22 files changed, 2143 insertions, 0 deletions

diff --git a/lib/io/Makemodule.am b/lib/io/Makemodule.am
new file mode 100644
index 0000000..63ce958
--- /dev/null
+++ b/lib/io/Makemodule.am
@@ -0,0 +1,45 @@
+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_CFLAGS = $(AM_CFLAGS) $(ZLIB_CFLAGS) $(XZ_CFLAGS)
+libio_a_CFLAGS += $(ZSTD_CFLAGS) $(BZIP2_CFLAGS)
+libio_a_CPPFLAGS = $(AM_CPPFLAGS)
+
+if WINDOWS
+libio_a_SOURCES += lib/io/win32/ostream.c
+libio_a_SOURCES += lib/io/win32/istream.c
+libio_a_CFLAGS += -DWINVER=0x0600 -D_WIN32_WINNT=0x0600
+else
+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
new file mode 100644
index 0000000..7f0c09a
--- /dev/null
+++ b/lib/io/compress/bzip2.c
@@ -0,0 +1,96 @@
+/* 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
new file mode 100644
index 0000000..b73a258
--- /dev/null
+++ b/lib/io/compress/gzip.c
@@ -0,0 +1,92 @@
+/* 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
new file mode 100644
index 0000000..314ce6b
--- /dev/null
+++ b/lib/io/compress/ostream_compressor.c
@@ -0,0 +1,108 @@
+/* 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_destroy(comp->wrapped);
+	free(comp);
+}
+
+ostream_t *ostream_compressor_create(ostream_t *strm, int comp_id)
+{
+	ostream_comp_t *comp = NULL;
+	sqfs_object_t *obj;
+	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;
+
+	comp->wrapped = strm;
+	comp->inbuf_used = 0;
+
+	base = (ostream_t *)comp;
+	base->append = comp_append;
+	base->flush = comp_flush;
+	base->get_filename = comp_get_filename;
+
+	obj = (sqfs_object_t *)comp;
+	obj->destroy = comp_destroy;
+	return base;
+}
diff --git a/lib/io/compress/xz.c b/lib/io/compress/xz.c
new file mode 100644
index 0000000..65bda0b
--- /dev/null
+++ b/lib/io/compress/xz.c
@@ -0,0 +1,80 @@
+/* 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
new file mode 100644
index 0000000..c0b002e
--- /dev/null
+++ b/lib/io/compress/zstd.c
@@ -0,0 +1,94 @@
+/* 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/get_line.c b/lib/io/get_line.c
new file mode 100644
index 0000000..f7e0b59
--- /dev/null
+++ b/lib/io/get_line.c
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * get_line.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "internal.h"
+
+static void ltrim(char *buffer)
+{
+	size_t i = 0;
+
+	while (isspace(buffer[i]))
+		++i;
+
+	if (i > 0)
+		memmove(buffer, buffer + i, strlen(buffer + i) + 1);
+}
+
+static void rtrim(char *buffer)
+{
+	size_t i = strlen(buffer);
+
+	while (i > 0 && isspace(buffer[i - 1]))
+		--i;
+
+	buffer[i] = '\0';
+}
+
+static size_t trim(char *buffer, int flags)
+{
+	if (flags & ISTREAM_LINE_LTRIM)
+		ltrim(buffer);
+
+	if (flags & ISTREAM_LINE_RTRIM)
+		rtrim(buffer);
+
+	return strlen(buffer);
+}
+
+int istream_get_line(istream_t *strm, char **out,
+		     size_t *line_num, int flags)
+{
+	char *line = NULL, *new;
+	size_t i, line_len = 0;
+	bool have_line = false;
+
+	*out = NULL;
+
+	for (;;) {
+		if (istream_precache(strm))
+			return -1;
+
+		if (strm->buffer_used == 0) {
+			if (line_len == 0)
+				goto out_eof;
+
+			line_len = trim(line, flags);
+
+			if (line_len == 0 &&
+			    (flags & ISTREAM_LINE_SKIP_EMPTY)) {
+				goto out_eof;
+			}
+			break;
+		}
+
+		for (i = 0; i < strm->buffer_used; ++i) {
+			if (strm->buffer[i] == '\n')
+				break;
+		}
+
+		if (i < strm->buffer_used) {
+			have_line = true;
+			strm->buffer_offset = i + 1;
+
+			if (i > 0 && strm->buffer[i - 1] == '\r')
+				--i;
+		} else {
+			strm->buffer_offset = i;
+		}
+
+		new = realloc(line, line_len + i + 1);
+		if (new == NULL)
+			goto fail_errno;
+
+		line = new;
+		memcpy(line + line_len, strm->buffer, i);
+		line_len += i;
+		line[line_len] = '\0';
