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>

16 files changed, 253 insertions, 1122 deletions

diff --git a/lib/io/Makemodule.am b/lib/io/Makemodule.am
index 63ce958..918ce50 100644
--- a/lib/io/Makemodule.am
+++ b/lib/io/Makemodule.am
@@ -1,11 +1,8 @@
 libio_a_SOURCES = lib/io/internal.h
 libio_a_SOURCES += include/io/istream.h lib/io/ostream.c lib/io/printf.c
 libio_a_SOURCES += include/io/ostream.h lib/io/istream.c lib/io/get_line.c
-libio_a_SOURCES += include/io/xfrm.h lib/io/xfrm.c
-libio_a_SOURCES += include/io/file.h include/io/std.h
-libio_a_SOURCES += lib/io/compress/ostream_compressor.c
-libio_a_SOURCES += lib/io/uncompress/istream_compressor.c
-libio_a_SOURCES += lib/io/uncompress/autodetect.c
+libio_a_SOURCES += include/io/xfrm.h include/io/file.h include/io/std.h
+libio_a_SOURCES += lib/io/xfrm/ostream.c lib/io/xfrm/istream.c
 libio_a_CFLAGS = $(AM_CFLAGS) $(ZLIB_CFLAGS) $(XZ_CFLAGS)
 libio_a_CFLAGS += $(ZSTD_CFLAGS) $(BZIP2_CFLAGS)
 libio_a_CPPFLAGS = $(AM_CPPFLAGS)
@@ -19,27 +16,4 @@ libio_a_SOURCES += lib/io/unix/ostream.c
 libio_a_SOURCES += lib/io/unix/istream.c
 endif
 
-if WITH_XZ
-libio_a_SOURCES += lib/io/compress/xz.c lib/io/uncompress/xz.c
-libio_a_CPPFLAGS += -DWITH_XZ
-endif
-
-if WITH_GZIP
-libio_a_SOURCES += lib/io/compress/gzip.c
-libio_a_SOURCES += lib/io/uncompress/gzip.c
-libio_a_CPPFLAGS += -DWITH_GZIP
-endif
-
-if WITH_ZSTD
-libio_a_SOURCES += lib/io/compress/zstd.c
-libio_a_SOURCES += lib/io/uncompress/zstd.c
-libio_a_CPPFLAGS += -DWITH_ZSTD
-endif
-
-if WITH_BZIP2
-libio_a_SOURCES += lib/io/compress/bzip2.c
-libio_a_SOURCES += lib/io/uncompress/bzip2.c
-libio_a_CPPFLAGS += -DWITH_BZIP2
-endif
-
 noinst_LIBRARIES += libio.a
diff --git a/lib/io/compress/bzip2.c b/lib/io/compress/bzip2.c
deleted file mode 100644
index 7f0c09a..0000000
--- a/lib/io/compress/bzip2.c
+++ /dev/null
@@ -1,96 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * bzip2.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <bzlib.h>
-
-typedef struct {
-	ostream_comp_t base;
-
-	bz_stream strm;
-} ostream_bzip2_t;
-
-static int flush_inbuf(ostream_comp_t *base, bool finish)
-{
-	ostream_bzip2_t *bzip2 = (ostream_bzip2_t *)base;
-	size_t have;
-	int ret;
-
-	bzip2->strm.next_in = (char *)base->inbuf;
-
-	if (base->inbuf_used > sizeof(base->inbuf))
-		base->inbuf_used = sizeof(base->inbuf);
-
-	if ((sizeof(size_t) > sizeof(unsigned int)) &&
-	    (base->inbuf_used > (size_t)UINT_MAX)) {
-		bzip2->strm.avail_in = UINT_MAX;
-	} else {
-		bzip2->strm.avail_in = (unsigned int)base->inbuf_used;
-	}
-
-	for (;;) {
-		bzip2->strm.next_out = (char *)base->outbuf;
-		bzip2->strm.avail_out = sizeof(base->outbuf);
-
-		ret = BZ2_bzCompress(&bzip2->strm, finish ? BZ_FINISH : BZ_RUN);
-
-		if (ret < 0 && ret != BZ_OUTBUFF_FULL) {
-			fprintf(stderr, "%s: internal error in bzip2 "
-				"compressor.\n",
-				base->wrapped->get_filename(base->wrapped));
-			return -1;
-		}
-
-		have = sizeof(base->outbuf) - bzip2->strm.avail_out;
-
-		if (base->wrapped->append(base->wrapped, base->outbuf, have))
-			return -1;
-
-		if (ret == BZ_STREAM_END || ret == BZ_OUTBUFF_FULL ||
-		    bzip2->strm.avail_in == 0) {
-			break;
-		}
-	}
-
-	if (bzip2->strm.avail_in > 0) {
-		memmove(base->inbuf, bzip2->strm.next_in,
-			bzip2->strm.avail_in);
-	}
-
-	base->inbuf_used = bzip2->strm.avail_in;
-	return 0;
-}
-
-static void cleanup(ostream_comp_t *base)
-{
-	ostream_bzip2_t *bzip2 = (ostream_bzip2_t *)base;
-
-	BZ2_bzCompressEnd(&bzip2->strm);
-}
-
-ostream_comp_t *ostream_bzip2_create(const char *filename)
-{
-	ostream_bzip2_t *bzip2 = calloc(1, sizeof(*bzip2));
-	ostream_comp_t *base = (ostream_comp_t *)bzip2;
-
-	if (bzip2 == NULL) {
-		fprintf(stderr, "%s: creating bzip2 compressor: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	if (BZ2_bzCompressInit(&bzip2->strm, 9, 0, 30) != BZ_OK) {
-		fprintf(stderr, "%s: error initializing bzip2 compressor.\n",
-			filename);
-		free(bzip2);
-		return NULL;
-	}
-
-	base->flush_inbuf = flush_inbuf;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/compress/gzip.c b/lib/io/compress/gzip.c
