Archipelago » blktap-utils

/* 

 * Copyright (c) 2008, XenSource Inc.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *     * Redistributions of source code must retain the above copyright

 *       notice, this list of conditions and the following disclaimer.

 *     * 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.

 *     * Neither the name of XenSource Inc. 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.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <errno.h>

#include "tapdisk-ring.h"

static int

tapdisk_uring_create_ctlfd(td_uring_t *ring)

{

        int fd, err;

        struct sockaddr_un saddr;

        if (strnlen(ring->ctlfd_path, sizeof(saddr.sun_family)) >=

            sizeof(saddr.sun_family))

                return -ENAMETOOLONG;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);

        if (fd == -1)

                return -errno;

        memset(&saddr, 0, sizeof(struct sockaddr_un));

        saddr.sun_family = AF_UNIX;

        memcpy(saddr.sun_path, ring->ctlfd_path, strlen(ring->ctlfd_path));

        err = unlink(ring->ctlfd_path);

        if (err == -1 && errno != ENOENT) {

                err = -errno;

                goto fail;

        }

        err = bind(fd, &saddr, sizeof(struct sockaddr_un));

        if (err == -1) {

                err = -errno;

                goto fail;

        }

        err = listen(fd, 1);

        if (err == -1) {

                err = -errno;

                goto fail;

        }

        ring->ctlfd = fd;

        return 0;

fail:

        close(fd);

        return err;

}

static void

tapdisk_uring_destroy_ctlfd(td_uring_t *ring)

{

        if (ring->ctlfd) {

                close(ring->ctlfd);

                ring->ctlfd = 0;

        }

        if (ring->ctlfd_path) {

                unlink(ring->ctlfd_path);

                free(ring->ctlfd_path);

                ring->ctlfd_path = NULL;

        }

}

static int

tapdisk_uring_connect_ctlfd(td_uring_t *ring)

{

        int fd, err;

        struct sockaddr_un saddr;

        if (strnlen(ring->ctlfd_path, sizeof(saddr.sun_path)) >=

            sizeof(saddr.sun_path))

                return -ENAMETOOLONG;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);

        if (fd == -1)

                return -errno;

        memset(&saddr, 0, sizeof(struct sockaddr_un));

        saddr.sun_family = AF_UNIX;

        memcpy(saddr.sun_path, ring->ctlfd_path, strlen(ring->ctlfd_path));

        err = connect(fd, &saddr, sizeof(saddr));

        if (err == -1) {

                err = -errno;

                goto fail;

        }

        ring->ctlfd = fd;

        return 0;

fail:

        close(fd);

        return err;

}

static void

tapdisk_uring_disconnect_ctlfd(td_uring_t *ring)

{

        if (ring->ctlfd)

                close(ring->ctlfd);

        free(ring->ctlfd_path);

        ring->ctlfd_path = NULL;

}

static int

tapdisk_uring_create_shmem(td_uring_t *ring)

{

        int fd, err;

        fd = shm_open(ring->shmem_path, O_CREAT | O_RDWR, 0750);

        if (fd == -1)

                return -errno;

        err = ftruncate(fd, ring->shmem_size);

        if (err == -1) {

                err = -errno;

                goto out;

        }

        ring->shmem = mmap(NULL, ring->shmem_size,

                           PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

        if (ring->shmem == MAP_FAILED) {

                ring->shmem = NULL;

                err = -errno;

                goto out;

        }

        err = 0;

out:

        close(fd);

        return err;

}

static void

tapdisk_uring_destroy_shmem(td_uring_t *ring)

{

        if (ring->shmem) {

                munmap(ring->shmem, ring->shmem_size);

                ring->shmem = NULL;

        }

        if (ring->shmem_path) {

                shm_unlink(ring->shmem_path);

                free(ring->shmem_path);

                ring->shmem_path = NULL;

        }

}

static int

tapdisk_uring_connect_shmem(td_uring_t *ring)

{

        int fd, err;

        td_uring_header_t header, *p;

        fd = shm_open(ring->shmem_path, O_RDWR);

        if (fd == -1)

                return -errno;

        p = mmap(NULL, sizeof(td_uring_header_t),

                 PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

        if (p == MAP_FAILED) {

                err = -errno;

                goto out;

        }

        memcpy(&header, p, sizeof(td_uring_header_t));

        munmap(p, sizeof(td_uring_header_t));

        if (memcmp(header.cookie,

                   TAPDISK_URING_COOKIE, sizeof(header.cookie))) {

                err = -EINVAL;

                goto out;

        }

        if (header.version != TD_URING_CURRENT_VERSION) {

                err = -EINVAL;

                goto out;

        }

        ring->ring_size  = header.ring_size;

        ring->data_size  = header.data_size;

        ring->shmem_size = header.shmem_size;

        ring->shmem = mmap(NULL, ring->shmem_size,

                           PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

        if (ring->shmem == MAP_FAILED) {

                rint->shmem = NULL;

                err = -errno;

                goto out;

        }

        err = 0;

out:

        close(fd);

        return err;

}

static void

tapdisk_uring_disconnect_shmem(td_uring_t *ring)

