text: /****************************************************************************
   *
   * Copyright 2016 Samsung Electronics All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied. See the License for the specific
   * language governing permissions and limitations under the License.
   *
   ****************************************************************************/
  /****************************************************************************
   * kernel/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 <tinyara/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <sched.h>
  #include <string.h>
  #include <errno.h>
  #include <debug.h>
  
  #include <tinyara/arch.h>
  #include <tinyara/ttrace.h>
  
  #include "sched/sched.h"
  #include "pthread/pthread.h"
  #include "group/group.h"
  #include "task/task.h"
  #include "clock/clock.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 set as EBUSY, if already CONFIG_MAX_TASKS are running in system
   *
   ****************************************************************************/
  
  static int task_assignpid(FAR struct tcb_s *tcb)
  {
  	pid_t next_pid;
  	int hash_ndx;
  	int tries;
  
  	trace_begin(TTRACE_TAG_TASK, "task_assignpid");
  
  	/* 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;
  
  			/* Increment the task count */
  			g_alive_taskcount++;
  
  			(void)sched_unlock();
  			trace_end(TTRACE_TAG_TASK);
  			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();
  	set_errno(EBUSY);
  	trace_end(TTRACE_TAG_TASK);
  	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 = this_task();
  
  #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
  
  #ifndef CONFIG_DISABLE_PTHREAD
  	if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
  #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 = this_task();
  	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 fail for two reasons.
   *   1) If requested priority is beyond the allowed range, errno = EINVAL
   *   2) If it is unable to assign a new, unique task ID to the TCB. errno = EBUSY
   *   errno is set accodingly.
   *
   ****************************************************************************/
  
  static int thread_schedsetup(FAR struct tcb_s *tcb, int priority, start_t start, CODE void *entry, uint8_t ttype)
  {
  	int ret;
  
  	if (priority < SCHED_PRIORITY_MIN || priority > SCHED_PRIORITY_MAX) {
  		set_errno(EINVAL);
  		return ERROR;
  	}
  
  	trace_begin(TTRACE_TAG_TASK, "thread_schedsetup");
  
  	/* 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;
  
  #ifdef CONFIG_CANCELLATION_POINTS
  		/* Set the deferred cancellation type */
  		tcb->flags |= TCB_FLAG_CANCEL_DEFERRED;
  #endif
  
  		/* Save initial thread scheduling policy int the TCB */
  
  #if CONFIG_RR_INTERVAL > 0
  		tcb->flags |= TCB_FLAG_ROUND_ROBIN;
  		tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
  #else
  		tcb->flags &= ~TCB_FLAG_ROUND_ROBIN;
  #endif
  
  		/* 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();
  	}
  
  	trace_end(TTRACE_TAG_TASK);
  	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 fail for two reasons.
   *   1) If requested priority is beyond the allowed range, errno = EINVAL
   *   2) If it is unable to assign a new, unique task ID to the TCB. errno = EBUSY
   *   errno is set accodingly.
   *
   ****************************************************************************/
  
  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 fail for two reasons.
   *   1) If requested priority is beyond the allowed range, errno = EINVAL
   *   2) If it is unable to assign a new, unique task ID to the TCB. errno = EBUSY
   *   errno is set accodingly.
   *
   ****************************************************************************/
  
  #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);
  }
  