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sysfs_driver.c

/*
 * sysfs_driver.c
 *
 * Driver 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_driver_device(void *device)
{
      sysfs_close_device((struct sysfs_device *)device);
}

/** 
 * sysfs_close_driver: closes driver and deletes device lists too
 * @driver: driver to close
 */ 
void sysfs_close_driver(struct sysfs_driver *driver)
{
      if (driver != NULL) {
            if (driver->devices != NULL) 
                  dlist_destroy(driver->devices);
            if (driver->directory != NULL)
                  sysfs_close_directory(driver->directory);
            free(driver);
      }
}
            
/**
 * open_driver_dir: Open the sysfs_directory for this driver
 * @driver: Driver whose directory to be opened
 * Returns 0 on success and 1 on failure
 */ 
static int open_driver_dir(struct sysfs_driver *driver)
{
      if (driver == NULL) {
            errno = EINVAL;
            return 1;
      }
      if (driver->directory == NULL) {
            driver->directory = sysfs_open_directory(driver->path);
            if (driver->directory == NULL) {
                  dprintf("Error opening driver directory at %s\n", 
                              driver->path);
                  return 1;
            }
      }
      return 0;
}

/**
 * alloc_driver: allocates and initializes driver
 * returns struct sysfs_driver with success and NULL with error.
 */
static struct sysfs_driver *alloc_driver(void)
{
      return (struct sysfs_driver *)calloc(1, sizeof(struct sysfs_driver));
}

/**
 * sysfs_open_driver_path: opens and initializes driver structure
 * @path: path to driver directory
 * returns struct sysfs_driver with success and NULL with error
 */
struct sysfs_driver *sysfs_open_driver_path(const char *path)
{
      struct sysfs_driver *driver = NULL;

      if (path == NULL) {
            errno = EINVAL;
            return NULL;
      }
      if ((sysfs_path_is_dir(path)) != 0) {
            dprintf("Invalid path to driver: %s\n", path);
            return NULL;
      }
      driver = alloc_driver();
      if (driver == NULL) {
            dprintf("Error allocating driver at %s\n", path);
            return NULL;
      }
      if ((sysfs_get_name_from_path(path, driver->name, 
                              SYSFS_NAME_LEN)) != 0) {
            dprintf("Error getting driver name from path\n");
            free(driver);
            return NULL;
      }
      safestrcpy(driver->path, path);
      if ((sysfs_remove_trailing_slash(driver->path)) != 0) {
            dprintf("Invalid path to driver %s\n", driver->path);
            sysfs_close_driver(driver);
            return NULL;
      }
      
      return driver;
}

/**
 * sysfs_get_driver_attributes: gets list of attributes for the given driver
 * @driver: sysfs_driver for which attributes are required
 * returns a dlist of attributes corresponding to the driver if present
 *    NULL otherwise
 */
struct dlist *sysfs_get_driver_attributes(struct sysfs_driver *driver)
{
      if (driver == NULL) {
            errno = EINVAL;
            return NULL;
      }

      if (driver->directory == NULL) {
            if ((open_driver_dir(driver)) == 1) 
                  return NULL;
      }
      if (driver->directory->attributes == NULL) {
            if ((sysfs_read_dir_attributes(driver->directory)) != 0) 
                  return NULL;
      }
      return(driver->directory->attributes);
}

/**
 * sysfs_refresh_driver_attributes: refreshes the driver's list of attributes
 * @driver: sysfs_driver whose attributes to refresh
 *
 * NOTE: Upon return, prior references to sysfs_attributes for this driver
 *          _may_ not be valid
 *          
 * Returns list of attributes on success and NULL on failure
 */
struct dlist *sysfs_refresh_driver_attributes(struct sysfs_driver *driver)
{
      if (driver == NULL) {
            errno = EINVAL;
            return NULL;
      }
      if (driver->directory == NULL)
            return (sysfs_get_driver_attributes(driver));
      
      if ((sysfs_refresh_dir_attributes(driver->directory)) != 0) {
            dprintf("Error refreshing driver attributes\n");
            return NULL;
      }
      return (driver->directory->attributes);
}