deleted file mode 100644
index b73a258..0000000
--- a/lib/io/compress/gzip.c
+++ /dev/null
@@ -1,92 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * gzip.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <zlib.h>
-
-typedef struct {
-	ostream_comp_t base;
-
-	z_stream strm;
-} ostream_gzip_t;
-
-static int flush_inbuf(ostream_comp_t *base, bool finish)
-{
-	ostream_gzip_t *gzip = (ostream_gzip_t *)base;
-	size_t have;
-	int ret;
-
-	if (base->inbuf_used > sizeof(base->inbuf))
-		base->inbuf_used = sizeof(base->inbuf);
-
-	if (sizeof(size_t) > sizeof(uInt)) {
-		gzip->strm.avail_in = ~((uInt)0);
-
-		if ((size_t)gzip->strm.avail_in > base->inbuf_used)
-			gzip->strm.avail_in = (uInt)base->inbuf_used;
-	} else {
-		gzip->strm.avail_in = (uInt)base->inbuf_used;
-	}
-
-	gzip->strm.next_in = base->inbuf;
-
-	do {
-		gzip->strm.avail_out = BUFSZ;
-		gzip->strm.next_out = base->outbuf;
-
-		ret = deflate(&gzip->strm, finish ? Z_FINISH : Z_NO_FLUSH);
-
-		if (ret == Z_STREAM_ERROR) {
-			fprintf(stderr,
-				"%s: internal error in gzip compressor.\n",
-				base->wrapped->get_filename(base->wrapped));
-			return -1;
-		}
-
-		have = BUFSZ - gzip->strm.avail_out;
-
-		if (base->wrapped->append(base->wrapped, base->outbuf, have))
-			return -1;
-	} while (gzip->strm.avail_out == 0);
-
-	base->inbuf_used = 0;
-	return 0;
-}
-
-static void cleanup(ostream_comp_t *base)
-{
-	ostream_gzip_t *gzip = (ostream_gzip_t *)base;
-
-	deflateEnd(&gzip->strm);
-}
-
-ostream_comp_t *ostream_gzip_create(const char *filename)
-{
-	ostream_gzip_t *gzip = calloc(1, sizeof(*gzip));
-	ostream_comp_t *base = (ostream_comp_t *)gzip;
-	int ret;
-
-	if (gzip == NULL) {
-		fprintf(stderr, "%s: creating gzip wrapper: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	ret = deflateInit2(&gzip->strm, 9, Z_DEFLATED, 16 + 15, 8,
-			   Z_DEFAULT_STRATEGY);
-	if (ret != Z_OK) {
-		fprintf(stderr,
-			"%s: internal error creating gzip compressor.\n",
-			filename);
-		free(gzip);
-		return NULL;
-	}
-
-	base->flush_inbuf = flush_inbuf;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/compress/ostream_compressor.c b/lib/io/compress/ostream_compressor.c
deleted file mode 100644
index a5f16d5..0000000
--- a/lib/io/compress/ostream_compressor.c
+++ /dev/null
@@ -1,106 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * ostream_compressor.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-static int comp_append(ostream_t *strm, const void *data, size_t size)
-{
-	ostream_comp_t *comp = (ostream_comp_t *)strm;
-	size_t diff;
-
-	while (size > 0) {
-		if (comp->inbuf_used >= BUFSZ) {
-			if (comp->flush_inbuf(comp, false))
-				return -1;
-		}
-
-		diff = BUFSZ - comp->inbuf_used;
-
-		if (diff > size)
-			diff = size;
-
-		memcpy(comp->inbuf + comp->inbuf_used, data, diff);
-
-		comp->inbuf_used += diff;
-		data = (const char *)data + diff;
-		size -= diff;
-	}
-
-	return 0;
-}
-
-static int comp_flush(ostream_t *strm)
-{
-	ostream_comp_t *comp = (ostream_comp_t *)strm;
-
-	if (comp->inbuf_used > 0) {
-		if (comp->flush_inbuf(comp, true))
-			return -1;
-	}
-
-	return comp->wrapped->flush(comp->wrapped);
-}
-
-static const char *comp_get_filename(ostream_t *strm)
-{
-	ostream_comp_t *comp = (ostream_comp_t *)strm;
-
-	return comp->wrapped->get_filename(comp->wrapped);
-}
-
-static void comp_destroy(sqfs_object_t *obj)
-{
-	ostream_comp_t *comp = (ostream_comp_t *)obj;
-
-	comp->cleanup(comp);
-	sqfs_drop(comp->wrapped);
-	free(comp);
-}
-
-ostream_t *ostream_compressor_create(ostream_t *strm, int comp_id)
-{
-	ostream_comp_t *comp = NULL;
-	ostream_t *base;
-
-	switch (comp_id) {
-	case IO_COMPRESSOR_GZIP:
-#ifdef WITH_GZIP
-		comp = ostream_gzip_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_XZ:
-#ifdef WITH_XZ
-		comp = ostream_xz_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_ZSTD:
-#if defined(WITH_ZSTD) && defined(HAVE_ZSTD_STREAM)
-		comp = ostream_zstd_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_BZIP2:
-#ifdef WITH_BZIP2
-		comp = ostream_bzip2_create(strm->get_filename(strm));
-#endif
-		break;
