/core/systemerror.h>
8 #include <msp/strings/format.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