+
+		if (have_line) {
+			line_len = trim(line, flags);
+
+			if (line_len == 0 &&
+			    (flags & ISTREAM_LINE_SKIP_EMPTY)) {
+				free(line);
+				line = NULL;
+				have_line = false;
+				*line_num += 1;
+				continue;
+			}
+			break;
+		}
+	}
+
+	*out = line;
+	return 0;
+fail_errno:
+	fprintf(stderr, "%s: " PRI_SZ ": %s.\n", strm->get_filename(strm),
+		*line_num, strerror(errno));
+	free(line);
+	*out = NULL;
+	return -1;
+out_eof:
+	free(line);
+	*out = NULL;
+	return 1;
+}
diff --git a/lib/io/internal.h b/lib/io/internal.h
new file mode 100644
index 0000000..4ac38f5
--- /dev/null
+++ b/lib/io/internal.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * internal.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef INTERNAL_H
+#define INTERNAL_H
+
+#include "config.h"
+#include "compat.h"
+#include "io/istream.h"
+#include "io/ostream.h"
+#include "io/file.h"
+#include "io/xfrm.h"
+#include "io/std.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+
+#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/istream.c b/lib/io/istream.c
new file mode 100644
index 0000000..6318a23
--- /dev/null
+++ b/lib/io/istream.c
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "internal.h"
+
+
+sqfs_s32 istream_read(istream_t *strm, void *data, size_t size)
+{
+	sqfs_s32 total = 0;
+	size_t diff;
+
+	if (size > 0x7FFFFFFF)
+		size = 0x7FFFFFFF;
+
+	while (size > 0) {
+		if (strm->buffer_offset >= strm->buffer_used) {
+			if (istream_precache(strm))
+				return -1;
+
+			if (strm->buffer_used == 0)
+				break;
+		}
+
+		diff = strm->buffer_used - strm->buffer_offset;
+		if (diff > size)
+			diff = size;
+
+		memcpy(data, strm->buffer + strm->buffer_offset, diff);
+		data = (char *)data + diff;
+		strm->buffer_offset += diff;
+		size -= diff;
+		total += diff;
+	}
+
+	return total;
+}
+
+int istream_precache(istream_t *strm)
+{
+	if (strm->buffer_offset >= strm->buffer_used) {
+		strm->buffer_offset = 0;
+		strm->buffer_used = 0;
+	} else if (strm->buffer_offset > 0) {
+		memmove(strm->buffer,
+			strm->buffer + strm->buffer_offset,
+			strm->buffer_used - strm->buffer_offset);
+
+		strm->buffer_used -= strm->buffer_offset;
+		strm->buffer_offset = 0;
+	}
+
+	if (strm->eof)
+		return 0;
+
+	return strm->precache(strm);
+}
+
+const char *istream_get_filename(istream_t *strm)
+{
+	return strm->get_filename(strm);
+}
+
+int istream_skip(istream_t *strm, sqfs_u64 size)
+{
+	size_t diff;
+
+	while (size > 0) {
+		if (strm->buffer_offset >= strm->buffer_used) {
+			if (istream_precache(strm))
+				return -1;
+
+			if (strm->buffer_used == 0) {
+				fprintf(stderr, "%s: unexpected end-of-file\n",
+					strm->get_filename(strm));
+				return -1;
+			}
+		}
+
+		diff = strm->buffer_used - strm->buffer_offset;
+		if ((sqfs_u64)diff > size)
+			diff = size;
+
+		strm->buffer_offset += diff;
+		size -= diff;
+	}
+
+	return 0;
+}
diff --git a/lib/io/ostream.c b/lib/io/ostream.c
new file mode 100644
index 0000000..afe76e8
--- /dev/null
+++ b/lib/io/ostream.c
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "internal.h"
+
+
+static int append_sparse_fallback(ostream_t *strm, size_t size)
+{
+	char buffer[512];
+	size_t diff;
+
+	memset(buffer, 0, sizeof(buffer));
+
+	while (size > 0) {
+		diff = size < sizeof(buffer) ? size : sizeof(buffer);
+
+		if (strm->append(strm, buffer, diff))
+			return -1;
+
+		size -= diff;
+	}
+
+	return 0;
+}
+
+
+int ostream_append(ostream_t *strm, const void *data, size_t size)
+{
+	return strm->append(strm, data, size);
+}
+
+int ostream_append_sparse(ostream_t *strm, size_t size)
+{
+	if (strm->append_sparse == NULL)
+		return append_sparse_fallback(strm, size);
+
