mq.c

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/*
 * Written by Gilles Chanteperdrix <[e-mail]>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/**
 * @ingroup posix
 * @defgroup posix_mq Message queues services.
 *
 * Message queues services.
 *
 * A message queue allow exchanging data between real-time threads. Maximum
 * message length and maximum number of messages are fixed when the queue is
 * created (see mq_open()).
 *
 *@{*/

#include <stdarg.h>

#include <nucleus/queue.h>

#include <posix/registry.h>
#include <posix/internal.h>     /* Magics, time conversion */
#include <posix/thread.h>       /* errno. */
#include <posix/sig.h>          /* pse51_siginfo_t. */

/* Temporary definitions. */
struct pse51_mq {
    pse51_node_t nodebase;

#define node2mq(naddr) \
    ((pse51_mq_t *) (((char *)naddr) - offsetof(pse51_mq_t, nodebase)))

    unsigned long flags;

    xnpqueue_t queued;
    xnsynch_t receivers;
    xnsynch_t senders;
    size_t memsize;
    char *mem;
    xnqueue_t avail;

    /* mq_notify */
    pse51_siginfo_t si;
    pthread_t target;

    struct mq_attr attr;

    xnholder_t link;            /* link in mqq */

#define link2mq(laddr) \
    ((pse51_mq_t *) (((char *)laddr) - offsetof(pse51_mq_t, link)))
};

typedef struct pse51_mq pse51_mq_t;

typedef struct pse51_msg {
    xnpholder_t link;
    size_t len;

#define link2msg(laddr) \
    ((pse51_msg_t *)(((char *)laddr) - offsetof(pse51_msg_t, link)))
    char data[0];
} pse51_msg_t;

typedef struct pse51_direct_msg {
    char *buf;
    size_t *lenp;
    unsigned *priop;
    int used;
} pse51_direct_msg_t;

static xnqueue_t pse51_mqq;

static pse51_msg_t *pse51_mq_msg_alloc(pse51_mq_t *mq)
{
    xnpholder_t *holder = (xnpholder_t *) getq(&mq->avail);

    if(!holder)
        return NULL;

    initph(holder);
    return link2msg(holder);
}

static void pse51_mq_msg_free(pse51_mq_t *mq, pse51_msg_t *msg)
{
    xnholder_t *holder = (xnholder_t *) (&msg->link);
    inith(holder);
    prependq(&mq->avail, holder); /* For earliest re-use of the block. */
}

static int pse51_mq_init(pse51_mq_t *mq, const struct mq_attr *attr)
{
    unsigned i, msgsize, memsize;
    char *mem;

    if (xnpod_asynch_p() || !xnpod_root_p())
        return EPERM;

    if(!attr->mq_maxmsg)
        return EINVAL;

    msgsize = attr->mq_msgsize + sizeof(pse51_msg_t);

    /* Align msgsize on natural boundary. */
    if ((msgsize % sizeof(unsigned long)))
        msgsize += sizeof(unsigned long) - (msgsize % sizeof(unsigned long));

    memsize = msgsize * attr->mq_maxmsg;
    memsize = PAGE_ALIGN(memsize);

    mem = (char *) xnarch_sysalloc(memsize);

    if (!mem)
        return ENOSPC;

    mq->flags = 0;
    mq->memsize = memsize;
    initpq(&mq->queued, xnqueue_down, 0);
    xnsynch_init(&mq->receivers, XNSYNCH_PRIO | XNSYNCH_NOPIP);
    xnsynch_init(&mq->senders, XNSYNCH_PRIO | XNSYNCH_NOPIP);
    mq->mem = mem;

