chore: added cron code
commit
f50bc4a3c4
GPG Key ID:
B75D4F293C7052DB
|
|
@ -0,0 +1,118 @@
|
|||
#include "expression.h"
|
||||
#include <time.h>
|
||||
|
||||
const uint8_t month_days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
|
||||
|
||||
cron_expression *ce_init() { return malloc(sizeof(cron_expression)); }
|
||||
|
||||
void ce_free(cron_expression *ce) {
|
||||
free(ce->months);
|
||||
free(ce->days);
|
||||
free(ce->hours);
|
||||
free(ce->minutes);
|
||||
free(ce);
|
||||
}
|
||||
|
||||
void ce_next(cron_simple_time *out, cron_expression *ce,
|
||||
cron_simple_time *ref) {
|
||||
// For all of these values, the rule is the following: if their value is
|
||||
// the length of their respective array in the CronExpression object, that
|
||||
// means we've looped back around. This means that the "bigger" value has
|
||||
// to be incremented by one. For example, if the minutes have looped
|
||||
// around, that means that the hour has to be incremented as well.
|
||||
uint8_t month_index = 0;
|
||||
uint8_t day_index = 0;
|
||||
uint8_t hour_index = 0;
|
||||
uint8_t minute_index = 0;
|
||||
|
||||
// This chain is the same logic multiple times, namely that if a "bigger"
|
||||
// value loops around, then the smaller value will always reset as well.
|
||||
// For example, if we're going to a new day, the hour & minute will always
|
||||
// be their smallest value again.
|
||||
while (month_index < ce->month_count &&
|
||||
ref->month > ce->months[month_index]) {
|
||||
month_index++;
|
||||
}
|
||||
|
||||
if (month_index < ce->month_count &&
|
||||
ref->month == ce->months[month_index]) {
|
||||
while (day_index < ce->day_count && ref->day > ce->days[day_index]) {
|
||||
day_index++;
|
||||
}
|
||||
|
||||
if (day_index < ce->day_count && ref->day == ce->days[day_index]) {
|
||||
while (hour_index < ce->hour_count &&
|
||||
ref->hour > ce->hours[hour_index]) {
|
||||
hour_index++;
|
||||
}
|
||||
|
||||
if (hour_index < ce->hour_count &&
|
||||
ref->hour == ce->hours[hour_index]) {
|
||||
// Minute is the only value where we explicitely make sure we
|
||||
// can't match sref's value exactly. This is to ensure we only
|
||||
// return values in the future.
|
||||
while (minute_index < ce->minute_count &&
|
||||
ref->minute >= ce->minutes[minute_index]) {
|
||||
minute_index++;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Here, we increment the "bigger" values by one if the smaller ones loop
|
||||
// around. The order is important, as it allows a sort-of waterfall effect
|
||||
// to occur which updates all values if required.
|
||||
if (minute_index == ce->minute_count && hour_index < ce->hour_count) {
|
||||
hour_index++;
|
||||
}
|
||||
|
||||
if (hour_index == ce->hour_count && day_index < ce->day_count) {
|
||||
day_index++;
|
||||
}
|
||||
|
||||
if (day_index == ce->day_count && month_index < ce->month_count) {
|
||||
month_index++;
|
||||
}
|
||||
|
||||
out->minute = ce->minutes[minute_index % ce->minute_count];
|
||||
out->hour = ce->hours[hour_index % ce->hour_count];
|
||||
out->day = ce->days[day_index % ce->day_count];
|
||||
|
||||
// Sometimes, we end up with a day that does not exist within the selected
|
||||
// month, e.g. day 30 in February. When this occurs, we reset day back to
|
||||
// the smallest value & loop over to the next month that does have this
|
||||
// day.
