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#define _POSIX_C_SOURCE 1
#define _XOPEN_SOURCE 1 // for timezone
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include "timeutil.h"
#include "stringutil.h"
#include <stdio.h>
char *format_string(enum time_format t) {
switch(t) {
case RSS_TIME_FORMAT:
return "%a, %d %b %Y %T %z";
// both remaining cases still need a UTC offset
// part at the end which is not supported by
// strftime(3), so we do this ourselves in
// flocaltime
case HTML_TIME_FORMAT_READABLE:
return "%Y-%m-%d %T";
case ATOM_TIME_FORMAT:
default:
return "%Y-%m-%dT%T";
}
}
size_t flocaltime(char *b, enum time_format type, size_t size, const time_t *time) {
tzset();
struct tm *local = localtime(time);
char *format = format_string(type);
size_t res = strftime(b, size, format, local);
if(res == 0) {
return 0;
}
size_t offset_len = 0;
if(type == ATOM_TIME_FORMAT || type == HTML_TIME_FORMAT_READABLE) {
// for these formats we need to append a RFC3339 UTC offset
// unfortunately it is *not* exactly provided by strftime,
// but in hindsight it might be better to do a little string
// manipulation than this madness, since the libc timezone
// API is horrible (at least POSIX / glibc)
size_t offset_size = 7;
char offset[offset_size];
if(timezone == 0 && !local->tm_isdst) {
offset[0] = 'Z';
offset[1] = '\0';
offset_len = 1;
} else {
// for some reason timezone is seconds *west* of UTC which
// is inverse to how UTC offsets are denoted
long real_offset = (-1) * timezone;
if(daylight) {
// TODO is this correct in all cases?
if(local->tm_isdst == 1) {
real_offset += 3600;
}
}
char sign;
if(real_offset > 0) {
sign = '+';
} else {
sign = '-';
}
long abso = labs(real_offset);
long hour = abso / 3600;
long minute = (abso % 3600) / 60;
offset[0] = sign;
offset[1] = nibble_hex((short) hour / 10);
offset[2] = nibble_hex((short) hour % 10);
offset[3] = ':';
offset[4] = nibble_hex((short) minute / 10);
offset[5] = nibble_hex((short) minute % 10);
offset[6] = '\0';
offset_len = 6;
}
if(res > 0 && res + offset_size <= size) {
memcpy(b + res, offset, offset_size);
}
}
// prevent any buffer overflows
b[size - 1] = '\0';
return res + offset_len;
}
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