/****************************************************************************
 * sched/task/task_setup.c
 *
 *   Copyright (C) 2007-2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <sched.h>
#include <string.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/arch.h>

#include "sched/sched.h"
#include "pthread/pthread.h"
#include "group/group.h"
#include "task/task.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/
/* This is an artificial limit to detect error conditions where an argv[]
 * list is not properly terminated.
 */

#define MAX_STACK_ARGS 256

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Global Variables
 ****************************************************************************/

/****************************************************************************
 * Private Variables
 ****************************************************************************/

/* This is the name for un-named tasks */

static const char g_noname[] = "<noname>";

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int task_assignpid(FAR struct tcb_s* tcb);

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: task_assignpid
 *
 * Description:
 *   This function assigns the next unique task ID to a task.
 *
 * Inputs:
 *   tcb - TCB of task
 *
 * Return:
 *   OK on success; ERROR on failure (errno is not set)
 *
 ****************************************************************************/

static int task_assignpid(FAR struct tcb_s *tcb)
{
  pid_t next_pid;
  int   hash_ndx;
  int   tries;

  /* Disable pre-emption.  This should provide sufficient protection
   * for the following operation.
   */

  (void)sched_lock();

  /* We'll try every allowable pid */

  for (tries = 0; tries < CONFIG_MAX_TASKS; tries++)
    {
      /* Get the next process ID candidate */

      next_pid = ++g_lastpid;

      /* Verify that the next_pid is in the valid range */

      if (next_pid <= 0)
        {
          g_lastpid = 1;
          next_pid  = 1;
        }

      /* Get the hash_ndx associated with the next_pid */

      hash_ndx = PIDHASH(next_pid);

      /* Check if there is a (potential) duplicate of this pid */

      if (!g_pidhash[hash_ndx].tcb)
        {
          /* Assign this PID to the task */

          g_pidhash[hash_ndx].tcb   = tcb;
          g_pidhash[hash_ndx].pid   = next_pid;
#ifdef CONFIG_SCHED_CPULOAD
          g_pidhash[hash_ndx].ticks = 0;
#endif
          tcb->pid = next_pid;

          (void)sched_unlock();
          return OK;
        }
    }

  /* If we get here, then the g_pidhash[] table is completely full.
   * We cannot allow another task to be started.
   */

  (void)sched_unlock();
  return ERROR;
}

/****************************************************************************
 * Name: task_saveparent
 *
 * Description:
 *   Save the task ID of the parent task in the child task's TCB and allocate
 *   a child status structure to catch the child task's exit status.
 *
 * Parameters:
 *   tcb   - The TCB of the new, child task.
 *   ttype - Type of the new thread: task, pthread, or kernel thread
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *   The parent of the new task is the task at the head of the ready-to-run
 *   list.
 *
 ****************************************************************************/

#ifdef CONFIG_SCHED_HAVE_PARENT
static inline void task_saveparent(FAR struct tcb_s *tcb, uint8_t ttype)
{
  FAR struct tcb_s *rtcb = (FAR struct tcb_s*)g_readytorun.head;

#if defined(HAVE_GROUP_MEMBERS) || defined(CONFIG_SCHED_CHILD_STATUS)
  DEBUGASSERT(tcb && tcb->group && rtcb->group);
#else
#endif

#ifdef HAVE_GROUP_MEMBERS
  /* Save the ID of the parent tasks' task group in the child's task group.
   * Do nothing for pthreads.  The parent and the child are both members of
   * the same task group.
   */

#ifndef CONFIG_DISABLE_PTHREAD
  if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
#endif
    {
      /* This is a new task in a new task group, we have to copy the ID from
       * the parent's task group structure to child's task group.
       */

      tcb->group->tg_pgid = rtcb->group->tg_gid;
    }

#else
  DEBUGASSERT(tcb);

  /* Save the parent task's ID in the child task's TCB.  I am not sure if
   * this makes sense for the case of pthreads or not, but I don't think it
   * is harmful in any event.
   */

  tcb->ppid = rtcb->pid;
#endif

#ifdef CONFIG_SCHED_CHILD_STATUS
  /* Tasks can also suppress retention of their child status by applying
   * the SA_NOCLDWAIT flag with sigaction().
   */

  if ((rtcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0)
    {
      FAR struct child_status_s *child;