-	default:
-		break;
-	}
-
-	if (comp == NULL)
-		return NULL;
-
-	sqfs_object_init(comp, comp_destroy, NULL);
-
-	comp->wrapped = sqfs_grab(strm);
-	comp->inbuf_used = 0;
-
-	base = (ostream_t *)comp;
-	base->append = comp_append;
-	base->flush = comp_flush;
-	base->get_filename = comp_get_filename;
-	return base;
-}
diff --git a/lib/io/compress/xz.c b/lib/io/compress/xz.c
deleted file mode 100644
index 65bda0b..0000000
--- a/lib/io/compress/xz.c
+++ /dev/null
@@ -1,80 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * xz.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <lzma.h>
-
-typedef struct {
-	ostream_comp_t base;
-
-	lzma_stream strm;
-} ostream_xz_t;
-
-static int flush_inbuf(ostream_comp_t *base, bool finish)
-{
-	ostream_xz_t *xz = (ostream_xz_t *)base;
-	lzma_ret ret_xz;
-	size_t have;
-
-	xz->strm.next_in = base->inbuf;
-	xz->strm.avail_in = base->inbuf_used;
-
-	do {
-		xz->strm.next_out = base->outbuf;
-		xz->strm.avail_out = BUFSZ;
-
-		ret_xz = lzma_code(&xz->strm, finish ? LZMA_FINISH : LZMA_RUN);
-
-		if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) {
-			fprintf(stderr,
-				"%s: internal error in XZ compressor.\n",
-				base->wrapped->get_filename(base->wrapped));
-			return -1;
-		}
-
-		have = BUFSZ - xz->strm.avail_out;
-
-		if (base->wrapped->append(base->wrapped, base->outbuf, have))
-			return -1;
-	} while (xz->strm.avail_out == 0);
-
-	base->inbuf_used = 0;
-	return 0;
-}
-
-static void cleanup(ostream_comp_t *base)
-{
-	ostream_xz_t *xz = (ostream_xz_t *)base;
-
-	lzma_end(&xz->strm);
-}
-
-ostream_comp_t *ostream_xz_create(const char *filename)
-{
-	ostream_xz_t *xz = calloc(1, sizeof(*xz));
-	ostream_comp_t *base = (ostream_comp_t *)xz;
-	lzma_ret ret_xz;
-
-	if (xz == NULL) {
-		fprintf(stderr, "%s: creating xz wrapper: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	ret_xz = lzma_easy_encoder(&xz->strm, LZMA_PRESET_DEFAULT,
-				   LZMA_CHECK_CRC64);
-	if (ret_xz != LZMA_OK) {
-		fprintf(stderr, "%s: error initializing XZ compressor\n",
-			filename);
-		free(xz);
-		return NULL;
-	}
-
-	base->flush_inbuf = flush_inbuf;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/compress/zstd.c b/lib/io/compress/zstd.c
deleted file mode 100644
index c0b002e..0000000
--- a/lib/io/compress/zstd.c
+++ /dev/null
@@ -1,94 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * zstd.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <zstd.h>
-
-#ifdef HAVE_ZSTD_STREAM
-typedef struct {
-	ostream_comp_t base;
-
-	ZSTD_CStream *strm;
-} ostream_zstd_t;
-
-static int flush_inbuf(ostream_comp_t *base, bool finish)
-{
-	ostream_zstd_t *zstd = (ostream_zstd_t *)base;
-	ZSTD_EndDirective op;
-	ZSTD_outBuffer out;
-	ZSTD_inBuffer in;
-	size_t ret;
-
-	op = finish ? ZSTD_e_end : ZSTD_e_continue;
-
-	do {
-		memset(&in, 0, sizeof(in));
-		memset(&out, 0, sizeof(out));
-
-		in.src = base->inbuf;
-		in.size = base->inbuf_used;
-
-		out.dst = base->outbuf;
-		out.size = BUFSZ;
-
-		ret = ZSTD_compressStream2(zstd->strm, &out, &in, op);
-
-		if (ZSTD_isError(ret)) {
-			fprintf(stderr, "%s: error in zstd compressor.\n",
-				base->wrapped->get_filename(base->wrapped));
-			return -1;
-		}
-
-		if (base->wrapped->append(base->wrapped, base->outbuf,
-					  out.pos)) {
-			return -1;
-		}
-
-		if (in.pos < in.size) {
-			base->inbuf_used = in.size - in.pos;
-
-			memmove(base->inbuf, base->inbuf + in.pos,
-				base->inbuf_used);
-		} else {
-			base->inbuf_used = 0;
-		}
-	} while (finish && ret != 0);
-
-	return 0;
-}
-
-static void cleanup(ostream_comp_t *base)
-{
-	ostream_zstd_t *zstd = (ostream_zstd_t *)base;
-
-	ZSTD_freeCStream(zstd->strm);
-}
-
-ostream_comp_t *ostream_zstd_create(const char *filename)
-{
-	ostream_zstd_t *zstd = calloc(1, sizeof(*zstd));
-	ostream_comp_t *base = (ostream_comp_t *)zstd;
-
-	if (zstd == NULL) {
-		fprintf(stderr, "%s: creating zstd wrapper: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	zstd->strm = ZSTD_createCStream();
-	if (zstd->strm == NULL) {
-		fprintf(stderr, "%s: error creating zstd decoder.\n",
-			filename);
-		free(zstd);
