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/*
* Copyright (C) 2018 "IoT.bzh"
* Author José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/******************************************************************************/
/******************************************************************************/
/* CONVERTION OF EXPIRATIONS TO AND FROM TEXT */
/******************************************************************************/
/******************************************************************************/
#include <stdbool.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include "expire.h"
static const int SEC = 1;
static const int MIN = 60;
static const int HOUR = 60*60;
static const int DAY = 24*60*60;
static const int WEEK = 7*24*60*60;
static const int YEAR = 365*24*60*60 + 24*60*60/4; /* average includes leap */
static const time_t TMAX = ~((time_t)1 << ((CHAR_BIT * sizeof(time_t)) - 1));
/** add positives x and y with saturation */
static time_t pt_add(time_t x, time_t y)
{
time_t r = x + y;
return r < 0 ? TMAX : r;
}
/** multiply positive x by m with saturation */
static time_t pt_mul(time_t x, int m)
{
time_t r;
if (m <= 1)
r = 0;
else {
r = pt_mul(x, m >> 1) << 1;
if (r < 0)
r = TMAX;
}
return (m & 1) ? pt_add(r, x) : r;
}
/** multiply positive x by m and then add y with saturation */
static time_t pt_muladd(time_t x, int m, time_t y)
{
return pt_add(pt_mul(x, m), y);
}
/** multiply positive x by 10 and then add d with saturation */
static time_t pt_tm10a(time_t x, int d)
{
return pt_muladd(x, 10, (time_t)d);
}
/** translate the string 'txt' to its time representation */
static bool parse_time_spec(const char *txt, time_t *time_out)
{
time_t r, x;
/* parse */
r = 0;
while(*txt) {
x = 0;
while('0' <= *txt && *txt <= '9')
x = pt_tm10a(x, *txt++ - '0');
switch(*txt) {
case 'y': r = pt_muladd(x, YEAR, r); txt++; break;
case 'w': r = pt_muladd(x, WEEK, r); txt++; break;
case 'd': r = pt_muladd(x, DAY, r); txt++; break;
case 'h': r = pt_muladd(x, HOUR, r); txt++; break;
case 'm': r = pt_muladd(x, MIN, r); txt++; break;
case 's': txt++; /*@fallthrough@*/
case 0: r = pt_muladd(x, SEC, r); break;
default: return false;
}
}
*time_out = r;
return true;
}
/* see expire.h */
bool txt2exp(const char *txt, time_t *time_out, bool absolute)
{
bool nocache;
time_t r;
/* no cache */
nocache = txt[0] == '-';
txt += nocache;
/* infinite time */
if (!txt[0] || !strcmp(txt, "always") || !strcmp(txt, "forever") || !strcmp(txt, "*")) {
r = 0;
} else {
/* parse */
if (!parse_time_spec(txt, &r))
return false;
if (absolute) {
/* absolute time */
r = pt_add(r, time(NULL));
}
}
*time_out = nocache ? -(r + 1) : r;
return true;
}
/* see expire.h */
size_t exp2txt(time_t expire, bool absolute, char *buffer, size_t buflen)
{
char b[100];
size_t l, n;
n = 0;
if (expire < 0) {
b[n++] = '-';
b[n] = 0;
expire = -(expire + 1);
}
if (!expire) {
if (!n)
strncpy(b, "forever", sizeof b);
} else {
if (absolute)
expire -= time(NULL);
#define ADD(C,U) \
if (expire >= U) { \
n += (size_t)snprintf(&b[n], sizeof b - (size_t)n, "%lld" #C, (long long)(expire / U)); \
expire %= U; \
}
ADD(y,YEAR)
ADD(w,WEEK)
ADD(d,DAY)
ADD(h,HOUR)
ADD(m,MIN)
ADD(s,SEC)
#undef ADD
}
l = strlen(b);
strncpy(buffer, b, buflen);
return l;
}
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