+	return strm->append_sparse(strm, size);
+}
+
+int ostream_flush(ostream_t *strm)
+{
+	return strm->flush(strm);
+}
+
+const char *ostream_get_filename(ostream_t *strm)
+{
+	return strm->get_filename(strm);
+}
+
+sqfs_s32 ostream_append_from_istream(ostream_t *out, istream_t *in,
+				     sqfs_u32 size)
+{
+	sqfs_s32 total = 0;
+	size_t diff;
+
+	if (size > 0x7FFFFFFF)
+		size = 0x7FFFFFFF;
+
+	while (size > 0) {
+		if (in->buffer_offset >= in->buffer_used) {
+			if (istream_precache(in))
+				return -1;
+
+			if (in->buffer_used == 0)
+				break;
+		}
+
+		diff = in->buffer_used - in->buffer_offset;
+		if (diff > size)
+			diff = size;
+
+		if (out->append(out, in->buffer + in->buffer_offset, diff))
+			return -1;
+
+		in->buffer_offset += diff;
+		size -= diff;
+		total += diff;
+	}
+
+	return total;
+}
diff --git a/lib/io/printf.c b/lib/io/printf.c
new file mode 100644
index 0000000..3850487
--- /dev/null
+++ b/lib/io/printf.c
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * printf.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "internal.h"
+
+int ostream_printf(ostream_t *strm, const char *fmt, ...)
+{
+	char *temp = NULL;
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+
+	ret = vasprintf(&temp, fmt, ap);
+	if (ret < 0)
+		perror(strm->get_filename(strm));
+	va_end(ap);
+
+	if (ret < 0)
+		return -1;
+
+	if (strm->append(strm, temp, ret))
+		ret = -1;
+
+	free(temp);
+	return ret;
+}
diff --git a/lib/io/uncompress/autodetect.c b/lib/io/uncompress/autodetect.c
new file mode 100644
index 0000000..dde33c8
--- /dev/null
+++ b/lib/io/uncompress/autodetect.c
@@ -0,0 +1,55 @@
+/* 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
new file mode 100644
index 0000000..3b44383
--- /dev/null
+++ b/lib/io/uncompress/bzip2.c
@@ -0,0 +1,118 @@
+/* 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
new file mode 100644
index 0000000..1d6274c
--- /dev/null
+++ b/lib/io/uncompress/gzip.c
@@ -0,0 +1,106 @@
+/* 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;
+	size_t avail_in, avail_out;
+	int ret;
+
+	for (;;) {
+		ret = istream_precache(wrapped);
+		if (ret != 0)
+			return ret;
+
+		avail_in = wrapped->buffer_used;
+		avail_out = BUFSZ - base->buffer_used;
+
+		if (sizeof(size_t) > sizeof(uInt)) {
+			gzip->strm.avail_in = ~((uInt)0U);
+			gzip->strm.avail_out = ~((uInt)0U);
+
+			if ((size_t)gzip->strm.avail_in > avail_in)
+				gzip->strm.avail_in = (uInt)avail_in;
+
+			if ((size_t)gzip->strm.avail_out > avail_out)
+				gzip->strm.avail_out = (uInt)avail_out;
+		} else {
+			gzip->strm.avail_in = (uInt)avail_in;
+			gzip->strm.avail_out = (uInt)avail_out;
+		}
+
+		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
new file mode 100644
index 0000000..ab9ad8b
--- /dev/null
+++ b/lib/io/uncompress/istream_compressor.c
@@ -0,0 +1,69 @@
+/* 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_destroy(comp->wrapped);
+	free(comp);
+}
+
+istream_t *istream_compressor_create(istream_t *strm, int comp_id)
+{
+	istream_comp_t *comp = NULL;
+	sqfs_object_t *obj;
+	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;
+
+	comp->wrapped = strm;
+
+	base = (istream_t *)comp;
+	base->get_filename = comp_get_filename;
+	base->buffer = comp->uncompressed;
+	base->eof = false;
+
+	obj = (sqfs_object_t *)comp;
+	obj->destroy = comp_destroy;
+	return base;
+}
diff --git a/lib/io/uncompress/xz.c b/lib/io/uncompress/xz.c
new file mode 100644
index 0000000..0fd9ce6
--- /dev/null
+++ b/lib/io/uncompress/xz.c
@@ -0,0 +1,96 @@
+/* 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
new file mode 100644
index 0000000..fd22cbf
--- /dev/null
+++ b/lib/io/uncompress/zstd.c
@@ -0,0 +1,81 @@
