systemd/libsysfs/sysfs_class.c

/*
 * sysfs_class.c
 *
 * Generic class utility functions for libsysfs
 *
 * Copyright (C) IBM Corp. 2003
 *
 *  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"

static void sysfs_close_cls_dev(void *dev)
{
	sysfs_close_class_device((struct sysfs_class_device *)dev);
}

/**
 * class_name_equal: compares class_devices' name
 * @a: class_name looking for
 * @b: sysfs_class_device being compared
 */
static int class_name_equal(void *a, void *b)
{
	if (a == NULL || b == NULL)
		return 0;

	if (strcmp(((char *)a), ((struct sysfs_class_device *)b)->name) == 0)
		return 1;

	return 0;
}

/**
 * sysfs_close_class_device: closes a single class device.
 * @dev: class device to close.
 */
void sysfs_close_class_device(struct sysfs_class_device *dev)
{
	if (dev != NULL) {
		if (dev->directory != NULL)
			sysfs_close_directory(dev->directory);
		if (dev->sysdevice != NULL)
			sysfs_close_device(dev->sysdevice);
		if (dev->driver != NULL)
			sysfs_close_driver(dev->driver);
		if (dev->parent != NULL)
			sysfs_close_class_device(dev->parent);
		free(dev);
	}
}

/**
 * sysfs_close_class: close single class
 * @cls: class structure
 */
void sysfs_close_class(struct sysfs_class *cls)
{
	if (cls != NULL) {
		if (cls->directory != NULL)
			sysfs_close_directory(cls->directory);
		if (cls->devices != NULL) 
			dlist_destroy(cls->devices);
		free(cls);
	}
}

/**
 * alloc_class_device: mallocs and initializes new class device struct.
 * returns sysfs_class_device or NULL.
 */
static struct sysfs_class_device *alloc_class_device(void)
{
	return (struct sysfs_class_device *)
				calloc(1, sizeof(struct sysfs_class_device));
}

/**
 * alloc_class: mallocs new class structure
 * returns sysfs_class struct or NULL
 */
static struct sysfs_class *alloc_class(void)
{
	return (struct sysfs_class *)calloc(1, sizeof(struct sysfs_class));
}

/** 
 * set_classdev_classname: Grabs classname from path
 * @cdev: class device to set
 * Returns nothing
 */
static void set_classdev_classname(struct sysfs_class_device *cdev)
{
	char *c = NULL, *e = NULL;
	int count = 0;

	c = strstr(cdev->path, SYSFS_CLASS_NAME);
	if (c == NULL) {
		c = strstr(cdev->path, SYSFS_BLOCK_NAME);
	} else {
		c = strchr(c, '/');
	}

	if (c == NULL)
		safestrcpy(cdev->classname, SYSFS_UNKNOWN);
	else {
		if (*c == '/')
			c++;
		e = c;
		while (e != NULL && *e != '/' && *e != '\0') {
			e++;
			count++;
		}
		strncpy(cdev->classname, c, count);
	}
}

/**
 * sysfs_open_class_device_path: Opens and populates class device
 * @path: path to class device.
 * returns struct sysfs_class_device with success and NULL with error.
 */
struct sysfs_class_device *sysfs_open_class_device_path(const char *path)
{
	struct sysfs_class_device *cdev = NULL;

	if (path == NULL) {
		errno = EINVAL;
		return NULL;
	}
	if ((sysfs_path_is_dir(path)) != 0) {
		dprintf("%s is not a valid path to a class device\n", path);
		return NULL;
	}
	cdev = alloc_class_device();
	if (cdev == NULL) {
		dprintf("calloc failed\n");
		return NULL;
	}
	if ((sysfs_get_name_from_path(path, cdev->name, SYSFS_NAME_LEN)) != 0) {
		errno = EINVAL;
		dprintf("Error getting class device name\n");
		sysfs_close_class_device(cdev);
		return NULL;
	}

	safestrcpy(cdev->path, path);
	if ((sysfs_remove_trailing_slash(cdev->path)) != 0) {
		dprintf("Invalid path to class device %s\n", cdev->path);
		sysfs_close_class_device(cdev);
		return NULL;
	}
	set_classdev_classname(cdev);

