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Add strftime(3).

This commit is contained in:
Jonas 'Sortie' Termansen 2013-03-22 00:13:30 +01:00
parent 8162011b5d
commit 440e34ef62
3 changed files with 286 additions and 0 deletions
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1
libc/Makefile
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@ -121,6 +121,7 @@ strtok.o \
strtok_r.o \
strxfrm.o \
timespec.o \
time/strftime.o \
ungetc.o \
vfscanf.o \
vsscanf.o \

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