source: trunk/server/source3/libsmb/clireadwrite.c

/*
   Unix SMB/CIFS implementation.
   client file read/write routines
   Copyright (C) Andrew Tridgell 1994-1998

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "libsmb/libsmb.h"
#include "../lib/util/tevent_ntstatus.h"
#include "async_smb.h"
#include "trans2.h"

/****************************************************************************
  Calculate the recommended read buffer size
****************************************************************************/
static size_t cli_read_max_bufsize(struct cli_state *cli)
{
        size_t data_offset = smb_size - 4;
        size_t wct = 12;

        size_t useable_space;

        if (!client_is_signing_on(cli) && !cli_encryption_on(cli)
            && (cli->server_posix_capabilities & CIFS_UNIX_LARGE_READ_CAP)) {
                return CLI_SAMBA_MAX_POSIX_LARGE_READX_SIZE;
        }
        if (cli->capabilities & CAP_LARGE_READX) {
                return cli->is_samba
                        ? CLI_SAMBA_MAX_LARGE_READX_SIZE
                        : CLI_WINDOWS_MAX_LARGE_READX_SIZE;
        }

        data_offset += wct * sizeof(uint16_t);
        data_offset += 1; /* pad */

        useable_space = cli->max_xmit - data_offset;

        return useable_space;
}

/****************************************************************************
  Calculate the recommended write buffer size
****************************************************************************/
static size_t cli_write_max_bufsize(struct cli_state *cli,
                                    uint16_t write_mode,
                                    uint8_t wct)
{
        if (write_mode == 0 &&
            !client_is_signing_on(cli) &&
            !cli_encryption_on(cli) &&
            (cli->server_posix_capabilities & CIFS_UNIX_LARGE_WRITE_CAP) &&
            (cli->capabilities & CAP_LARGE_FILES)) {
                /* Only do massive writes if we can do them direct
                 * with no signing or encrypting - not on a pipe. */
                return CLI_SAMBA_MAX_POSIX_LARGE_WRITEX_SIZE;
        }

        if (cli->is_samba) {
                return CLI_SAMBA_MAX_LARGE_WRITEX_SIZE;
        }

        if (((cli->capabilities & CAP_LARGE_WRITEX) == 0)
            || client_is_signing_on(cli)
            || strequal(cli->dev, "LPT1:")) {
                size_t data_offset = smb_size - 4;
                size_t useable_space;

                data_offset += wct * sizeof(uint16_t);
                data_offset += 1; /* pad */

                useable_space = cli->max_xmit - data_offset;

                return useable_space;
        }

        return CLI_WINDOWS_MAX_LARGE_WRITEX_SIZE;
}

struct cli_read_andx_state {
        size_t size;
        uint16_t vwv[12];
        NTSTATUS status;
        size_t received;
        uint8_t *buf;
};

static void cli_read_andx_done(struct tevent_req *subreq);

struct tevent_req *cli_read_andx_create(TALLOC_CTX *mem_ctx,
                                        struct event_context *ev,
                                        struct cli_state *cli, uint16_t fnum,
                                        off_t offset, size_t size,
                                        struct tevent_req **psmbreq)
{
        struct tevent_req *req, *subreq;
        struct cli_read_andx_state *state;
        uint8_t wct = 10;

        if (size > cli_read_max_bufsize(cli)) {
                DEBUG(0, ("cli_read_andx_send got size=%d, can only handle "
                          "size=%d\n", (int)size,
                          (int)cli_read_max_bufsize(cli)));
                return NULL;
        }

        req = tevent_req_create(mem_ctx, &state, struct cli_read_andx_state);
        if (req == NULL) {
                return NULL;
        }
        state->size = size;

        SCVAL(state->vwv + 0, 0, 0xFF);
        SCVAL(state->vwv + 0, 1, 0);
        SSVAL(state->vwv + 1, 0, 0);
        SSVAL(state->vwv + 2, 0, fnum);
        SIVAL(state->vwv + 3, 0, offset);
        SSVAL(state->vwv + 5, 0, size);
        SSVAL(state->vwv + 6, 0, size);
        SSVAL(state->vwv + 7, 0, (size >> 16));
        SSVAL(state->vwv + 8, 0, 0);
        SSVAL(state->vwv + 9, 0, 0);