+/* 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/unix/istream.c b/lib/io/unix/istream.c
new file mode 100644
index 0000000..5898141
--- /dev/null
+++ b/lib/io/unix/istream.c
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct {
+	istream_t base;
+	char *path;
+	int fd;
+	bool eof;
+
+	sqfs_u8 buffer[BUFSZ];
+} file_istream_t;
+
+static int file_precache(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+	ssize_t ret;
+	size_t diff;
+
+	while (strm->buffer_used < sizeof(file->buffer)) {
+		diff = sizeof(file->buffer) - strm->buffer_used;
+
+		ret = read(file->fd, strm->buffer + strm->buffer_used, diff);
+
+		if (ret == 0) {
+			file->eof = true;
+			break;
+		}
+
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+
+			perror(file->path);
+			return -1;
+		}
+
+		strm->buffer_used += ret;
+	}
+
+	return 0;
+}
+
+static const char *file_get_filename(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	return file->path;
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_istream_t *file = (file_istream_t *)obj;
+
+	if (file->fd != STDIN_FILENO)
+		close(file->fd);
+
+	free(file->path);
+	free(file);
+}
+
+istream_t *istream_open_file(const char *path)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	file->fd = open(path, O_RDONLY);
+	if (file->fd < 0) {
+		perror(path);
+		goto fail_path;
+	}
+
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(file);
+	return NULL;
+}
+
+istream_t *istream_open_stdin(void)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+
+	if (file == NULL)
+		goto fail;
+
+	file->path = strdup("stdin");
+	if (file->path == NULL)
+		goto fail;
+
+	file->fd = STDIN_FILENO;
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail:
+	perror("creating file wrapper for stdin");
+	free(file);
+	return NULL;
+}
diff --git a/lib/io/unix/ostream.c b/lib/io/unix/ostream.c
new file mode 100644
index 0000000..17f1998
--- /dev/null
+++ b/lib/io/unix/ostream.c
@@ -0,0 +1,173 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct {
+	ostream_t base;
+	char *path;
+	int fd;
+
+	off_t sparse_count;
+	off_t size;
+} file_ostream_t;
+
+static int file_append(ostream_t *strm, const void *data, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+	ssize_t ret;
+
+	if (size == 0)
+		return 0;
+
+	if (file->sparse_count > 0) {
+		if (lseek(file->fd, file->sparse_count, SEEK_CUR) == (off_t)-1)
+			goto fail_errno;
+
+		file->sparse_count = 0;
+	}
+
+	while (size > 0) {
+		ret = write(file->fd, data, size);
+
+		if (ret == 0) {
+			fprintf(stderr, "%s: truncated data write.\n",
+				file->path);
+			return -1;
+		}
+
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			goto fail_errno;
+		}
+
+		file->size += ret;
+		size -= ret;
+		data = (const char *)data + ret;
+	}
+
+	return 0;
+fail_errno:
+	perror(file->path);
+	return -1;
+}
+
+static int file_append_sparse(ostream_t *strm, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	file->sparse_count += size;
+	file->size += size;
+	return 0;
+}
+
+static int file_flush(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	if (file->sparse_count > 0) {
+		if (ftruncate(file->fd, file->size) != 0)
+			goto fail;
+	}
+
+	if (fsync(file->fd) != 0) {
+		if (errno == EINVAL)
+			return 0;
+		goto fail;
+	}
+
+	return 0;
+fail:
+	perror(file->path);
+	return -1;
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_ostream_t *file = (file_ostream_t *)obj;
+
+	if (file->fd != STDOUT_FILENO)
+		close(file->fd);
+
+	free(file->path);
+	free(file);
+}
+
+static const char *file_get_filename(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	return file->path;
+}
+
+ostream_t *ostream_open_file(const char *path, int flags)
+{
