151 lines
4.8 KiB
C++
151 lines
4.8 KiB
C++
#include <luna/Check.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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struct strftime_state
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{
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char* const buf;
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const size_t max;
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size_t pos;
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};
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static bool try_put_char(strftime_state& state, char c)
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{
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if (state.pos == state.max) return false;
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state.buf[state.pos++] = c;
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return true;
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}
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static bool try_put_string(strftime_state& state, const char* s)
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{
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if (state.pos + strlen(s) == (state.max - 1)) return false;
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memcpy(state.buf + state.pos, s, strlen(s));
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state.pos += strlen(s);
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return true;
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}
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static bool try_format(strftime_state& state, const char* format, ...)
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{
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va_list ap;
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va_start(ap, format);
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char buf[BUFSIZ];
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vsnprintf(buf, sizeof(buf), format, ap);
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va_end(ap);
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return try_put_string(state, buf);
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}
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static const char* abday_names[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
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static const char* day_names[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
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static const char* abmon_names[] = {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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static const char* mon_names[] = { "January", "February", "March", "April", "May", "June",
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"July", "August", "September", "October", "November", "December" };
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extern "C"
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{
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size_t strftime(char* buf, size_t max, const char* format, const struct tm* tm)
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{
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strftime_state state = { .buf = buf, .max = max, .pos = 0 };
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while (*format)
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{
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if (*format != '%')
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{
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if (!try_put_char(state, *format)) return 0;
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format++;
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continue;
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}
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else
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{
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format++;
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switch (*format)
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{
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case 'a':
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if (!try_put_string(state, abday_names[tm->tm_wday])) return 0;
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break;
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case 'A':
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if (!try_put_string(state, day_names[tm->tm_wday])) return 0;
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break;
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case 'b':
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if (!try_put_string(state, abmon_names[tm->tm_mon])) return 0;
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break;
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case 'B':
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if (!try_put_string(state, mon_names[tm->tm_mon])) return 0;
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break;
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case 'c':
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if (!try_format(state, "%s %s %.2d %.2d:%.2d:%.2d %d", abday_names[tm->tm_wday],
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abmon_names[tm->tm_mon], tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec,
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tm->tm_year + 1900))
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return 0;
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break;
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case 'd':
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if (!try_format(state, "%.2d", tm->tm_mday)) return 0;
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break;
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case 'H':
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if (!try_format(state, "%.2d", tm->tm_hour)) return 0;
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break;
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case 'I': {
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int hour = tm->tm_hour % 12;
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if (hour == 0) hour = 12;
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if (!try_format(state, "%.2d", hour)) return 0;
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break;
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}
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case 'j': todo();
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case 'm':
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if (!try_format(state, "%.2d", tm->tm_mon + 1)) return 0;
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break;
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case 'M':
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if (!try_format(state, "%.2d", tm->tm_min)) return 0;
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break;
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case 'p':
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if (tm->tm_hour >= 12)
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{
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if (!try_put_string(state, "PM")) return 0;
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}
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else
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{
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if (!try_put_string(state, "AM")) return 0;
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}
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break;
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case 'S':
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if (!try_format(state, "%.2d", tm->tm_sec)) return 0;
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break;
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case 'x':
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// Sorry, Americans, but I ain't doing m/d/y.
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if (!try_format(state, "%.2d/%.2d/%.2d", tm->tm_mday, tm->tm_mon + 1, tm->tm_year + 1900)) return 0;
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break;
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case 'X':
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if (!try_format(state, "%.2d:%.2d:%.2d", tm->tm_hour, tm->tm_min, tm->tm_sec)) return 0;
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break;
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case 'y':
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if (!try_format(state, "%.2d", (tm->tm_year + 1900) % 100)) return 0;
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break;
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case 'Y':
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if (!try_format(state, "%d", tm->tm_year + 1900)) return 0;
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break;
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default: fprintf(stderr, "strftime: unexpected conversion specifier %%%c\n", *format); exit(255);
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}
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format++;
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continue;
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}
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}
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state.buf[state.pos] = '\0';
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return state.pos;
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}
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}
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