        if (cli->capabilities & CAP_LARGE_FILES) {
                SIVAL(state->vwv + 10, 0,
                      (((uint64_t)offset)>>32) & 0xffffffff);
                wct = 12;
        } else {
                if ((((uint64_t)offset) & 0xffffffff00000000LL) != 0) {
                        DEBUG(10, ("cli_read_andx_send got large offset where "
                                   "the server does not support it\n"));
                        tevent_req_nterror(req, NT_STATUS_INVALID_PARAMETER);
                        return tevent_req_post(req, ev);
                }
        }

        subreq = cli_smb_req_create(state, ev, cli, SMBreadX, 0, wct,
                                    state->vwv, 0, NULL);
        if (subreq == NULL) {
                TALLOC_FREE(req);
                return NULL;
        }
        tevent_req_set_callback(subreq, cli_read_andx_done, req);
        *psmbreq = subreq;
        return req;
}

struct tevent_req *cli_read_andx_send(TALLOC_CTX *mem_ctx,
                                      struct event_context *ev,
                                      struct cli_state *cli, uint16_t fnum,
                                      off_t offset, size_t size)
{
        struct tevent_req *req, *subreq;
        NTSTATUS status;

        req = cli_read_andx_create(mem_ctx, ev, cli, fnum, offset, size,
                                   &subreq);
        if (req == NULL) {
                return NULL;
        }

        status = cli_smb_req_send(subreq);
        if (tevent_req_nterror(req, status)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void cli_read_andx_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_read_andx_state *state = tevent_req_data(
                req, struct cli_read_andx_state);
        uint8_t *inbuf;
        uint8_t wct;
        uint16_t *vwv;
        uint32_t num_bytes;
        uint8_t *bytes;

        state->status = cli_smb_recv(subreq, state, &inbuf, 12, &wct, &vwv,
                                     &num_bytes, &bytes);
        TALLOC_FREE(subreq);
        if (NT_STATUS_IS_ERR(state->status)) {
                tevent_req_nterror(req, state->status);
                return;
        }

        /* size is the number of bytes the server returned.
         * Might be zero. */
        state->received = SVAL(vwv + 5, 0);
        state->received |= (((unsigned int)SVAL(vwv + 7, 0)) << 16);

        if (state->received > state->size) {
                DEBUG(5,("server returned more than we wanted!\n"));
                tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
                return;
        }

        /*
         * bcc field must be valid for small reads, for large reads the 16-bit
         * bcc field can't be correct.
         */

        if ((state->received < 0xffff) && (state->received > num_bytes)) {
                DEBUG(5, ("server announced more bytes than sent\n"));
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        state->buf = (uint8_t *)smb_base(inbuf) + SVAL(vwv+6, 0);

        if (trans_oob(smb_len_large(inbuf), SVAL(vwv+6, 0), state->received)
            || ((state->received != 0) && (state->buf < bytes))) {
                DEBUG(5, ("server returned invalid read&x data offset\n"));
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }
        tevent_req_done(req);
}

/*
 * Pull the data out of a finished async read_and_x request. rcvbuf is
 * talloced from the request, so better make sure that you copy it away before
 * you talloc_free(req). "rcvbuf" is NOT a talloc_ctx of its own, so do not
 * talloc_move it!
 */

NTSTATUS cli_read_andx_recv(struct tevent_req *req, ssize_t *received,
                            uint8_t **rcvbuf)
{
        struct cli_read_andx_state *state = tevent_req_data(
                req, struct cli_read_andx_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        *received = state->received;
        *rcvbuf = state->buf;
        return NT_STATUS_OK;
}

struct cli_readall_state {
        struct tevent_context *ev;
        struct cli_state *cli;
        uint16_t fnum;
        off_t start_offset;
        size_t size;
        size_t received;
        uint8_t *buf;
};

static void cli_readall_done(struct tevent_req *subreq);

static struct tevent_req *cli_readall_send(TALLOC_CTX *mem_ctx,
                                           struct event_context *ev,
                                           struct cli_state *cli,
                                           uint16_t fnum,
                                           off_t offset, size_t size)
{
        struct tevent_req *req, *subreq;
        struct cli_readall_state *state;

        req = tevent_req_create(mem_ctx, &state, struct cli_readall_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->cli = cli;
        state->fnum = fnum;
        state->start_offset = offset;
        state->size = size;
        state->received = 0;
        state->buf = NULL;

        subreq = cli_read_andx_send(state, ev, cli, fnum, offset, size);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, cli_readall_done, req);
        return req;
}

static void cli_readall_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_readall_state *state = tevent_req_data(
                req, struct cli_readall_state);
        ssize_t received;
        uint8_t *buf;
        NTSTATUS status;

        status = cli_read_andx_recv(subreq, &received, &buf);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        if (received == 0) {
                /* EOF */
                tevent_req_done(req);
                return;
        }

        if ((state->received == 0) && (received == state->size)) {
                /* Ideal case: Got it all in one run */
                state->buf = buf;
                state->received += received;
                tevent_req_done(req);
                return;
        }

