1 files changed, 105 insertions, 0 deletions
diff --git a/fs/jffs2/compr_zlib.c b/fs/jffs2/compr_zlib.c
new file mode 100644
index 0000000000..222e0d6e5f
--- /dev/null
+++ b/fs/jffs2/compr_zlib.c
@@ -0,0 +1,105 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <common.h>
+#include <linux/kernel.h>
+#include <linux/zlib.h>
+#include <linux/zutil.h>
+#include "nodelist.h"
+#include "compr.h"
+
+	/* Plan: call deflate() with avail_in == *sourcelen,
+		avail_out = *dstlen - 12 and flush == Z_FINISH.
+		If it doesn't manage to finish,	call it again with
+		avail_in == 0 and avail_out set to the remaining 12
+		bytes for it to clean up.
+	   Q: Is 12 bytes sufficient?
+	*/
+#define STREAM_END_SPACE 12
+
+static struct z_stream_s inf_strm;
+
+static int jffs2_zlib_decompress(unsigned char *data_in,
+				 unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	int ret;
+	int wbits = MAX_WBITS;
+
+	inf_strm.next_in = data_in;
+	inf_strm.avail_in = srclen;
+	inf_strm.total_in = 0;
+
+	inf_strm.next_out = cpage_out;
+	inf_strm.avail_out = destlen;
+	inf_strm.total_out = 0;
+
+	/* If it's deflate, and it's got no preset dictionary, then
+	   we can tell zlib to skip the adler32 check. */
+	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
+	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
+	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
+
+		jffs2_dbg(2, "inflate skipping adler32\n");
+		wbits = -((data_in[0] >> 4) + 8);
+		inf_strm.next_in += 2;
+		inf_strm.avail_in -= 2;
+	} else {
+		/* Let this remain D1 for now -- it should never happen */
+		jffs2_dbg(1, "inflate not skipping adler32\n");
+	}
+
+
+	if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
+		pr_warn("inflateInit failed\n");
+		return 1;
+	}
+
+	while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
+		;
+	if (ret != Z_STREAM_END) {
+		pr_notice("inflate returned %d\n", ret);
+	}
+	zlib_inflateEnd(&inf_strm);
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_zlib_comp = {
+    .priority = JFFS2_ZLIB_PRIORITY,
+    .name = "zlib",
+    .compr = JFFS2_COMPR_ZLIB,
+    .decompress = &jffs2_zlib_decompress,
+#ifdef JFFS2_ZLIB_DISABLED
+    .disabled = 1,
+#else
+    .disabled = 0,
+#endif
+};
+
+int __init jffs2_zlib_init(void)
+{
+    int ret;
+
+    inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
+    jffs2_dbg(1, "Allocated %d bytes for inflate workspace\n",
+	      zlib_inflate_workspacesize());
+
+    ret = jffs2_register_compressor(&jffs2_zlib_comp);
+
+    return ret;
+}
+
+void jffs2_zlib_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_zlib_comp);
+	vfree(inf_strm.workspace);
+}