Cleanup: rename libfstream to libio, split headers

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

10 files changed, 492 insertions, 406 deletions

diff --git a/include/common.h b/include/common.h
index df3017a..ab07461 100644
--- a/include/common.h
+++ b/include/common.h
@@ -20,7 +20,9 @@
 
 #include "simple_writer.h"
 #include "compress_cli.h"
-#include "fstream.h"
+#include "io/ostream.h"
+#include "io/file.h"
+#include "io/std.h"
 #include "compat.h"
 #include "fstree.h"
 #include "tar.h"
diff --git a/include/compat.h b/include/compat.h
index 6b4d83d..8969d6c 100644
--- a/include/compat.h
+++ b/include/compat.h
@@ -8,7 +8,7 @@
 #define COMPAT_H
 
 #include "sqfs/predef.h"
-#include "fstream.h"
+#include "io/ostream.h"
 #include "config.h"
 
 #include <limits.h>
diff --git a/include/fstream.h b/include/fstream.h
deleted file mode 100644
index 0e8905e..0000000
--- a/include/fstream.h
+++ /dev/null
@@ -1,402 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * fstream.h
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#ifndef FSTREAM_H
-#define FSTREAM_H
-
-#include "sqfs/predef.h"
-
-#if defined(__GNUC__) || defined(__clang__)
-#	define PRINTF_ATTRIB(fmt, elipsis)			\
-		__attribute__ ((format (printf, fmt, elipsis)))
-#else
-#	define PRINTF_ATTRIB(fmt, elipsis)
-#endif
-
-/**
- * @struct ostream_t
- *
- * @extends sqfs_object_t
- *
- * @brief An append-only data stream.
- */
-typedef struct ostream_t {
-	sqfs_object_t base;
-
-	int (*append)(struct ostream_t *strm, const void *data, size_t size);
-
-	int (*append_sparse)(struct ostream_t *strm, size_t size);
-
-	int (*flush)(struct ostream_t *strm);
-
-	const char *(*get_filename)(struct ostream_t *strm);
-} ostream_t;
-
-/**
- * @struct istream_t
- *
- * @extends sqfs_object_t
- *
- * @brief A sequential, read-only data stream.
- */
-typedef struct istream_t {
-	sqfs_object_t base;
-
-	size_t buffer_used;
-	size_t buffer_offset;
-	bool eof;
-
-	sqfs_u8 *buffer;
-
-	int (*precache)(struct istream_t *strm);
-
-	const char *(*get_filename)(struct istream_t *strm);
-} istream_t;
-
-
-enum {
-	OSTREAM_OPEN_OVERWRITE = 0x01,
-	OSTREAM_OPEN_SPARSE = 0x02,
-};
-
-enum {
-	ISTREAM_LINE_LTRIM = 0x01,
-	ISTREAM_LINE_RTRIM = 0x02,
-	ISTREAM_LINE_SKIP_EMPTY = 0x04,
-};
-
-enum {
-	/**
-	 * @brief Deflate compressor with gzip headers.
-	 *
-	 * This actually creates a gzip compatible file, including a
-	 * gzip header and trailer.
-	 */
-	FSTREAM_COMPRESSOR_GZIP = 1,
-
-	FSTREAM_COMPRESSOR_XZ = 2,
-
-	FSTREAM_COMPRESSOR_ZSTD = 3,
-
-	FSTREAM_COMPRESSOR_BZIP2 = 4,
-
-	FSTREAM_COMPRESSOR_MIN = 1,
-	FSTREAM_COMPRESSOR_MAX = 4,
-};
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/**
- * @brief Create an output stream that writes to a file.
- *
- * @memberof ostream_t
- *
- * If the file does not yet exist, it is created. If it does exist this
- * function fails, unless the flag OSTREAM_OPEN_OVERWRITE is set, in which
- * case the file is opened and its contents are discarded.
- *
- * If the flag OSTREAM_OPEN_SPARSE is set, the underlying implementation tries
- * to support sparse output files. If the flag is not set, holes will always
- * be filled with zero bytes.
- *
- * @param path A path to the file to open or create.
- * @param flags A combination of flags controling how to open/create the file.
- *
- * @return A pointer to an output stream on success, NULL on failure.
- */
-SQFS_INTERNAL ostream_t *ostream_open_file(const char *path, int flags);
-
-/**
- * @brief Create an output stream that writes to standard output.