        /*
         * We got a short read, issue a read for the
         * rest. Unfortunately we have to allocate the buffer
         * ourselves now, as our caller expects to receive a single
         * buffer. cli_read_andx does it from the buffer received from
         * the net, but with a short read we have to put it together
         * from several reads.
         */

        if (state->buf == NULL) {
                state->buf = talloc_array(state, uint8_t, state->size);
                if (tevent_req_nomem(state->buf, req)) {
                        return;
                }
        }
        memcpy(state->buf + state->received, buf, received);
        state->received += received;

        TALLOC_FREE(subreq);

        if (state->received >= state->size) {
                tevent_req_done(req);
                return;
        }

        subreq = cli_read_andx_send(state, state->ev, state->cli, state->fnum,
                                    state->start_offset + state->received,
                                    state->size - state->received);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, cli_readall_done, req);
}

static NTSTATUS cli_readall_recv(struct tevent_req *req, ssize_t *received,
                                 uint8_t **rcvbuf)
{
        struct cli_readall_state *state = tevent_req_data(
                req, struct cli_readall_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        *received = state->received;
        *rcvbuf = state->buf;
        return NT_STATUS_OK;
}

struct cli_pull_subreq {
        struct tevent_req *req;
        ssize_t received;
        uint8_t *buf;
};

/*
 * Parallel read support.
 *
 * cli_pull sends as many read&x requests as the server would allow via
 * max_mux at a time. When replies flow back in, the data is written into
 * the callback function "sink" in the right order.
 */

struct cli_pull_state {
        struct tevent_req *req;

        struct event_context *ev;
        struct cli_state *cli;
        uint16_t fnum;
        off_t start_offset;
        SMB_OFF_T size;

        NTSTATUS (*sink)(char *buf, size_t n, void *priv);
        void *priv;

        size_t chunk_size;

        /*
         * Outstanding requests
         */
        int num_reqs;
        struct cli_pull_subreq *reqs;

        /*
         * For how many bytes did we send requests already?
         */
        SMB_OFF_T requested;

        /*
         * Next request index to push into "sink". This walks around the "req"
         * array, taking care that the requests are pushed to "sink" in the
         * right order. If necessary (i.e. replies don't come in in the right
         * order), replies are held back in "reqs".
         */
        int top_req;

        /*
         * How many bytes did we push into "sink"?
         */

        SMB_OFF_T pushed;
};

static char *cli_pull_print(struct tevent_req *req, TALLOC_CTX *mem_ctx)
{
        struct cli_pull_state *state = tevent_req_data(
                req, struct cli_pull_state);
        char *result;

        result = tevent_req_default_print(req, mem_ctx);
        if (result == NULL) {
                return NULL;
        }

        return talloc_asprintf_append_buffer(
                result, "num_reqs=%d, top_req=%d",
                state->num_reqs, state->top_req);
}

static void cli_pull_read_done(struct tevent_req *read_req);

/*
 * Prepare an async pull request
 */

struct tevent_req *cli_pull_send(TALLOC_CTX *mem_ctx,
                                 struct event_context *ev,
                                 struct cli_state *cli,
                                 uint16_t fnum, off_t start_offset,
                                 SMB_OFF_T size, size_t window_size,
                                 NTSTATUS (*sink)(char *buf, size_t n,
                                                  void *priv),
                                 void *priv)
{
        struct tevent_req *req;
        struct cli_pull_state *state;
        int i;

        req = tevent_req_create(mem_ctx, &state, struct cli_pull_state);
        if (req == NULL) {
                return NULL;
        }
        tevent_req_set_print_fn(req, cli_pull_print);
        state->req = req;

        state->cli = cli;
        state->ev = ev;
        state->fnum = fnum;
        state->start_offset = start_offset;
        state->size = size;
        state->sink = sink;
        state->priv = priv;