	return cdev;
}

/**
 * sysfs_get_class_devices: gets all devices for class
 * @cls: class to get devices for
 * returns dlist of class_devices with success and NULL with error
 */
struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
{
	struct sysfs_class_device *dev = NULL;
	struct sysfs_directory *cur = NULL;

	if (cls == NULL) {
		errno = EINVAL;
		return NULL;
	}

	if (cls->devices != NULL) 
		return cls->devices;

	if (cls->directory == NULL) {
		cls->directory = sysfs_open_directory(cls->path);
		if (cls->directory == NULL) 
			return NULL;
	}

	if ((sysfs_read_dir_subdirs(cls->directory)) != 0) 
		return NULL;

	if (cls->directory->subdirs != NULL) {
		dlist_for_each_data(cls->directory->subdirs, cur, 
						struct sysfs_directory) {
			dev = sysfs_open_class_device_path(cur->path);
			if (dev == NULL) {
				dprintf("Error opening device at %s\n",	
								cur->path);
				continue;
			}
			if (cls->devices == NULL)
				cls->devices = dlist_new_with_delete
					(sizeof(struct sysfs_class_device),
					 		sysfs_close_cls_dev);
			dlist_unshift_sorted(cls->devices, dev, sort_list);
		}
	}
	return cls->devices;
}

/**
 * sysfs_open_class: opens specific class and all its devices on system
 * returns sysfs_class structure with success or NULL with error.
 */
struct sysfs_class *sysfs_open_class(const char *name)
{
	struct sysfs_class *cls = NULL;
	char classpath[SYSFS_PATH_MAX];

	if (name == NULL) {
		errno = EINVAL;
		return NULL;
	}

	memset(classpath, 0, SYSFS_PATH_MAX);
        if ((sysfs_get_mnt_path(classpath, SYSFS_PATH_MAX)) != 0) {
                dprintf("Sysfs not supported on this system\n");
                return NULL;
        }

	/* 
	 * We shall now treat "block" also as a class. Hence, check here
	 * if "name" is "block" and proceed accordingly
	 */
	if (strcmp(name, SYSFS_BLOCK_NAME) == 0) {
		safestrcat(classpath, "/");
		safestrcat(classpath, SYSFS_BLOCK_NAME);
	} else {
		safestrcat(classpath, "/");
		safestrcat(classpath, SYSFS_CLASS_NAME);
		safestrcat(classpath, "/");
		safestrcat(classpath, name);
	}
	if ((sysfs_path_is_dir(classpath)) != 0) {
		dprintf("Class %s not found on the system\n", name);
		return NULL;
	}

	cls = alloc_class();
	if (cls == NULL) {
		dprintf("calloc failed\n");
		return NULL;
	}
	safestrcpy(cls->name, name);	
	safestrcpy(cls->path, classpath);
	if ((sysfs_remove_trailing_slash(cls->path)) != 0) {
		dprintf("Invalid path to class device %s\n", cls->path);
		sysfs_close_class(cls);
		return NULL;
	}
	
	return cls;
}

/**
 * sysfs_get_class_device: Get specific class device using the device's id
 * @class: class to find device on
 * @name: class name of the device
 */ 
struct sysfs_class_device *sysfs_get_class_device(struct sysfs_class *cls,
					char *name)
{
	if (cls == NULL || name == NULL) {
		errno = EINVAL;
		return NULL;
	}

	if (cls->devices == NULL) {
		cls->devices = sysfs_get_class_devices(cls);
		if (cls->devices == NULL) 
			return NULL;
	}
	return (struct sysfs_class_device *)dlist_find_custom(cls->devices,
			name, class_name_equal);
}

/**
 * sysfs_get_classdev_device: returns the sysfs_device corresponding to
 * 		sysfs_class_device, if present
 * @clsdev: class device whose sysfs_device is required
 * Returns sysfs_device on success, NULL on error or if device is not
 * implemented
 */ 
struct sysfs_device *sysfs_get_classdev_device
			(struct sysfs_class_device *clsdev)
{
	struct sysfs_link *devlink = NULL;
	char devpath[SYSFS_PATH_MAX];
	
