From 551dd3879c288a2b6b6fbaca5c09c04fbe994ff4 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Tue, 13 Dec 2022 09:15:19 +0100
Subject: Split stream compression out of libio

Move it to a separate libxfrm library, where it can be independently
tested as well. The bulk of the new code is also mainly test cases
for the compressors.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
---
 lib/xfrm/gzip.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 lib/xfrm/gzip.c

(limited to 'lib/xfrm/gzip.c')

diff --git a/lib/xfrm/gzip.c b/lib/xfrm/gzip.c
new file mode 100644
index 0000000..67224f7
--- /dev/null
+++ b/lib/xfrm/gzip.c
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * gzip.c
+ *
+ * Copyright (C) 2021 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <zlib.h>
+
+#include "xfrm/stream.h"
+#include "xfrm/compress.h"
+
+typedef struct {
+	xfrm_stream_t base;
+
+	z_stream strm;
+	bool compress;
+} xfrm_stream_gzip_t;
+
+static const int zlib_action[] = {
+	[XFRM_STREAM_FLUSH_NONE] = Z_NO_FLUSH,
+	[XFRM_STREAM_FLUSH_SYNC] = Z_SYNC_FLUSH,
+	[XFRM_STREAM_FLUSH_FULL] = Z_FINISH,
+};
+
+static int process_data(xfrm_stream_t *stream, const void *in,
+			sqfs_u32 in_size, void *out, sqfs_u32 out_size,
+			sqfs_u32 *in_read, sqfs_u32 *out_written,
+			int flush_mode)
+{
+	xfrm_stream_gzip_t *gzip = (xfrm_stream_gzip_t *)stream;
+	sqfs_u32 diff;
+	int ret;
+
+	if (flush_mode < 0 || flush_mode >= XFRM_STREAM_FLUSH_COUNT)
+		flush_mode = XFRM_STREAM_FLUSH_NONE;
+
+	while (in_size > 0 && out_size > 0) {
+		gzip->strm.next_in = (void *)in;
+		gzip->strm.avail_in = in_size;
+
+		gzip->strm.next_out = out;
+		gzip->strm.avail_out = out_size;
+
+		if (gzip->compress) {
+			ret = deflate(&gzip->strm, zlib_action[flush_mode]);
+		} else {
+			ret = inflate(&gzip->strm, zlib_action[flush_mode]);
+		}
+
+		if (ret == Z_STREAM_ERROR)
+			return XFRM_STREAM_ERROR;
+
+		diff = in_size - gzip->strm.avail_in;
+		in = (const char *)in + diff;
+		in_size -= diff;
+		*in_read += diff;
+
+		diff = out_size - gzip->strm.avail_out;
+		out = (char *)out + diff;
+		out_size -= diff;
+		*out_written += diff;
+
+		if (ret == Z_STREAM_END) {
+			if (gzip->compress) {
+				ret = deflateReset(&gzip->strm);
+			} else {
+				ret = inflateReset(&gzip->strm);
+			}
+
+			if (ret != Z_OK)
+				return XFRM_STREAM_ERROR;
+
+			return XFRM_STREAM_END;
+		}
+
+		if (ret == Z_BUF_ERROR)
+			return XFRM_STREAM_BUFFER_FULL;
+	}
+
+	return XFRM_STREAM_OK;
+}
+
+static void destroy(sqfs_object_t *obj)
+{
+	xfrm_stream_gzip_t *gzip = (xfrm_stream_gzip_t *)obj;
+
+	if (gzip->compress) {
+		deflateEnd(&gzip->strm);
+	} else {
+		inflateEnd(&gzip->strm);
+	}
+	free(gzip);
+}
+
+static xfrm_stream_t *create_stream(const compressor_config_t *cfg,
+				    bool compress)
+{
+	xfrm_stream_gzip_t *gzip = calloc(1, sizeof(*gzip));
+	xfrm_stream_t *xfrm = (xfrm_stream_t *)gzip;
+	int ret;
+
+	if (gzip == NULL) {
+		perror("creating gzip stream compressor");
+		return NULL;
+	}
+
+	if (compress) {
+		int level = COMP_GZIP_DEFAULT_LEVEL;
+		int wnd = COMP_GZIP_DEFAULT_WINDOW;
+
+		if (cfg != NULL) {
+			level = cfg->level;
+			wnd = cfg->opt.gzip.window_size;
+		}
+
+		ret = deflateInit2(&gzip->strm, level, Z_DEFLATED,
+				   wnd + 16, 8, Z_DEFAULT_STRATEGY);
+	} else {
+		ret = inflateInit2(&gzip->strm, 16 + 15);
+	}
+
+	if (ret != Z_OK) {
+		fputs("internal error creating gzip compressor.\n", stderr);
+		free(gzip);
+		return NULL;
+	}
+
+	gzip->compress = compress;
+	xfrm->process_data = process_data;
+	sqfs_object_init(xfrm, destroy, NULL);
+	return xfrm;
+}
+
+xfrm_stream_t *compressor_stream_gzip_create(const compressor_config_t *cfg)
+{
+	return create_stream(cfg, true);
+}
+
+xfrm_stream_t *decompressor_stream_gzip_create(void)
+{
+	return create_stream(NULL, false);
+}
-- 
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