|
||||
if (out->day > month_days[ce->months[month_index % ce->month_count] - 1]) {
|
||||
out->day = ce->days[0];
|
||||
month_index++;
|
||||
|
||||
while (out->day >
|
||||
month_days[ce->months[month_index % ce->month_count] - 1]) {
|
||||
month_index++;
|
||||
}
|
||||
}
|
||||
|
||||
out->month = ce->months[month_index % ce->month_count];
|
||||
|
||||
if (month_index >= ce->month_count) {
|
||||
out->year = ref->year + 1;
|
||||
} else {
|
||||
out->year = ref->year;
|
||||
}
|
||||
}
|
||||
|
||||
void ce_next_from_now(cron_simple_time *out, cron_expression *ce) {
|
||||
time_t t = time(NULL);
|
||||
struct tm gm;
|
||||
gmtime_r(&t, &gm);
|
||||
|
||||
cron_simple_time ref = {// tm_year contains years since 1900
|
||||
.year = 1900 + gm.tm_year,
|
||||
// tm_mon goes from 0 to 11
|
||||
.month = gm.tm_mon + 1,
|
||||
.day = gm.tm_mday,
|
||||
.hour = gm.tm_hour,
|
||||
.minute = gm.tm_min};
|
||||
|
||||
ce_next(out, ce, &ref);
|
||||
}
|
||||
|
|
@ -0,0 +1,50 @@
|
|||
#ifndef VIETER_CRON
|
||||
#define VIETER_CRON
|
||||
|
||||
#include <stdbool.h>
|
||||
#include <stdint.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <time.h>
|
||||
|
||||
typedef enum cron_parse_error {
|
||||
cron_parse_ok = 0,
|
||||
cron_parse_invalid_expression = 1,
|
||||
cron_parse_invalid_number = 2,
|
||||
cron_parse_out_of_range = 3,
|
||||
cron_parse_too_many_parts = 4,
|
||||
cron_parse_not_enough_parts = 5
|
||||
} cron_parse_error;
|
||||
|
||||
typedef struct cron_expression {
|
||||
uint8_t *minutes;
|
||||
uint8_t *hours;
|
||||
uint8_t *days;
|
||||
uint8_t *months;
|
||||
uint8_t minute_count;
|
||||
uint8_t hour_count;
|
||||
uint8_t day_count;
|
||||
uint8_t month_count;
|
||||
} cron_expression;
|
||||
|
||||
typedef struct cron_simple_time {
|
||||
int year;
|
||||
int month;
|
||||
int day;
|
||||
int hour;
|
||||
int minute;
|
||||
} cron_simple_time;
|
||||
|
||||
cron_expression *ce_init();
|
||||
|
||||
void cron_ce_free(cron_expression *ce);
|
||||
|
||||
void cron_ce_next(cron_simple_time *out, cron_expression *ce,
|
||||
cron_simple_time *ref);
|
||||
|
||||
void cron_ce_next_from_now(cron_simple_time *out, cron_expression *ce);
|
||||
|
||||
enum cron_parse_error cron_ce_parse_expression(cron_expression *out,
|
||||
const char *expression);
|
||||
|
||||
#endif
|
||||
|
|
@ -0,0 +1,335 @@
|
|||
#include "expression.h"
|
||||
|
||||
// This prefix is needed to properly compile
|
||||
const uint8_t parse_month_days[] = {31, 28, 31, 30, 31, 30,
|
||||
31, 31, 30, 31, 30, 31};
|
||||
|
||||
// Allowed value ranges for the minute, hour, day and month field
|
||||
const uint8_t min[4] = {0, 0, 1, 1};
|
||||
const uint8_t max[4] = {59, 23, 31, 12};
|
||||
|
||||
const uint8_t min_parts = 2;
|
||||
const uint8_t max_parts = 4;
|
||||
|
||||
// Convert a string into a uint8_t value by parsing it using atoi and checking
|
||||
// whether it's contained within the given range
|
||||
#define SAFE_ATOI(v, s, min, max) \
|
||||
int _##v = atoi(s); \
|
||||
if ((_##v) == 0 && strcmp((s), "0") != 0) { \
|
||||
return cron_parse_invalid_number; \
|
||||
} \
|
||||
if (((_##v) < (min)) || ((_##v) > (max))) { \
|
||||
return cron_parse_out_of_range; \
|
||||
} \
|
||||
v = (uint8_t)(_##v);
|
||||
|
||||
#define MAX(x, y) (((x) > (y)) ? (x) : (y))
|
||||
|
||||
/**
|
||||
* Given a range expression, produce a bit field defining what numbers in the
|
||||
* min-max range the expression represents. Bit 0 (starting from the
|
||||
* right) corresponds to min, the bit max - min to max. All trailing bits
|
||||
* after this should be ignored. The given bitfield is modified in-place, so
|
||||
* multiple calls of this function can be performed on the same value to create
|
||||
* the effect of ORing their values.
