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- /****************************************************************************
- * sched/task/task_spawn.c
- *
- * Copyright (C) 2013, 2018-2019 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/wait.h>
- #include <sched.h>
- #include <spawn.h>
- #include <debug.h>
- #include <nuttx/sched.h>
- #include <nuttx/kthread.h>
- #include "sched/sched.h"
- #include "group/group.h"
- #include "task/spawn.h"
- #include "task/task.h"
- #ifndef CONFIG_BUILD_KERNEL
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxtask_spawn_exec
- *
- * Description:
- * Execute the task from the file system.
- *
- * Input Parameters:
- *
- * pidp - Upon successful completion, this will return the task ID of the
- * child task in the variable pointed to by a non-NULL 'pid' argument.|
- *
- * name - The name to assign to the child task.
- *
- * entry - The child task's entry point (an address in memory)
- *
- * attr - If the value of the 'attr' parameter is NULL, the all default
- * values for the POSIX spawn attributes will be used. Otherwise, the
- * attributes will be set according to the spawn flags. The
- * following spawn flags are supported:
- *
- * - POSIX_SPAWN_SETSCHEDPARAM: Set new tasks priority to the sched_param
- * value.
- * - POSIX_SPAWN_SETSCHEDULER: Set the new tasks scheduler priority to
- * the sched_policy value.
- *
- * NOTE: POSIX_SPAWN_SETSIGMASK is handled in nxtask_spawn_proxy().
- *
- * argv - argv[] is the argument list for the new task. argv[] is an
- * array of pointers to null-terminated strings. The list is terminated
- * with a null pointer.
- *
- * Returned Value:
- * This function will return zero on success. Otherwise, an error number
- * will be returned as the function return value to indicate the error.
- * This errno value may be that set by execv(), sched_setpolicy(), or
- * sched_setparam().
- *
- ****************************************************************************/
- static int nxtask_spawn_exec(FAR pid_t *pidp, FAR const char *name,
- main_t entry, FAR const posix_spawnattr_t *attr,
- FAR char * const *argv)
- {
- size_t stacksize;
- int priority;
- int pid;
- int ret = OK;
- /* Disable pre-emption so that we can modify the task parameters after
- * we start the new task; the new task will not actually begin execution
- * until we re-enable pre-emption.
- */
- sched_lock();
- /* Use the default task priority and stack size if no attributes are provided */
- if (attr)
- {
- priority = attr->priority;
- stacksize = attr->stacksize;
- }
- else
- {
- struct sched_param param;
- /* Set the default priority to the same priority as this task */
- ret = nxsched_getparam(0, ¶m);
- if (ret < 0)
- {
- ret = -ret;
- goto errout;
- }
- priority = param.sched_priority;
- stacksize = CONFIG_TASK_SPAWN_DEFAULT_STACKSIZE;
- }
- /* Start the task */
- pid = nxtask_create(name, priority, stacksize, entry, argv);
- if (pid < 0)
- {
- ret = -pid;
- serr("ERROR: nxtask_create failed: %d\n", ret);
- goto errout;
- }
- /* Return the task ID to the caller */
- if (pid)
- {
- *pidp = pid;
- }
- /* Now set the attributes. Note that we ignore all of the return values
- * here because we have already successfully started the task. If we
- * return an error value, then we would also have to stop the task.
- */
- if (attr)
- {
- (void)spawn_execattrs(pid, attr);
- }
- /* Re-enable pre-emption and return */
- errout:
- sched_unlock();
- return ret;
- }
- /****************************************************************************
- * Name: nxtask_spawn_proxy
- *
- * Description:
- * Perform file_actions, then execute the task from the file system.
- *
- * Do we really need a proxy task in this case? Isn't that wasteful?
- *
- * Q: Why can we do what we need to do here and the just call the
- * new task's entry point.
- * A: This would require setting up the name, priority, and stacksize from
- * the task_spawn, but it do-able. The only issue I can think of is
- * that NuttX supports task_restart(), and you would never be able to
- * restart a task from this point.
- *
- * Q: Why not use a starthook so that there is callout from nxtask_start()
- * to perform these operations?