- *
- * @memberof ostream_t
- *
- * @return A pointer to an output stream on success, NULL on failure.
- */
-SQFS_INTERNAL ostream_t *ostream_open_stdout(void);
-
-/**
- * @brief Create an input stream that reads from a file.
- *
- * @memberof istream_t
- *
- * @param path A path to the file to open or create.
- *
- * @return A pointer to an output stream on success, NULL on failure.
- */
-SQFS_INTERNAL istream_t *istream_open_file(const char *path);
-
-/**
- * @brief Create an input stream that reads from standard input.
- *
- * @memberof istream_t
- *
- * @return A pointer to an input stream on success, NULL on failure.
- */
-SQFS_INTERNAL istream_t *istream_open_stdin(void);
-
-/**
- * @brief Create an output stream that transparently compresses 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.
- *
- * @param strm A pointer to another stream that should be wrapped.
- * @param comp_id An identifier describing the compressor 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 Create an input stream that transparently uncompresses 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
- * 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.
- *
- * @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);
-
-/**
- * @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 Append a block of data to an output stream.
- *
- * @memberof ostream_t
- *
- * @param strm A pointer to an output stream.
- * @param data A pointer to the data block to append.
- * @param size The number of bytes to append.
- *
- * @return Zero on success, -1 on failure.
- */
-SQFS_INTERNAL int ostream_append(ostream_t *strm, const void *data,
-				 size_t size);
-
-/**
- * @brief Append a number of zero bytes to an output stream.
- *
- * @memberof ostream_t
- *
- * If the unerlying implementation supports sparse files, this function can be
- * used to create a "hole". If the implementation does not support it, a
- * fallback is used that just appends a block of zeros manualy.
- *
- * @param strm A pointer to an output stream.
- * @param size The number of zero bytes to append.
- *
- * @return Zero on success, -1 on failure.
- */
-SQFS_INTERNAL int ostream_append_sparse(ostream_t *strm, size_t size);
-
-/**
- * @brief Process all pending, buffered data and flush it to disk.
- *
- * @memberof ostream_t
- *
- * If the stream performs some kind of transformation (e.g. transparent data
- * compression), flushing caues the wrapped format to insert a termination
- * token. Only call this function when you are absolutely DONE appending data,
- * shortly before destroying the stream.
- *
- * @param strm A pointer to an output stream.
- *
- * @return Zero on success, -1 on failure.
- */
-SQFS_INTERNAL int ostream_flush(ostream_t *strm);
-
-/**
- * @brief Get the underlying filename of a output stream.
- *
- * @memberof ostream_t
- *
- * @param strm The output stream to get the filename from.
- *
- * @return A string holding the underlying filename.
- */
-SQFS_INTERNAL const char *ostream_get_filename(ostream_t *strm);
-
-/**
- * @brief Printf like function that appends to an output stream
- *
- * @memberof ostream_t
- *
- * @param strm The output stream to append to.
- * @param fmt A printf style format string.
- *
- * @return The number of characters written on success, -1 on failure.
- */
-SQFS_INTERNAL int ostream_printf(ostream_t *strm, const char *fmt, ...)
-	PRINTF_ATTRIB(2, 3);
-
-/**
- * @brief Read a line of text from an input stream
- *
- * @memberof istream_t
- *
- * The line returned is allocated using malloc and must subsequently be
- * freed when it is no longer needed. The line itself is always null-terminated
- * and never includes the line break characters (LF or CR-LF).
- *
- * If the flag @ref ISTREAM_LINE_LTRIM is set, leading white space characters
- * are removed. If the flag @ref ISTREAM_LINE_RTRIM is set, trailing white space
- * characters are remvoed.
- *
- * If the flag @ref ISTREAM_LINE_SKIP_EMPTY is set and a line is discovered to
- * be empty (after the optional trimming), the function discards the empty line
- * and retries. The given line_num pointer is used to increment the line
- * number.
- *
- * @param strm A pointer to an input stream.
- * @param out Returns a pointer to a line on success.
- * @param line_num This is incremented if lines are skipped.
- * @param flags A combination of flags controling the functions behaviour.
- *
- * @return Zero on success, a negative value on error, a positive value if
- *         end-of-file was reached without reading any data.
- */
-SQFS_INTERNAL int istream_get_line(istream_t *strm, char **out,
-				   size_t *line_num, int flags);
-
-/**
- * @brief Read data from an input stream
- *
- * @memberof istream_t
- *
- * @param strm A pointer to an input stream.