-		return NULL;
-	}
-
-	base->flush_inbuf = flush_inbuf;
-	base->cleanup = cleanup;
-	return base;
-}
-#endif /* HAVE_ZSTD_STREAM */
diff --git a/lib/io/internal.h b/lib/io/internal.h
index 4ac38f5..25a0196 100644
--- a/lib/io/internal.h
+++ b/lib/io/internal.h
@@ -14,6 +14,7 @@
 #include "io/file.h"
 #include "io/xfrm.h"
 #include "io/std.h"
+#include "xfrm/compress.h"
 
 #include <string.h>
 #include <stdlib.h>
@@ -27,55 +28,4 @@
 
 #define BUFSZ (262144)
 
-typedef struct ostream_comp_t {
-	ostream_t base;
-
-	ostream_t *wrapped;
-
-	size_t inbuf_used;
-
-	sqfs_u8 inbuf[BUFSZ];
-	sqfs_u8 outbuf[BUFSZ];
-
-	int (*flush_inbuf)(struct ostream_comp_t *ostrm, bool finish);
-
-	void (*cleanup)(struct ostream_comp_t *ostrm);
-} ostream_comp_t;
-
-typedef struct istream_comp_t {
-	istream_t base;
-
-	istream_t *wrapped;
-
-	sqfs_u8 uncompressed[BUFSZ];
-
-	bool eof;
-
-	void (*cleanup)(struct istream_comp_t *strm);
-} istream_comp_t;
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-SQFS_INTERNAL ostream_comp_t *ostream_gzip_create(const char *filename);
-
-SQFS_INTERNAL ostream_comp_t *ostream_xz_create(const char *filename);
-
-SQFS_INTERNAL ostream_comp_t *ostream_zstd_create(const char *filename);
-
-SQFS_INTERNAL ostream_comp_t *ostream_bzip2_create(const char *filename);
-
-SQFS_INTERNAL istream_comp_t *istream_gzip_create(const char *filename);
-
-SQFS_INTERNAL istream_comp_t *istream_xz_create(const char *filename);
-
-SQFS_INTERNAL istream_comp_t *istream_zstd_create(const char *filename);
-
-SQFS_INTERNAL istream_comp_t *istream_bzip2_create(const char *filename);
-
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* INTERNAL_H */
diff --git a/lib/io/uncompress/autodetect.c b/lib/io/uncompress/autodetect.c
deleted file mode 100644
index dde33c8..0000000
--- a/lib/io/uncompress/autodetect.c
+++ /dev/null
@@ -1,55 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * autodetect.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-static const struct {
-	int id;
-	const sqfs_u8 *value;
-	size_t len;
-} magic[] = {
-	{ IO_COMPRESSOR_GZIP, (const sqfs_u8 *)"\x1F\x8B\x08", 3 },
-	{ IO_COMPRESSOR_XZ, (const sqfs_u8 *)("\xFD" "7zXZ"), 6 },
-	{ IO_COMPRESSOR_ZSTD, (const sqfs_u8 *)"\x28\xB5\x2F\xFD", 4 },
-	{ IO_COMPRESSOR_BZIP2, (const sqfs_u8 *)"BZh", 3 },
-};
-
-int istream_detect_compressor(istream_t *strm,
-			      int (*probe)(const sqfs_u8 *data, size_t size))
-{
-	size_t i;
-	int ret;
-
-	ret = istream_precache(strm);
-	if (ret != 0)
-		return ret;
-
-	if (probe != NULL) {
-		ret = probe(strm->buffer + strm->buffer_offset,
-			    strm->buffer_used - strm->buffer_offset);
-		if (ret < 0)
-			return ret;
-
-		/* XXX: this means the data is uncompressed. We do this check
-		   first since it might be perfectly OK for the uncompressed
-		   data to contain a magic number from the table. */
-		if (ret > 0)
-			return 0;
-	}
-
-	for (i = 0; i < sizeof(magic) / sizeof(magic[0]); ++i) {
-		if ((strm->buffer_used - strm->buffer_offset) < magic[i].len)
-			continue;
-
-		ret = memcmp(strm->buffer + strm->buffer_offset,
-			     magic[i].value, magic[i].len);
-
-		if (ret == 0)
-			return magic[i].id;
-	}
-
-	return 0;
-}
diff --git a/lib/io/uncompress/bzip2.c b/lib/io/uncompress/bzip2.c
deleted file mode 100644
index 3b44383..0000000
--- a/lib/io/uncompress/bzip2.c
+++ /dev/null
@@ -1,118 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * bzip2.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <bzlib.h>
-
-typedef struct {
-	istream_comp_t base;
-
-	bool initialized;
-	bz_stream strm;
-} istream_bzip2_t;
-
-static int precache(istream_t *base)
-{
-	istream_bzip2_t *bzip2 = (istream_bzip2_t *)base;
-	istream_t *wrapped = ((istream_comp_t *)base)->wrapped;
-	size_t avail;
-	int ret;
-
-	for (;;) {
-		if (!bzip2->initialized) {
-			if (BZ2_bzDecompressInit(&bzip2->strm, 0, 0) != BZ_OK) {
-				fprintf(stderr, "%s: error initializing "
-					"bzip2 decompressor.\n",
-					wrapped->get_filename(wrapped));
-				return -1;
-			}
-
-			bzip2->initialized = true;
-		}
-
-		ret = istream_precache(wrapped);