- * A: Good idea, except that existing nxtask_starthook() implementation
- * cannot be used here unless we get rid of task_create and, instead,
- * use task_init() and task_activate(). start_taskhook() could then
- * be called between task_init() and task)activate(). task_restart()
- * would still be an issue.
- *
- * Input Parameters:
- * Standard task start-up parameters
- *
- * Returned Value:
- * Standard task return value.
- *
- ****************************************************************************/
- static int nxtask_spawn_proxy(int argc, FAR char *argv[])
- {
- int ret;
- /* Perform file actions and/or set a custom signal mask. We get here only
- * if the file_actions parameter to task_spawn[p] was non-NULL and/or the
- * option to change the signal mask was selected.
- */
- DEBUGASSERT(g_spawn_parms.file_actions ||
- (g_spawn_parms.attr &&
- (g_spawn_parms.attr->flags & POSIX_SPAWN_SETSIGMASK) != 0));
- /* Set the attributes and perform the file actions as appropriate */
- ret = spawn_proxyattrs(g_spawn_parms.attr, g_spawn_parms.file_actions);
- if (ret == OK)
- {
- /* Start the task */
- ret = nxtask_spawn_exec(g_spawn_parms.pid, g_spawn_parms.u.task.name,
- g_spawn_parms.u.task.entry, g_spawn_parms.attr,
- g_spawn_parms.argv);
- #ifdef CONFIG_SCHED_HAVE_PARENT
- if (ret == OK)
- {
- /* Change of the parent of the task we just spawned to our parent.
- * What should we do in the event of a failure?
- */
- int tmp = task_reparent(0, *g_spawn_parms.pid);
- if (tmp < 0)
- {
- serr("ERROR: task_reparent() failed: %d\n", tmp);
- }
- }
- #endif
- }
- /* Post the semaphore to inform the parent task that we have completed
- * what we need to do.
- */
- g_spawn_parms.result = ret;
- #ifndef CONFIG_SCHED_WAITPID
- spawn_semgive(&g_spawn_execsem);
- #endif
- return OK;
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: task_spawn
- *
- * Description:
- * The task_spawn() function will create a new, child task, where the
- * entry point to the task is an address in memory.
- *
- * Input Parameters:
- *
- * pid - Upon successful completion, task_spawn() will return the task ID
- * of the child task to the parent task, in the variable pointed to by
- * a non-NULL 'pid' argument. If the 'pid' argument is a null pointer,
- * the process ID of the child is not returned to the caller.
- *
- * name - The name to assign to the child task.
- *
- * entry - The child task's entry point (an address in memory)
- *
- * file_actions - If 'file_actions' is a null pointer, then file
- * descriptors open in the calling process will remain open in the
- * child process (unless CONFIG_FDCLONE_STDIO is defined). If
- * 'file_actions' is not NULL, then the file descriptors open in the
- * child process will be those open in the calling process as modified
- * by the spawn file actions object pointed to by file_actions.
- *
- * attr - If the value of the 'attr' parameter is NULL, the all default
- * values for the POSIX spawn attributes will be used. Otherwise, the
- * attributes will be set according to the spawn flags. The
- * task_spawnattr_t spawn attributes object type is defined in spawn.h.
- * It will contains these attributes, not all of which are supported by
- * NuttX:
- *
- * - POSIX_SPAWN_SETPGROUP: Setting of the new task's process group is
- * not supported. NuttX does not support process groups.
- * - POSIX_SPAWN_SETSCHEDPARAM: Set new tasks priority to the sched_param
- * value.
- * - POSIX_SPAWN_SETSCHEDULER: Set the new task's scheduler policy to
- * the sched_policy value.
- * - POSIX_SPAWN_RESETIDS: Resetting of the effective user ID of the child
- * process is not supported. NuttX does not support effective user
- * IDs.
- * - POSIX_SPAWN_SETSIGMASK: Set the new task's signal mask.
- * - POSIX_SPAWN_SETSIGDEF: Resetting signal default actions is not
- * supported. NuttX does not support default signal actions.
- *
- * And the non-standard:
- *
- * - TASK_SPAWN_SETSTACKSIZE: Set the stack size for the new task.
- *
- * argv - argv[] is the argument list for the new task. argv[] is an
- * array of pointers to null-terminated strings. The list is terminated
- * with a null pointer.