+	file_ostream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	ostream_t *strm = (ostream_t *)file;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	if (flags & OSTREAM_OPEN_OVERWRITE) {
+		file->fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	} else {
+		file->fd = open(path, O_WRONLY | O_CREAT | O_EXCL, 0644);
+	}
+
+	if (file->fd < 0) {
+		perror(path);
+		goto fail_path;
+	}
+
+	if (flags & OSTREAM_OPEN_SPARSE)
+		strm->append_sparse = file_append_sparse;
+
+	strm->append = file_append;
+	strm->flush = file_flush;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(file);
+	return NULL;
+}
+
+ostream_t *ostream_open_stdout(void)
+{
+	file_ostream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	ostream_t *strm = (ostream_t *)file;
+
+	if (file == NULL)
+		goto fail;
+
+	file->path = strdup("stdout");
+	if (file->path == NULL)
+		goto fail;
+
+	file->fd = STDOUT_FILENO;
+	strm->append = file_append;
+	strm->flush = file_flush;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail:
+	perror("creating file wrapper for stdout");
+	free(file);
+	return NULL;
+}
diff --git a/lib/io/win32/istream.c b/lib/io/win32/istream.c
new file mode 100644
index 0000000..b591584
--- /dev/null
+++ b/lib/io/win32/istream.c
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+typedef struct {
+	istream_t base;
+	char *path;
+	HANDLE hnd;
+
+	sqfs_u8 buffer[BUFSZ];
+} file_istream_t;
+
+static int file_precache(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+	DWORD diff, actual;
+	HANDLE hnd;
+
+	hnd = file->path == NULL ? GetStdHandle(STD_INPUT_HANDLE) : file->hnd;
+
+	while (strm->buffer_used < sizeof(file->buffer)) {
+		diff = sizeof(file->buffer) - strm->buffer_used;
+
+		if (!ReadFile(hnd, strm->buffer + strm->buffer_used,
+			      diff, &actual, NULL)) {
+			DWORD error = GetLastError();
+
+			if (error == ERROR_HANDLE_EOF ||
+			    error == ERROR_BROKEN_PIPE) {
+				strm->eof = true;
+				break;
+			}
+
+			SetLastError(error);
+
+			w32_perror(file->path == NULL ? "stdin" : file->path);
+			return -1;
+		}
+
+		if (actual == 0) {
+			strm->eof = true;
+			break;
+		}
+
+		strm->buffer_used += actual;
+	}
+
+	return 0;
+}
+
+static const char *file_get_filename(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	return file->path == NULL ? "stdin" : file->path;
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_istream_t *file = (file_istream_t *)obj;
+
+	if (file->path != NULL) {
+		CloseHandle(file->hnd);
+		free(file->path);
+	}
+
+	free(file);
+}
+
+istream_t *istream_open_file(const char *path)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+	WCHAR *wpath = NULL;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	wpath = path_to_windows(path);
+	if (wpath == NULL)
+		goto fail_free;
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	file->hnd = CreateFileW(wpath, GENERIC_READ, FILE_SHARE_READ, NULL,
+			       OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+
+	if (file->hnd == INVALID_HANDLE_VALUE) {
+		perror(path);
+		goto fail_path;
+	}
+
+	free(wpath);
+
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(wpath);
+	free(file);
+	return NULL;
+}
+
+istream_t *istream_open_stdin(void)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+
+	if (file == NULL) {
+		perror("stdin");
+		return NULL;
+	}
+
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+}
diff --git a/lib/io/win32/ostream.c b/lib/io/win32/ostream.c
new file mode 100644
index 0000000..2bd78c8
--- /dev/null
+++ b/lib/io/win32/ostream.c
@@ -0,0 +1,197 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+typedef struct {
+	ostream_t base;
+	char *path;
+	HANDLE hnd;
+} file_ostream_t;
+