	if (clsdev == NULL) {
		errno = EINVAL;
		return NULL;
	}
	safestrcpy(devpath, clsdev->path);
	safestrcat(devpath, "/device");
	if ((sysfs_path_is_link(devpath)) != 0) {
		if (clsdev->sysdevice != NULL) {
			sysfs_close_device(clsdev->sysdevice);
			clsdev->sysdevice = NULL;
		}
		return NULL;
	}
	
	if (clsdev->directory == NULL) {
		clsdev->directory = sysfs_open_directory(clsdev->path);
		if (clsdev->directory == NULL)
			return NULL;
	}
	devlink = sysfs_get_directory_link(clsdev->directory, "device");
	if (devlink == NULL) {
		if (clsdev->sysdevice != NULL) {
			dprintf("Device link no longer exists\n");
			sysfs_close_device(clsdev->sysdevice);
			clsdev->sysdevice = NULL;
		}
		return NULL;
	}

	if (clsdev->sysdevice != NULL) {
		if (!strncmp(devlink->target, clsdev->sysdevice->path,
						SYSFS_PATH_MAX)) 
			/* sysdevice hasn't changed */
			return (clsdev->sysdevice);
		else 
			/* come here only if the device link for has changed */
			sysfs_close_device(clsdev->sysdevice);
	}

	clsdev->sysdevice = sysfs_open_device_path(devlink->target);
	if (clsdev->sysdevice == NULL)
		return NULL;

	return (clsdev->sysdevice);
}
				
/**
 * sysfs_get_classdev_driver: returns the sysfs_driver corresponding to
 * 		sysfs_class_device, if present
 * @clsdev: class device whose sysfs_device is required
 * Returns sysfs_driver on success, NULL on error or if driver is not
 * implemented
 */ 
struct sysfs_driver *sysfs_get_classdev_driver
			(struct sysfs_class_device *clsdev)
{
	struct sysfs_link *drvlink = NULL;
	char drvpath[SYSFS_PATH_MAX];
	
	if (clsdev == NULL) {
		errno = EINVAL;
		return NULL;
	}
 	safestrcpy(drvpath, clsdev->path);
	safestrcat(drvpath, "/driver");
	if ((sysfs_path_is_link(drvpath)) != 0) {
		if (clsdev->driver != NULL) {
			sysfs_close_driver(clsdev->driver);
			clsdev->driver = NULL;
		}
		return NULL;
	}
	 
	if (clsdev->directory == NULL) {
		clsdev->directory = sysfs_open_directory(clsdev->path);
		if (clsdev->directory == NULL)
			return NULL;
	}
	drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
	if (drvlink == NULL) {
		if (clsdev->driver != NULL) {
			dprintf("Driver link no longer exists\n");
			sysfs_close_driver(clsdev->driver);
			clsdev->driver = NULL;
		}
		return NULL;
	}
	if (clsdev->driver != NULL) {
		if (!strncmp(drvlink->target, clsdev->driver->path,
	      						SYSFS_PATH_MAX))
			/* driver hasn't changed */
	 		return (clsdev->driver);
 		else
			/* come here only if the device link for has changed */
			sysfs_close_driver(clsdev->driver);
	}
		
	clsdev->driver = sysfs_open_driver_path(drvlink->target);
	if (clsdev->driver == NULL)
		return NULL;

	return (clsdev->driver);
}

/** 
 * get_blockdev_parent: Get the parent class device for a "block" subsystem 
 * 		device if present
 * @clsdev: block subsystem class device whose parent needs to be found
 * Returns 0 on success and 1 on error
 */
static int get_blockdev_parent(struct sysfs_class_device *clsdev)
{
	char parent_path[SYSFS_PATH_MAX], *c = NULL;

	safestrcpy(parent_path, clsdev->path);
	c = strstr(parent_path, SYSFS_BLOCK_NAME);
	if (c == NULL) {
		dprintf("Class device %s does not belong to BLOCK subsystem\n",
				clsdev->name);
		return 1;
	}
	c += strlen(SYSFS_BLOCK_NAME);
	if (*c == '/')
		c++;
	else
		goto errout;

       /* validate whether the given class device is a partition or not */
        if ((strncmp(c, clsdev->name, strlen(clsdev->name))) == 0) {
                dprintf("%s not a partition\n", clsdev->name);
                return 1;
        }
		      
      	c = strchr(c, '/');
	if (c == NULL)
		goto errout;