      /* Make sure that there is not already a structure for this PID in the
       * parent TCB.  There should not be.
       */

      child = group_findchild(rtcb->group, tcb->pid);
      DEBUGASSERT(!child);
      if (!child)
        {
          /* Allocate a new status structure  */

          child = group_allocchild();
        }

      /* Did we successfully find/allocate the child status structure? */

      DEBUGASSERT(child);
      if (child)
        {
          /* Yes.. Initialize the structure */

          child->ch_flags  = ttype;
          child->ch_pid    = tcb->pid;
          child->ch_status = 0;

          /* Add the entry into the TCB list of children */

          group_addchild(rtcb->group, child);
        }
    }
#else
  DEBUGASSERT(rtcb->nchildren < UINT16_MAX);
  rtcb->nchildren++;
#endif
}
#else
#  define task_saveparent(tcb,ttype)
#endif

/****************************************************************************
 * Name: task_dupdspace
 *
 * Description:
 *   When a new task or thread is created from a PIC module, then that
 *   module (probably) intends the task or thread to execute in the same
 *   D-Space.  This function will duplicate the D-Space for that purpose.
 *
 * Parameters:
 *   tcb - The TCB of the new task.
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *   The parent of the new task is the task at the head of the ready-to-run
 *   list.
 *
 ****************************************************************************/

#ifdef CONFIG_PIC
static inline void task_dupdspace(FAR struct tcb_s *tcb)
{
  FAR struct tcb_s *rtcb = (FAR struct tcb_s*)g_readytorun.head;
  if (rtcb->dspace != NULL)
    {
      /* Copy the D-Space structure reference and increment the reference
       * count on the memory.  The D-Space memory will persist until the
       * last thread exits (see sched_releasetcb()).
       */

      tcb->dspace = rtcb->dspace;
      tcb->dspace->crefs++;
    }
}
#else
#  define task_dupdspace(tcb)
#endif

/****************************************************************************
 * Name: thread_schedsetup
 *
 * Description:
 *   This functions initializes the common portions of the Task Control Block
 *   (TCB) in preparation for starting a new thread.
 *
 *   thread_schedsetup() is called from task_schedsetup() and
 *   pthread_schedsetup().
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   priority   - Priority of the new task
 *   start      - Thread startup routine
 *   entry      - Thread user entry point
 *   ttype      - Type of the new thread: task, pthread, or kernel thread
 *
 * Return Value:
 *   OK on success; ERROR on failure.
 *
 *   This function can only failure is it is unable to assign a new, unique
 *   task ID to the TCB (errno is not set).
 *
 ****************************************************************************/

static int thread_schedsetup(FAR struct tcb_s *tcb, int priority,
                             start_t start, CODE void *entry, uint8_t ttype)
{
  int ret;

  /* Assign a unique task ID to the task. */

  ret = task_assignpid(tcb);
  if (ret == OK)
    {
      /* Save task priority and entry point in the TCB */

      tcb->sched_priority = (uint8_t)priority;
#ifdef CONFIG_PRIORITY_INHERITANCE
      tcb->base_priority  = (uint8_t)priority;
#endif
      tcb->start          = start;
      tcb->entry.main     = (main_t)entry;

      /* Save the thread type.  This setting will be needed in
       * up_initial_state() is called.
       */

      ttype              &= TCB_FLAG_TTYPE_MASK;
      tcb->flags         &= ~TCB_FLAG_TTYPE_MASK;
      tcb->flags         |= ttype;

      /* Save the task ID of the parent task in the TCB and allocate
       * a child status structure.
       */

      task_saveparent(tcb, ttype);

      /* exec(), pthread_create(), task_create(), and vfork() all
       * inherit the signal mask of the parent thread.
       */

#ifndef CONFIG_DISABLE_SIGNALS
      (void)sigprocmask(SIG_SETMASK, NULL, &tcb->sigprocmask);
#endif

      /* Initialize the task state.  It does not get a valid state
       * until it is activated.
       */

      tcb->task_state = TSTATE_TASK_INVALID;

      /* Clone the parent tasks D-Space (if it was running PIC).  This
       * must be done before calling up_initial_state() so that the
       * state setup will take the PIC address base into account.
       */

      task_dupdspace(tcb);

      /* Initialize the processor-specific portion of the TCB */

      up_initial_state(tcb);