    /* Fill the pool. */
    initq(&mq->avail);
    for (i = 0; i < attr->mq_maxmsg; i++)
        {
        pse51_msg_t *msg = (pse51_msg_t *) (mem + i * msgsize);
        pse51_mq_msg_free(mq, msg);
        }

    mq->attr = *attr;
    mq->target = NULL;

    return 0;
}

static void pse51_mq_destroy(pse51_mq_t *mq)
{
    int need_resched;
    spl_t s;

    xnlock_get_irqsave(&nklock, s);
    need_resched = (xnsynch_destroy(&mq->receivers) == XNSYNCH_RESCHED);
    need_resched =
        (xnsynch_destroy(&mq->senders) == XNSYNCH_RESCHED) || need_resched;
    removeq(&pse51_mqq, &mq->link);
    xnlock_put_irqrestore(&nklock, s);
    xnarch_sysfree(mq->mem, mq->memsize);

    if (need_resched)
        xnpod_schedule();
}

/**
 * Get a attribute object of a message queue.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/mq_getattr.html
 * 
 */
int mq_getattr(mqd_t fd, struct mq_attr *attr)
{
    pse51_desc_t *desc;
    pse51_mq_t *mq;
    spl_t s;
    int err;

    xnlock_get_irqsave(&nklock, s);

    err = pse51_desc_get(&desc, fd, PSE51_MQ_MAGIC);

    if(err)
        {
        xnlock_put_irqrestore(&nklock, s);
        thread_set_errno(err);
        return -1;
        }
    
    mq = node2mq(pse51_desc_node(desc));
    *attr = mq->attr;
    attr->mq_flags = pse51_desc_getflags(desc);
    attr->mq_curmsgs = countpq(&mq->queued);
    xnlock_put_irqrestore(&nklock, s);

    return 0;
}

/**
 * Set flags of a message queue.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/mq_setattr.html
 * 
 */
int mq_setattr(mqd_t fd,
               const struct mq_attr *__restrict__ attr,
               struct mq_attr *__restrict__ oattr)
{
    pse51_desc_t *desc;
    pse51_mq_t *mq;
    long flags;
    spl_t s;
    int err;

    xnlock_get_irqsave(&nklock, s);

    err = pse51_desc_get(&desc, fd, PSE51_MQ_MAGIC);

    if(err)
        {
        xnlock_put_irqrestore(&nklock, s);
        thread_set_errno(err);
        return -1;
        }

    mq = node2mq(pse51_desc_node(desc));
    if(oattr)
        {
        *oattr = mq->attr;
        oattr->mq_flags = pse51_desc_getflags(desc);
        oattr->mq_curmsgs = countpq(&mq->queued);
        }
    flags = (pse51_desc_getflags(desc) & PSE51_PERMS_MASK)
        | (attr->mq_flags & ~PSE51_PERMS_MASK);
    pse51_desc_setflags(desc, flags);
    xnlock_put_irqrestore(&nklock, s);

    return 0;
}

static int pse51_mq_trysend(pse51_desc_t *desc,
                            const char *buffer,
                            size_t len,
                            unsigned prio)
{
    xnthread_t *reader;
    pthread_t thread;
    pse51_mq_t *mq;
    unsigned flags;

    mq = node2mq(pse51_desc_node(desc));
    flags = pse51_desc_getflags(desc) & PSE51_PERMS_MASK;

    if(flags != O_WRONLY && flags != O_RDWR)
        return EPERM;

    if(len > mq->attr.mq_msgsize)
        return EMSGSIZE;

    reader = xnsynch_wakeup_one_sleeper(&mq->receivers);
    thread = thread2pthread(reader);

    if(thread)
        {
        pse51_direct_msg_t *msg = (pse51_direct_msg_t *) thread->arg;

        memcpy(msg->buf, buffer, len);
        *(msg->lenp) = len;
        if(msg->priop)
            *(msg->priop) = prio;
        msg->used = 1;
        }
    else
        {
        pse51_msg_t *msg = pse51_mq_msg_alloc(mq);

        if(!msg)
            return EAGAIN;

        memcpy(&msg->data[0], buffer, len);
        msg->len = len;
        insertpqf(&mq->queued, &msg->link, prio);