	*c = '\0';
					
	clsdev->parent = sysfs_open_class_device_path(parent_path);
	if (clsdev->parent == NULL) {
		dprintf("Error opening the parent class device at %s\n", 
								parent_path);
		return 1;
	}
	return 0;

errout:
	dprintf("Invalid path %s\n", clsdev->path);
	return 1;
}

/**
 * sysfs_get_classdev_parent: Retrieves the parent of a class device. 
 * 	eg., when working with hda1, this function can be used to retrieve the
 * 		sysfs_class_device for hda
 * 		
 * @clsdev: class device whose parent details are required.
 * Returns sysfs_class_device of the parent on success, NULL on failure
 */ 
struct sysfs_class_device *sysfs_get_classdev_parent
				(struct sysfs_class_device *clsdev)
{
	if (clsdev == NULL) {
		errno = EINVAL;
		return NULL;
	}
	if (clsdev->parent != NULL)
		return (clsdev->parent);
	
	/* 
	 * As of now, only block devices have a parent child heirarchy in sysfs
	 * We do not know, if, in the future, more classes will have a similar
	 * structure. Hence, we now call a specialized function for block and
	 * later we can add support functions for other subsystems as required.
	 */ 
	if (!(strncmp(clsdev->classname, SYSFS_BLOCK_NAME, 
					sizeof(SYSFS_BLOCK_NAME)))) {
		if ((get_blockdev_parent(clsdev)) == 0) 
			return (clsdev->parent);
	}
	return NULL;
}

/**
 * get_classdev_path: given the class and a device in the class, return the
 * 		absolute path to the device
 * @classname: name of the class
 * @clsdev: the class device
 * @path: buffer to return path
 * @psize: size of "path"
 * Returns 0 on SUCCESS or -1 on error
 */
static int get_classdev_path(const char *classname, const char *clsdev, 
		char *path, size_t len)
{
	if (classname == NULL || clsdev == NULL || path == NULL) {
		errno = EINVAL;
		return -1;
	}
        if (sysfs_get_mnt_path(path, len) != 0) {
                dprintf("Error getting sysfs mount path\n");
                return -1;
	}
	if (strncmp(classname, SYSFS_BLOCK_NAME,
				sizeof(SYSFS_BLOCK_NAME)) == 0) {
		safestrcatmax(path, "/", len);
		safestrcatmax(path, SYSFS_BLOCK_NAME, len);
	} else {
		safestrcatmax(path, "/", len);
		safestrcatmax(path, SYSFS_CLASS_NAME, len);
		safestrcatmax(path, "/", len);
		safestrcatmax(path, classname, len);
	}
	safestrcatmax(path, "/", len);
	safestrcatmax(path, clsdev, len);
	return 0;
}

/**
 * sysfs_open_class_device: Locates a specific class_device and returns it.
 * Class_device must be closed using sysfs_close_class_device
 * @classname: Class to search
 * @name: name of the class_device
 * 
 * NOTE:
 * 	Call sysfs_close_class_device() to close the class device
 */
struct sysfs_class_device *sysfs_open_class_device
		(const char *classname, const char *name)
{
	char devpath[SYSFS_PATH_MAX];
	struct sysfs_class_device *cdev = NULL;

	if (classname == NULL || name == NULL) {
		errno = EINVAL;
		return NULL;
	}
	
	memset(devpath, 0, SYSFS_PATH_MAX);
	if ((get_classdev_path(classname, name, devpath, 
					SYSFS_PATH_MAX)) != 0) {
		dprintf("Error getting to device %s on class %s\n",
							name, classname);
		return NULL;
	}
	
	cdev = sysfs_open_class_device_path(devpath);
	if (cdev == NULL) {
		dprintf("Error getting class device %s from class %s\n",
				name, classname);
		return NULL;
	}
	return cdev;
}

/**
 * sysfs_get_classdev_attributes: returns a dlist of attributes for
 * 	the requested class_device
 * @cdev: sysfs_class_dev for which attributes are needed
 * returns a dlist of attributes if exists, NULL otherwise
 */
struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *cdev)
{
	if (cdev == NULL)
		return NULL;

	if (cdev->directory == NULL) {
		cdev->directory = sysfs_open_directory(cdev->path);
		if (cdev->directory == NULL) 
			return NULL;
	}
	if (cdev->directory->attributes == NULL) {
		if ((sysfs_read_dir_attributes(cdev->directory)) != 0) 
			return NULL;
	}
	return (cdev->directory->attributes);
}