|
||||
*
|
||||
* A range expression has one of the following forms:
|
||||
*
|
||||
* - *
|
||||
* - a
|
||||
* - a-b
|
||||
* - a/c
|
||||
* - a-b/c
|
||||
*/
|
||||
cron_parse_error ce_parse_range(uint64_t *out, char *s, uint8_t min,
|
||||
uint8_t max) {
|
||||
size_t slash_index = 0, dash_index = 0;
|
||||
size_t s_index = 0;
|
||||
char cur_char;
|
||||
bool is_valid_character;
|
||||
|
||||
while ((cur_char = s[s_index]) != '\0') {
|
||||
is_valid_character = cur_char == '/' || cur_char == '-' ||
|
||||
cur_char == '*' ||
|
||||
(cur_char >= '0' && cur_char <= '9');
|
||||
|
||||
if (!is_valid_character) {
|
||||
return cron_parse_invalid_expression;
|
||||
}
|
||||
|
||||
if (cur_char == '/') {
|
||||
if (s_index == 0 || slash_index != 0) {
|
||||
return cron_parse_invalid_expression;
|
||||
}
|
||||
|
||||
slash_index = s_index;
|
||||
|
||||
s[s_index] = '\0';
|
||||
} else if (cur_char == '-') {
|
||||
// At most one dash is allowed, and it must be before the slash
|
||||
if (s_index == 0 || dash_index != 0 || slash_index != 0) {
|
||||
return cron_parse_invalid_expression;
|
||||
}
|
||||
|
||||
dash_index = s_index;
|
||||
|
||||
s[s_index] = '\0';
|
||||
}
|
||||
|
||||
s_index++;
|
||||
}
|
||||
|
||||
uint8_t start;
|
||||
uint8_t end = max;
|
||||
uint8_t interval = 0;
|
||||
|
||||
if (s[0] == '*') {
|
||||
if (s[1] != '\0' || dash_index != 0) {
|
||||
return cron_parse_invalid_expression;
|
||||
}
|
||||
|
||||
start = min;
|
||||
interval = 1;
|
||||
} else {
|
||||
SAFE_ATOI(start, s, min, max);
|
||||
|
||||
if (dash_index > 0) {
|
||||
SAFE_ATOI(end, &s[dash_index + 1], min, max);
|
||||
interval = 1;
|
||||
}
|
||||
}
|
||||
|
||||
if (slash_index > 0) {
|
||||
SAFE_ATOI(interval, &s[slash_index + 1], 1, max - min);
|
||||
}
|
||||
|
||||
if (interval == 0) {
|
||||
*out |= ((uint64_t)1) << (start - min);
|
||||
} else {
|
||||
while (start <= end) {
|
||||
*out |= ((uint64_t)1) << (start - min);
|
||||
start += interval;
|
||||
}
|
||||
}
|
||||
|
||||
return cron_parse_ok;
|
||||
}
|
||||
|
||||
/*
|
||||
* Given an expression part, produce a bitfield defining what numbers in the
|
||||
* min-max range the part represents. A part consists of one or more range
|
||||
* expressions, separated by commas.
