config.c

/**
 * Copyright © 2016 IBM Corporation
 *
 * 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.
 */

#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>

#include <sys/mman.h>
#include <sys/stat.h>

static const char *config_default_filename = SYSCONFDIR "/obmc-console.conf";

struct config_item {
	char			*name;
	char			*value;
	struct config_item	*next;
};

struct config {
	struct config_item	*items;
};

const char *config_get_value(struct config *config, const char *name)
{
	struct config_item *item;

	for (item = config->items; item; item = item->next)
		if (!strcasecmp(item->name, name))
			return item->value;

	return NULL;
}

static void config_parse(struct config *config, char *buf)
{
	struct config_item *item;
	char *name, *value;
	char *p, *line;
	int rc;

	for (p = NULL, line = strtok_r(buf, "\n", &p); line;
			line = strtok_r(NULL, "\n", &p)) {

		/* trim leading space */
		for (;*line == ' ' || *line == '\t'; line++)
			;

		/* skip comments */
		if (*line == '#')
			continue;

		name = value = NULL;

		rc = sscanf(line, "%m[^ =] = %ms ", &name, &value);
		if (rc != 2 || !strlen(name) || !strlen(value)) {
			free(name);
			free(value);
			continue;
		}

		/* create a new item and add to our list */
		item = malloc(sizeof(*item));
		item->name = name;
		item->value = value;
		item->next = config->items;
		config->items = item;
	}
}

static struct config *config_init_fd(int fd, const char *filename)
{
	struct config *config;
	size_t size, len;
	char *buf;
	int rc;

	size = 4096;
	len = 0;
	buf = malloc(size + 1);
	config = NULL;

	for (;;) {
		rc = read(fd, buf + len, size - len);
		if (rc < 0) {
			warn("Can't read from configuration file %s", filename);
			goto out_free;

		} else if (!rc) {
			break;
		}
		len += rc;
		if (len == size) {
			size <<= 1;
			buf = realloc(buf, size + 1);
		}

	}
	buf[len] = '\0';

	config = malloc(sizeof(*config));
	config->items = NULL;

	config_parse(config, buf);

out_free:
	free(buf);
	return config;
}

struct config *config_init(const char *filename)
{
	struct config *config;
	int fd;

	if (!filename)
		filename = config_default_filename;

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		warn("Can't open configuration file %s", filename);
		return NULL;
	}

	config = config_init_fd(fd, filename);

	close(fd);

	return config;
}

void config_fini(struct config *config)
{
	struct config_item *item, *next;

	for (item = config->items; item; item = next) {
		next = item->next;
		free(item->name);
		free(item->value);
		free(item);
	}

	free(config);
}

#ifdef CONFIG_TEST
int main(void)
{
	struct config_item *item;
	struct config *config;

	config = config_init_fd(STDIN_FILENO, "<stdin>");
	if (!config)
		return EXIT_FAILURE;

	for (item = config->items; item; item = item->next)
		printf("%s: %s\n", item->name, item->value);

	config_fini(config);

	return EXIT_SUCCESS;

}
#endif