3ff49e86f5
Locking the scheduler prior to calling posix_spawn() might lock the scheduler for a relatively long time, if the file to be loaded is large. posix_spawn() loads the process into memory, possibly linking it as well if the binary format is linkable (elf). This can take tens / hundreds of milliseconds, which basically destroys the OS's real time performance. Missing the death-of-child signal is a very trivial penalty considering the alternative.
335 lines
11 KiB
C
335 lines
11 KiB
C
/****************************************************************************
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* apps/nshlib/nsh_fileapps.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#ifdef CONFIG_SCHED_WAITPID
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# include <sys/ioctl.h>
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# include <sys/wait.h>
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#endif
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#include <stdbool.h>
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#include <stdlib.h>
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#include <spawn.h>
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#include <errno.h>
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#include <string.h>
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#include <libgen.h>
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#include <nuttx/lib/builtin.h>
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#include "nsh.h"
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#include "nsh_console.h"
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#ifdef CONFIG_NSH_FILE_APPS
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nsh_fileapp
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*
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* Description:
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* Attempt to execute the application task whose name is 'cmd'
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*
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* Returned Value:
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* <0 If posix_spawn() fails, then the negated errno value
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* is returned.
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* -1 (ERROR) if the application task corresponding to 'cmd' could not
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* be started (possibly because it doesn not exist).
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* 0 (OK) if the application task corresponding to 'cmd' was
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* and successfully started. If CONFIG_SCHED_WAITPID is
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* defined, this return value also indicates that the
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* application returned successful status (EXIT_SUCCESS)
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* 1 If CONFIG_SCHED_WAITPID is defined, then this return value
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* indicates that the application task was spawned successfully
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* but returned failure exit status.
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*
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****************************************************************************/
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int nsh_fileapp(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
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FAR char **argv, FAR const char *redirfile, int oflags)
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{
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posix_spawn_file_actions_t file_actions;
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posix_spawnattr_t attr;
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pid_t pid;
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int rc = 0;
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int ret;
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#ifdef CONFIG_BUILTIN
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FAR char *appname;
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int index;
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#endif
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/* Initialize the attributes file actions structure */
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ret = posix_spawn_file_actions_init(&file_actions);
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if (ret != 0)
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{
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/* posix_spawn_file_actions_init returns a positive errno value on
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* failure.
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*/
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nsh_error(vtbl, g_fmtcmdfailed, cmd, "posix_spawn_file_actions_init",
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NSH_ERRNO_OF(ret));
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goto errout;
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}
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ret = posix_spawnattr_init(&attr);
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if (ret != 0)
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{
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/* posix_spawnattr_init returns a positive errno value on failure. */
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nsh_error(vtbl, g_fmtcmdfailed, cmd, "posix_spawnattr_init",
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NSH_ERRNO);
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goto errout_with_actions;
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}
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/* Handle re-direction of output */
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if (redirfile)
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{
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ret = posix_spawn_file_actions_addopen(&file_actions, 1, redirfile,
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oflags, 0644);
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if (ret != 0)
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{
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/* posix_spawn_file_actions_addopen returns a positive errno
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* value on failure.
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*/
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nsh_error(vtbl, g_fmtcmdfailed, cmd,
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"posix_spawn_file_actions_addopen",
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NSH_ERRNO);
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goto errout_with_attrs;
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}
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}
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#ifdef CONFIG_BUILTIN
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/* Check if a builtin application with this name exists */
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appname = basename((FAR char *)cmd);
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index = builtin_isavail(appname);
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if (index >= 0)
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{
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FAR const struct builtin_s *builtin;
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struct sched_param param;
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/* Get information about the builtin */
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builtin = builtin_for_index(index);
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if (builtin == NULL)
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{
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ret = ENOENT;
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goto errout_with_actions;
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}
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/* Set the correct task size and priority */
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param.sched_priority = builtin->priority;
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ret = posix_spawnattr_setschedparam(&attr, ¶m);
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if (ret != 0)
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{
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goto errout_with_actions;
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}
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ret = posix_spawnattr_setstacksize(&attr, builtin->stacksize);
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if (ret != 0)
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{
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goto errout_with_actions;
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}
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}
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#endif
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/* Execute the program. posix_spawnp returns a positive errno value on
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* failure.
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*/
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ret = posix_spawnp(&pid, cmd, &file_actions, &attr, argv, environ);
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if (ret == OK)
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{
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/* The application was successfully started with pre-emption disabled.
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* In the simplest cases, the application will not have run because the
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* the scheduler is locked. But in the case where I/O was redirected,
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* a proxy task ran and broke our lock. As result, the application may
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* have aso ran if its priority was higher than than the priority of
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* this thread.
