1 files changed, 151 insertions, 0 deletions
diff --git a/lib/xfrm/src/istream.c b/lib/xfrm/src/istream.c
new file mode 100644
index 0000000..ecf0887
--- /dev/null
+++ b/lib/xfrm/src/istream.c
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+#include "compat.h"
+#include "sqfs/io.h"
+#include "sqfs/error.h"
+#include "xfrm/compress.h"
+#include "xfrm/wrap.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+
+#define BUFSZ (262144)
+
+typedef struct istream_xfrm_t {
+	sqfs_istream_t base;
+
+	sqfs_istream_t *wrapped;
+	xfrm_stream_t *xfrm;
+
+	size_t buffer_offset;
+	size_t buffer_used;
+	sqfs_u8 uncompressed[BUFSZ];
+} istream_xfrm_t;
+
+static int precache(sqfs_istream_t *base)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)base;
+	int ret;
+
+	if (xfrm->buffer_offset > 0 &&
+	    xfrm->buffer_offset < xfrm->buffer_used) {
+		memmove(xfrm->uncompressed,
+			xfrm->uncompressed + xfrm->buffer_offset,
+			xfrm->buffer_used - xfrm->buffer_offset);
+	}
+
+	xfrm->buffer_used -= xfrm->buffer_offset;
+	xfrm->buffer_offset = 0;
+
+	for (;;) {
+		sqfs_u32 in_off = 0, out_off = xfrm->buffer_used;
+		int mode = XFRM_STREAM_FLUSH_NONE;
+		const sqfs_u8 *ptr;
+		size_t avail;
+
+		ret = xfrm->wrapped->get_buffered_data(xfrm->wrapped, &ptr,
+						       &avail, BUFSZ);
+		if (ret < 0)
+			return ret;
+		if (ret > 0)
+			mode = XFRM_STREAM_FLUSH_FULL;
+
+		ret = xfrm->xfrm->process_data(xfrm->xfrm,
+					       ptr, avail,
+					       xfrm->uncompressed + out_off,
+					       BUFSZ - out_off,
+					       &in_off, &out_off, mode);
+
+		if (ret == XFRM_STREAM_ERROR)
+			return SQFS_ERROR_COMPRESSOR;
+
+		xfrm->buffer_used = out_off;
+		xfrm->wrapped->advance_buffer(xfrm->wrapped, in_off);
+
+		if (ret == XFRM_STREAM_BUFFER_FULL || out_off >= BUFSZ)
+			break;
+
+		if (mode == XFRM_STREAM_FLUSH_FULL)
+			break;
+	}
+
+	return 0;
+}
+
+static int xfrm_get_buffered_data(sqfs_istream_t *strm, const sqfs_u8 **out,
+				  size_t *size, size_t want)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	if (want > BUFSZ)
+		want = BUFSZ;
+
+	if (xfrm->buffer_used == 0 ||
+	    (xfrm->buffer_used - xfrm->buffer_offset) < want) {
+		int ret = precache(strm);
+		if (ret)
+			return ret;
+	}
+
+	*out = xfrm->uncompressed + xfrm->buffer_offset;
+	*size = xfrm->buffer_used - xfrm->buffer_offset;
+	return (*size == 0) ? 1 : 0;
+}
+
+static void xfrm_advance_buffer(sqfs_istream_t *strm, size_t count)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	assert(count <= xfrm->buffer_used);
+
+	xfrm->buffer_offset += count;
+
+	assert(xfrm->buffer_offset <= xfrm->buffer_used);
+}
+
+static const char *xfrm_get_filename(sqfs_istream_t *strm)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	return xfrm->wrapped->get_filename(xfrm->wrapped);
+}
+
+static void xfrm_destroy(sqfs_object_t *obj)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)obj;
+
+	sqfs_drop(xfrm->xfrm);
+	sqfs_drop(xfrm->wrapped);
+	free(xfrm);
+}
+
+sqfs_istream_t *istream_xfrm_create(sqfs_istream_t *strm, xfrm_stream_t *xfrm)
+{
+	istream_xfrm_t *stream = calloc(1, sizeof(*stream));
+	sqfs_istream_t *base = (sqfs_istream_t *)stream;
+
+	if (stream == NULL)
+		goto fail;
+
+	sqfs_object_init(stream, xfrm_destroy, NULL);
+
+	stream->wrapped = sqfs_grab(strm);
+	stream->xfrm = sqfs_grab(xfrm);
+
+	base->get_buffered_data = xfrm_get_buffered_data;
+	base->advance_buffer = xfrm_advance_buffer;
+	base->get_filename = xfrm_get_filename;
+	return base;
+fail:
+	fprintf(stderr, "%s: error initializing decompressor stream.\n",
+		strm->get_filename(strm));
+	return NULL;
+}