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glibc/time/asctime.c
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/* Copyright (C) 1991-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU 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 2.1 of the License, or (at your option) any later version. | |
The GNU 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 GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include "../locale/localeinfo.h" | |
#include <errno.h> | |
#include <limits.h> | |
#include <stdio.h> | |
#include <time.h> | |
/* This is defined in locale/C-time.c in the GNU libc. */ | |
extern const struct __locale_data _nl_C_LC_TIME attribute_hidden; | |
#define ab_day_name(DAY) (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABDAY_1)+(DAY)].string) | |
#define ab_month_name(MON) (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABMON_1)+(MON)].string) | |
static const char format[] = "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n"; | |
static char result[ 3+1+ 3+1+20+1+20+1+20+1+20+1+20+1 + 1]; | |
static char * | |
asctime_internal (const struct tm *tp, char *buf, size_t buflen) | |
{ | |
if (tp == NULL) | |
{ | |
__set_errno (EINVAL); | |
return NULL; | |
} | |
/* We limit the size of the year which can be printed. Using the %d | |
format specifier used the addition of 1900 would overflow the | |
number and a negative vaue is printed. For some architectures we | |
could in theory use %ld or an evern larger integer format but | |
this would mean the output needs more space. This would not be a | |
problem if the 'asctime_r' interface would be defined sanely and | |
a buffer size would be passed. */ | |
if (__glibc_unlikely (tp->tm_year > INT_MAX - 1900)) | |
{ | |
eoverflow: | |
__set_errno (EOVERFLOW); | |
return NULL; | |
} | |
int n = __snprintf (buf, buflen, format, | |
(tp->tm_wday < 0 || tp->tm_wday >= 7 ? | |
"???" : ab_day_name (tp->tm_wday)), | |
(tp->tm_mon < 0 || tp->tm_mon >= 12 ? | |
"???" : ab_month_name (tp->tm_mon)), | |
tp->tm_mday, tp->tm_hour, tp->tm_min, | |
tp->tm_sec, 1900 + tp->tm_year); | |
if (n < 0) | |
return NULL; | |
if (n >= buflen) | |
goto eoverflow; | |
return buf; | |
} | |
/* Like asctime, but write result to the user supplied buffer. The | |
buffer is only guaranteed to be 26 bytes in length. */ | |
char * | |
__asctime_r (const struct tm *tp, char *buf) | |
{ | |
return asctime_internal (tp, buf, 26); | |
} | |
weak_alias (__asctime_r, asctime_r) | |
/* Returns a string of the form "Day Mon dd hh:mm:ss yyyy\n" | |
which is the representation of TP in that form. */ | |
char * | |
asctime (const struct tm *tp) | |
{ | |
return asctime_internal (tp, result, sizeof (result)); | |
} | |
libc_hidden_def (asctime) |