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*
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* If the application did not run to completion and if the application
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* was not backgrounded, then we need to wait here for the application
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* to exit. This only works works with the following options:
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*
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* - CONFIG_NSH_DISABLEBG - Do not run commands in background
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* - CONFIG_SCHED_WAITPID - Required to run external commands in
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* foreground
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*/
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#ifdef CONFIG_SCHED_WAITPID
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/* CONFIG_SCHED_WAITPID is selected, so we may run the command in
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* foreground unless we were specifically requested to run the command
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* in background (and running commands in background is enabled).
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*/
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# ifndef CONFIG_NSH_DISABLEBG
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if (vtbl->np.np_bg == false)
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# endif /* CONFIG_NSH_DISABLEBG */
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{
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int tc = 0;
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if (vtbl->isctty)
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{
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/* Setup up to receive SIGINT if control-C entered. */
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tc = nsh_ioctl(vtbl, TIOCSCTTY, pid);
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}
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/* Wait for the application to exit. We did lock the scheduler
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* above, but that does not guarantee that the application did not
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* already run to completion in the case where I/O was redirected.
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* Here the scheduler will be unlocked while waitpid is waiting
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* and if the application has not yet run, it will now be able to
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* do so.
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*
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* NOTE: WUNTRACED does nothing in the default case, but in the
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* case the where CONFIG_SIG_SIGSTOP_ACTION=y, the file app
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* may also be stopped. In that case WUNTRACED will force
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* waitpid() to return with ECHILD.
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*/
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ret = waitpid(pid, &rc, WUNTRACED);
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if (ret < 0)
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{
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/* If the child thread doesn't exist, waitpid() will return the
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* error ECHLD. Since we know that the task was successfully
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* started, this must be one of the cases described above; we
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* have to assume that the task already exit'ed. In this case,
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* we have no idea if the application ran successfully or not
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* (because NuttX does not retain exit status of child tasks).
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* Let's assume that is did run successfully.
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*/
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int errcode = errno;
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if (errcode == ECHILD)
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{
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ret = OK;
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}
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else
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{
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nsh_error(vtbl, g_fmtcmdfailed, cmd, "waitpid",
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NSH_ERRNO_OF(errcode));
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}
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}
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/* Waitpid completed the wait successfully */
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else
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{
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/* Ignore the returned child pid */
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ret = OK;
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/* TODO: Set the environment variable '?' to a string
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* corresponding to WEXITSTATUS(rc) so that $? will expand
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* to the exit status of the most recently executed task.
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*/
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}
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if (vtbl->isctty && tc == 0)
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{
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nsh_ioctl(vtbl, TIOCNOTTY, 0);
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}
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}
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# ifndef CONFIG_NSH_DISABLEBG
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else
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# endif /* CONFIG_NSH_DISABLEBG */
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#endif /* CONFIG_SCHED_WAITPID */
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/* We get here if either:
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*
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* - CONFIG_SCHED_WAITPID is not selected meaning that all commands
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* have to be run in background, or
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* - CONFIG_SCHED_WAITPID and CONFIG_NSH_DISABLEBG are both selected,
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* but the user requested to run the command in background.
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*
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* NOTE that the case of a) CONFIG_SCHED_WAITPID is not selected and
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* b) CONFIG_NSH_DISABLEBG selected cannot be supported. In that event,
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* all commands will have to run in background. The waitpid() API must
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* be available to support running the command in foreground.
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*/
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#if !defined(CONFIG_SCHED_WAITPID) || !defined(CONFIG_NSH_DISABLEBG)
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{
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struct sched_param param;
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sched_getparam(ret, ¶m);
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nsh_output(vtbl, "%s [%d:%d]\n", cmd, ret, param.sched_priority);
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/* Backgrounded commands always 'succeed' as long as we can start
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* them.
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*/
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ret = OK;
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}
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#endif /* !CONFIG_SCHED_WAITPID || !CONFIG_NSH_DISABLEBG */
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}
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/* Free attributes and file actions. Ignoring return values in the case
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* of an error.
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*/
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errout_with_actions:
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posix_spawn_file_actions_destroy(&file_actions);
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errout_with_attrs:
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posix_spawnattr_destroy(&attr);
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errout:
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/* Most posix_spawn interfaces return a positive errno value on failure
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* and do not set the errno variable.
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*/
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if (ret > 0)
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{
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/* Set the errno value and return -1 */
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errno = ret;
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ret = ERROR;
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}
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else if (ret < 0)
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{
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/* Return -1 on failure. errno should have been set. */
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ret = ERROR;
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}
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else if (rc != 0)
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{
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/* We can't return the exact status (nsh has nowhere to put it)
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* so just pass back zero/nonzero in a fashion that doesn't look
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* like an error.
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*/
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ret = 1;
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}
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return ret;
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}
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#endif /* CONFIG_NSH_FILE_APPS */
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