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/*

 * Copyright (c) 2006, Kohsuke Ohtani

 * All rights reserved.

 *

 * 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 of the author nor the names of any co-contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.

 */

#include <sys/prex.h>

#include <sys/posix.h>

#include <sys/signal.h>

#include <ipc/proc.h>

#include <ipc/fs.h>

#include <ipc/ipc.h>

#include <stddef.h>

#include <setjmp.h>

#include <errno.h>

static void __parent_entry(void);

static void __child_entry(void);

static jmp_buf __fork_env;

static pid_t __child_pid;

static thread_t __parent_thread;

/*

 * vfork() - vfork for No-MMU system.

 *

 * RETURN VALUE:

 *

 *  vfork() returns 0 to the child process and return the process

 *  ID of the child process to the parent process. Or, -1 will be

 *  returned to the parent process if error.

 *

 * ERRORS:

 *

 *  EAGAIN

 *  ENOMEM

 *

 * NOTE:

 *

 *  Since no thread is created by task_create(), thread_create()

 *  must be called follwing task_crate(). But, when new thread is

 *  created by thread_create(), the stack pointer of new thread is

 *  used at thread_create() although the stack image is copied at

 *  task_create(). So, the stack pointer must be reset to same

 *  address of thread_create() before calling task_create();

 *  This is a little tricky...

 *

 * The new process is an exact copy of the calling process

 * except as detailed below:

 * - Process IDs are different.

 * - tms_* is set to 0.

 * - Alarm clock is set to 0.

 * - Opend semaphore is inherited.

 * - Pending signals are cleared.

 *

 * - File lock is not inherited.

 * - File descriptor is shared.

 * - Directory stream is shared.

 */

pid_t

vfork(void)

{

        struct msg m;

        task_t tsk;

        thread_t t;

        int error, sts, pri;

        /* Save current stack pointer */

        sts = setjmp(__fork_env);

        if (sts == 0) {

                /*

                 * Create new task

                 */

                if ((error = task_create(task_self(), VM_SHARE, &tsk)) != 0) {

                        errno = error;

                        return -1;

                }

                if ((error = thread_create(tsk, &t)) != 0) {

                        task_terminate(tsk);

                        errno = error;

                        return -1;

                }

                /*

                 * Notify to file system server

                 */

                m.hdr.code = FS_FORK;

                m.data[0] = tsk;                /* child task */

                if (__posix_call(__fs_obj, &m, sizeof(m), 1) != 0)

                        return -1;

                /*

                 * Notify to process server

                 */

                m.hdr.code = PS_FORK;

                m.data[0] = tsk;                /* child task */

                m.data[1] = 1;                        /* fork type */

                if (__posix_call(__proc_obj, &m, sizeof(m), 1) != 0)

                        return -1;

                __child_pid = m.data[0];

                /*

                 * Start child task.

                 *

                 * TODO:

                 * In order to synchronize the execution, we change

                 * the child's priority to lower value. This ugly hack

                 * will be replaced by some other methods...

                 */

                thread_load(t, __child_entry, NULL);

                thread_getpri(t, &pri);

                thread_setpri(t, pri + 1);

                thread_resume(t);

                /*

                 * Suspend until child process calls exec() or exit()

                 */

                __parent_thread = thread_self();

                task_suspend(task_self());

        } else if (sts == 1) {

                /*

                 * Child task

                 */

                thread_load(__parent_thread, __parent_entry, NULL);

                t = thread_self();

                thread_getpri(t, &pri);

                thread_setpri(t, pri - 1);

#ifdef _REENTRANT

                error = mutex_init(&__sig_lock);

#endif

                __sig_pending = 0;

                thread_yield();

                return 0;

        }

        return __child_pid;

}

static void

__parent_entry(void)

{

        longjmp(__fork_env, 2);

        /* NOTREACHED */

}

static void

__child_entry(void)

{

        longjmp(__fork_env, 1);

        /* NOTREACHED */

}

/*

 * fork() is not supported on NOMMU system.

 */

pid_t

fork(void)

{

        return ENOSYS;

}