        state->pushed = 0;
        state->top_req = 0;

        if (size == 0) {
                tevent_req_done(req);
                return tevent_req_post(req, ev);
        }

        state->chunk_size = cli_read_max_bufsize(cli);

        state->num_reqs = MAX(window_size/state->chunk_size, 1);
        state->num_reqs = MIN(state->num_reqs, cli->max_mux);

        state->reqs = TALLOC_ZERO_ARRAY(state, struct cli_pull_subreq,
                                        state->num_reqs);
        if (state->reqs == NULL) {
                goto failed;
        }

        state->requested = 0;

        for (i=0; i<state->num_reqs; i++) {
                struct cli_pull_subreq *subreq = &state->reqs[i];
                SMB_OFF_T size_left;
                size_t request_thistime;

                if (state->requested >= size) {
                        state->num_reqs = i;
                        break;
                }

                size_left = size - state->requested;
                request_thistime = MIN(size_left, state->chunk_size);

                subreq->req = cli_readall_send(
                        state->reqs, ev, cli, fnum,
                        state->start_offset + state->requested,
                        request_thistime);

                if (subreq->req == NULL) {
                        goto failed;
                }
                tevent_req_set_callback(subreq->req, cli_pull_read_done, req);
                state->requested += request_thistime;
        }
        return req;

failed:
        TALLOC_FREE(req);
        return NULL;
}

/*
 * Handle incoming read replies, push the data into sink and send out new
 * requests if necessary.
 */

static void cli_pull_read_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_pull_state *state = tevent_req_data(
                req, struct cli_pull_state);
        struct cli_pull_subreq *pull_subreq = NULL;
        NTSTATUS status;
        int i;

        for (i = 0; i < state->num_reqs; i++) {
                pull_subreq = &state->reqs[i];
                if (subreq == pull_subreq->req) {
                        break;
                }
        }
        if (i == state->num_reqs) {
                /* Huh -- received something we did not send?? */
                tevent_req_nterror(req, NT_STATUS_INTERNAL_ERROR);
                return;
        }

        status = cli_readall_recv(subreq, &pull_subreq->received,
                                  &pull_subreq->buf);
        if (!NT_STATUS_IS_OK(status)) {
                tevent_req_nterror(state->req, status);
                return;
        }

        /*
         * This loop is the one to take care of out-of-order replies. All
         * pending requests are in state->reqs, state->reqs[top_req] is the
         * one that is to be pushed next. If however a request later than
         * top_req is replied to, then we can't push yet. If top_req is
         * replied to at a later point then, we need to push all the finished
         * requests.
         */

        while (state->reqs[state->top_req].req != NULL) {
                struct cli_pull_subreq *top_subreq;

                DEBUG(11, ("cli_pull_read_done: top_req = %d\n",
                           state->top_req));

                top_subreq = &state->reqs[state->top_req];

                if (tevent_req_is_in_progress(top_subreq->req)) {
                        DEBUG(11, ("cli_pull_read_done: top request not yet "
                                   "done\n"));
                        return;
                }

                DEBUG(10, ("cli_pull_read_done: Pushing %d bytes, %d already "
                           "pushed\n", (int)top_subreq->received,
                           (int)state->pushed));

                status = state->sink((char *)top_subreq->buf,
                                     top_subreq->received, state->priv);
                if (tevent_req_nterror(state->req, status)) {
                        return;
                }
                state->pushed += top_subreq->received;

                TALLOC_FREE(state->reqs[state->top_req].req);

                if (state->requested < state->size) {
                        struct tevent_req *new_req;
                        SMB_OFF_T size_left;
                        size_t request_thistime;

                        size_left = state->size - state->requested;
                        request_thistime = MIN(size_left, state->chunk_size);

                        DEBUG(10, ("cli_pull_read_done: Requesting %d bytes "
                                   "at %d, position %d\n",
                                   (int)request_thistime,
                                   (int)(state->start_offset
                                         + state->requested),
                                   state->top_req));

                        new_req = cli_readall_send(
                                state->reqs, state->ev, state->cli,
                                state->fnum,
                                state->start_offset + state->requested,
                                request_thistime);

                        if (tevent_req_nomem(new_req, state->req)) {
                                return;
                        }
                        tevent_req_set_callback(new_req, cli_pull_read_done,
                                                req);

