systemd/libsysfs/sysfs_device.c

/*
 * sysfs_device.c
 *
 * Generic device utility functions for libsysfs
 *
 * Copyright (C) 2003 International Business Machines, Inc.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */
#include "libsysfs.h"
#include "sysfs.h"

/**
 * sysfs_close_device: closes and cleans up a device
 * @dev = device to clean up
 */
void sysfs_close_device(struct sysfs_device *dev)
{
	if (dev != NULL) {
		dev->next = NULL;
		dev->driver = NULL;
		if (dev->directory != NULL)
			sysfs_close_directory(dev->directory);
		dev->children = NULL;
		free(dev);
	}
}

/**
 * alloc_device: allocates and initializes device structure
 * returns struct sysfs_device
 */
static struct sysfs_device *alloc_device(void)
{
	return (struct sysfs_device *)calloc(1, sizeof(struct sysfs_device));
}

/**
 * sysfs_get_device_attr: searches dev's attributes by name
 * @dev: device to look through
 * @name: attribute name to get
 * returns sysfs_attribute reference with success or NULL with error.
 */
struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
						const char *name)
{
	struct sysfs_attribute *cur = NULL;
	char attrname[SYSFS_NAME_LEN];

	if (dev == NULL || dev->directory == NULL || name == NULL) {
		errno = EINVAL;
		return NULL;
	}
	for (cur = dev->directory->attributes; cur != NULL; cur = cur->next) {
		if ((sysfs_get_name_from_path(cur->path, attrname, 
		    SYSFS_NAME_LEN)) != 0) 
			continue;
		if (strcmp(name, attrname) != 0)
			continue;

		return cur;
	}

	return NULL;
}

/**
 * sysfs_open_device: opens and populates device structure
 * @path: path to device, this is the /sys/devices/ path
 * returns sysfs_device structure with success or NULL with error
 */
struct sysfs_device *sysfs_open_device(const char *path)
{
	struct sysfs_device *dev = NULL;
	struct sysfs_directory *sdir = NULL;
	char *p = NULL;

	if (path == NULL) {
		errno = EINVAL;
		return NULL;
	}
	dev = alloc_device();	
	if (dev == NULL) {
		dprintf(stderr, "Error allocating device at %s\n", path);
		return NULL;
	}
	sdir = sysfs_open_directory(path);
	if (sdir == NULL) {
		dprintf(stderr, "Invalid device at %s\n", path);
		errno = EINVAL;
		sysfs_close_device(dev);
		return NULL;
	}
	if ((sysfs_read_directory(sdir)) != 0) {
		dprintf(stderr, "Error reading device directory at %s\n", path);
		sysfs_close_directory(sdir);
		sysfs_close_device(dev);
		return NULL;
	}
	dev->directory = sdir;
	sysfs_get_name_from_path(sdir->path, dev->bus_id, SYSFS_NAME_LEN);
	/* get device name */
	p = sysfs_get_value_from_attributes(sdir->attributes,	
							SYSFS_NAME_ATTRIBUTE);
	if (p != NULL) {
		strncpy(dev->name, p, SYSFS_NAME_LEN);
		p = dev->name + strlen(dev->name) - 1;
		if ((strlen(dev->name) > 0) && *p == '\n')
			*p = '\0';
	}

	return dev;
}

/**
 * sysfs_close_device_tree: closes every device in the supplied tree, 
 * 	closing children only.
 * @devroot: device root of tree.
 */
void sysfs_close_device_tree(struct sysfs_device *devroot)
{
	if (devroot != NULL) {
		if (devroot->children != NULL) {
			struct sysfs_device *child = NULL, *next = NULL;
	
			for (child = devroot->children; child != NULL;
			     child = next) {
				next = child->next;
				sysfs_close_device_tree(child);
			}
		}
		sysfs_close_device(devroot);
	}
}

/**
 * add_device_child_to_parent: adds child device to parent
 * @parent: parent device.
 * @child: child device to add.
 */
static void add_device_child_to_parent(struct sysfs_device *parent,
					struct sysfs_device *child)
{
	if (parent != NULL && child != NULL) {
		child->next = parent->children;
		parent->children = child;
		child->parent = parent;
	}
}

/**
 * sysfs_open_device_tree: opens root device and all of its children,
 *	creating a tree of devices. Only opens children.
 * @path: sysfs path to devices
 * returns struct sysfs_device and its children with success or NULL with
 *	error.
 */
struct sysfs_device *sysfs_open_device_tree(const char *path)
{
	struct sysfs_device *rootdev = NULL, *new = NULL;
	struct sysfs_directory *cur = NULL;

	if (path == NULL) {
		errno = EINVAL;
		return NULL;
	}
	rootdev = sysfs_open_device(path);
	if (rootdev == NULL) {
		dprintf(stderr, "Error opening root device at %s\n", path);
		return NULL;
	}
	cur = rootdev->directory->subdirs;
	while (cur != NULL) {
		new = sysfs_open_device_tree(cur->path);
		if (new == NULL) {
			dprintf(stderr, "Error opening device tree at %s\n",
				cur->path);
			sysfs_close_device_tree(rootdev);
			return NULL;
		}
		add_device_child_to_parent(rootdev, new);	
		cur = cur->next;
	}

	return rootdev;
}