- * @param data A buffer to read into.
- * @param size The number of bytes to read into the buffer.
- *
- * @return The number of bytes actually read on success, -1 on failure,
- *         0 on end-of-file.
- */
-SQFS_INTERNAL sqfs_s32 istream_read(istream_t *strm, void *data, size_t size);
-
-/**
- * @brief Adjust and refill the internal buffer of an input stream
- *
- * @memberof istream_t
- *
- * This function resets the buffer offset of an input stream (moving any unread
- * data up front if it has to) and calls an internal callback of the input
- * stream to fill the rest of the buffer to the extent possible.
- *
- * @param strm A pointer to an input stream.
- *
- * @return 0 on success, -1 on failure.
- */
-SQFS_INTERNAL int istream_precache(istream_t *strm);
-
-/**
- * @brief Get the underlying filename of an input stream.
- *
- * @memberof istream_t
- *
- * @param strm The input stream to get the filename from.
- *
- * @return A string holding the underlying filename.
- */
-SQFS_INTERNAL const char *istream_get_filename(istream_t *strm);
-
-/**
- * @brief Skip over a number of bytes in an input stream.
- *
- * @memberof istream_t
- *
- * @param strm A pointer to an input stream.
- * @param size The number of bytes to seek forward.
- *
- * @return Zero on success, -1 on failure.
- */
-SQFS_INTERNAL int istream_skip(istream_t *strm, sqfs_u64 size);
-
-/**
- * @brief Read data from an input stream and append it to an output stream
- *
- * @memberof ostream_t
- *
- * @param out A pointer to an output stream to append to.
- * @param in A pointer to an input stream to read from.
- * @param size The number of bytes to copy over.
- *
- * @return The number of bytes copied on success, -1 on failure,
- *         0 on end-of-file.
- */
-SQFS_INTERNAL sqfs_s32 ostream_append_from_istream(ostream_t *out,
-						   istream_t *in,
-						   sqfs_u32 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 fstream_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 *fstream_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 fstream_compressor_exists(int id);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* FSTREAM_H */
diff --git a/include/fstree.h b/include/fstree.h
index 58936d7..3fb4f47 100644
--- a/include/fstree.h
+++ b/include/fstree.h
@@ -15,7 +15,7 @@
 #include <stdio.h>
 
 #include "sqfs/predef.h"
-#include "fstream.h"
+#include "io/istream.h"
 #include "compat.h"
 
 enum {
diff --git a/include/io/file.h b/include/io/file.h
new file mode 100644
index 0000000..8c6e851
--- /dev/null
+++ b/include/io/file.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * file.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_FILE_H
+#define IO_FILE_H
+
+#include "io/istream.h"
+#include "io/ostream.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Create an input stream that reads from a file.
+ *
+ * @memberof istream_t
+ *
+ * @param path A path to the file to open or create.
+ *
+ * @return A pointer to an output stream on success, NULL on failure.
+ */
+SQFS_INTERNAL istream_t *istream_open_file(const char *path);
+
+/**
+ * @brief Create an output stream that writes to a file.
+ *
+ * @memberof ostream_t
+ *
+ * If the file does not yet exist, it is created. If it does exist this
+ * function fails, unless the flag OSTREAM_OPEN_OVERWRITE is set, in which
+ * case the file is opened and its contents are discarded.
+ *
+ * If the flag OSTREAM_OPEN_SPARSE is set, the underlying implementation tries
+ * to support sparse output files. If the flag is not set, holes will always
+ * be filled with zero bytes.
+ *
+ * @param path A path to the file to open or create.
+ * @param flags A combination of flags controling how to open/create the file.
+ *
+ * @return A pointer to an output stream on success, NULL on failure.
+ */
+SQFS_INTERNAL ostream_t *ostream_open_file(const char *path, int flags);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_FILE_H */
diff --git a/include/io/istream.h b/include/io/istream.h
new file mode 100644
index 0000000..567d7e3
--- /dev/null
+++ b/include/io/istream.h
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_ISTREAM_H
+#define IO_ISTREAM_H
+
+#include "sqfs/predef.h"
+
+/**
+ * @struct istream_t
+ *
+ * @extends sqfs_object_t
+ *
+ * @brief A sequential, read-only data stream.
