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-rw-r--r--fs/cramfs/uncompress.c80
1 files changed, 80 insertions, 0 deletions
diff --git a/fs/cramfs/uncompress.c b/fs/cramfs/uncompress.c
new file mode 100644
index 000000000..975d98fc2
--- /dev/null
+++ b/fs/cramfs/uncompress.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * uncompress.c
+ *
+ * (C) Copyright 1999 Linus Torvalds
+ *
+ * cramfs interfaces to the uncompression library. There's really just
+ * three entrypoints:
+ *
+ * - cramfs_uncompress_init() - called to initialize the thing.
+ * - cramfs_uncompress_exit() - tell me when you're done
+ * - cramfs_uncompress_block() - uncompress a block.
+ *
+ * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
+ * only have one stream, and we'll initialize it only once even if it
+ * then is used by multiple filesystems.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+#include "internal.h"
+
+static z_stream stream;
+static int initialized;
+
+/* Returns length of decompressed data. */
+int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
+{
+ int err;
+
+ stream.next_in = src;
+ stream.avail_in = srclen;
+
+ stream.next_out = dst;
+ stream.avail_out = dstlen;
+
+ err = zlib_inflateReset(&stream);
+ if (err != Z_OK) {
+ pr_err("zlib_inflateReset error %d\n", err);
+ zlib_inflateEnd(&stream);
+ zlib_inflateInit(&stream);
+ }
+
+ err = zlib_inflate(&stream, Z_FINISH);
+ if (err != Z_STREAM_END)
+ goto err;
+ return stream.total_out;
+
+err:
+ pr_err("Error %d while decompressing!\n", err);
+ pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
+ return -EIO;
+}
+
+int cramfs_uncompress_init(void)
+{
+ if (!initialized++) {
+ stream.workspace = vmalloc(zlib_inflate_workspacesize());
+ if (!stream.workspace) {
+ initialized = 0;
+ return -ENOMEM;
+ }
+ stream.next_in = NULL;
+ stream.avail_in = 0;
+ zlib_inflateInit(&stream);
+ }
+ return 0;
+}
+
+void cramfs_uncompress_exit(void)
+{
+ if (!--initialized) {
+ zlib_inflateEnd(&stream);
+ vfree(stream.workspace);
+ }
+}