+static int w32_append(HANDLE hnd, const char *filename,
+		      const void *data, size_t size)
+{
+	DWORD diff;
+
+	while (size > 0) {
+		if (!WriteFile(hnd, data, size, &diff, NULL)) {
+			w32_perror(filename);
+			return -1;
+		}
+
+		size -= diff;
+		data = (const char *)data + diff;
+	}
+
+	return 0;
+}
+
+static int w32_flush(HANDLE hnd, const char *filename)
+{
+	if (!FlushFileBuffers(hnd)) {
+		w32_perror(filename);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*****************************************************************************/
+
+static int file_append(ostream_t *strm, const void *data, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	return w32_append(file->hnd, file->path, data, size);
+}
+
+static int file_append_sparse(ostream_t *strm, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+	LARGE_INTEGER pos;
+
+	pos.QuadPart = size;
+
+	if (!SetFilePointerEx(file->hnd, pos, NULL, FILE_CURRENT))
+		goto fail;
+
+	if (!SetEndOfFile(file->hnd))
+		goto fail;
+
+	return 0;
+fail:
+	w32_perror(file->path);
+	return -1;
+}
+
+static int file_flush(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	return w32_flush(file->hnd, file->path);
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_ostream_t *file = (file_ostream_t *)obj;
+
+	CloseHandle(file->hnd);
+	free(file->path);
+	free(file);
+}
+
+static const char *file_get_filename(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	return file->path;
+}
+
+/*****************************************************************************/
+
+static int stdout_append(ostream_t *strm, const void *data, size_t size)
+{
+	(void)strm;
+	return w32_append(GetStdHandle(STD_OUTPUT_HANDLE), "stdout",
+			  data, size);
+}
+
+static int stdout_flush(ostream_t *strm)
+{
+	(void)strm;
+	return w32_flush(GetStdHandle(STD_OUTPUT_HANDLE), "stdout");
+}
+
+static void stdout_destroy(sqfs_object_t *obj)
+{
+	free(obj);
+}
+
+static const char *stdout_get_filename(ostream_t *strm)
+{
+	(void)strm;
+	return "stdout";
+}
+
+/*****************************************************************************/
+
+ostream_t *ostream_open_file(const char *path, int flags)
+{
+	file_ostream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	ostream_t *strm = (ostream_t *)file;
+	int access_flags, creation_mode;
+	WCHAR *wpath = NULL;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	wpath = path_to_windows(path);
+	if (wpath == NULL)
+		goto fail_free;
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	access_flags = GENERIC_WRITE;
+
+	if (flags & OSTREAM_OPEN_OVERWRITE) {
+		creation_mode = CREATE_ALWAYS;
+	} else {
+		creation_mode = CREATE_NEW;
+	}
+
+	file->hnd = CreateFileW(wpath, access_flags, 0, NULL, creation_mode,
+				FILE_ATTRIBUTE_NORMAL, NULL);
+
+	if (file->hnd == INVALID_HANDLE_VALUE) {
+		w32_perror(path);
+		goto fail_path;
+	}
+
+	free(wpath);
+
+	if (flags & OSTREAM_OPEN_SPARSE)
+		strm->append_sparse = file_append_sparse;
+
+	strm->append = file_append;
+	strm->flush = file_flush;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(file);
+	free(wpath);
+	return NULL;
+}
+
+ostream_t *ostream_open_stdout(void)
+{
+	ostream_t *strm = calloc(1, sizeof(*strm));
+	sqfs_object_t *obj = (sqfs_object_t *)strm;
+
+	if (strm == NULL) {
+		perror("creating stdout file wrapper");
+		return NULL;
+	}
+
+	strm->append = stdout_append;
+	strm->flush = stdout_flush;
+	strm->get_filename = stdout_get_filename;
+	obj->destroy = stdout_destroy;
+	return strm;
+}
diff --git a/lib/io/xfrm.c b/lib/io/xfrm.c
new file mode 100644
index 0000000..22fd953
--- /dev/null
+++ b/lib/io/xfrm.c
@@ -0,0 +1,67 @@
+/* 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;
+}