                        state->reqs[state->top_req].req = new_req;
                        state->requested += request_thistime;
                }

                state->top_req = (state->top_req+1) % state->num_reqs;
        }

        tevent_req_done(req);
}

NTSTATUS cli_pull_recv(struct tevent_req *req, SMB_OFF_T *received)
{
        struct cli_pull_state *state = tevent_req_data(
                req, struct cli_pull_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        *received = state->pushed;
        return NT_STATUS_OK;
}

NTSTATUS cli_pull(struct cli_state *cli, uint16_t fnum,
                  off_t start_offset, SMB_OFF_T size, size_t window_size,
                  NTSTATUS (*sink)(char *buf, size_t n, void *priv),
                  void *priv, SMB_OFF_T *received)
{
        TALLOC_CTX *frame = talloc_stackframe();
        struct event_context *ev;
        struct tevent_req *req;
        NTSTATUS status = NT_STATUS_OK;

        if (cli_has_async_calls(cli)) {
                /*
                 * Can't use sync call while an async call is in flight
                 */
                status = NT_STATUS_INVALID_PARAMETER;
                goto fail;
        }

        ev = event_context_init(frame);
        if (ev == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }

        req = cli_pull_send(frame, ev, cli, fnum, start_offset, size,
                            window_size, sink, priv);
        if (req == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }

        if (!tevent_req_poll(req, ev)) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }

        status = cli_pull_recv(req, received);
 fail:
        TALLOC_FREE(frame);
        return status;
}

static NTSTATUS cli_read_sink(char *buf, size_t n, void *priv)
{
        char **pbuf = (char **)priv;
        memcpy(*pbuf, buf, n);
        *pbuf += n;
        return NT_STATUS_OK;
}

ssize_t cli_read(struct cli_state *cli, uint16_t fnum, char *buf,
                 off_t offset, size_t size)
{
        NTSTATUS status;
        SMB_OFF_T ret;

        status = cli_pull(cli, fnum, offset, size, size,
                          cli_read_sink, &buf, &ret);
        if (!NT_STATUS_IS_OK(status)) {
                return -1;
        }
        return ret;
}

/****************************************************************************
  write to a file using a SMBwrite and not bypassing 0 byte writes
****************************************************************************/

NTSTATUS cli_smbwrite(struct cli_state *cli, uint16_t fnum, char *buf,
                      off_t offset, size_t size1, size_t *ptotal)
{
        uint8_t *bytes;
        ssize_t total = 0;

        /*
         * 3 bytes prefix
         */

        bytes = TALLOC_ARRAY(talloc_tos(), uint8_t, 3);
        if (bytes == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        bytes[0] = 1;

        do {
                size_t size = MIN(size1, cli->max_xmit - 48);
                struct tevent_req *req;
                uint16_t vwv[5];
                uint16_t *ret_vwv;
                NTSTATUS status;

                SSVAL(vwv+0, 0, fnum);
                SSVAL(vwv+1, 0, size);
                SIVAL(vwv+2, 0, offset);
                SSVAL(vwv+4, 0, 0);

                bytes = TALLOC_REALLOC_ARRAY(talloc_tos(), bytes, uint8_t,
                                             size+3);
                if (bytes == NULL) {
                        return NT_STATUS_NO_MEMORY;
                }
                SSVAL(bytes, 1, size);
                memcpy(bytes + 3, buf + total, size);

                status = cli_smb(talloc_tos(), cli, SMBwrite, 0, 5, vwv,
                                 size+3, bytes, &req, 1, NULL, &ret_vwv,
                                 NULL, NULL);
                if (!NT_STATUS_IS_OK(status)) {
                        TALLOC_FREE(bytes);
                        return status;
                }

                size = SVAL(ret_vwv+0, 0);
                TALLOC_FREE(req);
                if (size == 0) {
                        break;
                }
                size1 -= size;
                total += size;
                offset += size;

        } while (size1);

        TALLOC_FREE(bytes);

        if (ptotal != NULL) {
                *ptotal = total;
        }
        return NT_STATUS_OK;
}