|
||||
*/
|
||||
cron_parse_error ce_parse_part(uint64_t *out, char *s, uint8_t min,
|
||||
uint8_t max) {
|
||||
*out = 0;
|
||||
|
||||
char *next;
|
||||
cron_parse_error res;
|
||||
|
||||
while ((next = strchr(s, ',')) != NULL) {
|
||||
next[0] = '\0';
|
||||
|
||||
res = ce_parse_range(out, s, min, max);
|
||||
|
||||
if (res != cron_parse_ok) {
|
||||
return res;
|
||||
}
|
||||
|
||||
s = next + 1;
|
||||
}
|
||||
|
||||
// Make sure to parse the final range as well
|
||||
return ce_parse_range(out, s, min, max);
|
||||
}
|
||||
|
||||
/*
|
||||
* Return how many bits are set in the bitfield, better known as popcount. I
|
||||
* added my own implementation (taken from my algorithms course) as I don't want
|
||||
* to be dependent on GCC-specific extensions.
|
||||
*/
|
||||
uint8_t uint64_t_popcount(uint64_t n) {
|
||||
uint8_t set_bits = 0;
|
||||
|
||||
while (n != 0) {
|
||||
// This sets the least significant bit to zero (very cool)
|
||||
n &= n - 1;
|
||||
|
||||
set_bits++;
|
||||
}
|
||||
|
||||
return set_bits;
|
||||
}
|
||||
|
||||
/*
|
||||
* Convert a bitfield into an array containing the numbers in the min-max range
|
||||
* it represents.
|
||||
*/
|
||||
uint8_t bf_to_nums(uint8_t **out, uint64_t bf, uint8_t min, uint8_t max) {
|
||||
// Each bit field only has `max - min + 1` meaningful bits. All other bits
|
||||
// should be ignored, and can be any value. By shifting the bit field back
|
||||
// and forth, we set these excessive bits to zero, ensuring popcount returns
|
||||
// the correct value.
|
||||
uint8_t excess_bits = 64 - (max - min + 1);
|
||||
bf = (bf << excess_bits) >> excess_bits;
|
||||
|
||||
uint8_t size = uint64_t_popcount(bf);
|
||||
uint8_t *buf = malloc(size * sizeof(uint8_t));
|
||||
|
||||
uint8_t bit_index = 0, buf_index = 0;
|
||||
|
||||
while (buf_index < size && bit_index <= max - min) {
|
||||
if (((uint64_t)1 << bit_index) & bf) {
|
||||
// Resize buffer if needed
|
||||
buf[buf_index] = min + bit_index;
|
||||
buf_index++;
|
||||
}
|
||||
|
||||
bit_index++;
|
||||
}
|
||||
|
||||
*out = buf;
|
||||
|
||||
return size;
|
||||
}
|
||||
|
||||
/*
|
||||
* Parse a cron expression string into a cron_expression struct.
|
||||
*/
|
||||
cron_parse_error ce_parse_expression(cron_expression *out,
|
||||
const char *expression) {
|
||||
// The parsing functions modify the input string in-place
|
||||
char *s = strdup(expression);
|
||||
char *orig_s = s;
|
||||
|
||||
cron_parse_error res = cron_parse_ok;
|
||||
|
||||
// First we divide the input string into its parts, divided by spaces.
|
||||
// Each part is delimited by a NULL byte.
|
||||
uint8_t part_count = 0;
|
||||
char *parts[max_parts];
|
||||
char *next_space;
|
||||
|
||||
// Skip leading spaces
|
||||
size_t offset = 0;
|
||||
|
||||
while (s[offset] == ' ') {
|
||||
offset++;
|
||||
}
|
||||
|
||||
s += offset;
|
||||
|
||||
while (part_count < max_parts && ((next_space = strchr(s, ' ')) != NULL)) {
|
||||
next_space[0] = '\0';
|
||||
|
||||
parts[part_count] = s;
|
||||
part_count++;
|
||||
|
||||
// Skip multiple spaces
|
||||
offset = 1;
|
||||
while (next_space[offset] == ' ') {
|
||||
offset++;
|
||||
}
|
||||
s = next_space + offset;
|
||||
}
|
||||
|
||||
// Each iteration of the loop skips all trailing spaces. This means that, if
|
||||
// s[0] isn't '\0', there's still another part before the end of the string.
