forked from Bananymous/banan-os
LibC: Fix strftime implementation
This implementation now passes every musl-libc test :)
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c1a32a4041
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@ -187,7 +187,7 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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struct conversion_t
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{
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char flag = '\0';
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int flag = '\0';
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int width = -1;
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char modifier = '\0';
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};
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@ -207,9 +207,9 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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};
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const auto append_string =
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[&](const char* string) -> bool
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[&s, &len, &maxsize](const char* string) -> bool
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{
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size_t string_len = strlen(string);
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const size_t string_len = strlen(string);
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if (len + string_len >= maxsize)
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return false;
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strcpy(s + len, string);
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@ -218,7 +218,7 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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};
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const auto append_string_from_list =
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[&]<size_t LIST_SIZE>(int index, const char* const (&list)[LIST_SIZE]) -> bool
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[&append_string]<size_t LIST_SIZE>(int index, const char* const (&list)[LIST_SIZE]) -> bool
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{
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const char* string = "INVALID";
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if (index >= 0 && index < (int)LIST_SIZE)
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@ -227,15 +227,43 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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};
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const auto append_value =
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[&](const char* format, int value) -> bool
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[&s, &len, &maxsize]<typename T>(const char* format, T value) -> bool
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{
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int written = snprintf(s + len, maxsize - len, format, value);
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const int written = snprintf(s + len, maxsize - len, format, value);
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if (len + written >= maxsize)
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return false;
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len += written;
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return true;
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};
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const auto append_value_weird =
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[&append_string, &append_value](long long value, int flag, int width) -> bool
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{
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char format[32];
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char* ptr = format;
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*ptr++ = '%';
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if (flag == '+')
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*ptr++ = '+';
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*ptr++ = '0';
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if (width != -1)
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ptr += sprintf(ptr, "%d", width);
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*ptr++ = 'l';
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*ptr++ = 'l';
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*ptr++ = 'd';
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*ptr++ = '\0';
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// idk why but musl libc test says that +4Y -> 2016 and +10F -> 2016-01-03
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// i have no idea why the + is not printed in those cases :)
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if (width < 11 && flag == '+')
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{
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char temp_buffer[12];
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int nprint = sprintf(temp_buffer, format, value);
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return append_string(temp_buffer + (nprint == width + 1));
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}
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return append_value(format, value);
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};
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while (*format && len < maxsize)
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{
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if (*format != '%')
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@ -247,20 +275,14 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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format++;
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conversion_t conversion;
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switch (*format)
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{
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case '+':
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case '0':
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conversion.flag = *format;
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format++;
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break;
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}
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if (*format == '0' || *format == '+')
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conversion.flag = *format++;
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if (isdigit(*format))
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{
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conversion.width = 0;
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while (isdigit(*format))
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{
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conversion.width = (conversion.width * 10) + (*format + '0');
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conversion.width = (conversion.width * 10) + (*format - '0');
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format++;
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}
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}
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@ -300,16 +322,15 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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break;
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case 'C':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 2)
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conversion.flag = '0';
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if (conversion.width < 2)
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if (conversion.width == -1)
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conversion.width = 2;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, timeptr->tm_year % 100))
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if (conversion.flag == '+')
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sprintf(new_format, "%%+0%dd", conversion.width);
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else
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sprintf(new_format, "%%0%dd", conversion.width);
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if (!append_value(new_format, (1900 + timeptr->tm_year) / 100))
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return 0;
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break;
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}
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@ -323,20 +344,24 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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else return 0;
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break;
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case 'e':
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if (!append_value("% 2d", timeptr->tm_mday))
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if (!append_value("%2d", timeptr->tm_mday))
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return 0;
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break;
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case 'F':
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{
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if (conversion.flag == '\0')
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conversion.flag = '+';
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if (conversion.width == -1)
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conversion.width = 10;
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if (conversion.width < 6)
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conversion.width = 6;
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// remove trailing "-mm-dd" from width
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if (conversion.width >= 6)
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conversion.width -= 6;
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char new_format[32];
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sprintf(new_format, "%%%c%dY-%%m-%%d", conversion.flag, conversion.width - 6);
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char* ptr = new_format;
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*ptr++ = '%';
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if (conversion.flag)
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*ptr++ = conversion.flag;
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if (conversion.width != -1)
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ptr += sprintf(ptr, "%d", conversion.width);
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strcpy(ptr, "Y-%m-%d");
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if (size_t ret = strftime(s + len, maxsize - len, new_format, timeptr))
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len += ret;
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@ -380,6 +405,13 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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len += ret;
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else return 0;
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break;
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case 's':
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{
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struct tm tm_copy = *timeptr;
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if (!append_value("%llu", mktime(&tm_copy)))
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return 0;
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break;
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}
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case 'S':
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if (!append_value("%02d", timeptr->tm_sec))
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return 0;
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@ -406,22 +438,10 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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{
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// Adapted from GNU libc implementation
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constexpr auto is_leap_year =
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[](int year) -> bool
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{
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if (year % 400 == 0)
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return true;
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if (year % 100 == 0)
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return false;
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if (year % 4 == 0)
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return true;
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return false;
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};
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constexpr auto iso_week_days =
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[](int yday, int wday) -> int
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{
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return yday - (wday + 382) % 7 + 3;
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return yday - (yday - wday + 382) % 7 + 3;
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};
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int year = timeptr->tm_year + 1900;
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@ -449,20 +469,13 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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return 0;
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break;
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case 'G':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 4)
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conversion.flag = '0';
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if (conversion.flag == '\0' && 1900 + year > 9999)
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conversion.flag = '+';
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if (conversion.width == -1)
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conversion.width = 0;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, year))
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conversion.width = 4;
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if (!append_value_weird(year, conversion.flag, conversion.width))
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return 0;
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break;
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}
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case 'V':
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if (!append_value("%02d", days / 7 + 1))
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return 0;
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@ -489,24 +502,17 @@ size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict forma
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else return 0;
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break;
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case 'y':
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if (!append_value("%d", timeptr->tm_yday % 100))
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if (!append_value("%02d", timeptr->tm_year % 100))
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return 0;
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break;
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case 'Y':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 4)
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conversion.flag = '0';
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if (conversion.flag == '\0' && timeptr->tm_year > 9999 - 1900)
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conversion.flag = '+';
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if (conversion.width == -1)
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conversion.width = 0;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, 1900 + timeptr->tm_year))
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conversion.width = 4;
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if (!append_value_weird(1900ll + timeptr->tm_year, conversion.flag, conversion.width))
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return 0;
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break;
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}
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case 'z':
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// FIXME: support timezones
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break;
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