/*
 * Send a write&x request
 */

struct cli_write_andx_state {
        size_t size;
        uint16_t vwv[14];
        size_t written;
        uint8_t pad;
        struct iovec iov[2];
};

static void cli_write_andx_done(struct tevent_req *subreq);

struct tevent_req *cli_write_andx_create(TALLOC_CTX *mem_ctx,
                                         struct event_context *ev,
                                         struct cli_state *cli, uint16_t fnum,
                                         uint16_t mode, const uint8_t *buf,
                                         off_t offset, size_t size,
                                         struct tevent_req **reqs_before,
                                         int num_reqs_before,
                                         struct tevent_req **psmbreq)
{
        struct tevent_req *req, *subreq;
        struct cli_write_andx_state *state;
        bool bigoffset = ((cli->capabilities & CAP_LARGE_FILES) != 0);
        uint8_t wct = bigoffset ? 14 : 12;
        size_t max_write = cli_write_max_bufsize(cli, mode, wct);
        uint16_t *vwv;

        req = tevent_req_create(mem_ctx, &state, struct cli_write_andx_state);
        if (req == NULL) {
                return NULL;
        }

        state->size = MIN(size, max_write);

        vwv = state->vwv;

        SCVAL(vwv+0, 0, 0xFF);
        SCVAL(vwv+0, 1, 0);
        SSVAL(vwv+1, 0, 0);
        SSVAL(vwv+2, 0, fnum);
        SIVAL(vwv+3, 0, offset);
        SIVAL(vwv+5, 0, 0);
        SSVAL(vwv+7, 0, mode);
        SSVAL(vwv+8, 0, 0);
        SSVAL(vwv+9, 0, (state->size>>16));
        SSVAL(vwv+10, 0, state->size);

        SSVAL(vwv+11, 0,
              cli_smb_wct_ofs(reqs_before, num_reqs_before)
              + 1               /* the wct field */
              + wct * 2         /* vwv */
              + 2               /* num_bytes field */
              + 1               /* pad */);

        if (bigoffset) {
                SIVAL(vwv+12, 0, (((uint64_t)offset)>>32) & 0xffffffff);
        }

        state->pad = 0;
        state->iov[0].iov_base = (void *)&state->pad;
        state->iov[0].iov_len = 1;
        state->iov[1].iov_base = CONST_DISCARD(void *, buf);
        state->iov[1].iov_len = state->size;

        subreq = cli_smb_req_create(state, ev, cli, SMBwriteX, 0, wct, vwv,
                                    2, state->iov);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, cli_write_andx_done, req);
        *psmbreq = subreq;
        return req;
}

struct tevent_req *cli_write_andx_send(TALLOC_CTX *mem_ctx,
                                       struct event_context *ev,
                                       struct cli_state *cli, uint16_t fnum,
                                       uint16_t mode, const uint8_t *buf,
                                       off_t offset, size_t size)
{
        struct tevent_req *req, *subreq;
        NTSTATUS status;

        req = cli_write_andx_create(mem_ctx, ev, cli, fnum, mode, buf, offset,
                                    size, NULL, 0, &subreq);
        if (req == NULL) {
                return NULL;
        }

        status = cli_smb_req_send(subreq);
        if (tevent_req_nterror(req, status)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void cli_write_andx_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_write_andx_state *state = tevent_req_data(
                req, struct cli_write_andx_state);
        uint8_t wct;
        uint16_t *vwv;
        uint8_t *inbuf;
        NTSTATUS status;

        status = cli_smb_recv(subreq, state, &inbuf, 6, &wct, &vwv,
                              NULL, NULL);
        TALLOC_FREE(subreq);
        if (NT_STATUS_IS_ERR(status)) {
                tevent_req_nterror(req, status);
                return;
        }
        state->written = SVAL(vwv+2, 0);
        if (state->size > UINT16_MAX) {
                /*
                 * It is important that we only set the
                 * high bits only if we asked for a large write.
                 *
                 * OS/2 print shares get this wrong and may send
                 * invalid values.
                 *
                 * See bug #5326.
                 */
                state->written |= SVAL(vwv+4, 0)<<16;
        }
        tevent_req_done(req);
}

