cb823fe147
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4421 42af7a65-404d-4744-a932-0658087f49c3
247 lines
10 KiB
C
247 lines
10 KiB
C
/*****************************************************************************
|
|
* sched/sched_waitpid.c
|
|
*
|
|
* Copyright (C) 2011-2012 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 <semaphore.h>
|
|
#include <errno.h>
|
|
|
|
#include <nuttx/sched.h>
|
|
|
|
#include "os_internal.h"
|
|
|
|
#ifdef CONFIG_SCHED_WAITPID /* Experimental */
|
|
|
|
/*****************************************************************************
|
|
* Private Functions
|
|
*****************************************************************************/
|
|
|
|
/*****************************************************************************
|
|
* Public Functions
|
|
*****************************************************************************/
|
|
|
|
/*****************************************************************************
|
|
* Function: sched_waitpid
|
|
*
|
|
* Description:
|
|
*
|
|
* The waitpid() functions will obtain status information pertaining to one
|
|
* of the caller's child processes. The waitpid() function will suspend
|
|
* execution of the calling thread until status information for one of the
|
|
* terminated child processes of the calling process is available, or until
|
|
* delivery of a signal whose action is either to execute a signal-catching
|
|
* function or to terminate the process. If more than one thread is suspended
|
|
* in waitpid() awaiting termination of the same process, exactly one thread
|
|
* will return the process status at the time of the target process
|
|
* termination. If status information is available prior to the call to
|
|
* waitpid(), return will be immediate.
|
|
*
|
|
* The pid argument specifies a set of child processes for which status is
|
|
* requested. The waitpid() function will only return the status of a child
|
|
* process from this set:
|
|
*
|
|
* - If pid is equal to (pid_t)-1, status is requested for any child process.
|
|
* In this respect, waitpid() is then equivalent to wait().
|
|
* - If pid is greater than 0, it specifies the process ID of a single child
|
|
* process for which status is requested.
|
|
* - If pid is 0, status is requested for any child process whose process
|
|
* group ID is equal to that of the calling process.
|
|
* - If pid is less than (pid_t)-1, status is requested for any child process
|
|
* whose process group ID is equal to the absolute value of pid.
|
|
*
|
|
* The options argument is constructed from the bitwise-inclusive OR of zero
|
|
* or more of the following flags, defined in the <sys/wait.h> header:
|
|
*
|
|
* WCONTINUED - The waitpid() function will report the status of any
|
|
* continued child process specified by pid whose status has not been
|
|
* reported since it continued from a job control stop.
|
|
* WNOHANG - The waitpid() function will not suspend execution of the
|
|
* calling thread if status is not immediately available for one of the
|
|
* child processes specified by pid.
|
|
* WUNTRACED - The status of any child processes specified by pid that are
|
|
* stopped, and whose status has not yet been reported since they stopped,
|
|
* will also be reported to the requesting process.
|
|
*
|
|
* If the calling process has SA_NOCLDWAIT set or has SIGCHLD set to
|
|
* SIG_IGN, and the process has no unwaited-for children that were
|
|
* transformed into zombie processes, the calling thread will block until all
|
|
* of the children of the process containing the calling thread terminate, and
|
|
* waitpid() will fail and set errno to ECHILD.
|
|
*
|
|
* If waitpid() returns because the status of a child process is available,
|
|
* these functions will return a value equal to the process ID of the child
|
|
* process. In this case, if the value of the argument stat_loc is not a
|
|
* null pointer, information will be stored in the location pointed to by
|
|
* stat_loc. The value stored at the location pointed to by stat_loc will be
|
|
* 0 if and only if the status returned is from a terminated child process
|
|
* that terminated by one of the following means:
|
|
*
|
|
* 1. The process returned 0 from main().
|
|
* 2. The process called _exit() or exit() with a status argument of 0.
|
|
* 3. The process was terminated because the last thread in the process terminated.
|
|
*
|
|
* Regardless of its value, this information may be interpreted using the
|
|
* following macros, which are defined in <sys/wait.h> and evaluate to
|
|
* integral expressions; the stat_val argument is the integer value pointed
|
|
* to by stat_loc.
|
|
*
|
|
* WIFEXITED(stat_val) - Evaluates to a non-zero value if status was
|
|
* returned for a child process that terminated normally.
|
|
* WEXITSTATUS(stat_val) - If the value of WIFEXITED(stat_val) is non-zero,
|
|
* this macro evaluates to the low-order 8 bits of the status argument
|
|
* that the child process passed to _exit() or exit(), or the value the
|
|
* child process returned from main().