+ */
+typedef struct istream_t {
+	sqfs_object_t base;
+
+	size_t buffer_used;
+	size_t buffer_offset;
+	bool eof;
+
+	sqfs_u8 *buffer;
+
+	int (*precache)(struct istream_t *strm);
+
+	const char *(*get_filename)(struct istream_t *strm);
+} istream_t;
+
+enum {
+	ISTREAM_LINE_LTRIM = 0x01,
+	ISTREAM_LINE_RTRIM = 0x02,
+	ISTREAM_LINE_SKIP_EMPTY = 0x04,
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Read a line of text from an input stream
+ *
+ * @memberof istream_t
+ *
+ * The line returned is allocated using malloc and must subsequently be
+ * freed when it is no longer needed. The line itself is always null-terminated
+ * and never includes the line break characters (LF or CR-LF).
+ *
+ * If the flag @ref ISTREAM_LINE_LTRIM is set, leading white space characters
+ * are removed. If the flag @ref ISTREAM_LINE_RTRIM is set, trailing white space
+ * characters are remvoed.
+ *
+ * If the flag @ref ISTREAM_LINE_SKIP_EMPTY is set and a line is discovered to
+ * be empty (after the optional trimming), the function discards the empty line
+ * and retries. The given line_num pointer is used to increment the line
+ * number.
+ *
+ * @param strm A pointer to an input stream.
+ * @param out Returns a pointer to a line on success.
+ * @param line_num This is incremented if lines are skipped.
+ * @param flags A combination of flags controling the functions behaviour.
+ *
+ * @return Zero on success, a negative value on error, a positive value if
+ *         end-of-file was reached without reading any data.
+ */
+SQFS_INTERNAL int istream_get_line(istream_t *strm, char **out,
+				   size_t *line_num, int flags);
+
+/**
+ * @brief Read data from an input stream
+ *
+ * @memberof istream_t
+ *
+ * @param strm A pointer to an input stream.
+ * @param data A buffer to read into.
+ * @param size The number of bytes to read into the buffer.
+ *
+ * @return The number of bytes actually read on success, -1 on failure,
+ *         0 on end-of-file.
+ */
+SQFS_INTERNAL sqfs_s32 istream_read(istream_t *strm, void *data, size_t size);
+
+/**
+ * @brief Adjust and refill the internal buffer of an input stream
+ *
+ * @memberof istream_t
+ *
+ * This function resets the buffer offset of an input stream (moving any unread
+ * data up front if it has to) and calls an internal callback of the input
+ * stream to fill the rest of the buffer to the extent possible.
+ *
+ * @param strm A pointer to an input stream.
+ *
+ * @return 0 on success, -1 on failure.
+ */
+SQFS_INTERNAL int istream_precache(istream_t *strm);
+
+/**
+ * @brief Get the underlying filename of an input stream.
+ *
+ * @memberof istream_t
+ *
+ * @param strm The input stream to get the filename from.
+ *
+ * @return A string holding the underlying filename.
+ */
+SQFS_INTERNAL const char *istream_get_filename(istream_t *strm);
+
+/**
+ * @brief Skip over a number of bytes in an input stream.
+ *
+ * @memberof istream_t
+ *
+ * @param strm A pointer to an input stream.
+ * @param size The number of bytes to seek forward.
+ *
+ * @return Zero on success, -1 on failure.
+ */
+SQFS_INTERNAL int istream_skip(istream_t *strm, sqfs_u64 size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_ISTREAM_H */
diff --git a/include/io/ostream.h b/include/io/ostream.h
new file mode 100644
index 0000000..15585f9
--- /dev/null
+++ b/include/io/ostream.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_OSTREAM_H
+#define IO_OSTREAM_H
+
+#include "sqfs/predef.h"
+#include "io/istream.h"
+
+#if defined(__GNUC__) || defined(__clang__)
+#	define PRINTF_ATTRIB(fmt, elipsis)			\
+		__attribute__ ((format (printf, fmt, elipsis)))
+#else
+#	define PRINTF_ATTRIB(fmt, elipsis)
+#endif
+
+/**
+ * @struct ostream_t
+ *
+ * @extends sqfs_object_t
+ *
+ * @brief An append-only data stream.
+ */
+typedef struct ostream_t {
+	sqfs_object_t base;
+
+	int (*append)(struct ostream_t *strm, const void *data, size_t size);
+
+	int (*append_sparse)(struct ostream_t *strm, size_t size);
+
+	int (*flush)(struct ostream_t *strm);
+
+	const char *(*get_filename)(struct ostream_t *strm);
+} ostream_t;
+
+enum {
+	OSTREAM_OPEN_OVERWRITE = 0x01,
+	OSTREAM_OPEN_SPARSE = 0x02,
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Append a block of data to an output stream.