- *
- * envp - The envp[] argument is not used by NuttX and may be NULL.
- *
- * Returned Value:
- * task_spawn() will return zero on success. Otherwise, an error number
- * will be returned as the function return value to indicate the error:
- *
- * - EINVAL: The value specified by 'file_actions' or 'attr' is invalid.
- * - Any errors that might have been return if vfork() and excec[l|v]()
- * had been called.
- *
- ****************************************************************************/
- int task_spawn(FAR pid_t *pid, FAR const char *name, main_t entry,
- FAR const posix_spawn_file_actions_t *file_actions,
- FAR const posix_spawnattr_t *attr,
- FAR char *const argv[], FAR char *const envp[])
- {
- struct sched_param param;
- pid_t proxy;
- #ifdef CONFIG_SCHED_WAITPID
- int status;
- #endif
- int ret;
- sinfo("pid=%p name=%s entry=%p file_actions=%p attr=%p argv=%p\n",
- pid, name, entry, file_actions, attr, argv);
- /* If there are no file actions to be performed and there is no change to
- * the signal mask, then start the new child task directly from the parent
- * task.
- */
- if ((file_actions == NULL || *file_actions == NULL) &&
- (attr == NULL || (attr->flags & POSIX_SPAWN_SETSIGMASK) == 0))
- {
- return nxtask_spawn_exec(pid, name, entry, attr, argv);
- }
- /* Otherwise, we will have to go through an intermediary/proxy task in order
- * to perform the I/O redirection. This would be a natural place to fork().
- * However, true fork() behavior requires an MMU and most implementations
- * of vfork() are not capable of these operations.
- *
- * Even without fork(), we can still do the job, but parameter passing is
- * messier. Unfortunately, there is no (clean) way to pass binary values
- * as a task parameter, so we will use a semaphore-protected global
- * structure.
- */
- /* Get exclusive access to the global parameter structure */
- spawn_semtake(&g_spawn_parmsem);
- /* Populate the parameter structure */
- g_spawn_parms.result = ENOSYS;
- g_spawn_parms.pid = pid;
- g_spawn_parms.file_actions = file_actions ? *file_actions : NULL;
- g_spawn_parms.attr = attr;
- g_spawn_parms.argv = argv;
- g_spawn_parms.u.task.name = name;
- g_spawn_parms.u.task.entry = entry;
- /* Get the priority of this (parent) task */
- ret = nxsched_getparam(0, ¶m);
- if (ret < 0)
- {
- serr("ERROR: nxsched_getparam failed: %d\n", ret);
- spawn_semgive(&g_spawn_parmsem);
- return -ret;
- }
- #ifdef CONFIG_SCHED_WAITPID
- /* Disable pre-emption so that the proxy does not run until waitpid
- * is called. This is probably unnecessary since the nxtask_spawn_proxy
- * has the same priority as this thread; it should be schedule behind
- * this task in the ready-to-run list.
- *
- * REVISIT: This will may not have the desired effect in SMP mode.
- */
- sched_lock();
- #endif
- /* Start the intermediary/proxy task at the same priority as the parent
- * task.
- */
- proxy = nxtask_create("nxtask_spawn_proxy", param.sched_priority,
- CONFIG_POSIX_SPAWN_PROXY_STACKSIZE,
- (main_t)nxtask_spawn_proxy,
- (FAR char * const *)NULL);
- if (proxy < 0)
- {
- ret = -proxy;
- serr("ERROR: Failed to start nxtask_spawn_proxy: %d\n", ret);
- goto errout_with_lock;
- }
- /* Wait for the proxy to complete its job */
- #ifdef CONFIG_SCHED_WAITPID
- ret = waitpid(proxy, &status, 0);
- if (ret < 0)
- {
- serr("ERROR: waitpid() failed: %d\n", errno);
- goto errout_with_lock;
- }
- #else
- spawn_semtake(&g_spawn_execsem);
- #endif
- /* Get the result and relinquish our access to the parameter structure */
- ret = g_spawn_parms.result;
- errout_with_lock:
- #ifdef CONFIG_SCHED_WAITPID
- sched_unlock();
- #endif
- spawn_semgive(&g_spawn_parmsem);
- return ret;
- }
- #endif /* CONFIG_BUILD_KERNEL */
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