132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
/*
|
|
* Copyright (c) 2013, 2021, 2023 Jonas 'Sortie' Termansen.
|
|
* Copyright (c) 2022 Juhani 'nortti' Krekelä.
|
|
* Copyright (c) 2022 Dennis Wölfing.
|
|
*
|
|
* Permission to use, copy, modify, and distribute this software for any
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
* copyright notice and this permission notice appear in all copies.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
|
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
*
|
|
* date.c
|
|
* Print or set system date and time.
|
|
*/
|
|
|
|
#include <sys/stat.h>
|
|
|
|
#include <err.h>
|
|
#include <stdbool.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <time.h>
|
|
#include <unistd.h>
|
|
|
|
// Note: There's no way to discern whether the format string was too long for
|
|
// the output buffer or if the output was simply empty, so don't call this
|
|
// function with a format that could produce an empty string. E.g. use a prefix
|
|
// like '+' and skip it when using the string.
|
|
static char* astrftime(const char* format, const struct tm* tm)
|
|
{
|
|
size_t format_size = strlen(format) + 1;
|
|
size_t buffer_size = format_size;
|
|
while ( true )
|
|
{
|
|
char* buffer = calloc(buffer_size, 2);
|
|
if ( !buffer )
|
|
return NULL;
|
|
buffer_size *= 2;
|
|
if ( strftime(buffer, buffer_size, format, tm) )
|
|
return buffer;
|
|
free(buffer);
|
|
}
|
|
}
|
|
|
|
int main(int argc, char* argv[])
|
|
{
|
|
const char* date = NULL;
|
|
bool set = false;
|
|
const char* reference = NULL;
|
|
|
|
int opt;
|
|
while ( (opt = getopt(argc, argv, "d:r:s:u")) != -1 )
|
|
{
|
|
switch ( opt )
|
|
{
|
|
case 'd': date = optarg; break;
|
|
case 'r': reference = optarg; break;
|
|
case 's': date = optarg; set = true; break;
|
|
case 'u':
|
|
if ( setenv("TZ", "UTC0", 1) )
|
|
err(1, "setenv");
|
|
break;
|
|
default: return 1;
|
|
}
|
|
}
|
|
|
|
if ( date && reference )
|
|
errx(1, "the -d and -r options are mutually incompatible");
|
|
if ( set && reference )
|
|
errx(1, "the -s and -r options are mutually incompatible");
|
|
|
|
const char* format = "+%a %b %e %H:%M:%S %Z %Y";
|
|
if ( 1 <= argc - optind )
|
|
{
|
|
if ( argv[optind][0] != '+' )
|
|
errx(1, "the format specifier must start with a +");
|
|
format = argv[optind];
|
|
}
|
|
if ( 2 <= argc - optind )
|
|
errx(1, "unexpected extra operand: %s", argv[optind + 1]);
|
|
|
|
struct timespec moment = {0};
|
|
struct tm tm = {0};
|
|
|
|
if ( date )
|
|
{
|
|
memset(&tm, 0, sizeof(tm));
|
|
if ( !strptime(date, format + 1, &tm) )
|
|
errx(1, "date didn't match %s: %s", format + 1, date);
|
|
moment.tv_sec = timegm(&tm); // TODO: timelocal
|
|
}
|
|
else
|
|
{
|
|
if ( reference )
|
|
{
|
|
struct stat st;
|
|
if ( stat(reference, &st) < 0 )
|
|
err(1, "%s", reference);
|
|
moment = st.st_mtim;
|
|
}
|
|
else
|
|
clock_gettime(CLOCK_REALTIME, &moment);
|
|
if ( !localtime_r(&moment.tv_sec, &tm) )
|
|
err(1, "localtime_r(%ji)", (intmax_t) moment.tv_sec);
|
|
}
|
|
|
|
if ( set )
|
|
{
|
|
if ( clock_settime(CLOCK_REALTIME, &moment) < 0 )
|
|
err(1, "clock_settime: CLOCK_REALTIME");
|
|
return 0;
|
|
}
|
|
|
|
char* string = astrftime(format, &tm);
|
|
if ( !string )
|
|
err(1, "malloc");
|
|
if ( printf("%s\n", string + 1) == EOF )
|
|
err(1, "stdout");
|
|
free(string);
|
|
if ( ferror(stdout) || fflush(stdout) == EOF )
|
|
err(1, "stdout");
|
|
return 0;
|
|
}
|