-		if (ret != 0)
-			return ret;
-
-		avail = wrapped->buffer_used;
-		if ((sizeof(size_t) > sizeof(unsigned int)) &&
-		    (avail > (size_t)UINT_MAX)) {
-			avail = UINT_MAX;
-		}
-
-		bzip2->strm.next_in = (char *)wrapped->buffer;
-		bzip2->strm.avail_in = (unsigned int)avail;
-
-		if (base->buffer_used > BUFSZ)
-			base->buffer_used = BUFSZ;
-
-		avail = BUFSZ - base->buffer_used;
-
-		if ((sizeof(size_t) > sizeof(unsigned int)) &&
-		    (avail > (size_t)UINT_MAX)) {
-			avail = UINT_MAX;
-		}
-
-		bzip2->strm.next_out = (char *)base->buffer + base->buffer_used;
-		bzip2->strm.avail_out = (unsigned int)avail;
-
-		if (bzip2->strm.avail_out < 1)
-			break;
-
-		ret = BZ2_bzDecompress(&bzip2->strm);
-
-		if (ret < 0) {
-			fprintf(stderr, "%s: internal error in bzip2 "
-				"decompressor.\n",
-				wrapped->get_filename(wrapped));
-			return -1;
-		}
-
-		base->buffer_used = BUFSZ - bzip2->strm.avail_out;
-		wrapped->buffer_offset = wrapped->buffer_used -
-					 bzip2->strm.avail_in;
-
-		if (ret == BZ_STREAM_END) {
-			if (istream_precache(wrapped))
-				return -1;
-
-			BZ2_bzDecompressEnd(&bzip2->strm);
-			bzip2->initialized = false;
-
-			if (wrapped->buffer_used == 0) {
-				base->eof = true;
-				break;
-			}
-		}
-	}
-
-	return 0;
-}
-
-static void cleanup(istream_comp_t *base)
-{
-	istream_bzip2_t *bzip2 = (istream_bzip2_t *)base;
-
-	if (bzip2->initialized)
-		BZ2_bzDecompressEnd(&bzip2->strm);
-}
-
-istream_comp_t *istream_bzip2_create(const char *filename)
-{
-	istream_bzip2_t *bzip2 = calloc(1, sizeof(*bzip2));
-	istream_comp_t *base = (istream_comp_t *)bzip2;
-
-	if (bzip2 == NULL) {
-		fprintf(stderr, "%s: creating bzip2 compressor: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	((istream_t *)base)->precache = precache;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/uncompress/gzip.c b/lib/io/uncompress/gzip.c
deleted file mode 100644
index bce7f0a..0000000
--- a/lib/io/uncompress/gzip.c
+++ /dev/null
@@ -1,91 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * gzip.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <zlib.h>
-
-typedef struct {
-	istream_comp_t base;
-
-	z_stream strm;
-} istream_gzip_t;
-
-static int precache(istream_t *base)
-{
-	istream_t *wrapped = ((istream_comp_t *)base)->wrapped;
-	istream_gzip_t *gzip = (istream_gzip_t *)base;
-	int ret;
-
-	for (;;) {
-		ret = istream_precache(wrapped);
-		if (ret != 0)
-			return ret;
-
-		gzip->strm.avail_in = (uInt)wrapped->buffer_used;
-		gzip->strm.avail_out = (uInt)(BUFSZ - base->buffer_used);
-
-		gzip->strm.next_in = wrapped->buffer;
-		gzip->strm.next_out = base->buffer + base->buffer_used;
-
-		ret = inflate(&gzip->strm, Z_NO_FLUSH);
-
-		wrapped->buffer_offset = wrapped->buffer_used -
-					 gzip->strm.avail_in;
-
-		base->buffer_used = BUFSZ - gzip->strm.avail_out;
-
-		if (ret == Z_BUF_ERROR)
-			break;
-
-		if (ret == Z_STREAM_END) {
-			base->eof = true;
-			break;
-		}
-
-		if (ret != Z_OK) {
-			fprintf(stderr,
-				"%s: internal error in gzip decoder.\n",
-				wrapped->get_filename(wrapped));
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
-static void cleanup(istream_comp_t *base)
-{
-	istream_gzip_t *gzip = (istream_gzip_t *)base;
-
-	inflateEnd(&gzip->strm);
-}
-
-istream_comp_t *istream_gzip_create(const char *filename)
-{
-	istream_gzip_t *gzip = calloc(1, sizeof(*gzip));
-	istream_comp_t *base = (istream_comp_t *)gzip;
-	int ret;
-
-	if (gzip == NULL) {
-		fprintf(stderr, "%s: creating gzip decoder: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	ret = inflateInit2(&gzip->strm, 16 + 15);
-	if (ret != Z_OK) {
-		fprintf(stderr,
-			"%s: internal error creating gzip reader.\n",
-			filename);
-		free(gzip);
-		return NULL;
-	}
-
-	((istream_t *)base)->precache = precache;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/uncompress/istream_compressor.c b/lib/io/uncompress/istream_compressor.c
deleted file mode 100644
index d4e1aea..0000000
--- a/lib/io/uncompress/istream_compressor.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * istream_compressor.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-static const char *comp_get_filename(istream_t *strm)
