/* util.c - miscellaneous utility functions
 *
 * Copyright (C) 2016  Luke Shumaker
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

#include <ctype.h> /* for isdigit */
#include <stdlib.h>
#include <error.h>
#include <errno.h>

#include "util.h"

void *xrealloc(void *ptr, size_t size)
{
	void *ret = realloc(ptr, size);
	if (ret == NULL) {
		if (ptr==NULL)
			error(1, errno, "Could not allocate memory");
		else
			error(1, errno, "Could not re-allocate memory");
	}
	return ret;
}

bool is_numeric(const char *str) {
	for (size_t i = 0; str[i] != '\0'; i++)
		if (!isdigit(str[i]))
			return false;
	if (str[0] == '\0')
		return false;
	return true;
}	

int get_fd(const char *addr) {
	int sock;
	if (strcmp(addr, "stdin") == 0) {
		sock = 0;
	} else if (strcmp(addr, "stdout") == 0) {
		sock = 1;
	} else if (strcmp(addr, "stderr") == 0) {
		sock = 2;
	} else if (strncmp(addr, "systemd", strlen("systemd")) == 0) {
		sock = 3; /* <systemd/sd-daemon.h>:SD_LISTEN_FDS_START */
		addr = &addr[strlen("systemd")];
		switch (addr[0]) {
		case '\0':
			/* do nothing */
			break;
		case ':':
			addr = &addr[1];
			if (is_numeric(addr)) {
				sock += atoi(addr);
			} else {
				const char *e = getenv("LISTEN_FDNAMES");
				if (e == NULL)
					return -ENOTCONN;
				char *names = strdupa(e);
				char *name = NULL;
				int i = -1;
				do {
					name = strsep(&names, ":");
					i++;
				} while (name != NULL && strcmp(name, addr) != 0);
				if (name == NULL)
					return -ENOENT;
				sock += i;
			}
		}
	} else {
		if (!is_numeric(addr))
			return -EINVAL;
		sock = atoi(addr);
	}
	return sock;
}