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Diffstat (limited to 'nuttx/sched/sched_waitid.c')
-rw-r--r-- | nuttx/sched/sched_waitid.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/nuttx/sched/sched_waitid.c b/nuttx/sched/sched_waitid.c new file mode 100644 index 000000000..eabc69afe --- /dev/null +++ b/nuttx/sched/sched_waitid.c @@ -0,0 +1,256 @@ +/***************************************************************************** + * sched/sched_waitid.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 <signal.h> +#include <errno.h> + +#include <nuttx/sched.h> + +#include "os_internal.h" + +#if defined(CONFIG_SCHED_WAITPID) && defined(CONFIG_SCHED_HAVE_PARENT) + +/***************************************************************************** + * Private Functions + *****************************************************************************/ + +/***************************************************************************** + * Public Functions + *****************************************************************************/ + +/***************************************************************************** + * Name: waitid + * + * Description: + * The waitid() function suspends the calling thread until one child of + * the process containing the calling thread changes state. It records the + * current state of a child in the structure pointed to by 'info'. If a + * child process changed state prior to the call to waitid(), waitid() + * returns immediately. If more than one thread is suspended in wait() or + * waitpid() waiting termination of the same process, exactly one thread + * will return the process status at the time of the target process + * termination + * + * The idtype and id arguments are used to specify which children waitid() + * will wait for. + * + * If idtype is P_PID, waitid() will wait for the child with a process + * ID equal to (pid_t)id. + * + * If idtype is P_PGID, waitid() will wait for any child with a process + * group ID equal to (pid_t)id. + * + * If idtype is P_ALL, waitid() will wait for any children and id is + * ignored. + * + * The options argument is used to specify which state changes waitid() + * will will wait for. It is formed by OR-ing together one or more of the + * following flags: + * + * WEXITED - Wait for processes that have exited. + * WSTOPPED - Status will be returned for any child that has stopped + * upon receipt of a signal. + * WCONTINUED - Status will be returned for any child that was stopped + * and has been continued. + * WNOHANG - Return immediately if there are no children to wait for. + * WNOWAIT - Keep the process whose status is returned in 'info' in a + * waitable state. This will not affect the state of the process; the + * process may be waited for again after this call completes. + * + * The 'info' argument must point to a siginfo_t structure. If waitid() + * returns because a child process was found that satisfied the conditions + * indicated by the arguments idtype and options, then the structure pointed + * to by 'info' will be filled in by the system with the status of the + * process. The si_signo member will always be equal to SIGCHLD. + * + * Input Parameters: + * See description. + * + * Returned Value: + * If waitid() returns due to the change of state of one of its children, + * 0 is returned. Otherwise, -1 is returned and errno is set to indicate + * the error. + * + * The waitid() function will fail if: + * + * ECHILD - The calling process has no existing unwaited-for child + * processes. + * EINTR - The waitid() function was interrupted by a signal. + * EINVAL - An invalid value was specified for options, or idtype and id + * specify an invalid set of processes. + * + *****************************************************************************/ + +int waitid(idtype_t idtype, id_t id, siginfo_t *info, int options) +{ + FAR _TCB *rtcb = (FAR _TCB *)g_readytorun.head; + sigset_t sigset; + int err; + int ret; + + /* MISSING LOGIC: If WNOHANG is provided in the options, then this function + * should returned immediately. However, there is no mechanism available now + * know if the thread has child: The children remember their parents (if + * CONFIG_SCHED_HAVE_PARENT) but the parents do not remember their children. + */ + + /* None of the options are supported except for WEXITED (which must be + * provided. Currently SIGCHILD always reports CLD_EXITED so we cannot + * distinguish any other events. + */ + +#ifdef CONFIG_DEBUG + if (options != WEXITED) + { + set_errno(ENOSYS); + return ERROR; + } +#endif + + /* Create a signal set that contains only SIGCHLD */ + + (void)sigemptyset(&sigset); + (void)sigaddset(&sigset, SIGCHLD); + + /* Disable pre-emption so that nothing changes while the loop executes */ + + sched_lock(); + + /* Verify that this task actually has children and that the the requeste + * TCB is actually a child of this task. + */ + + if (rtcb->nchildren == 0) + { + err = ECHILD; + goto errout_with_errno; + } + else if (idtype == P_PID) + { + /* Get the TCB corresponding to this PID and make sure it is our child. */ + + FAR _TCB *ctcb = sched_gettcb((pid_t)id); + if (!ctcb || ctcb->parent != rtcb->pid) + { + err = ECHILD; + goto errout_with_errno; + } + } + + /* Loop until the child that we are waiting for dies */ + + for (;;) + { + /* Check if the task has already died. Signals are not queued in + * NuttX. So a possibility is that the child has died and we + * missed the death of child signal (we got some other signal + * instead). + */ + + if (rtcb->nchildren == 0 || + (idtype == P_PID && (ret = kill((pid_t)id, 0)) < 0)) + { + /* We know that the child task was running okay we stared, + * so we must have lost the signal. What can we do? + * Let's claim we were interrupted by a signal. + */ + + err = EINTR; + goto errout_with_errno; + } + + /* Wait for any death-of-child signal */ + + ret = sigwaitinfo(&sigset, info); + if (ret < 0) + { + goto errout; + } + + /* Make there this was SIGCHLD */ + + if (info->si_signo == SIGCHLD) + { + /* Yes.. Are we waiting for the death of a specific child? */ + + if (idtype == P_PID) + { + /* Was this the death of the thread we were waiting for? */ + + if (info->si_pid == (pid_t)id) + { + /* Yes... return success */ + + break; + } + } + + /* Are we waiting for any child to change state? */ + + else if (idtype == P_ALL) + { + /* Return success */ + + break; + } + + /* Other ID types are not supported */ + + else /* if (idtype == P_PGID) */ + { + set_errno(ENOSYS); + goto errout; + } + } + } + + sched_unlock(); + return OK; + +errout_with_errno: + set_errno(err); +errout: + sched_unlock(); + return ERROR; +} + +#endif /* CONFIG_SCHED_WAITPID && CONFIG_SCHED_HAVE_PARENT*/ |