src/lib/istream-unix.c

/* Copyright (c) 2014-2018 Dovecot authors, see the included COPYING file */

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

struct unix_istream {
    struct file_istream fstream;
    bool next_read_fd;
    int read_fd;
};

static void
i_stream_unix_close(struct iostream_private *stream, bool close_parent)
{
    struct unix_istream *ustream = (struct unix_istream *)stream;

    i_close_fd(&ustream->read_fd);
    i_stream_file_close(stream, close_parent);
}

static ssize_t i_stream_unix_read(struct istream_private *stream)
{
    struct unix_istream *ustream = (struct unix_istream *)stream;
    size_t size;
    ssize_t ret;

    if (!ustream->next_read_fd)
        return i_stream_file_read(stream);

    i_assert(ustream->read_fd == -1);
    i_assert(ustream->fstream.skip_left == 0); /* not supported here.. */
    if (!i_stream_try_alloc(stream, 1, &size))
        return -2;

    ret = fd_read(stream->fd, stream->w_buffer + stream->pos, size,
              &ustream->read_fd);
    if (ustream->read_fd != -1)
        ustream->next_read_fd = FALSE;

    if (ret == 0) {
        /* EOF */
        stream->istream.eof = TRUE;
        ustream->fstream.seen_eof = TRUE;
        return -1;
    }

    if (unlikely(ret < 0)) {
        if ((errno == EINTR || errno == EAGAIN) &&
            !stream->istream.blocking) {
            return 0;
        } else {
            i_assert(errno != 0);
            /* if we get EBADF for a valid fd, it means something's
               really wrong and we'd better just crash. */
            i_assert(errno != EBADF);
            stream->istream.stream_errno = errno;
            return -1;
        }
    }
    stream->pos += ret;
    return ret;
}

struct istream *i_stream_create_unix(int fd, size_t max_buffer_size)
{
    struct unix_istream *ustream;
    struct istream *input;

    i_assert(fd != -1);

    ustream = i_new(struct unix_istream, 1);
    ustream->read_fd = -1;
    input = i_stream_create_file_common(&ustream->fstream, fd, NULL,
                        max_buffer_size, FALSE);
    input->real_stream->iostream.close = i_stream_unix_close;
    input->real_stream->read = i_stream_unix_read;
    return input;
}

void i_stream_unix_set_read_fd(struct istream *input)
{
    struct unix_istream *ustream =
        (struct unix_istream *)input->real_stream;

    ustream->next_read_fd = TRUE;
}

void i_stream_unix_unset_read_fd(struct istream *input)
{
    struct unix_istream *ustream =
        (struct unix_istream *)input->real_stream;

    ustream->next_read_fd = FALSE;
}

int i_stream_unix_get_read_fd(struct istream *input)
{
    struct unix_istream *ustream =
        (struct unix_istream *)input->real_stream;
    int fd;

    fd = ustream->read_fd;
    ustream->read_fd = -1;
    return fd;
}