nbd: Implement NBD_INFO_BLOCK_SIZE on server

[qemu.git] / util / iohandler.c

/*
 * QEMU System Emulator - managing I/O handler
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "qemu/queue.h"
#include "block/aio.h"
#include "qemu/main-loop.h"

#ifndef _WIN32
#include <sys/wait.h>
#endif

/* This context runs on top of main loop. We can't reuse qemu_aio_context
 * because iohandlers mustn't be polled by aio_poll(qemu_aio_context). */
static AioContext *iohandler_ctx;

static void iohandler_init(void)
{
    if (!iohandler_ctx) {
        iohandler_ctx = aio_context_new(&error_abort);
    }
}

AioContext *iohandler_get_aio_context(void)
{
    iohandler_init();
    return iohandler_ctx;
}

GSource *iohandler_get_g_source(void)
{
    iohandler_init();
    return aio_get_g_source(iohandler_ctx);
}

void qemu_set_fd_handler(int fd,
                         IOHandler *fd_read,
                         IOHandler *fd_write,
                         void *opaque)
{
    iohandler_init();
    aio_set_fd_handler(iohandler_ctx, fd, false,
                       fd_read, fd_write, NULL, opaque);
}

void event_notifier_set_handler(EventNotifier *e,
                                EventNotifierHandler *handler)
{
    iohandler_init();
    aio_set_event_notifier(iohandler_ctx, e, false,
                           handler, NULL);
}

/* reaping of zombies.  right now we're not passing the status to
   anyone, but it would be possible to add a callback.  */
#ifndef _WIN32
typedef struct ChildProcessRecord {
    int pid;
    QLIST_ENTRY(ChildProcessRecord) next;
} ChildProcessRecord;

static QLIST_HEAD(, ChildProcessRecord) child_watches =
    QLIST_HEAD_INITIALIZER(child_watches);

static QEMUBH *sigchld_bh;

static void sigchld_handler(int signal)
{
    qemu_bh_schedule(sigchld_bh);
}

static void sigchld_bh_handler(void *opaque)
{
    ChildProcessRecord *rec, *next;

    QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
        if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
            QLIST_REMOVE(rec, next);
            g_free(rec);
        }
    }
}

static void qemu_init_child_watch(void)
{
    struct sigaction act;
    sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);

    memset(&act, 0, sizeof(act));
    act.sa_handler = sigchld_handler;
    act.sa_flags = SA_NOCLDSTOP;
    sigaction(SIGCHLD, &act, NULL);
}

int qemu_add_child_watch(pid_t pid)
{
    ChildProcessRecord *rec;

    if (!sigchld_bh) {
        qemu_init_child_watch();
    }

    QLIST_FOREACH(rec, &child_watches, next) {
        if (rec->pid == pid) {
            return 1;
        }
    }
    rec = g_malloc0(sizeof(ChildProcessRecord));
    rec->pid = pid;
    QLIST_INSERT_HEAD(&child_watches, rec, next);
    return 0;
}
#endif