Archipelago » qemu

/*

 * Helpers for getting linearized buffers from iov / filling buffers into iovs

 *

 * Copyright IBM, Corp. 2007, 2008

 * Copyright (C) 2010 Red Hat, Inc.

 *

 * Author(s):

 *  Anthony Liguori <aliguori@us.ibm.com>

 *  Amit Shah <amit.shah@redhat.com>

 *  Michael Tokarev <mjt@tls.msk.ru>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 * Contributions after 2012-01-13 are licensed under the terms of the

 * GNU GPL, version 2 or (at your option) any later version.

 */

#include "qemu/iov.h"

#ifdef _WIN32

# include <windows.h>

# include <winsock2.h>

#else

# include <sys/types.h>

# include <sys/socket.h>

#endif

size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,

                    size_t offset, const void *buf, size_t bytes)

{

    size_t done;

    unsigned int i;

    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {

        if (offset < iov[i].iov_len) {

            size_t len = MIN(iov[i].iov_len - offset, bytes - done);

            memcpy(iov[i].iov_base + offset, buf + done, len);

            done += len;

            offset = 0;

        } else {

            offset -= iov[i].iov_len;

        }

    }

    assert(offset == 0);

    return done;

}

size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,

                  size_t offset, void *buf, size_t bytes)

{

    size_t done;

    unsigned int i;

    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {

        if (offset < iov[i].iov_len) {

            size_t len = MIN(iov[i].iov_len - offset, bytes - done);

            memcpy(buf + done, iov[i].iov_base + offset, len);

            done += len;

            offset = 0;

        } else {

            offset -= iov[i].iov_len;

        }

    }

    assert(offset == 0);

    return done;

}

size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,

                  size_t offset, int fillc, size_t bytes)

{

    size_t done;

    unsigned int i;

    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {

        if (offset < iov[i].iov_len) {

            size_t len = MIN(iov[i].iov_len - offset, bytes - done);

            memset(iov[i].iov_base + offset, fillc, len);

            done += len;

            offset = 0;

        } else {

            offset -= iov[i].iov_len;

        }

    }

    assert(offset == 0);

    return done;

}

size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)

{

    size_t len;

    unsigned int i;

    len = 0;

    for (i = 0; i < iov_cnt; i++) {

        len += iov[i].iov_len;

    }

    return len;

}

/* helper function for iov_send_recv() */

static ssize_t

do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send)

{

#ifdef CONFIG_POSIX

    ssize_t ret;

    struct msghdr msg;

    memset(&msg, 0, sizeof(msg));

    msg.msg_iov = iov;

    msg.msg_iovlen = iov_cnt;

    do {

        ret = do_send

            ? sendmsg(sockfd, &msg, 0)

            : recvmsg(sockfd, &msg, 0);

    } while (ret < 0 && errno == EINTR);

    return ret;

#else

    /* else send piece-by-piece */

    /*XXX Note: windows has WSASend() and WSARecv() */

    unsigned i = 0;

    ssize_t ret = 0;

    while (i < iov_cnt) {

        ssize_t r = do_send

            ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0)

            : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0);

        if (r > 0) {

            ret += r;

        } else if (!r) {

            break;

        } else if (errno == EINTR) {

            continue;

        } else {

            /* else it is some "other" error,

             * only return if there was no data processed. */

            if (ret == 0) {

                ret = -1;

            }

            break;

        }

        i++;

    }

    return ret;

#endif

}

ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,

                      size_t offset, size_t bytes,

                      bool do_send)

{

    ssize_t total = 0;

    ssize_t ret;

    size_t orig_len, tail;

    unsigned niov;

    while (bytes > 0) {

        /* Find the start position, skipping `offset' bytes:

         * first, skip all full-sized vector elements, */

        for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) {

            offset -= iov[niov].iov_len;

        }

        /* niov == iov_cnt would only be valid if bytes == 0, which

         * we already ruled out in the loop condition.  */

        assert(niov < iov_cnt);

        iov += niov;

        iov_cnt -= niov;

        if (offset) {

            /* second, skip `offset' bytes from the (now) first element,

             * undo it on exit */

            iov[0].iov_base += offset;

            iov[0].iov_len -= offset;

        }

        /* Find the end position skipping `bytes' bytes: */

        /* first, skip all full-sized elements */

        tail = bytes;

        for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) {

            tail -= iov[niov].iov_len;

        }

        if (tail) {

            /* second, fixup the last element, and remember the original

             * length */

            assert(niov < iov_cnt);

            assert(iov[niov].iov_len > tail);

            orig_len = iov[niov].iov_len;

            iov[niov++].iov_len = tail;

        }

        ret = do_send_recv(sockfd, iov, niov, do_send);

        /* Undo the changes above before checking for errors */

        if (tail) {

            iov[niov-1].iov_len = orig_len;

        }

        if (offset) {

            iov[0].iov_base -= offset;

            iov[0].iov_len += offset;

        }

        if (ret < 0) {

            assert(errno != EINTR);

            if (errno == EAGAIN && total > 0) {

                return total;

            }

            return -1;

        }

        if (ret == 0 && !do_send) {

            /* recv returns 0 when the peer has performed an orderly

             * shutdown. */

            break;