/**
 * sysfs_get_driver_attr: searches driver's attributes by name
 * @drv: driver to look through
 * @name: attribute name to get
 * returns sysfs_attribute reference on success or NULL with error
 */ 
struct sysfs_attribute *sysfs_get_driver_attr(struct sysfs_driver *drv,
                              const char *name)
{
      struct dlist *attrlist = NULL;

        if (drv == NULL) {
                errno = EINVAL;
                return NULL;
        }
      
      attrlist = sysfs_get_driver_attributes(drv);
      if (attrlist == NULL) 
            return NULL;

      return sysfs_get_directory_attribute(drv->directory, (char *)name);
}

/**
 * sysfs_get_driver_links: gets list of links from the given driver
 * @driver: sysfs_driver for which links list is required
 * returns a dlist of links corresponding to the driver if present
 *    NULL otherwise
 */
struct dlist *sysfs_get_driver_links(struct sysfs_driver *driver)
{
      if (driver == NULL) {
            errno = EINVAL;
            return NULL;
      }

      if (driver->directory == NULL) 
            if ((open_driver_dir(driver)) == 1)
                  return NULL;
      
      if (driver->directory->links == NULL)
            if ((sysfs_read_dir_links(driver->directory)) != 0) 
                  return NULL;
            
      return(driver->directory->links);
}

/**
 * sysfs_get_driver_devices: open up the list of devices this driver supports
 * @driver: sysfs_driver for which devices are needed
 * Returns dlist of devices on SUCCESS or NULL with ERROR
 */ 
struct dlist *sysfs_get_driver_devices(struct sysfs_driver *driver)
{
      struct sysfs_link *curlink = NULL;
      struct sysfs_device *device = NULL;

      if (driver == NULL) {
            errno = EINVAL;
            return NULL;
      }
      
      if (driver->devices != NULL)
            return (driver->devices);

      if (driver->directory == NULL || driver->directory->links == NULL) {
            struct dlist *list = NULL;
            list = sysfs_get_driver_links(driver);
      }
      
      if (driver->directory->links != NULL) {
            dlist_for_each_data(driver->directory->links, curlink, 
                                    struct sysfs_link) {
                  device = sysfs_open_device_path(curlink->target);
                  if (device == NULL) {
                        dprintf("Error opening device at %s\n", 
                                    curlink->target);
                        return NULL;
                  }
                  if (driver->devices == NULL) 
                        driver->devices = dlist_new_with_delete
                                    (sizeof(struct sysfs_device),
                                     sysfs_close_driver_device);
                  dlist_unshift_sorted(driver->devices, device, 
                                                sort_list);
            }
      }
      return (driver->devices);
}

/**
 * sysfs_refresh_driver_devices: Refreshes drivers list of devices
 * @driver: sysfs_driver whose devices list needs to be refreshed
 *
 * NOTE: Upon return from this function, prior sysfs_device references from
 *          this driver's list of devices _may_ not be valid
 *          
 * Returns dlist of devices on success and NULL on failure
 */
struct dlist *sysfs_refresh_driver_devices(struct sysfs_driver *driver)
{
      if (driver == NULL) {
            errno = EINVAL;
            return NULL;
      }
      
      if (driver->devices != NULL) {
            dlist_destroy(driver->devices);
            driver->devices = NULL;
      }
      
      if (driver->directory == NULL)
            return (sysfs_get_driver_devices(driver));

      if ((sysfs_refresh_dir_links(driver->directory)) != 0) {
            dprintf("Error refreshing driver links\n");
            return NULL;
      }
      
      return (sysfs_get_driver_devices(driver));
}

/**
 * sysfs_get_driver_device: looks up a device from a list of driver's devices
 *    and returns its sysfs_device corresponding to it
 * @driver: sysfs_driver on which to search
 * @name: name of the device to search
 * Returns a sysfs_device if found, NULL otherwise
 */
struct sysfs_device *sysfs_get_driver_device(struct sysfs_driver *driver,
                        const char *name)
{
      struct sysfs_device *device = NULL;
      struct dlist *devlist = NULL;

