source: vendor/3.6.23/source3/lib/util_tsock.c

/*
   Unix SMB/CIFS implementation.
   Utilities around tsocket
   Copyright (C) Volker Lendecke 2009

   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 "../lib/tsocket/tsocket.h"
#include "../lib/util/tevent_unix.h"

struct tstream_read_packet_state {
        struct tevent_context *ev;
        struct tstream_context *stream;
        ssize_t (*more)(uint8_t *buf, size_t buflen, void *private_data);
        void *private_data;
        uint8_t *buf;
        struct iovec iov;
};

static void tstream_read_packet_done(struct tevent_req *subreq);

struct tevent_req *tstream_read_packet_send(TALLOC_CTX *mem_ctx,
                                            struct tevent_context *ev,
                                            struct tstream_context *stream,
                                            size_t initial,
                                            ssize_t (*more)(uint8_t *buf,
                                                            size_t buflen,
                                                            void *private_data),
                                            void *private_data)
{
        struct tevent_req *req, *subreq;
        struct tstream_read_packet_state *state;

        req = tevent_req_create(mem_ctx, &state,
                                struct tstream_read_packet_state);
        if (req == NULL) {
                return NULL;
        }
        state->buf = talloc_array(state, uint8_t, initial);
        if (tevent_req_nomem(state->buf, req)) {
                return tevent_req_post(req, ev);
        }
        state->iov.iov_base = (void *)state->buf;
        state->iov.iov_len = initial;

        state->ev = ev;
        state->stream = stream;
        state->more = more;
        state->private_data = private_data;

        subreq = tstream_readv_send(state, ev, stream, &state->iov, 1);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, tstream_read_packet_done, req);

        return req;
}

static void tstream_read_packet_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct tstream_read_packet_state *state = tevent_req_data(
                req, struct tstream_read_packet_state);
        int ret, err;
        size_t total;
        ssize_t more;
        uint8_t *tmp;

        ret = tstream_readv_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (ret == 0) {
                err = EPIPE;
        }
        if (ret <= 0) {
                tevent_req_error(req, err);
                return;
        }

        if (state->more == NULL) {
                /* Nobody to ask, this is a async read_data */
                tevent_req_done(req);
                return;
        }
        total = talloc_array_length(state->buf);

        more = state->more(state->buf, total, state->private_data);
        if (more == -1) {
                /* We got an invalid packet, tell the caller */
                tevent_req_error(req, EIO);
                return;
        }
        if (more == 0) {
                /* We're done, full packet received */
                tevent_req_done(req);
                return;
        }

        if (total + more < total) {
                tevent_req_error(req, EMSGSIZE);
                return;
        }

        tmp = talloc_realloc(state, state->buf, uint8_t, total+more);
        if (tevent_req_nomem(tmp, req)) {
                return;
        }
        state->buf = tmp;

        state->iov.iov_base = (void *)(state->buf + total);
        state->iov.iov_len = more;

        subreq = tstream_readv_send(state, state->ev, state->stream,
                                    &state->iov, 1);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, tstream_read_packet_done, req);
}

ssize_t tstream_read_packet_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                                 uint8_t **pbuf, int *perrno)
{
        struct tstream_read_packet_state *state =
                tevent_req_data(req, struct tstream_read_packet_state);

        if (tevent_req_is_unix_error(req, perrno)) {
                return -1;
        }
        *pbuf = talloc_move(mem_ctx, &state->buf);
        return talloc_array_length(*pbuf);
}