NTSTATUS cli_write_andx_recv(struct tevent_req *req, size_t *pwritten)
{
        struct cli_write_andx_state *state = tevent_req_data(
                req, struct cli_write_andx_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        *pwritten = state->written;
        return NT_STATUS_OK;
}

struct cli_writeall_state {
        struct event_context *ev;
        struct cli_state *cli;
        uint16_t fnum;
        uint16_t mode;
        const uint8_t *buf;
        off_t offset;
        size_t size;
        size_t written;
};

static void cli_writeall_written(struct tevent_req *req);

static struct tevent_req *cli_writeall_send(TALLOC_CTX *mem_ctx,
                                            struct event_context *ev,
                                            struct cli_state *cli,
                                            uint16_t fnum,
                                            uint16_t mode,
                                            const uint8_t *buf,
                                            off_t offset, size_t size)
{
        struct tevent_req *req, *subreq;
        struct cli_writeall_state *state;

        req = tevent_req_create(mem_ctx, &state, struct cli_writeall_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->cli = cli;
        state->fnum = fnum;
        state->mode = mode;
        state->buf = buf;
        state->offset = offset;
        state->size = size;
        state->written = 0;

        subreq = cli_write_andx_send(state, state->ev, state->cli, state->fnum,
                                     state->mode, state->buf, state->offset,
                                     state->size);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, cli_writeall_written, req);
        return req;
}

static void cli_writeall_written(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_writeall_state *state = tevent_req_data(
                req, struct cli_writeall_state);
        NTSTATUS status;
        size_t written, to_write;

        status = cli_write_andx_recv(subreq, &written);
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        state->written += written;

        if (state->written > state->size) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        to_write = state->size - state->written;

        if (to_write == 0) {
                tevent_req_done(req);
                return;
        }

        subreq = cli_write_andx_send(state, state->ev, state->cli, state->fnum,
                                     state->mode,
                                     state->buf + state->written,
                                     state->offset + state->written, to_write);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, cli_writeall_written, req);
}

static NTSTATUS cli_writeall_recv(struct tevent_req *req,
                                  size_t *pwritten)
{
        struct cli_writeall_state *state = tevent_req_data(
                req, struct cli_writeall_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        if (pwritten != NULL) {
                *pwritten = state->written;
        }
        return NT_STATUS_OK;
}

NTSTATUS cli_writeall(struct cli_state *cli, uint16_t fnum, uint16_t mode,
                      const uint8_t *buf, off_t offset, size_t size,
                      size_t *pwritten)
{
        TALLOC_CTX *frame = talloc_stackframe();
        struct event_context *ev;
        struct tevent_req *req;
        NTSTATUS status = NT_STATUS_NO_MEMORY;

        if (cli_has_async_calls(cli)) {
                /*
                 * Can't use sync call while an async call is in flight
                 */
                status = NT_STATUS_INVALID_PARAMETER;
                goto fail;
        }
        ev = event_context_init(frame);
        if (ev == NULL) {
                goto fail;
        }
        req = cli_writeall_send(frame, ev, cli, fnum, mode, buf, offset, size);
        if (req == NULL) {
                goto fail;
        }
        if (!tevent_req_poll(req, ev)) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }
        status = cli_writeall_recv(req, pwritten);
 fail:
        TALLOC_FREE(frame);
        return status;
}

struct cli_push_write_state {
        struct tevent_req *req;/* This is the main request! Not the subreq */
        uint32_t idx;
        off_t ofs;
        uint8_t *buf;
        size_t size;
};

struct cli_push_state {
        struct event_context *ev;
        struct cli_state *cli;
        uint16_t fnum;
        uint16_t mode;
        off_t start_offset;
        size_t window_size;

        size_t (*source)(uint8_t *buf, size_t n, void *priv);
        void *priv;

        bool eof;

        size_t chunk_size;
        off_t next_offset;

        /*
         * Outstanding requests
         */
        uint32_t pending;
        uint32_t num_reqs;
        struct cli_push_write_state **reqs;
};

static void cli_push_written(struct tevent_req *req);

static bool cli_push_write_setup(struct tevent_req *req,
                                 struct cli_push_state *state,
                                 uint32_t idx)
{
        struct cli_push_write_state *substate;
        struct tevent_req *subreq;

        substate = talloc(state->reqs, struct cli_push_write_state);
        if (!substate) {
                return false;
        }
        substate->req = req;
        substate->idx = idx;
        substate->ofs = state->next_offset;
        substate->buf = talloc_array(substate, uint8_t, state->chunk_size);
        if (!substate->buf) {
                talloc_free(substate);
                return false;
        }
        substate->size = state->source(substate->buf,
                                       state->chunk_size,
                                       state->priv);
        if (substate->size == 0) {
                state->eof = true;
                /* nothing to send */
                talloc_free(substate);
                return true;
        }

