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Diffstat (limited to 'nuttx/sched/task/task_posixspawn.c')
| -rw-r--r-- | nuttx/sched/task/task_posixspawn.c | 462 |
1 files changed, 462 insertions, 0 deletions
diff --git a/nuttx/sched/task/task_posixspawn.c b/nuttx/sched/task/task_posixspawn.c new file mode 100644 index 000000000..9d4f8f9a3 --- /dev/null +++ b/nuttx/sched/task/task_posixspawn.c @@ -0,0 +1,462 @@ +/**************************************************************************** + * sched/task/task_posixspawn.c + * + * Copyright (C) 2013 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 <spawn.h> +#include <debug.h> + +#include <nuttx/binfmt/binfmt.h> + +#include "os_internal.h" +#include "group/group.h" +#include "task/spawn.h" +#include "task/task.h" + +/**************************************************************************** + * Private Types + ****************************************************************************/ + +/**************************************************************************** + * Public Data + ****************************************************************************/ + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: posix_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.| + * + * path - The 'path' argument identifies the file to execute. If + * CONFIG_BINFMT_EXEPATH is defined, this may be either a relative or + * or an absolute path. Otherwise, it must be an absolute path. + * + * 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 ps_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 posix_spawn_exec(FAR pid_t *pidp, FAR const char *path, + FAR const posix_spawnattr_t *attr, + FAR char * const argv[]) +{ + FAR const struct symtab_s *symtab; + int nsymbols; + int pid; + int ret = OK; + + DEBUGASSERT(path); + + /* Get the current symbol table selection */ + + exec_getsymtab(&symtab, &nsymbols); + + /* 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(); + + /* Start the task */ + + pid = exec(path, (FAR char * const *)argv, symtab, nsymbols); + if (pid < 0) + { + ret = errno; + sdbg("ERROR: exec 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: posix_spawn_proxy + * + * Description: + * Perform file_actions, then execute the task from the file system. + * + * Do we really need this proxy task? Isn't that wasteful? + * + * Q: Why not use a starthook so that there is callout from task_start() + * to perform these operations after the file is loaded from + * the file system? + * A: That existing task_starthook() implementation cannot be used in + * this context; any of task_starthook() will also conflict with + * binfmt's use of the start hook to call C++ static initializers. + * task_restart() would also be an issue. + * + * Input Parameters: + * Standard task start-up parameters + * + * Returned Value: + * Standard task return value. + * + ****************************************************************************/ + +static int posix_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 posix_spawn[p] was non-NULL and/or the + * option to change the signal mask was selected. + */ + +#ifndef CONFIG_DISABLE_SIGNALS + DEBUGASSERT(g_spawn_parms.file_actions || + (g_spawn_parms.attr && + (g_spawn_parms.attr->flags & POSIX_SPAWN_SETSIGMASK) != 0)); +#else + DEBUGASSERT(g_spawn_parms.file_actions); +#endif + + /* 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 = posix_spawn_exec(g_spawn_parms.pid, g_spawn_parms.u.posix.path, + 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) + { + sdbg("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: posix_spawn + * + * Description: + * The posix_spawn() and posix_spawnp() functions will create a new, + * child task, constructed from a regular executable file. + * + * Input Parameters: + * + * pid - Upon successful completion, posix_spawn() and posix_spawnp() 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. + * + * path - The 'path' argument to posix_spawn() is the absolute path that + * identifies the file to execute. The 'path' argument to posix_spawnp() + * may also be a relative path and will be used to construct a pathname + * that identifies the file to execute. In the case of a relative path, + * the path prefix for the file will be obtained by a search of the + * directories passed as the environment variable PATH. + * + * NOTE: NuttX provides only one implementation: If + * CONFIG_BINFMT_EXEPATH is defined, then only posix_spawnp() behavior + * is supported; otherwise, only posix_spawn behavior is supported. + * + * 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 + * posix_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. + * + * 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. In + * standard implementations, envp[] is an array of character pointers to + * null-terminated strings that provide the environment for the new + * process image. The environment array is terminated by a null pointer. + * In NuttX, the envp[] argument is ignored and the new task will simply + * inherit the environment of the parent task. + * + * Returned Value: + * posix_spawn() and posix_spawnp() 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. + * + * Assumptions/Limitations: + * - NuttX provides only posix_spawn() or posix_spawnp() behavior + * depending upon the setting of CONFIG_BINFMT_EXEPATH: If + * CONFIG_BINFMT_EXEPATH is defined, then only posix_spawnp() behavior + * is supported; otherwise, only posix_spawn behavior is supported. + * - The 'envp' argument is not used and the 'environ' variable is not + * altered (NuttX does not support the 'environ' variable). + * - Process groups are not supported (POSIX_SPAWN_SETPGROUP). + * - Effective user IDs are not supported (POSIX_SPAWN_RESETIDS). + * - Signal default actions cannot be modified in the newly task executed + * because NuttX does not support default signal actions + * (POSIX_SPAWN_SETSIGDEF). + * + * POSIX Compatibility + * - The value of the argv[0] received by the child task is assigned by + * NuttX. For the caller of posix_spawn(), the provided argv[0] will + * correspond to argv[1] received by the new task. + * + ****************************************************************************/ + +#ifdef CONFIG_BINFMT_EXEPATH +int posix_spawnp(FAR pid_t *pid, FAR const char *path, + FAR const posix_spawn_file_actions_t *file_actions, + FAR const posix_spawnattr_t *attr, + FAR char *const argv[], FAR char *const envp[]) +#else +int posix_spawn(FAR pid_t *pid, FAR const char *path, + FAR const posix_spawn_file_actions_t *file_actions, + FAR const posix_spawnattr_t *attr, + FAR char *const argv[], FAR char *const envp[]) +#endif +{ + struct sched_param param; + pid_t proxy; +#ifdef CONFIG_SCHED_WAITPID + int status; +#endif + int ret; + + DEBUGASSERT(path); + + svdbg("pid=%p path=%s file_actions=%p attr=%p argv=%p\n", + pid, path, 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. + */ + +#ifndef CONFIG_DISABLE_SIGNALS + if ((file_actions == NULL || *file_actions == NULL) && + (attr == NULL || (attr->flags & POSIX_SPAWN_SETSIGMASK) == 0)) +#else + if (file_actions == NULL || *file_actions == NULL) +#endif + { + return posix_spawn_exec(pid, path, 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.posix.path = path; + + /* Get the priority of this (parent) task */ + + ret = sched_getparam(0, ¶m); + if (ret < 0) + { + int errcode = errno; + + sdbg("ERROR: sched_getparam failed: %d\n", errcode); + spawn_semgive(&g_spawn_parmsem); + return errcode; + } + + /* Disable pre-emption so that the proxy does not run until waitpid + * is called. This is probably unnecessary since the posix_spawn_proxy has + * the same priority as this thread; it should be schedule behind this + * task in the ready-to-run list. + */ + +#ifdef CONFIG_SCHED_WAITPID + sched_lock(); +#endif + + /* Start the intermediary/proxy task at the same priority as the parent + * task. + */ + + proxy = TASK_CREATE("posix_spawn_proxy", param.sched_priority, + CONFIG_POSIX_SPAWN_PROXY_STACKSIZE, + (main_t)posix_spawn_proxy, + (FAR char * const *)NULL); + if (proxy < 0) + { + ret = get_errno(); + sdbg("ERROR: Failed to start posix_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) + { + sdbg("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; +} |