istream-crlf.c   [plain text]

/* Copyright (c) 2007-2011 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 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);
}