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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* Copyright (C) 2018 - David Oberhollenzer
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include "service.h"
static bool has_dependencies(service_t *list, service_t *svc)
{
size_t i;
while (list != NULL) {
if (svc->after != NULL) {
for (i = 0; svc->after[i] != NULL; ++i) {
if (!strcmp(svc->after[i], list->name))
return true;
}
}
if (list->before != NULL) {
for (i = 0; list->before[i] != NULL; ++i) {
if (!strcmp(list->before[i], svc->name))
return true;
}
}
list = list->next;
}
return false;
}
service_t *svc_tsort(service_t *list)
{
service_t *nl = NULL, *end = NULL;
service_t *svc, *prev;
while (list != NULL) {
/* remove first service without dependencies */
prev = NULL;
svc = list;
while (svc != NULL) {
if (has_dependencies(list, svc)) {
prev = svc;
svc = svc->next;
} else {
if (prev != NULL) {
prev->next = svc->next;
} else {
list = svc->next;
}
svc->next = NULL;
break;
}
}
/* cycle! */
if (svc == NULL) {
if (end == NULL) {
nl = list;
} else {
end->next = list;
}
errno = ELOOP;
break;
}
/* append to new list */
if (end == NULL) {
nl = end = svc;
} else {
end->next = svc;
end = svc;
}
}
return nl;
}
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