{

        if (ring->shmem)

                munmap(ring->shmem, ring->shmem_size);

        free(ring->shmem_path);

        ring->shmem_path = NULL;

}

int

tapdisk_uring_create(td_uring_t *ring, const char *location,

                    uint32_t ring_size, uint32_t data_size)

{

        int fd, err;

        memset(ring, 0, sizeof(td_uring_t));

        ring->ring_size  = ring_size;

        ring->data_size  = data_size;

        ring->shmem_size = ring_size + data_size + sizeof(td_uring_header_t);

        err = asprintf(&ring->shmem_path, "%s.shm", location);

        if (err == -1) {

                ring->shmem_path = NULL;

                err = -errno;

                goto fail;

        }

        err = asprintf(&ring->ctlfd_path, "%s.cfd", location);

        if (err == -1) {

                ring->ctlfd_path = NULL;

                err = -errno;

                goto fail;

        }

        err = tapdisk_uring_create_ctlfd(ring);

        if (err)

                goto fail;

        err = tapdisk_uring_create_shmem(ring);

        if (err)

                goto fail;

        ring->ring_area = (unsigned long)ring->shmem + sizeof(td_uring_header_t);

        ring->data_area = (unsigned long)ring->ring_area + ring->ring_size;

        return 0;

fail:

        tapdisk_uring_destroy(ring);

        return err;

}

int

tapdisk_uring_destroy(td_uring_t *ring)

{

        tapdisk_uring_destroy_shmem(ring);

        tapdisk_uring_destroy_ctlfd(ring);

        return 0;

}

int

tapdisk_uring_connect(td_uring_t *ring, const char *location)

{

        int fd, err;

        memset(ring, 0, sizeof(td_uring_t));

        err = asprintf(&ring->shmem_path, "%s.shm", location);

        if (err == -1) {

                ring->shmem_path = NULL;

                err = -errno;

                goto fail;

        }

        err = asprintf(&ring->ctlfd_path, "%s.cfd", location);

        if (err == -1) {

                ring->ctlfd_path = NULL;

                err = -errno;

                goto fail;

        }

        err = tapdisk_uring_connect_ctlfd(ring);

        if (err)

                goto fail;

        err = tapdisk_uring_connect_shmem(ring);

        if (err)

                goto fail;

        err = 0;

fail:

}

int

tapdisk_uring_disconnect(td_uring_t *ring)

{

        tapdisk_uring_disconnect_shmem(ring);

        tapdisk_uring_disconnect_ctlfd(ring);

        return 0;

}

static int

tapdisk_ring_read_message(int fd, td_uring_message_t *message, int timeout)

{

        fd_set readfds;

        int ret, len, offset;

        struct timeval tv, *t;

        t      = NULL;

        offset = 0;

        len    = sizeof(td_uring_message_t);

        if (timeout) {

                tv.tv_sec  = timeout;

                tv.tv_usec = 0;

                t = &tv;

        }

        while (offset < len) {

                FD_ZERO(&readfds);

                FD_SET(fd, &readfds);

                /* we don't bother reinitializing tv. at worst, it will wait a

                 * bit more time than expected. */

                ret = select(fd + 1, &readfds, NULL, NULL, t);

                if (ret == -1)

                        break;

                else if (FD_ISSET(fd, &readfds)) {

                        ret = read(fd, message + offset, len - offset);

                        if (ret <= 0)

                                break;

                        offset += ret;

                } else

                        break;

        }

        if (offset != len)

                return -EIO;

        return 0;

}

static int

tapdisk_ring_write_message(int fd, td_uring_message_t *message, int timeout)

{

        fd_set writefds;

        int ret, len, offset;

        struct timeval tv, *t;

        t      = NULL;

        offset = 0;

        len    = sizeof(td_uring_message_t);

        if (timeout) {

                tv.tv_sec  = timeout;

                tv.tv_usec = 0;

                t = &tv;

        }

        while (offset < len) {

                FD_ZERO(&writefds);

                FD_SET(fd, &writefds);

                /* we don't bother reinitializing tv. at worst, it will wait a

                 * bit more time than expected. */

                ret = select(fd + 1, NULL, &writefds, NULL, t);

                if (ret == -1)

                        break;

                else if (FD_ISSET(fd, &writefds)) {

                        ret = write(fd, message + offset, len - offset);

                        if (ret <= 0)

                                break;

                        offset += ret;

                } else

                        break;

        }

        if (offset != len)

                return -EIO;

        return 0;

}

int

tapdisk_uring_poll(td_uring_t *ring)

{

        int err;

        td_uring_message_t message;

        err = tapdisk_uring_read_message(ring->ctlfd, &message, 1);

        if (err)

                return err;

        if (message.type != TAPDISK_URING_MESSAGE_KICK)

                return -EINVAL;

        return 0;

}

int

tapdisk_uring_kick(td_uring_t *ring)

{

        td_uring_message_t message;

        memset(&message, 0, sizeof(td_uring_message_t));

        message.type = TAPDISK_URING_MESSAGE_KICK;

        return tapdisk_uring_write_message(ring->ctlfd, &message, 1);

}