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>
---
 include/io/xfrm.h | 98 ++++++++-----------------------------------------------
 1 file changed, 13 insertions(+), 85 deletions(-)

(limited to 'include/io')

diff --git a/include/io/xfrm.h b/include/io/xfrm.h
index 22a42b6..3e601ea 100644
--- a/include/io/xfrm.h
+++ b/include/io/xfrm.h
@@ -9,117 +9,45 @@
 
 #include "io/istream.h"
 #include "io/ostream.h"
-
-enum {
-	/**
-	 * @brief Deflate compressor with gzip headers.
-	 *
-	 * This actually creates a gzip compatible file, including a
-	 * gzip header and trailer.
-	 */
-	IO_COMPRESSOR_GZIP = 1,
-
-	IO_COMPRESSOR_XZ = 2,
-
-	IO_COMPRESSOR_ZSTD = 3,
-
-	IO_COMPRESSOR_BZIP2 = 4,
-
-	IO_COMPRESSOR_MIN = 1,
-	IO_COMPRESSOR_MAX = 4,
-};
+#include "xfrm/stream.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /**
- * @brief Create an input stream that transparently uncompresses data.
+ * @brief Create an input stream that transparently decodes data.
  *
  * @memberof istream_t
  *
  * This function creates an input stream that wraps an underlying input stream
- * that is compressed and transparently uncompresses the data when reading
+ * that is encoded/compressed and transparently decodes the data when reading
  * from it.
  *
- * The new stream takes ownership of the wrapped stream and destroys it when
- * the compressor stream is destroyed. If this function fails, the wrapped
- * stream is also destroyed.
- *
  * @param strm A pointer to another stream that should be wrapped.
- * @param comp_id An identifier describing the compressor to use.
+ * @param xfrm The transformation stream to use.
  *
  * @return A pointer to an input stream on success, NULL on failure.
  */
-SQFS_INTERNAL istream_t *istream_compressor_create(istream_t *strm,
-						   int comp_id);
+SQFS_INTERNAL istream_t *istream_xfrm_create(istream_t *strm,
+					     xfrm_stream_t *xfrm);
 
 /**
- * @brief Create an output stream that transparently compresses data.
+ * @brief Create an output stream that transparently encodes data.
  *
  * @memberof ostream_t
  *
- * This function creates an output stream that transparently compresses all
- * data appended to it and writes the compressed data to an underlying, wrapped
- * output stream.
- *
- * The new stream takes ownership of the wrapped stream and destroys it when
- * the compressor stream is destroyed. If this function fails, the wrapped
- * stream is also destroyed.
+ * This function creates an output stream that transparently encodes
+ * (e.g. compresses) all data appended to it and writes it to an
+ * underlying, wrapped output stream.
  *
  * @param strm A pointer to another stream that should be wrapped.
- * @param comp_id An identifier describing the compressor to use.
+ * @param xfrm The transformation stream to use.
  *
  * @return A pointer to an output stream on success, NULL on failure.
  */
-SQFS_INTERNAL ostream_t *ostream_compressor_create(ostream_t *strm,
-						   int comp_id);
-
-/**
- * @brief Probe the buffered data in an istream to check if it is compressed.
- *
- * @memberof istream_t
- *
- * This function peeks into the internal buffer of an input stream to check
- * for magic signatures of various compressors.
- *
- * @param strm A pointer to an input stream to check
- * @param probe A callback used to check if raw/decoded data matches an
- *              expected format. Returns 0 if not, -1 on failure and +1
- *              on success.
- *
- * @return A compressor ID on success, 0 if no match was found, -1 on failure.
- */
-SQFS_INTERNAL int istream_detect_compressor(istream_t *strm,
-					    int (*probe)(const sqfs_u8 *data,
-							 size_t size));
-
-/**
- * @brief Resolve a compressor name to an ID.
- *
- * @param name A compressor name.
- *
- * @return A compressor ID on success, -1 on failure.
- */
-SQFS_INTERNAL int io_compressor_id_from_name(const char *name);
-
-/**
- * @brief Resolve a id to a  compressor name.
- *
- * @param id A compressor ID.
- *
- * @return A compressor name on success, NULL on failure.
- */
-SQFS_INTERNAL const char *io_compressor_name_from_id(int id);
-
-/**
- * @brief Check if support for a given compressor has been built in.
- *
- * @param id A compressor ID.
- *
- * @return True if the compressor is supported, false if not.
- */
-SQFS_INTERNAL bool io_compressor_exists(int id);
+SQFS_INTERNAL ostream_t *ostream_xfrm_create(ostream_t *strm,
+					     xfrm_stream_t *xfrm);
 
 #ifdef __cplusplus
 }
-- 
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