/*

 * Copyright (c) 2020 Red Hat, Inc.

 *

 * 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 2

 * 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA. 

 *

 * $Id: //eng/uds-releases/jasper/kernelLinux/uds/sysfs.c#4 $

 */

#include "sysfs.h"

#include <linux/kobject.h>

#include <linux/module.h>

#include <linux/slab.h>

#include "logger.h"

#include "memoryAlloc.h"

#include "stringUtils.h"

#include "uds.h"

static struct {

  struct kobject kobj;               // /sys/uds

  struct kobject parameterKobj;      // /sys/uds/parameter

  // These flags are used to ensure a clean shutdown

  bool flag;               // /sys/uds

  bool parameterFlag;      // /sys/uds/parameter

} objectRoot;

/**********************************************************************/

static char *bufferToString(const char *buf, size_t length)

{

  char *string;

  if (ALLOCATE(length + 1, char, __func__, &string) != UDS_SUCCESS) {

    return NULL;

  }

  memcpy(string, buf, length);

  string[length] = '\0';

  if (string[length - 1] == '\n') {

    string[length - 1] = '\0';

  }

  return string;

}

/**********************************************************************/

// This is the code for a directory in the /sys/<module_name> tree that

// contains no regular files (only subdirectories).

/**********************************************************************/

/**********************************************************************/

static void emptyRelease(struct kobject *kobj)

{

  // Many of our sysfs share this release function that does nothing.

}

/**********************************************************************/

static ssize_t emptyShow(struct kobject   *kobj,

                         struct attribute *attr,

                         char             *buf)

{

  return 0;

}

/**********************************************************************/

static ssize_t emptyStore(struct kobject   *kobj,

                          struct attribute *attr,

                          const char       *buf,

                          size_t            length)

{

  return length;

}

static struct sysfs_ops emptyOps = {

  .show  = emptyShow,

  .store = emptyStore,

};

static struct attribute *emptyAttrs[] = {

  NULL,

};

static struct kobj_type emptyObjectType = {

  .release       = emptyRelease,

  .sysfs_ops     = &emptyOps,

  .default_attrs = emptyAttrs,

};

/**********************************************************************/

// This is the the code for the /sys/<module_name>/parameter directory.

//

// <dir>/log_level                 UDS_LOG_LEVEL

//

/**********************************************************************/

typedef struct {

  struct attribute  attr;

  const char *(*showString)(void);

  void (*storeString)(const char *);

} ParameterAttribute;

/**********************************************************************/

static ssize_t parameterShow(struct kobject   *kobj,

                             struct attribute *attr,

                             char             *buf)

{

  ParameterAttribute *pa = container_of(attr, ParameterAttribute, attr);

  if (pa->showString != NULL) {

    return sprintf(buf, "%s\n", pa->showString());

  } else {

    return -EINVAL;

  }

}

/**********************************************************************/

static ssize_t parameterStore(struct kobject   *kobj,

                              struct attribute *attr,

                              const char       *buf,

                              size_t            length)

{

  ParameterAttribute *pa = container_of(attr, ParameterAttribute, attr);

  char *string = bufferToString(buf, length);

  if (string == NULL) {

    return -ENOMEM;

  }

  int result = UDS_SUCCESS;

  if (pa->storeString != NULL) {

    pa->storeString(string);

  } else {

    return -EINVAL;

  }

  FREE(string);

  return result == UDS_SUCCESS ? length : result;

}

/**********************************************************************/

static const char *parameterShowLogLevel(void)

{

  return priorityToString(getLogLevel());

}

/**********************************************************************/

static void parameterStoreLogLevel(const char *string)

{

  setLogLevel(stringToPriority(string));

}

/**********************************************************************/

static ParameterAttribute logLevelAttr = {

  .attr        = { .name = "log_level", .mode = 0600 },

  .showString  = parameterShowLogLevel,

  .storeString = parameterStoreLogLevel,

};

static struct attribute *parameterAttrs[] = {

  &logLevelAttr.attr,

  NULL,

};

static struct sysfs_ops parameterOps = {

  .show  = parameterShow,

  .store = parameterStore,

};

static struct kobj_type parameterObjectType = {

  .release       = emptyRelease,

  .sysfs_ops     = &parameterOps,

  .default_attrs = parameterAttrs,

};

/**********************************************************************/

int initSysfs(void)

{

  memset(&objectRoot, 0, sizeof(objectRoot));

  kobject_init(&objectRoot.kobj, &emptyObjectType);

  int result = kobject_add(&objectRoot.kobj, NULL, THIS_MODULE->name);

  if (result == 0) {

    objectRoot.flag = true;

    kobject_init(&objectRoot.parameterKobj, &parameterObjectType);

    result = kobject_add(&objectRoot.parameterKobj, &objectRoot.kobj,

                         "parameter");

    if (result == 0) {

      objectRoot.parameterFlag = true;

    }

  }

  if (result != 0) {

    putSysfs();

  }

  return result;

}

/**********************************************************************/

void putSysfs()

{

  if (objectRoot.parameterFlag) {

    kobject_put(&objectRoot.parameterKobj);

  }

  if (objectRoot.flag) {

    kobject_put(&objectRoot.kobj);

  }

}