mirror of
https://gitlab.com/sortix/sortix.git
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285 lines
7.7 KiB
C++
285 lines
7.7 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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time/strftime.cpp
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Format time and date into a string.
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*******************************************************************************/
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#include <errno.h>
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#include <stdio.h>
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#include <time.h>
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static const char* GetWeekdayAbbreviated(const struct tm* tm)
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{
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switch ( tm->tm_wday % 7 )
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{
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case 0: return "Sun";
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case 1: return "Mon";
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case 2: return "Tue";
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case 3: return "Wed";
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case 4: return "Thu";
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case 5: return "Fri";
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case 6: return "Sat";
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default: __builtin_unreachable();
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}
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}
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static const char* GetWeekday(const struct tm* tm)
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{
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switch ( tm->tm_wday % 7 )
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{
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case 0: return "Sunday";
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case 1: return "Monday";
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case 2: return "Tuesday";
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case 3: return "Wednesday";
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case 4: return "Thursday";
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case 5: return "Friday";
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case 6: return "Saturday";
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default: __builtin_unreachable();
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}
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}
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static const char* GetMonthAbbreviated(const struct tm* tm)
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{
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switch ( tm->tm_mon % 12 )
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{
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case 0: return "Jan";
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case 1: return "Feb";
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case 2: return "Mar";
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case 3: return "Apr";
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case 4: return "May";
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case 5: return "Jun";
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case 6: return "Jul";
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case 7: return "Aug";
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case 8: return "Sep";
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case 9: return "Oct";
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case 10: return "Nov";
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case 11: return "Dec";
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default: __builtin_unreachable();
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}
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}
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static const char* GetMonth(const struct tm* tm)
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{
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switch ( tm->tm_mon % 12 )
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{
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case 0: return "January";
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case 1: return "February";
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case 2: return "March";
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case 3: return "April";
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case 4: return "May";
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case 5: return "June";
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case 6: return "July";
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case 7: return "August";
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case 8: return "Sepember";
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case 9: return "October";
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case 10: return "November";
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case 11: return "December";
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default: __builtin_unreachable();
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}
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}
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extern "C"
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size_t strftime(char* s, size_t max, const char* format, const struct tm* tm)
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{
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const char* orig_format = format;
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size_t ret = 0;
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#define OUTPUT_CHAR(expr) \
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do { \
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if ( ret == max ) \
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return errno = ERANGE, 0; \
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s[ret++] = expr; \
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} while ( 0 )
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#define OUTPUT_STRING(expr) \
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do { \
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const char* out_str = expr; \
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while ( *out_str ) \
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OUTPUT_CHAR(*out_str++); \
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} while ( 0 )
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#define OUTPUT_STRFTIME(expr) \
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do { \
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int old_errno = errno; \
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errno = 0; \
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size_t subret = strftime(s + ret, max - ret, expr, tm); \
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if ( !subret && errno ) \
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return 0; \
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errno = old_errno; \
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ret += subret; \
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} while ( 0 )
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#define OUTPUT_INT_PADDED(valexpr, widthexpr, padexpr) \
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do { \
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int val = valexpr; \
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size_t width = widthexpr; \
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char pad = padexpr; \
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char str[sizeof(int) * 3]; str[0] = '\0'; \
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size_t got = (size_t) snprintf(str, sizeof(str), "%i", val); \
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while ( pad && got < width-- ) \
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OUTPUT_CHAR(pad); \
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OUTPUT_STRING(str); \
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} while ( 0 )
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#define OUTPUT_INT(valexpr) OUTPUT_INT_PADDED(valexpr, 0,'\0')
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#define OUTPUT_UNSUPPORTED() \
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do { \
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fprintf(stderr, "%s:%u: strftime: error: unsupported format string \"%s\" around \"%%%s\"\n", \
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__FILE__, __LINE__, orig_format, specifiers_begun_at); \
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return 0; \
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} while ( 0 )
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#define OUTPUT_UNDEFINED() OUTPUT_UNSUPPORTED()
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while ( char c = *format++ )
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{
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if ( c != '%' )
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{
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OUTPUT_CHAR(c);
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continue;
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}
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const char* specifiers_begun_at = format;
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c = *format++;
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// Process any optional flags.
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char padding_char = ' ';
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bool plus_padding = false;
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while ( true )
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{
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switch ( c )
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{
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case '0': padding_char = '0'; break;
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case '+': padding_char = '0'; plus_padding = true; break;
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default: goto end_of_flags;
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}
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c = *format++;
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}
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end_of_flags:
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// TODO: Support the '+' flag!
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if ( plus_padding )
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OUTPUT_UNSUPPORTED();
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// Process the optional minimum field width.
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size_t field_width = 0;
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while ( '0' <= c && c <= '9' )
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field_width = field_width * 10 + c - '0',
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c = *format++;
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// Process an optional E or O modifier.
