src/lib/istream-crlf.c

	istream-crlf.c revision 5f5870385cff47efd2f58e7892f251cf13761528
/* Copyright (c) 2007-2012 Dovecot authors, see the included COPYING file */

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

struct crlf_istream {
    struct istream_private istream;

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

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

    (void)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;
        }
        (void)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, *ptr, *src, *src_end;
    unsigned char *dest, *dest_end;
    size_t size, copy_len;
    ssize_t ret;

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

    /* at least one byte was read */
    data = i_stream_get_data(stream->parent, &size);

    dest = stream->w_buffer + stream->pos;
    dest_end = stream->w_buffer + stream->buffer_size;
    src = data;
    src_end = data + size;

    /* @UNSAFE: add missing CRs */
    if (*src == '\n') {
        if (!cstream->last_cr && dest < dest_end)
            *dest++ = '\r';

        if (dest < dest_end) {
            *dest++ = '\n';
            src++;
        }
    }

    while (dest < dest_end) {
        ptr = memchr(src, '\n', src_end - src);
        if (ptr == NULL)
            ptr = src_end;

        /* copy data up to LF */
        copy_len = ptr - src;
        if (dest + copy_len > dest_end)
            copy_len = dest_end - dest;

        if (copy_len > 0) {
            memcpy(dest, src, copy_len);

            dest += copy_len;
            src += copy_len;
        }

        i_assert(dest <= dest_end && src <= src_end);
        if (dest == dest_end || src == src_end)
            break;

        /* add the CR if necessary and copy the LF.
           (src >= data+1, because data[0]=='\n' was
           handled before this loop) */
        if (src[-1] != '\r')
            *dest++ = '\r';

        if (dest == dest_end)
            break;

        *dest++ = '\n';
        src++;
        i_assert(src == ptr + 1);
    }

    i_assert(dest != stream->w_buffer);
    cstream->last_cr = dest[-1] == '\r';
    i_stream_skip(stream->parent, src - data);

    ret = (dest - stream->w_buffer) - stream->pos;
    i_assert(ret > 0);
    stream->pos = dest - stream->w_buffer;
    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) {
                stream->pos++;
                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);
    }
    i_assert(ret > 0);
    stream->pos = dest;
    return ret;
}

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;

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

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

    cstream->istream.istream.readable_fd = FALSE;
    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);
}