src/lib/istream-crlf.c

	istream-crlf.c revision b52ab39e0900187a1b0d675922a8c91766373fb7
/* Copyright (c) 2007-2008 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "istream-internal.h"
#include "istream-crlf.h"

struct crlf_istream {
    struct istream_private istream;

    unsigned int pending_cr:1;
    unsigned int last_cr:1;
};

static void i_stream_crlf_destroy(struct iostream_private *stream)
{
    struct crlf_istream *cstream = (struct crlf_istream *)stream;

    i_free(cstream->istream.w_buffer);
    i_stream_unref(&cstream->istream.parent);
}

static void
i_stream_crlf_set_max_buffer_size(struct iostream_private *stream,
                   size_t max_size)
{
    struct crlf_istream *cstream = (struct crlf_istream *)stream;

    cstream->istream.max_buffer_size = max_size;
    i_stream_set_max_buffer_size(cstream->istream.parent, max_size);
}

static int i_stream_crlf_read_common(struct crlf_istream *cstream)
{
    struct istream_private *stream = &cstream->istream;
    const unsigned char *data;
    size_t size;
    ssize_t ret;

    data = i_stream_get_data(stream->parent, &size);
    if (size == 0) {
        ret = i_stream_read(stream->parent);
        if (ret <= 0 && (ret != -2 || stream->skip == 0)) {
            stream->istream.stream_errno =
                stream->parent->stream_errno;
            stream->istream.eof = stream->parent->eof;
            return ret;
        }
        data = i_stream_get_data(stream->parent, &size);
        i_assert(size != 0);
    }

    if (!i_stream_get_buffer_space(stream, size, NULL))
        return -2;
    return 1;
}

static ssize_t i_stream_crlf_read_crlf(struct istream_private *stream)
{
    struct crlf_istream *cstream = (struct crlf_istream *)stream;
    const unsigned char *data;
    size_t i, dest, size;
    ssize_t ret;

    ret = i_stream_crlf_read_common(cstream);
    if (ret <= 0)
        return ret;

    data = i_stream_get_data(stream->parent, &size);

    /* @UNSAFE: add missing CRs */
    dest = stream->pos;
    for (i = 0; i < size && dest < stream->buffer_size; i++) {
        if (data[i] == '\n') {
            if (i == 0) {
                if (!cstream->last_cr)
                    stream->w_buffer[dest++] = '\r';
            } else {
                if (data[i-1] != '\r')
                    stream->w_buffer[dest++] = '\r';
            }
            if (dest == stream->buffer_size)
                break;
        }
        stream->w_buffer[dest++] = data[i];
    }
    cstream->last_cr = stream->w_buffer[dest-1] == '\r';
    i_stream_skip(stream->parent, i);

    ret = dest - stream->pos;
    i_assert(ret != 0);
    stream->pos = dest;
    return ret;
}

static ssize_t i_stream_crlf_read_lf(struct istream_private *stream)
{
    struct crlf_istream *cstream = (struct crlf_istream *)stream;
    const unsigned char *data;
    size_t i, dest, size;
    ssize_t ret;
    int diff;

    ret = i_stream_crlf_read_common(cstream);
    if (ret <= 0)
        return ret;

    data = i_stream_get_data(stream->parent, &size);

    /* @UNSAFE */
    dest = stream->pos;
    if (data[0] == '\n') {
        stream->w_buffer[dest++] = '\n';
        cstream->pending_cr = FALSE;
    } else {
        if (cstream->pending_cr) {
            /* CR without LF */
            stream->w_buffer[dest++] = '\r';
            if (dest == stream->buffer_size) {
                cstream->pending_cr = FALSE;
                return 1;
            }
        }
        if (data[0] != '\r')
            stream->w_buffer[dest++] = data[0];
    }

    diff = -1;
    for (i = 1; i < size && dest < stream->buffer_size; i++) {
        if (data[i] == '\r') {
            if (data[i-1] != '\r')
                continue;
        } else if (data[i-1] == '\r' && data[i] != '\n') {
            stream->w_buffer[dest++] = '\r';
            if (dest == stream->buffer_size) {
                diff = 0;
                break;
            }
        }

        stream->w_buffer[dest++] = data[i];
    }
    cstream->pending_cr = data[i+diff] == '\r';
    i_stream_skip(stream->parent, i);

    ret = dest - stream->pos;
    if (ret == 0) {
        i_assert(cstream->pending_cr && size == 1);
        return i_stream_crlf_read_lf(stream);
    }
    stream->pos = dest;
    return ret;
}

static void
i_stream_crlf_seek(struct istream_private *stream,
           uoff_t v_offset, bool mark ATTR_UNUSED)
{
    size_t available;

    if (stream->istream.v_offset > v_offset)
        i_panic("crlf-istream: seeking unsupported currently");

    while (stream->istream.v_offset < v_offset) {
        (void)i_stream_crlf_read_crlf(stream);

        available = stream->pos - stream->skip;
        if (available == 0) {
            stream->istream.stream_errno = ESPIPE;
            return;
        }
        if (available <= v_offset - stream->istream.v_offset)
            i_stream_skip(&stream->istream, available);
        else {
            i_stream_skip(&stream->istream,
                      v_offset - stream->istream.v_offset);
        }
    }
}

static const struct stat *
i_stream_crlf_stat(struct istream_private *stream, bool exact)
{
    return i_stream_stat(stream->parent, exact);
}

static struct istream *
i_stream_create_crlf_full(struct istream *input, bool crlf)
{
    struct crlf_istream *cstream;

    i_stream_ref(input);

    cstream = i_new(struct crlf_istream, 1);
    cstream->istream.max_buffer_size = input->real_stream->max_buffer_size;

    cstream->istream.iostream.destroy = i_stream_crlf_destroy;
    cstream->istream.iostream.set_max_buffer_size =
        i_stream_crlf_set_max_buffer_size;

    cstream->istream.read = crlf ? i_stream_crlf_read_crlf :
        i_stream_crlf_read_lf;
    cstream->istream.seek = i_stream_crlf_seek;
    cstream->istream.stat = i_stream_crlf_stat;

    cstream->istream.istream.blocking = input->blocking;
    cstream->istream.istream.seekable = FALSE;
    return i_stream_create(&cstream->istream, input,
                   i_stream_get_fd(input));
}

struct istream *i_stream_create_crlf(struct istream *input)
{
    return i_stream_create_crlf_full(input, TRUE);
}

struct istream *i_stream_create_lf(struct istream *input)
{
    return i_stream_create_crlf_full(input, FALSE);
}