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bool e_modifier = false;
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bool o_modifier = false;
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if ( c == 'E' )
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e_modifier = true,
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c = *format++;
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else if ( c == 'O' )
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o_modifier = true,
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c = *format++;
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// TODO: Support the E and O modifiers where marked with the E and O
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// comments in the below switch.
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if ( e_modifier || o_modifier ) { }
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switch ( c )
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{
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case 'a': OUTPUT_STRING(GetWeekdayAbbreviated(tm)); break;
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case 'A': OUTPUT_STRING(GetWeekday(tm)); break;
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case 'b': OUTPUT_STRING(GetMonthAbbreviated(tm)); break;
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case 'B': OUTPUT_STRING(GetMonth(tm)); break;
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case 'c': /*E*/
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OUTPUT_STRING(GetWeekday(tm));
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OUTPUT_STRING(" ");
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OUTPUT_STRING(GetMonthAbbreviated(tm));
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OUTPUT_STRING(" ");
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OUTPUT_INT_PADDED(tm->tm_mday, 2, '0');
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OUTPUT_STRING(" ");
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OUTPUT_INT_PADDED(tm->tm_hour, 2, '0');
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OUTPUT_STRING(":");
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OUTPUT_INT_PADDED(tm->tm_min, 2, '0');
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OUTPUT_STRING(":");
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OUTPUT_INT_PADDED(tm->tm_sec, 2, '0');
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break;
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case 'C': /*E*/
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if ( !field_width )
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field_width = 2;
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OUTPUT_INT_PADDED((tm->tm_year + 1900) / 100, field_width, padding_char);
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break;
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case 'd': OUTPUT_INT_PADDED(tm->tm_mday, 2, '0'); break; /*O*/
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case 'D': OUTPUT_STRFTIME("%m/%d/%y"); break;
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case 'e': OUTPUT_INT_PADDED(tm->tm_mday, 2, ' '); break; /*O*/
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case 'F':
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// TODO: Revisit this.
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OUTPUT_UNSUPPORTED();
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break;
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case 'g':
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// TODO: These require a bit of intelligence.
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OUTPUT_UNSUPPORTED();
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break;
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case 'G':
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// TODO: These require a bit of intelligence.
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OUTPUT_UNSUPPORTED();
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break;
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case 'h': OUTPUT_STRFTIME("%b"); break;
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case 'H': OUTPUT_INT_PADDED(tm->tm_hour, 2, '0'); break; /*O*/
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case 'I': OUTPUT_INT_PADDED(tm->tm_hour % 12 + 1, 2, '0'); break; /*O*/
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case 'j': OUTPUT_INT_PADDED(tm->tm_yday + 1, 3, '0'); break;
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case 'm': OUTPUT_INT_PADDED(tm->tm_mon + 1, 2, '0'); break; /*O*/
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case 'M': OUTPUT_INT_PADDED(tm->tm_min, 2, '0'); break; /*O*/
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case 'n': OUTPUT_CHAR('\n'); break;
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case 'p': OUTPUT_STRING(tm->tm_hour < 12 ? "AM" : "PM"); break;
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case 'r': OUTPUT_STRFTIME("%I:%M:%S %p"); break;
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case 'R': OUTPUT_STRFTIME("%H:%M"); break;
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case 'S': OUTPUT_INT_PADDED(tm->tm_sec, 2, '0'); break; /*O*/
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case 't': OUTPUT_CHAR('\t'); break;
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case 'T': OUTPUT_STRFTIME("%H:%M:%S"); break;
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case 'u': OUTPUT_INT(tm->tm_yday); break; /*O*/
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case 'U': /*O*/
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// TODO: These require a bit of intelligence.
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OUTPUT_UNSUPPORTED();
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break;
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case 'V': /*O*/
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// TODO: These require a bit of intelligence.
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OUTPUT_UNSUPPORTED();
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break;
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case 'w': OUTPUT_INT(tm->tm_wday); break; /*O*/
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case 'W': /*O*/
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// TODO: These require a bit of intelligence.
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OUTPUT_UNSUPPORTED();
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break;
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case 'x': OUTPUT_STRFTIME("%m/%d/%y"); break; /*E*/
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case 'X': OUTPUT_STRFTIME("%H:%M:%S"); break; /*E*/
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case 'y': OUTPUT_INT_PADDED((tm->tm_year + 1900) % 100, 2, '0'); break; /*EO*/
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case 'Y': OUTPUT_INT(tm->tm_year + 1900); break; /*E*/
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case 'z':
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// TODO: struct tm doesn't have all this information available!
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break;
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case 'Z':
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// TODO: struct tm doesn't have all this information available!
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break;
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case '%': OUTPUT_CHAR('%'); break;
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default: OUTPUT_UNDEFINED(); break;
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}
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}
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if ( ret == max )
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return errno = ERANGE, 0;
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return s[ret] = '\0', ret;
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}
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