      /* Add the task to the inactive task list */

      sched_lock();
      dq_addfirst((FAR dq_entry_t*)tcb, (dq_queue_t*)&g_inactivetasks);
      tcb->task_state = TSTATE_TASK_INACTIVE;
      sched_unlock();
    }

  return ret;
}

/****************************************************************************
 * Name: task_namesetup
 *
 * Description:
 *   Assign the task name.
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   name       - Name of the new task
 *
 * Return Value:
 *  None
 *
 ****************************************************************************/

#if CONFIG_TASK_NAME_SIZE > 0
static void task_namesetup(FAR struct task_tcb_s *tcb, FAR const char *name)
{
  /* Give a name to the unnamed tasks */

  if (!name)
    {
      name = (FAR char *)g_noname;
    }

  /* Copy the name into the TCB */

  strncpy(tcb->cmn.name, name, CONFIG_TASK_NAME_SIZE);
  tcb->cmn.name[CONFIG_TASK_NAME_SIZE] = '\0';
}
#else
#  define task_namesetup(t,n)
#endif /* CONFIG_TASK_NAME_SIZE */

/****************************************************************************
 * Name: task_stackargsetup
 *
 * Description:
 *   This functions is called only from task_argsetup()  It will allocate
 *   space on the new task's stack and will copy the argv[] array and all
 *   strings to the task's stack where it is readily accessible to the
 *   task.  Data on the stack, on the other hand, is guaranteed to be
 *   accessible no matter what privilege mode the task runs in.
 *
 * Input Parameters:
 *   tcb  - Address of the new task's TCB
 *   argv - A pointer to an array of input parameters.  Up to
 *          CONFIG_MAX_TASK_ARG parameters may be provided. If fewer than
 *          CONFIG_MAX_TASK_ARG parameters are passed, the list should be
 *          terminated with a NULL argv[] value. If no parameters are
 *          required, argv may be NULL.
 *
 * Return Value:
 *  Zero (OK) on success; a negated errno on failure.
 *
 ****************************************************************************/

static inline int task_stackargsetup(FAR struct task_tcb_s *tcb,
                                     FAR char * const argv[])
{
  FAR char **stackargv;
  FAR const char *name;
  FAR char *str;
  size_t strtablen;
  size_t argvlen;
  int nbytes;
  int argc;
  int i;

  /* Get the name string that we will use as the first argument */

#if CONFIG_TASK_NAME_SIZE > 0
  name = tcb->cmn.name;
#else
  name = (FAR const char *)g_noname;
#endif /* CONFIG_TASK_NAME_SIZE */

  /* Get the size of the task name (including the NUL terminator) */

  strtablen = (strlen(name) + 1);

  /* Count the number of arguments and get the accumulated size of the
   * argument strings (including the null terminators).  The argument count
   * does not include the task name in that will be in argv[0].
   */

  argc = 0;
  if (argv)
    {
      /* A NULL argument terminates the list */

      while (argv[argc])
        {
          /* Add the size of this argument (with NUL terminator).
           * Check each time if the accumulated size exceeds the
           * size of the allocated stack.
           */

          strtablen += (strlen(argv[argc]) + 1);
          if (strtablen >= tcb->cmn.adj_stack_size)
            {
               return -ENAMETOOLONG;
            }

          /* Increment the number of args.  Here is a sanity check to
           * prevent running away with an unterminated argv[] list.
           * MAX_STACK_ARGS should be sufficiently large that this never
           * happens in normal usage.
           */

          if (++argc > MAX_STACK_ARGS)
            {
              return -E2BIG;
            }
        }
    }

  /* Allocate a stack frame to hold argv[] array and the strings.  NOTE
   * that argc + 2 entries are needed:  The number of arguments plus the
   * task name plus a NULL argv[] entry to terminate the list.
   */

  argvlen   = (argc + 2)*sizeof(FAR char*);
  stackargv = (FAR char **)up_stack_frame(&tcb->cmn, argvlen + strtablen);

  DEBUGASSERT(stackargv != NULL);
  if (stackargv == NULL)
    {
      return -ENOMEM;
    }

  /* Get the address of the string table that will lie immediately after
   * the argv[] array and mark it as a null string.
   */

  str = (FAR char *)stackargv + argvlen;

  /* Copy the task name.  Increment str to skip over the task name and its
   * NUL terminator in the string buffer.
   */

  stackargv[0] = str;
  nbytes       = strlen(name) + 1;
  strcpy(str, name);
  str         += nbytes;

