kotovalexarian-likes-gitlab/sortix--sortix
1
0
Fork 0
mirror of https://gitlab.com/sortix/sortix.git synced 2023-02-13 20:55:38 -05:00
Code Releases Activity

Add format support to date(1).

Browse source
This commit is contained in:
Jonas 'Sortie' Termansen 2021-04-02 15:40:49 +02:00
parent 6a778c6089
commit a8f8b4cfd6
1 changed files with 46 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

57
utils/date.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2013 Jonas 'Sortie' Termansen.
* Copyright (c) 2013, 2021 Jonas 'Sortie' Termansen.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@ -17,24 +17,59 @@
* Print or set system date and time.
*/
#include <errno.h>
#include <error.h>
#include <stdio.h>
#include <err.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
int main(void)
// 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* format = "+%a %b %e %H:%M:%S %Z %Y";
if ( 2 <= argc )
{
if ( argv[1][0] != '+' )
errx(1, "setting the system time is not implemented");
format = argv[1];
}
if ( 3 <= argc )
errx(1, "unexpected extra operand: %s", argv[2]);
time_t current_time = time(NULL);
struct tm tm;
if ( !localtime_r(&current_time, &tm) )
error(1, errno, "time(%ji)", (intmax_t) current_time);
const size_t BUFFER_SIZE = 256;
char buffer[BUFFER_SIZE];
strftime(buffer, BUFFER_SIZE, "%a %b %d %H:%M:%S %Y", &tm);
printf("%s\n", buffer);
err(1, "localtime_r(%ji)", (intmax_t) current_time);
char* string = astrftime(format, &tm);
if ( !string )
err(1, "malloc");
if ( printf("%s\n", string + 1) == EOF )
err(1, "stdout");
if ( ferror(stdout) || fflush(stdout) == EOF )
err(1, "stdout");
return 0;
}