        }

        /* Prepare for the next iteration */

        offset += ret;

        total += ret;

        bytes -= ret;

    }

    return total;

}

void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,

                 FILE *fp, const char *prefix, size_t limit)

{

    int v;

    size_t size = 0;

    char *buf;

    for (v = 0; v < iov_cnt; v++) {

        size += iov[v].iov_len;

    }

    size = size > limit ? limit : size;

    buf = g_malloc(size);

    iov_to_buf(iov, iov_cnt, 0, buf, size);

    qemu_hexdump(buf, fp, prefix, size);

    g_free(buf);

}

unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,

                 const struct iovec *iov, unsigned int iov_cnt,

                 size_t offset, size_t bytes)

{

    size_t len;

    unsigned int i, j;

    for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) {

        if (offset >= iov[i].iov_len) {

            offset -= iov[i].iov_len;

            continue;

        }

        len = MIN(bytes, iov[i].iov_len - offset);

        dst_iov[j].iov_base = iov[i].iov_base + offset;

        dst_iov[j].iov_len = len;

        j++;

        bytes -= len;

        offset = 0;

    }

    assert(offset == 0);

    return j;

}

/* io vectors */

void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)

{

    qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec));

    qiov->niov = 0;

    qiov->nalloc = alloc_hint;

    qiov->size = 0;

}

void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov)

{

    int i;

    qiov->iov = iov;

    qiov->niov = niov;

    qiov->nalloc = -1;

    qiov->size = 0;

    for (i = 0; i < niov; i++)

        qiov->size += iov[i].iov_len;

}

void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)

{

    assert(qiov->nalloc != -1);

    if (qiov->niov == qiov->nalloc) {

        qiov->nalloc = 2 * qiov->nalloc + 1;

        qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec));

    }

    qiov->iov[qiov->niov].iov_base = base;

    qiov->iov[qiov->niov].iov_len = len;

    qiov->size += len;

    ++qiov->niov;

}

/*

 * Concatenates (partial) iovecs from src_iov to the end of dst.

 * It starts copying after skipping `soffset' bytes at the

 * beginning of src and adds individual vectors from src to

 * dst copies up to `sbytes' bytes total, or up to the end

 * of src_iov if it comes first.  This way, it is okay to specify

 * very large value for `sbytes' to indicate "up to the end

 * of src".

 * Only vector pointers are processed, not the actual data buffers.

 */

void qemu_iovec_concat_iov(QEMUIOVector *dst,

                           struct iovec *src_iov, unsigned int src_cnt,

                           size_t soffset, size_t sbytes)

{

    int i;

    size_t done;

    if (!sbytes) {

        return;

    }

    assert(dst->nalloc != -1);

    for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {

        if (soffset < src_iov[i].iov_len) {

            size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done);

            qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len);

            done += len;

            soffset = 0;

        } else {

            soffset -= src_iov[i].iov_len;

        }

    }

    assert(soffset == 0); /* offset beyond end of src */

}

/*

 * Concatenates (partial) iovecs from src to the end of dst.

 * It starts copying after skipping `soffset' bytes at the

 * beginning of src and adds individual vectors from src to

 * dst copies up to `sbytes' bytes total, or up to the end

 * of src if it comes first.  This way, it is okay to specify

 * very large value for `sbytes' to indicate "up to the end

 * of src".

 * Only vector pointers are processed, not the actual data buffers.

 */

void qemu_iovec_concat(QEMUIOVector *dst,

                       QEMUIOVector *src, size_t soffset, size_t sbytes)

{

    qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);

}

void qemu_iovec_destroy(QEMUIOVector *qiov)

{

    assert(qiov->nalloc != -1);

    qemu_iovec_reset(qiov);

    g_free(qiov->iov);

    qiov->nalloc = 0;

    qiov->iov = NULL;

}

void qemu_iovec_reset(QEMUIOVector *qiov)

{

    assert(qiov->nalloc != -1);

    qiov->niov = 0;

    qiov->size = 0;

}

size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,

                         void *buf, size_t bytes)

{

    return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes);

}

size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,

                           const void *buf, size_t bytes)

{

    return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes);

}

size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,

                         int fillc, size_t bytes)

{

    return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);

}

size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt,

                         size_t bytes)

{

    size_t total = 0;

    struct iovec *cur;

    for (cur = *iov; *iov_cnt > 0; cur++) {

        if (cur->iov_len > bytes) {

            cur->iov_base += bytes;

            cur->iov_len -= bytes;

            total += bytes;

            break;

        }

        bytes -= cur->iov_len;

        total += cur->iov_len;

        *iov_cnt -= 1;

    }

    *iov = cur;

    return total;

}

size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,

                        size_t bytes)

{

    size_t total = 0;

    struct iovec *cur;

    if (*iov_cnt == 0) {

        return 0;

    }

    cur = iov + (*iov_cnt - 1);

    while (*iov_cnt > 0) {

        if (cur->iov_len > bytes) {

            cur->iov_len -= bytes;

            total += bytes;

            break;

        }

        bytes -= cur->iov_len;

        total += cur->iov_len;

        cur--;

        *iov_cnt -= 1;

    }

    return total;

}