-{
-	istream_comp_t *comp = (istream_comp_t *)strm;
-
-	return comp->wrapped->get_filename(comp->wrapped);
-}
-
-static void comp_destroy(sqfs_object_t *obj)
-{
-	istream_comp_t *comp = (istream_comp_t *)obj;
-
-	comp->cleanup(comp);
-	sqfs_drop(comp->wrapped);
-	free(comp);
-}
-
-istream_t *istream_compressor_create(istream_t *strm, int comp_id)
-{
-	istream_comp_t *comp = NULL;
-	istream_t *base;
-
-	switch (comp_id) {
-	case IO_COMPRESSOR_GZIP:
-#ifdef WITH_GZIP
-		comp = istream_gzip_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_XZ:
-#ifdef WITH_XZ
-		comp = istream_xz_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_ZSTD:
-#if defined(WITH_ZSTD) && defined(HAVE_ZSTD_STREAM)
-		comp = istream_zstd_create(strm->get_filename(strm));
-#endif
-		break;
-	case IO_COMPRESSOR_BZIP2:
-#ifdef WITH_BZIP2
-		comp = istream_bzip2_create(strm->get_filename(strm));
-#endif
-		break;
-	default:
-		break;
-	}
-
-	if (comp == NULL)
-		return NULL;
-
-	sqfs_object_init(comp, comp_destroy, NULL);
-
-	comp->wrapped = sqfs_grab(strm);
-
-	base = (istream_t *)comp;
-	base->get_filename = comp_get_filename;
-	base->buffer = comp->uncompressed;
-	base->eof = false;
-	return base;
-}
diff --git a/lib/io/uncompress/xz.c b/lib/io/uncompress/xz.c
deleted file mode 100644
index 0fd9ce6..0000000
--- a/lib/io/uncompress/xz.c
+++ /dev/null
@@ -1,96 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * xz.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <lzma.h>
-
-typedef struct {
-	istream_comp_t base;
-
-	lzma_stream strm;
-} istream_xz_t;
-
-static int precache(istream_t *base)
-{
-	istream_xz_t *xz = (istream_xz_t *)base;
-	istream_t *wrapped = ((istream_comp_t *)base)->wrapped;
-	lzma_action action;
-	lzma_ret ret_xz;
-	int ret;
-
-	for (;;) {
-		ret = istream_precache(wrapped);
-		if (ret != 0)
-			return ret;
-
-		action = wrapped->eof ? LZMA_FINISH : LZMA_RUN;
-
-		xz->strm.avail_in = wrapped->buffer_used;
-		xz->strm.next_in = wrapped->buffer;
-
-		xz->strm.avail_out = BUFSZ - base->buffer_used;
-		xz->strm.next_out = base->buffer + base->buffer_used;
-
-		ret_xz = lzma_code(&xz->strm, action);
-
-		base->buffer_used = BUFSZ - xz->strm.avail_out;
-		wrapped->buffer_offset = wrapped->buffer_used -
-					 xz->strm.avail_in;
-
-		if (ret_xz == LZMA_BUF_ERROR)
-			break;
-
-		if (ret_xz == LZMA_STREAM_END) {
-			base->eof = true;
-			break;
-		}
-
-		if (ret_xz != LZMA_OK) {
-			fprintf(stderr,
-				"%s: internal error in xz decoder.\n",
-				wrapped->get_filename(wrapped));
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
-static void cleanup(istream_comp_t *base)
-{
-	istream_xz_t *xz = (istream_xz_t *)base;
-
-	lzma_end(&xz->strm);
-}
-
-istream_comp_t *istream_xz_create(const char *filename)
-{
-	istream_xz_t *xz = calloc(1, sizeof(*xz));
-	istream_comp_t *base = (istream_comp_t *)xz;
-	sqfs_u64 memlimit = 65 * 1024 * 1024;
-	lzma_ret ret_xz;
-
-	if (xz == NULL) {
-		fprintf(stderr, "%s: creating xz decoder: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	ret_xz = lzma_stream_decoder(&xz->strm, memlimit, LZMA_CONCATENATED);
-
-	if (ret_xz != LZMA_OK) {
-		fprintf(stderr,
-			"%s: error initializing xz decoder.\n",
-			filename);
-		free(xz);
-		return NULL;
-	}
-
-	((istream_t *)base)->precache = precache;
-	base->cleanup = cleanup;
-	return base;
-}
diff --git a/lib/io/uncompress/zstd.c b/lib/io/uncompress/zstd.c
deleted file mode 100644
index fd22cbf..0000000
--- a/lib/io/uncompress/zstd.c
+++ /dev/null
@@ -1,81 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * zstd.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "../internal.h"
-
-#include <zstd.h>
-
-#ifdef HAVE_ZSTD_STREAM
-typedef struct {
-	istream_comp_t base;
-
-	ZSTD_DStream* strm;
-} istream_zstd_t;
-
-static int precache(istream_t *base)
-{
-	istream_zstd_t *zstd = (istream_zstd_t *)base;
-	istream_t *wrapped = ((istream_comp_t *)base)->wrapped;
-	ZSTD_outBuffer out;
-	ZSTD_inBuffer in;
-	size_t ret;
-
-	if (istream_precache(wrapped))
-		return -1;
-
