src/lib/ostream-unix.c

/* Copyright (c) 2015-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "fdpass.h"
#include "ostream-file-private.h"
#include "ostream-unix.h"

struct unix_ostream {
    struct file_ostream fstream;
    int write_fd;
};

static void
o_stream_unix_close(struct iostream_private *stream, bool close_parent)
{
    struct unix_ostream *ustream = (struct unix_ostream *)stream;

    i_close_fd(&ustream->write_fd);
    o_stream_file_close(stream, close_parent);
}

static ssize_t o_stream_unix_writev(struct file_ostream *fstream,
                   const struct const_iovec *iov,
                   unsigned int iov_count)
{
    struct unix_ostream *ustream = (struct unix_ostream *)fstream;
    size_t sent;
    ssize_t ret;

    if (ustream->write_fd == -1) {
        /* no fd */
        return o_stream_file_writev(fstream, iov, iov_count);
    }

    /* send first iovec along with fd */
    if (iov_count == 0)
        return 0;
    i_assert(iov[0].iov_len > 0);
    ret = fd_send(fstream->fd, ustream->write_fd,
        iov[0].iov_base, iov[0].iov_len);
    if (ret < 0)
        return ret;

    /* update stream */
    sent = ret;
    fstream->real_offset += sent;

    ustream->write_fd = -1;

    if (sent < iov[0].iov_len || iov_count == 1) {
        /* caller will call us again to write the rest */
        return sent;
    }

    /* send remaining iovecs */
    ret = o_stream_file_writev(fstream, &iov[1], iov_count-1);
    if (ret < 0)
        return  (errno == EAGAIN || errno == EINTR ? (ssize_t)sent : ret);
    sent += ret;
    return sent;
}

struct ostream *o_stream_create_unix(int fd, size_t max_buffer_size)
{
    struct unix_ostream *ustream;
    struct ostream *output;

    i_assert(fd != -1);

    ustream = i_new(struct unix_ostream, 1);
    ustream->write_fd = -1;
    output = o_stream_create_file_common(&ustream->fstream, fd,
                        max_buffer_size, FALSE);
    output->real_stream->iostream.close = o_stream_unix_close;
    ustream->fstream.writev = o_stream_unix_writev;

    return output;
}

bool o_stream_unix_write_fd(struct ostream *output, int fd)
{
    struct unix_ostream *ustream =
        (struct unix_ostream *)output->real_stream;

    i_assert(fd >= 0);

    if (ustream->write_fd >= 0)
        return FALSE;
    ustream->write_fd = fd;
    return TRUE;
}