/**
 * sysfs_refresh_clsassdev_attributes: refreshes the driver's list of attributes
 * @clsdev: sysfs_class_device whose attributes to refresh
 *
 * NOTE: Upon return, prior references to sysfs_attributes for this classdev
 *              _may_ not be valid
 *
 * Returns list of attributes on success and NULL on failure
 */
struct dlist *sysfs_refresh_classdev_attributes
			(struct sysfs_class_device *clsdev)
{
	if (clsdev == NULL) {
		errno = EINVAL;
		return NULL;
	}

	if (clsdev->directory == NULL)
		return (sysfs_get_classdev_attributes(clsdev));

	if ((sysfs_refresh_dir_attributes(clsdev->directory)) != 0) {
		dprintf("Error refreshing class_device attributes\n");
		return NULL;
	}

	return (clsdev->directory->attributes);
}

/**
 * sysfs_get_classdev_attr: searches class device's attributes by name
 * @clsdev: class device to look through
 * @name: attribute name to get
 * returns sysfs_attribute reference with success or NULL with error
 */
struct sysfs_attribute *sysfs_get_classdev_attr
		(struct sysfs_class_device *clsdev, const char *name)
{
	struct sysfs_attribute *cur = NULL;
	struct sysfs_directory *sdir = NULL;
	struct dlist *attrlist = NULL;
	
	if (clsdev == NULL || name == NULL) {
		errno = EINVAL;
		return NULL;
	}
	
	/* 
	 * First, see if it's in the current directory. Then look at 
	 * subdirs since class devices can have subdirs of attributes.
	 */ 
	attrlist = sysfs_get_classdev_attributes(clsdev);
	if (attrlist != NULL) {
		cur = sysfs_get_directory_attribute(clsdev->directory,
						(char *)name);
		if (cur != NULL)
			return cur;
	}

	if (clsdev->directory == NULL)
		return NULL;

	if (clsdev->directory->subdirs == NULL) 
		if ((sysfs_read_dir_subdirs(clsdev->directory)) != 0 ||
		    clsdev->directory->subdirs == NULL) 
			return NULL;

	if (clsdev->directory->subdirs != NULL) {
		dlist_for_each_data(clsdev->directory->subdirs, sdir,
						struct sysfs_directory) {
			if ((sysfs_path_is_dir(sdir->path)) != 0) 
				continue;
			cur = sysfs_get_directory_attribute(sdir,
							(char *)name);
			if (cur == NULL)
				continue;
		}
	}
	return cur;
}

/**
 * sysfs_open_classdev_attr: read an attribute for a given class device
 * @classname: name of the class on which to look
 * @dev: class device name for which the attribute has to be read
 * @attrib: attribute to read
 * Returns sysfs_attribute * on SUCCESS and NULL on error
 * 
 * NOTE:
 * 	A call to sysfs_close_attribute() is required to close the
 * 	attribute returned and to free memory
 */
struct sysfs_attribute *sysfs_open_classdev_attr(const char *classname,
		const char *dev, const char *attrib)
{
	struct sysfs_attribute *attribute = NULL;
	char path[SYSFS_PATH_MAX];

	if (classname == NULL || dev == NULL || attrib == NULL) {
		errno = EINVAL;
		return NULL;
	}
	memset(path, 0, SYSFS_PATH_MAX);
	if ((get_classdev_path(classname, dev, path, SYSFS_PATH_MAX)) != 0) {
		dprintf("Error getting to device %s on class %s\n",
						dev, classname);
		return NULL;
	}
	safestrcat(path, "/");
	safestrcat(path, attrib);
	attribute = sysfs_open_attribute(path);
	if (attribute == NULL) {
		dprintf("Error opening attribute %s on class device %s\n",
				attrib, dev);
		return NULL;
	}
	if ((sysfs_read_attribute(attribute)) != 0) {
		dprintf("Error reading attribute %s for class device %s\n",
				attrib, dev);
		sysfs_close_attribute(attribute);
		return NULL;
	}
	return attribute;
}