-	memset(&in, 0, sizeof(in));
-	memset(&out, 0, sizeof(out));
-
-	in.src = wrapped->buffer;
-	in.size = wrapped->buffer_used;
-
-	out.dst = ((istream_comp_t *)base)->uncompressed + base->buffer_used;
-	out.size = BUFSZ - base->buffer_used;
-
-	ret = ZSTD_decompressStream(zstd->strm, &out, &in);
-
-	if (ZSTD_isError(ret)) {
-		fprintf(stderr, "%s: error in zstd decoder.\n",
-			wrapped->get_filename(wrapped));
-		return -1;
-	}
-
-	wrapped->buffer_offset = in.pos;
-	base->buffer_used += out.pos;
-	return 0;
-}
-
-static void cleanup(istream_comp_t *base)
-{
-	istream_zstd_t *zstd = (istream_zstd_t *)base;
-
-	ZSTD_freeDStream(zstd->strm);
-}
-
-istream_comp_t *istream_zstd_create(const char *filename)
-{
-	istream_zstd_t *zstd = calloc(1, sizeof(*zstd));
-	istream_comp_t *base = (istream_comp_t *)zstd;
-
-	if (zstd == NULL) {
-		fprintf(stderr, "%s: creating zstd decoder: %s.\n",
-			filename, strerror(errno));
-		return NULL;
-	}
-
-	zstd->strm = ZSTD_createDStream();
-	if (zstd->strm == NULL) {
-		fprintf(stderr, "%s: error creating zstd decoder.\n",
-			filename);
-		free(zstd);
-		return NULL;
-	}
-
-	((istream_t *)base)->precache = precache;
-	base->cleanup = cleanup;
-	return base;
-}
-#endif /* HAVE_ZSTD_STREAM */
diff --git a/lib/io/xfrm.c b/lib/io/xfrm.c
deleted file mode 100644
index 22fd953..0000000
--- a/lib/io/xfrm.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * compressor.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "internal.h"
-
-int io_compressor_id_from_name(const char *name)
-{
-	if (strcmp(name, "gzip") == 0)
-		return IO_COMPRESSOR_GZIP;
-
-	if (strcmp(name, "xz") == 0)
-		return IO_COMPRESSOR_XZ;
-
-	if (strcmp(name, "zstd") == 0)
-		return IO_COMPRESSOR_ZSTD;
-
-	if (strcmp(name, "bzip2") == 0)
-		return IO_COMPRESSOR_BZIP2;
-
-	return -1;
-}
-
-const char *io_compressor_name_from_id(int id)
-{
-	if (id == IO_COMPRESSOR_GZIP)
-		return "gzip";
-
-	if (id == IO_COMPRESSOR_XZ)
-		return "xz";
-
-	if (id == IO_COMPRESSOR_ZSTD)
-		return "zstd";
-
-	if (id == IO_COMPRESSOR_BZIP2)
-		return "bzip2";
-
-	return NULL;
-}
-
-bool io_compressor_exists(int id)
-{
-	switch (id) {
-#ifdef WITH_GZIP
-	case IO_COMPRESSOR_GZIP:
-		return true;
-#endif
-#ifdef WITH_XZ
-	case IO_COMPRESSOR_XZ:
-		return true;
-#endif
-#if defined(WITH_ZSTD) && defined(HAVE_ZSTD_STREAM)
-	case IO_COMPRESSOR_ZSTD:
-		return true;
-#endif
-#ifdef WITH_BZIP2
-	case IO_COMPRESSOR_BZIP2:
-		return true;
-#endif
-	default:
-		break;
-	}
-
-	return false;
-}
diff --git a/lib/io/xfrm/istream.c b/lib/io/xfrm/istream.c
new file mode 100644
index 0000000..4a1ad77
--- /dev/null
+++ b/lib/io/xfrm/istream.c
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct istream_xfrm_t {
+	istream_t base;
+
+	istream_t *wrapped;
+	xfrm_stream_t *xfrm;
+
+	sqfs_u8 uncompressed[BUFSZ];
+} istream_xfrm_t;
+
+static int xfrm_precache(istream_t *base)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)base;
+	int ret;
+
+	ret = istream_precache(xfrm->wrapped);
+	if (ret != 0)
+		return ret;
+
+	for (;;) {
+		const sqfs_u32 in_sz = xfrm->wrapped->buffer_used;
+		const sqfs_u32 out_sz = sizeof(xfrm->uncompressed);
+		sqfs_u32 in_off = 0, out_off = base->buffer_used;
+		int mode = XFRM_STREAM_FLUSH_NONE;
+
+		if (xfrm->wrapped->eof)
+			mode = XFRM_STREAM_FLUSH_FULL;
+
+		ret = xfrm->xfrm->process_data(xfrm->xfrm,
+					       xfrm->wrapped->buffer, in_sz,
+					       base->buffer + out_off,
+					       out_sz - out_off,
+					       &in_off, &out_off, mode);
+
+		if (ret == XFRM_STREAM_ERROR) {
+			fprintf(stderr, "%s: internal error in decompressor.\n",
+				base->get_filename(base));
+			return -1;
+		}
+
+		base->buffer_used = out_off;
+		xfrm->wrapped->buffer_offset = in_off;
+
+		if (ret == XFRM_STREAM_BUFFER_FULL || out_off >= out_sz)
+			break;
+
+		ret = istream_precache(xfrm->wrapped);
+		if (ret != 0)
+			return ret;
+
+		if (xfrm->wrapped->eof && xfrm->wrapped->buffer_used == 0) {
+			if (base->buffer_used == 0)