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

      if (driver->devices == NULL) {
            devlist = sysfs_get_driver_devices(driver);
            if (devlist == NULL) {
                  dprintf("Error getting driver devices\n");
                  return NULL;
            }
      }
      dlist_for_each_data(driver->devices, device, struct sysfs_device) {
            if (!(strncmp(device->name, name, SYSFS_NAME_LEN)))
                  return device;
      }
      return NULL;
}

/**
 * get_driver_path: looks up the bus the driver is on and builds path to
 *          the driver.
 * @bus: bus on which to search
 * @drv: driver to look for
 * @path: buffer to return path to driver
 * @psize: size of "path"
 * Returns 0 on success and -1 on error
 */
static int get_driver_path(const char *bus, const char *drv, 
                  char *path, size_t psize)
{
      if (bus == NULL || drv == NULL || path == NULL || psize == 0) {
            errno = EINVAL;
            return -1;
      }
      if (sysfs_get_mnt_path(path, psize) != 0) {
            dprintf("Error getting sysfs mount path\n");
            return -1;
      }
      safestrcatmax(path, "/", psize);
      safestrcatmax(path, SYSFS_BUS_NAME, psize);
      safestrcatmax(path, "/", psize);
      safestrcatmax(path, bus, psize);
      safestrcatmax(path, "/", psize);
      safestrcatmax(path, SYSFS_DRIVERS_NAME, psize);
      safestrcatmax(path, "/", psize);
      safestrcatmax(path, drv, psize);
      return 0;
}

/**
 * sysfs_open_driver_attr: read the user supplied driver attribute
 * @bus: bus on which to look 
 * @drv: driver whose attribute has to be read
 * @attrib: Attribute to be read
 * Returns struct sysfs_attribute on success and NULL on failure
 *
 * NOTE:
 *    A call to sysfs_close_attribute() is required to close the
 *    attribute returned and to free memory
 */ 
struct sysfs_attribute *sysfs_open_driver_attr(const char *bus, 
            const char *drv, const char *attrib)
{
      struct sysfs_attribute *attribute = NULL;
      char path[SYSFS_PATH_MAX];

      if (bus == NULL || drv == NULL || attrib == NULL) {
            errno = EINVAL;
            return NULL;
      }

      memset(path, 0, SYSFS_PATH_MAX);
      if ((get_driver_path(bus, drv, path, SYSFS_PATH_MAX)) != 0) {
            dprintf("Error getting to driver %s\n", drv);
            return NULL;
      }
      safestrcat(path, "/");
      safestrcat(path, attrib);
      attribute = sysfs_open_attribute(path);
        if (attribute == NULL) {
            dprintf("Error opening attribute %s for driver %s\n",
                        attrib, drv);
            return NULL;
      }
      if ((sysfs_read_attribute(attribute)) != 0) {
                dprintf("Error reading attribute %s for driver %s\n", 
                        attrib, drv);
            sysfs_close_attribute(attribute);
            return NULL;
      }
      return attribute;
}

/**
 * sysfs_open_driver: open driver by name, given its bus
 * @bus_name: Name of the bus
 * @drv_name: Name of the driver
 * Returns the sysfs_driver reference on success and NULL on failure
 */
struct sysfs_driver *sysfs_open_driver(const char *bus_name, 
                  const char *drv_name)
{
      char path[SYSFS_PATH_MAX];
      struct sysfs_driver *driver = NULL;

      if (drv_name == NULL || bus_name == NULL) {
            errno = EINVAL;
            return NULL;
      }

      memset(path, 0, SYSFS_PATH_MAX);
      if ((get_driver_path(bus_name, drv_name, path, SYSFS_PATH_MAX)) != 0) {
            dprintf("Error getting to driver %s\n", drv_name);
            return NULL;
      }
      driver = sysfs_open_driver_path(path);
      if (driver == NULL) {
            dprintf("Error opening driver at %s\n", path);
            return NULL;
      }
      return driver;
}


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