|
|
* WIFSIGNALED(stat_val) - Evaluates to a non-zero value if status was
|
|
* returned for a child process that terminated due to the receipt of a
|
|
* signal that was not caught (see <signal.h>).
|
|
* WTERMSIG(stat_val) - If the value of WIFSIGNALED(stat_val) is non-zero,
|
|
* this macro evaluates to the number of the signal that caused the
|
|
* termination of the child process.
|
|
* WIFSTOPPED(stat_val) - Evaluates to a non-zero value if status was
|
|
* returned for a child process that is currently stopped.
|
|
* WSTOPSIG(stat_val) - If the value of WIFSTOPPED(stat_val) is non-zero,
|
|
* this macro evaluates to the number of the signal that caused the child
|
|
* process to stop.
|
|
* WIFCONTINUED(stat_val) - Evaluates to a non-zero value if status was
|
|
* returned for a child process that has continued from a job control stop.
|
|
*
|
|
* Parameters:
|
|
* pid - The task ID of the thread to waid for
|
|
* stat_loc - The location to return the exit status
|
|
* options - ignored
|
|
*
|
|
* Return Value:
|
|
* If waitpid() returns because the status of a child process is available,
|
|
* it will return a value equal to the process ID of the child process for
|
|
* which status is reported.
|
|
*
|
|
* If waitpid() returns due to the delivery of a signal to the calling
|
|
* process, -1 will be returned and errno set to EINTR.
|
|
*
|
|
* If waitpid() was invoked with WNOHANG set in options, it has at least
|
|
* one child process specified by pid for which status is not available, and
|
|
* status is not available for any process specified by pid, 0 is returned.
|
|
*
|
|
* Otherwise, (pid_t)-1 will be returned, and errno set to indicate the error:
|
|
*
|
|
* ECHILD - The process specified by pid does not exist or is not a child of
|
|
* the calling process, or the process group specified by pid does not exist
|
|
* or does not have any member process that is a child of the calling process.
|
|
* EINTR - The function was interrupted by a signal. The value of the location
|
|
* pointed to by stat_loc is undefined.
|
|
* EINVAL - The options argument is not valid.
|
|
*
|
|
* Assumptions:
|
|
*
|
|
*****************************************************************************/
|
|
|
|
/***************************************************************************/
|
|
/* NOTE: This is a partially functional, experimental version of waitpid() */
|
|
/***************************************************************************/
|
|
|
|
pid_t waitpid(pid_t pid, int *stat_loc, int options)
|
|
{
|
|
_TCB *tcb = sched_gettcb(pid);
|
|
bool mystat;
|
|
int err;
|
|
int ret;
|
|
|
|
/* Disable pre-emption so that nothing changes in the following tests */
|
|
|
|
sched_lock();
|
|
if (!tcb)
|
|
{
|
|
err = ECHILD;
|
|
goto errout_with_errno;
|
|
}
|
|
|
|
/* None of the options are supported */
|
|
|
|
#ifdef CONFIG_DEBUG
|
|
if (options != 0)
|
|
{
|
|
err = ENOSYS;
|
|
goto errout_with_errno;
|
|
}
|
|
#endif
|
|
|
|
/* "If more than one thread is suspended in waitpid() awaiting termination of
|
|
* the same process, exactly one thread will return the process status at the
|
|
* time of the target process termination." Hmmm.. what do we return to the
|
|
* others?
|
|
*/
|
|
|
|
if (stat_loc != NULL && tcb->stat_loc == NULL)
|
|
{
|
|
tcb->stat_loc = stat_loc;
|
|
mystat = true;
|
|
}
|
|
|
|
/* Then wait for the task to exit */
|
|
|
|
ret = sem_wait(&tcb->exitsem);
|
|
if (ret < 0)
|
|
{
|
|
/* Unlock pre-emption and return the ERROR (sem_wait has already set
|
|
* the errno). Handle the awkward case of whether or not we need to
|
|
* nullify the stat_loc value.
|
|
*/
|
|
|
|
if (mystat)
|
|
{
|
|
tcb->stat_loc = NULL;
|
|
}
|
|
goto errout;
|
|
}
|
|
|
|
/* On success, return the PID */
|
|
|
|
sched_unlock();
|
|
return pid;
|
|
|
|
errout_with_errno:
|
|
errno = err;
|
|
errout:
|
|
sched_unlock();
|
|
return ERROR;
|
|
}
|
|
|
|
#endif /* CONFIG_SCHED_WAITPID */
|