|
||||
if (s[0] != '\0') {
|
||||
if (part_count == max_parts) {
|
||||
res = cron_parse_too_many_parts;
|
||||
goto end;
|
||||
}
|
||||
|
||||
parts[part_count] = s;
|
||||
part_count++;
|
||||
}
|
||||
|
||||
if (part_count < min_parts) {
|
||||
res = cron_parse_not_enough_parts;
|
||||
goto end;
|
||||
}
|
||||
|
||||
// We now parse the parts in reverse. This is because the month part
|
||||
// determines the maximum value of the day part.
|
||||
|
||||
uint64_t bit_field = 0;
|
||||
|
||||
// Months
|
||||
if (part_count >= 4) {
|
||||
res = ce_parse_part(&bit_field, parts[3], min[3], max[3]);
|
||||
|
||||
if (res != cron_parse_ok) {
|
||||
goto end;
|
||||
}
|
||||
|
||||
out->month_count = bf_to_nums(&out->months, bit_field, min[3], max[3]);
|
||||
}
|
||||
// If months aren't provided, they're replaced with a *
|
||||
else {
|
||||
out->month_count = bf_to_nums(&out->months, ~0, min[3], max[3]);
|
||||
}
|
||||
|
||||
// Determine what the largest allowed day value is, given the months
|
||||
uint8_t max_day_value = 0;
|
||||
|
||||
for (uint8_t i = 0; i < out->month_count; i++) {
|
||||
max_day_value =
|
||||
MAX(max_day_value, parse_month_days[out->months[i] - 1]);
|
||||
}
|
||||
|
||||
// Days
|
||||
if (part_count >= 3) {
|
||||
bit_field = 0;
|
||||
|
||||
res = ce_parse_part(&bit_field, parts[2], min[2], max_day_value);
|
||||
|
||||
if (res != cron_parse_ok) {
|
||||
free(out->months);
|
||||
|
||||
goto end;
|
||||
}
|
||||
|
||||
out->day_count =
|
||||
bf_to_nums(&out->days, bit_field, min[2], max_day_value);
|
||||
}
|
||||
// If days aren't provided, they're replaced with a *
|
||||
else {
|
||||
out->day_count = bf_to_nums(&out->days, ~0, min[2], max_day_value);
|
||||
}
|
||||
|
||||
// Hours
|
||||
bit_field = 0;
|
||||
|
||||
res = ce_parse_part(&bit_field, parts[1], min[1], max[1]);
|
||||
|
||||
if (res != cron_parse_ok) {
|
||||
free(out->months);
|
||||
free(out->days);
|
||||
|
||||
goto end;
|
||||
}
|
||||
|
||||
out->hour_count = bf_to_nums(&out->hours, bit_field, min[1], max[1]);
|
||||
|
||||
// Minutes
|
||||
bit_field = 0;
|
||||
|
||||
res = ce_parse_part(&bit_field, parts[0], min[0], max[0]);
|
||||
|
||||
if (res != cron_parse_ok) {
|
||||
free(out->months);
|
||||
free(out->days);
|
||||
free(out->hours);
|
||||
|
||||
goto end;
|
||||
}
|
||||
|
||||
out->minute_count = bf_to_nums(&out->minutes, bit_field, min[0], max[0]);
|
||||
|
||||
end:
|
||||
// s is cloned
|
||||
free(orig_s);
|
||||
|
||||
return res;
|
||||
}
|
||||
Loading…
Reference in New Issue