--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lib/istream-limit.c	Sun Nov 09 20:26:25 2003 +0200
@@ -0,0 +1,123 @@
+/* Copyright (C) 2003 Timo Sirainen */
+
+#include "lib.h"
+#include "istream-internal.h"
+
+struct limit_istream {
+	struct _istream istream;
+
+	struct istream *input;
+	uoff_t v_start_offset, v_size;
+};
+
+static void _close(struct _iostream *stream __attr_unused__)
+{
+}
+
+static void _destroy(struct _iostream *stream)
+{
+	struct limit_istream *lstream = (struct limit_istream *) stream;
+
+	/* get to same position in parent stream */
+	i_stream_seek(lstream->input, lstream->v_start_offset +
+		      lstream->istream.istream.v_offset);
+	i_stream_unref(lstream->input);
+}
+
+static void _set_max_buffer_size(struct _iostream *stream, size_t max_size)
+{
+	struct limit_istream *lstream = (struct limit_istream *) stream;
+
+	i_stream_set_max_buffer_size(lstream->input, max_size);
+}
+
+static void _set_blocking(struct _iostream *stream, int timeout_msecs,
+			  void (*timeout_cb)(void *), void *context)
+{
+	struct limit_istream *lstream = (struct limit_istream *) stream;
+
+	i_stream_set_blocking(lstream->input, timeout_msecs,
+			      timeout_cb, context);
+}
+
+static ssize_t _read(struct _istream *stream)
+{
+	struct limit_istream *lstream = (struct limit_istream *) stream;
+	uoff_t left;
+	ssize_t ret;
+	size_t pos;
+
+	if (stream->istream.v_offset >= lstream->v_size)
+		return -1;
+
+	if (lstream->input->v_offset !=
+	    lstream->v_start_offset + stream->istream.v_offset) {
+		i_stream_seek(lstream->input,
+			      lstream->v_start_offset + stream->istream.v_offset);
+	}
+
+	if (i_stream_read(lstream->input) == -2 && stream->buffer != NULL) {
+		if (lstream->istream.skip == 0)
+			return -2;
+		stream->istream.eof = lstream->input->eof;
+	}
+
+	stream->pos -= stream->skip;
+	stream->skip = 0;
+	stream->buffer = i_stream_get_data(lstream->input, &pos);
+
+	left = lstream->v_size - stream->istream.v_offset;
+	if (pos > left)
+		pos = left;
+
+	ret = pos <= lstream->istream.pos ? -1 :
+		(ssize_t) (pos - stream->pos);
+	lstream->istream.pos = pos;
+	return ret;
+}
+
+static void _seek(struct _istream *stream, uoff_t v_offset)
+{
+	stream->istream.stream_errno = 0;
+	stream->istream.v_offset = v_offset;
+	stream->skip = stream->pos = 0;
+}
+
+static uoff_t _get_size(struct _istream *stream)
+{
+	struct limit_istream *lstream = (struct limit_istream *) stream;
+
+	return lstream->v_size != (uoff_t)-1 ? lstream->v_size :
+		i_stream_get_size(lstream->input);
+}
+
+struct istream *i_stream_create_limit(pool_t pool, struct istream *input,
+				      uoff_t v_start_offset, uoff_t v_size)
+{
+	struct limit_istream *lstream;
+
+	i_stream_ref(input);
+
+	lstream = p_new(pool, struct limit_istream, 1);
+	lstream->input = input;
+	lstream->v_start_offset = v_start_offset;
+	lstream->v_size = v_size;
+
+	lstream->istream.istream.v_offset =
+		input->v_offset < v_start_offset ? 0 :
+		input->v_offset - v_start_offset > v_size ? v_size :
+		input->v_offset - v_start_offset;
+
+	lstream->istream.iostream.close = _close;
+	lstream->istream.iostream.destroy = _destroy;
+	lstream->istream.iostream.set_max_buffer_size = _set_max_buffer_size;
+	lstream->istream.iostream.set_blocking = _set_blocking;
+
+	lstream->istream.read = _read;
+	lstream->istream.seek = _seek;
+	lstream->istream.get_size = _get_size;
+
+	return _i_stream_create(&lstream->istream, pool, i_stream_get_fd(input),
+				input->real_stream->abs_start_offset +
+				v_start_offset);
+}