        subreq = cli_writeall_send(substate,
                                   state->ev, state->cli,
                                   state->fnum, state->mode,
                                   substate->buf,
                                   substate->ofs,
                                   substate->size);
        if (!subreq) {
                talloc_free(substate);
                return false;
        }
        tevent_req_set_callback(subreq, cli_push_written, substate);

        state->reqs[idx] = substate;
        state->pending += 1;
        state->next_offset += substate->size;

        return true;
}

struct tevent_req *cli_push_send(TALLOC_CTX *mem_ctx, struct event_context *ev,
                                 struct cli_state *cli,
                                 uint16_t fnum, uint16_t mode,
                                 off_t start_offset, size_t window_size,
                                 size_t (*source)(uint8_t *buf, size_t n,
                                                  void *priv),
                                 void *priv)
{
        struct tevent_req *req;
        struct cli_push_state *state;
        uint32_t i;

        req = tevent_req_create(mem_ctx, &state, struct cli_push_state);
        if (req == NULL) {
                return NULL;
        }
        state->cli = cli;
        state->ev = ev;
        state->fnum = fnum;
        state->start_offset = start_offset;
        state->mode = mode;
        state->source = source;
        state->priv = priv;
        state->eof = false;
        state->pending = 0;
        state->next_offset = start_offset;

        state->chunk_size = cli_write_max_bufsize(cli, mode, 14);

        if (window_size == 0) {
                window_size = cli->max_mux * state->chunk_size;
        }
        state->num_reqs = window_size/state->chunk_size;
        if ((window_size % state->chunk_size) > 0) {
                state->num_reqs += 1;
        }
        state->num_reqs = MIN(state->num_reqs, cli->max_mux);
        state->num_reqs = MAX(state->num_reqs, 1);

        state->reqs = TALLOC_ZERO_ARRAY(state, struct cli_push_write_state *,
                                        state->num_reqs);
        if (state->reqs == NULL) {
                goto failed;
        }

        for (i=0; i<state->num_reqs; i++) {
                if (!cli_push_write_setup(req, state, i)) {
                        goto failed;
                }

                if (state->eof) {
                        break;
                }
        }

        if (state->pending == 0) {
                tevent_req_done(req);
                return tevent_req_post(req, ev);
        }

        return req;

 failed:
        tevent_req_nterror(req, NT_STATUS_NO_MEMORY);
        return tevent_req_post(req, ev);
}

static void cli_push_written(struct tevent_req *subreq)
{
        struct cli_push_write_state *substate = tevent_req_callback_data(
                subreq, struct cli_push_write_state);
        struct tevent_req *req = substate->req;
        struct cli_push_state *state = tevent_req_data(
                req, struct cli_push_state);
        NTSTATUS status;
        uint32_t idx = substate->idx;

        state->reqs[idx] = NULL;
        state->pending -= 1;

        status = cli_writeall_recv(subreq, NULL);
        TALLOC_FREE(subreq);
        TALLOC_FREE(substate);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        if (!state->eof) {
                if (!cli_push_write_setup(req, state, idx)) {
                        tevent_req_nterror(req, NT_STATUS_NO_MEMORY);
                        return;
                }
        }

        if (state->pending == 0) {
                tevent_req_done(req);
                return;
        }
}

NTSTATUS cli_push_recv(struct tevent_req *req)
{
        return tevent_req_simple_recv_ntstatus(req);
}

NTSTATUS cli_push(struct cli_state *cli, uint16_t fnum, uint16_t mode,
                  off_t start_offset, size_t window_size,
                  size_t (*source)(uint8_t *buf, size_t n, void *priv),
                  void *priv)
{
        TALLOC_CTX *frame = talloc_stackframe();
        struct event_context *ev;
        struct tevent_req *req;
        NTSTATUS status = NT_STATUS_OK;

        if (cli_has_async_calls(cli)) {
                /*
                 * Can't use sync call while an async call is in flight
                 */
                status = NT_STATUS_INVALID_PARAMETER;
                goto fail;
        }

        ev = event_context_init(frame);
        if (ev == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }

        req = cli_push_send(frame, ev, cli, fnum, mode, start_offset,
                            window_size, source, priv);
        if (req == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto fail;
        }

        if (!tevent_req_poll(req, ev)) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }

        status = cli_push_recv(req);
 fail:
        TALLOC_FREE(frame);
        return status;
}