  /* Copy each argument */

  for (i = 0; i < argc; i++)
    {
      /* Save the pointer to the location in the string buffer and copy
       * the argument into the buffer.  Increment str to skip over the
       * argument and its NUL terminator in the string buffer.
       */

      stackargv[i+1] = str;
      nbytes         = strlen(argv[i]) + 1;
      strcpy(str, argv[i]);
      str           += nbytes;
    }

  /* Put a terminator entry at the end of the argv[] array.  Then save the
   * argv[] arry pointer in the TCB where it will be recovered later by
   * task_start().
   */

  stackargv[argc + 1] = NULL;
  tcb->argv = stackargv;

  return OK;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: task_schedsetup
 *
 * Description:
 *   This functions initializes a Task Control Block (TCB) in preparation
 *   for starting a new task.
 *
 *   task_schedsetup() is called from task_init() and task_start().
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   priority   - Priority of the new task
 *   start      - Start-up function (probably task_start())
 *   main       - Application start point of the new task
 *   ttype      - Type of the new thread: task or kernel thread
 *
 * Return Value:
 *   OK on success; ERROR on failure.
 *
 *   This function can only failure is it is unable to assign a new, unique
 *   task ID to the TCB (errno is not set).
 *
 ****************************************************************************/

int task_schedsetup(FAR struct task_tcb_s *tcb, int priority, start_t start,
                    main_t main, uint8_t ttype)
{
  int ret;

  /* Perform common thread setup */

  ret = thread_schedsetup((FAR struct tcb_s *)tcb, priority, start,
                          (CODE void *)main, ttype);
  if (ret == OK)
    {
      /* Save task restart priority */

      tcb->init_priority  = (uint8_t)priority;
    }

  return ret;
}

/****************************************************************************
 * Name: pthread_schedsetup
 *
 * Description:
 *   This functions initializes a Task Control Block (TCB) in preparation
 *   for starting a new pthread.
 *
 *   pthread_schedsetup() is called from pthread_create(),
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   priority   - Priority of the new task
 *   start      - Start-up function (probably pthread_start())
 *   entry      - Entry point of the new pthread
 *   ttype      - Type of the new thread: task, pthread, or kernel thread
 *
 * Return Value:
 *   OK on success; ERROR on failure.
 *
 *   This function can only failure is it is unable to assign a new, unique
 *   task ID to the TCB (errno is not set).
 *
 ****************************************************************************/

#ifndef CONFIG_DISABLE_PTHREAD
int pthread_schedsetup(FAR struct pthread_tcb_s *tcb, int priority, start_t start,
                       pthread_startroutine_t entry)
{
  /* Perform common thread setup */

  return thread_schedsetup((FAR struct tcb_s *)tcb, priority, start,
                           (CODE void *)entry, TCB_FLAG_TTYPE_PTHREAD);
}
#endif

/****************************************************************************
 * Name: task_argsetup
 *
 * Description:
 *   This functions sets up parameters in the Task Control Block (TCB) in
 *   preparation for starting a new thread.
 *
 *   task_argsetup() is called only from task_init() and task_start() to
 *   create a new task.  In the "normal" case, the argv[] array is a
 *   structure in the TCB, the arguments are cloned via strdup.
 *
 *   In the kernel build case, the argv[] array and all strings are copied
 *   to the task's stack.  This is done because the TCB (and kernel allocated
 *   strings) are only accessible in kernel-mode.  Data on the stack, on the
 *   other hand, is guaranteed to be accessible no matter what mode the
 *   task runs in.
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   name       - Name of the new task (not used)
 *   argv       - A pointer to an array of input parameters.
 *                Up to CONFIG_MAX_TASK_ARG parameters may be
 *                provided. If fewer than CONFIG_MAX_TASK_ARG
 *                parameters are passed, the list should be
 *                terminated with a NULL argv[] value.
 *                If no parameters are required, argv may be NULL.
 *
 * Return Value:
 *  OK
 *
 ****************************************************************************/

int task_argsetup(FAR struct task_tcb_s *tcb, FAR const char *name,
                  FAR char * const argv[])
{
  /* Setup the task name */

  task_namesetup(tcb, name);

  /* Copy the argv[] array and all strings are to the task's stack.  Data on
   * the stack is guaranteed to be accessible by the ask no matter what
   * privilege mode the task runs in.
   */

  return task_stackargsetup(tcb, argv);
}