+				base->eof = true;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static const char *xfrm_get_filename(istream_t *strm)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	return xfrm->wrapped->get_filename(xfrm->wrapped);
+}
+
+static void xfrm_destroy(sqfs_object_t *obj)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)obj;
+
+	sqfs_drop(xfrm->xfrm);
+	sqfs_drop(xfrm->wrapped);
+	free(xfrm);
+}
+
+istream_t *istream_xfrm_create(istream_t *strm, xfrm_stream_t *xfrm)
+{
+	istream_xfrm_t *stream = calloc(1, sizeof(*stream));
+	istream_t *base = (istream_t *)stream;
+
+	if (stream == NULL)
+		goto fail;
+
+	sqfs_object_init(stream, xfrm_destroy, NULL);
+
+	stream->wrapped = sqfs_grab(strm);
+	stream->xfrm = sqfs_grab(xfrm);
+
+	base->precache = xfrm_precache;
+	base->get_filename = xfrm_get_filename;
+	base->buffer = stream->uncompressed;
+	base->eof = false;
+	return base;
+fail:
+	fprintf(stderr, "%s: error initializing decompressor stream.\n",
+		strm->get_filename(strm));
+	return NULL;
+}
diff --git a/lib/io/xfrm/ostream.c b/lib/io/xfrm/ostream.c
new file mode 100644
index 0000000..bd94515
--- /dev/null
+++ b/lib/io/xfrm/ostream.c
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct ostream_xfrm_t {
+	ostream_t base;
+
+	ostream_t *wrapped;
+	xfrm_stream_t *xfrm;
+
+	size_t inbuf_used;
+
+	sqfs_u8 inbuf[BUFSZ];
+	sqfs_u8 outbuf[BUFSZ];
+} ostream_xfrm_t;
+
+static int flush_inbuf(ostream_xfrm_t *xfrm, bool finish)
+{
+	const sqfs_u32 avail_out = sizeof(xfrm->outbuf);
+	const sqfs_u32 avail_in = xfrm->inbuf_used;
+	const int mode = finish ? XFRM_STREAM_FLUSH_FULL :
+		XFRM_STREAM_FLUSH_NONE;
+	sqfs_u32 off_in = 0, off_out = 0;
+	int ret;
+
+	while (finish || off_in < avail_in) {
+		ret = xfrm->xfrm->process_data(xfrm->xfrm,
+					       xfrm->inbuf + off_in,
+					       avail_in - off_in,
+					       xfrm->outbuf + off_out,
+					       avail_out - off_out,
+					       &off_in, &off_out, mode);
+
+		if (ret == XFRM_STREAM_ERROR) {
+			fprintf(stderr,
+				"%s: internal error in compressor.\n",
+				xfrm->wrapped->get_filename(xfrm->wrapped));
+			return -1;
+		}
+
+		if (ostream_append(xfrm->wrapped, xfrm->outbuf, off_out))
+			return -1;
+
+		off_out = 0;
+
+		if (ret == XFRM_STREAM_END)
+			break;
+	}
+
+	if (off_out > 0) {
+		if (ostream_append(xfrm->wrapped, xfrm->outbuf, off_out))
+			return -1;
+	}
+
+	if (off_in < avail_in) {
+		memmove(xfrm->inbuf, xfrm->inbuf + off_in, avail_in - off_in);
+		xfrm->inbuf_used -= off_in;
+	} else {
+		xfrm->inbuf_used = 0;
+	}
+
+	return 0;
+}
+
+static int xfrm_append(ostream_t *strm, const void *data, size_t size)
+{
+	ostream_xfrm_t *xfrm = (ostream_xfrm_t *)strm;
+	size_t diff;
+
+	while (size > 0) {
+		if (xfrm->inbuf_used >= BUFSZ) {
+			if (flush_inbuf(xfrm, false))
+				return -1;
+		}
+
+		diff = BUFSZ - xfrm->inbuf_used;
+
+		if (diff > size)
+			diff = size;
+
+		memcpy(xfrm->inbuf + xfrm->inbuf_used, data, diff);
+
+		xfrm->inbuf_used += diff;
+		data = (const char *)data + diff;
+		size -= diff;
+	}
+
+	return 0;
+}
+
+static int xfrm_flush(ostream_t *strm)
+{
+	ostream_xfrm_t *xfrm = (ostream_xfrm_t *)strm;
+
+	if (xfrm->inbuf_used > 0) {
+		if (flush_inbuf(xfrm, true))
+			return -1;
+	}
+
+	return xfrm->wrapped->flush(xfrm->wrapped);
+}
+
+static const char *xfrm_get_filename(ostream_t *strm)
+{
+	ostream_xfrm_t *xfrm = (ostream_xfrm_t *)strm;
+
+	return xfrm->wrapped->get_filename(xfrm->wrapped);
+}
+
+static void xfrm_destroy(sqfs_object_t *obj)
+{
+	ostream_xfrm_t *xfrm = (ostream_xfrm_t *)obj;
+
+	sqfs_drop(xfrm->wrapped);
+	sqfs_drop(xfrm->xfrm);
+	free(xfrm);
+}
+
+ostream_t *ostream_xfrm_create(ostream_t *strm, xfrm_stream_t *xfrm)
+{
+	ostream_xfrm_t *stream = calloc(1, sizeof(*stream));
+	ostream_t *base = (ostream_t *)stream;
+
+	if (stream == NULL)
+		goto fail;
+
+	sqfs_object_init(stream, xfrm_destroy, NULL);
+
+	stream->wrapped = sqfs_grab(strm);
+	stream->xfrm = sqfs_grab(xfrm);
+	stream->inbuf_used = 0;
+	base->append = xfrm_append;
+	base->flush = xfrm_flush;
+	base->get_filename = xfrm_get_filename;
+	return base;
+fail:
+	fprintf(stderr, "%s: error initializing compressor.\n",
+		strm->get_filename(strm));
+	return NULL;
+}