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Annotation of prex-old/usr/server/proc/fork.c, Revision 1.1.1.1

1.1       nbrk        1: /*
                      2:  * Copyright (c) 2005-2006, Kohsuke Ohtani
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
                     13:  * 3. Neither the name of the author nor the names of any co-contributors
                     14:  *    may be used to endorse or promote products derived from this software
                     15:  *    without specific prior written permission.
                     16:  *
                     17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     27:  * SUCH DAMAGE.
                     28:  */
                     29:
                     30: /*
                     31:  * fork.c - fork() support
                     32:  */
                     33:
                     34: #include <prex/prex.h>
                     35: #include <server/proc.h>
                     36: #include <sys/list.h>
                     37:
                     38: #include <unistd.h>
                     39: #include <errno.h>
                     40: #include <stdlib.h>
                     41: #include <string.h>
                     42:
                     43: #include "proc.h"
                     44:
                     45: static int vfork_start(struct proc *proc);
                     46:
                     47: /*
                     48:  * fork() support.
                     49:  *
                     50:  * It creates new process data and update all process relations.
                     51:  * The task creation and the thread creation are done by the fork()
                     52:  * library stub.
                     53:  */
                     54: int
                     55: proc_fork(struct msg *msg)
                     56: {
                     57:        struct proc *p;
                     58:        struct pgrp *pgrp;
                     59:        task_t child;
                     60:        pid_t pid;
                     61:        int vfork;
                     62:
                     63:        if (curproc == NULL)
                     64:                return EINVAL;
                     65:
                     66:        child = (task_t)msg->data[0];
                     67:        vfork = msg->data[1];
                     68:
                     69:        dprintf("fork: parent=%x child=%x vfork=%d\n",
                     70:            msg->hdr.task, child, vfork);
                     71:
                     72:        if (task_to_proc(child) != NULL)
                     73:                return EINVAL;  /* Process already exists */
                     74:
                     75:        if ((pid = pid_assign()) == 0)
                     76:                return EAGAIN;  /* Too many processes */
                     77:
                     78:        if ((p = malloc(sizeof(struct proc))) == NULL)
                     79:                return ENOMEM;
                     80:
                     81:        p->parent = curproc;
                     82:        p->pgrp = curproc->pgrp;
                     83:        p->stat = SRUN;
                     84:        p->exit_code = 0;
                     85:        p->pid = pid;
                     86:        p->task = child;
                     87:        list_init(&p->children);
                     88:        proc_add(p);
                     89:
                     90:        list_insert(&curproc->children, &p->sibling);
                     91:
                     92:        pgrp = p->pgrp;
                     93:        list_insert(&pgrp->members, &p->pgrp_link);
                     94:
                     95:        list_insert(&allproc, &p->link);
                     96:
                     97:        if (vfork)
                     98:                vfork_start(curproc);
                     99:
                    100:        dprintf("fork: new pid=%d\n", p->pid);
                    101:        msg->data[0] = (int)p->pid;
                    102:        return 0;
                    103: }
                    104:
                    105: /*
                    106:  * Clean up all resource created by fork().
                    107:  */
                    108: void
                    109: proc_cleanup(struct proc *proc)
                    110: {
                    111:        struct proc *pp;
                    112:
                    113:        pp = proc->parent;
                    114:        list_remove(&proc->sibling);
                    115:        list_remove(&proc->pgrp_link);
                    116:        proc_remove(proc);
                    117:        list_remove(&proc->link);
                    118:        free(proc);
                    119: }
                    120:
                    121: static int
                    122: vfork_start(struct proc *proc)
                    123: {
                    124:        void *stack;
                    125:
                    126:        /*
                    127:         * Save parent's stack
                    128:         */
                    129:        if (vm_allocate(proc->task, &stack, USTACK_SIZE, 1) != 0)
                    130:                return ENOMEM;
                    131:
                    132:        memcpy(stack, proc->stack_base, USTACK_SIZE);
                    133:        proc->stack_saved = stack;
                    134:
                    135:        proc->wait_vfork = 1;
                    136:        dprintf("vfork_start: saved=%x org=%x\n", stack, proc->stack_base);
                    137:
                    138:        return 0;
                    139: }
                    140:
                    141: void
                    142: vfork_end(struct proc *proc)
                    143: {
                    144:
                    145:        dprintf("vfork_end: org=%x saved=%x\n", proc->stack_base,
                    146:                proc->stack_saved);
                    147:        /*
                    148:         * Restore parent's stack
                    149:         */
                    150:        memcpy(proc->stack_base, proc->stack_saved, USTACK_SIZE);
                    151:        vm_free(proc->task, proc->stack_saved);
                    152:
                    153:        /*
                    154:         * Resume parent
                    155:         */
                    156:        proc->wait_vfork = 0;
                    157:        task_resume(proc->task);
                    158: }