1 files changed, 77 insertions, 0 deletions

diff --git a/fs/cramfs/uncompress.c b/fs/cramfs/uncompress.c
new file mode 100644
index 000000000000..5034365b06a8
--- /dev/null
+++ b/fs/cramfs/uncompress.c
@@ -0,0 +1,77 @@
+/*
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.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) {
+                printk("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:
+        printk("Error %d while decompressing!\n", err);
+        printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
+        return 0;
+}
+
+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;
+}
+
+int cramfs_uncompress_exit(void)
+{
+        if (!--initialized) {
+                zlib_inflateEnd(&stream);
+                vfree(stream.workspace);
+        }
+        return 0;
+}