        /* First message and no pending reader, attempt to send a signal if
           mq_notify was called. */
        if (!reader && mq->target && countpq(&mq->queued) == 1)
            {
            pse51_sigqueue_inner(mq->target, &mq->si);
            mq->target = NULL;
            }
        }

    if(reader)
        xnpod_schedule();

    return 0;
}

static int pse51_mq_tryrcv(pse51_desc_t *desc,
                           char *__restrict__ buffer,
                           size_t *__restrict__ lenp,
                           unsigned *__restrict__ priop)
{
    xnpholder_t *holder;
    pse51_msg_t *msg;
    pse51_mq_t *mq;
    unsigned flags;

    mq = node2mq(pse51_desc_node(desc));
    flags = pse51_desc_getflags(desc) & PSE51_PERMS_MASK;

    if(flags != O_RDONLY && flags != O_RDWR)
        return EPERM;

    if(*lenp < mq->attr.mq_msgsize)
        return EMSGSIZE;

    if(!(holder = getpq(&mq->queued)))
        return EAGAIN;

    msg = link2msg(holder);
    if(priop)
        *priop = holder->prio;
    *lenp = msg->len;
    memcpy(buffer, &msg->data[0], msg->len);

    pse51_mq_msg_free(mq, msg);

    if(xnsynch_wakeup_one_sleeper(&mq->senders))
        xnpod_schedule();
    
    return 0;
}


static int pse51_mq_timedsend_inner(mqd_t fd,
                                    const char * buffer,
                                    size_t len,
                                    unsigned prio,
                                    xnticks_t abs_to)
{
    int rc;

    for (;;) {
        xnticks_t to = abs_to;
        pse51_desc_t *desc;
        pse51_mq_t *mq;
        xnthread_t *cur;
        
        if ((rc = pse51_desc_get(&desc, fd, PSE51_MQ_MAGIC)))
            return rc;

        if ((rc = pse51_mq_trysend(desc, buffer, len, prio)) != EAGAIN)
            return rc;

        if ((pse51_desc_getflags(desc) & O_NONBLOCK))
            return rc;

        if (xnpod_unblockable_p())
            return EPERM;

        if ((rc = clock_adjust_timeout(&to, CLOCK_REALTIME)))
            return rc;

        mq = node2mq(pse51_desc_node(desc));

        cur = xnpod_current_thread();

        thread_cancellation_point(cur);

        xnsynch_sleep_on(&mq->senders, to);

        thread_cancellation_point(cur);

        if (xnthread_test_flags(cur, XNBREAK))
            return EINTR;

        if (xnthread_test_flags(cur, XNTIMEO))
            return ETIMEDOUT;

        if (xnthread_test_flags(cur, XNRMID))
            return EBADF;
        }
}

static int pse51_mq_timedrcv_inner(mqd_t fd,
                                   char *__restrict__ buffer,
                                   size_t *__restrict__ lenp,
                                   unsigned *__restrict__ priop,
                                   xnticks_t abs_to)
{
    xnthread_t *cur = xnpod_current_thread();
    int rc;

    for (;;)
        {
        pse51_direct_msg_t msg;
        xnticks_t to = abs_to;
        pse51_desc_t *desc;
        pthread_t thread;
        pse51_mq_t *mq;
        int direct = 0;
        
        if ((rc = pse51_desc_get(&desc, fd, PSE51_MQ_MAGIC)))
            return rc;

        if ((rc = pse51_mq_tryrcv(desc, buffer, lenp, priop)) != EAGAIN)
            return rc;

        if ((pse51_desc_getflags(desc) & O_NONBLOCK))
            return rc;

        if (xnpod_unblockable_p())
            return EPERM;

        if ((rc = clock_adjust_timeout(&to, CLOCK_REALTIME)))
            return rc;

        mq = node2mq(pse51_desc_node(desc));

        thread = thread2pthread(cur);
        
        if(thread)
            {
            msg.buf = buffer;
            msg.lenp = lenp;
            msg.priop = priop;
            msg.used = 0;
            thread->arg = &msg;
            direct = 1;
            }

        thread_cancellation_point(cur);

        xnsynch_sleep_on(&mq->receivers, to);

        thread_cancellation_point(cur);