+ *
+ * @memberof ostream_t
+ *
+ * @param strm A pointer to an output stream.
+ * @param data A pointer to the data block to append.
+ * @param size The number of bytes to append.
+ *
+ * @return Zero on success, -1 on failure.
+ */
+SQFS_INTERNAL int ostream_append(ostream_t *strm, const void *data,
+				 size_t size);
+
+/**
+ * @brief Append a number of zero bytes to an output stream.
+ *
+ * @memberof ostream_t
+ *
+ * If the unerlying implementation supports sparse files, this function can be
+ * used to create a "hole". If the implementation does not support it, a
+ * fallback is used that just appends a block of zeros manualy.
+ *
+ * @param strm A pointer to an output stream.
+ * @param size The number of zero bytes to append.
+ *
+ * @return Zero on success, -1 on failure.
+ */
+SQFS_INTERNAL int ostream_append_sparse(ostream_t *strm, size_t size);
+
+/**
+ * @brief Process all pending, buffered data and flush it to disk.
+ *
+ * @memberof ostream_t
+ *
+ * If the stream performs some kind of transformation (e.g. transparent data
+ * compression), flushing caues the wrapped format to insert a termination
+ * token. Only call this function when you are absolutely DONE appending data,
+ * shortly before destroying the stream.
+ *
+ * @param strm A pointer to an output stream.
+ *
+ * @return Zero on success, -1 on failure.
+ */
+SQFS_INTERNAL int ostream_flush(ostream_t *strm);
+
+/**
+ * @brief Get the underlying filename of a output stream.
+ *
+ * @memberof ostream_t
+ *
+ * @param strm The output stream to get the filename from.
+ *
+ * @return A string holding the underlying filename.
+ */
+SQFS_INTERNAL const char *ostream_get_filename(ostream_t *strm);
+
+/**
+ * @brief Printf like function that appends to an output stream
+ *
+ * @memberof ostream_t
+ *
+ * @param strm The output stream to append to.
+ * @param fmt A printf style format string.
+ *
+ * @return The number of characters written on success, -1 on failure.
+ */
+SQFS_INTERNAL int ostream_printf(ostream_t *strm, const char *fmt, ...)
+	PRINTF_ATTRIB(2, 3);
+
+/**
+ * @brief Read data from an input stream and append it to an output stream
+ *
+ * @memberof ostream_t
+ *
+ * @param out A pointer to an output stream to append to.
+ * @param in A pointer to an input stream to read from.
+ * @param size The number of bytes to copy over.
+ *
+ * @return The number of bytes copied on success, -1 on failure,
+ *         0 on end-of-file.
+ */
+SQFS_INTERNAL sqfs_s32 ostream_append_from_istream(ostream_t *out,
+						   istream_t *in,
+						   sqfs_u32 size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_OSTREAM_H */
diff --git a/include/io/std.h b/include/io/std.h
new file mode 100644
index 0000000..805bebd
--- /dev/null
+++ b/include/io/std.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * std.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_STD_H
+#define IO_STD_H
+
+#include "io/istream.h"
+#include "io/ostream.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Create an input stream that reads from standard input.
+ *
+ * @memberof istream_t
+ *
+ * @return A pointer to an input stream on success, NULL on failure.
+ */
+SQFS_INTERNAL istream_t *istream_open_stdin(void);
+
+/**
+ * @brief Create an output stream that writes to standard output.
+ *
+ * @memberof ostream_t
+ *
+ * @return A pointer to an output stream on success, NULL on failure.
+ */
+SQFS_INTERNAL ostream_t *ostream_open_stdout(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_STD_H */
diff --git a/include/io/xfrm.h b/include/io/xfrm.h
new file mode 100644
index 0000000..22a42b6
--- /dev/null
+++ b/include/io/xfrm.h
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * xfrm.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_XFRM_H
+#define IO_XFRM_H
+
+#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,
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Create an input stream that transparently uncompresses 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
+ * 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.
+ *
+ * @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);
+
+/**
+ * @brief Create an output stream that transparently compresses 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.
+ *
+ * @param strm A pointer to another stream that should be wrapped.
+ * @param comp_id An identifier describing the compressor 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);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_XFRM_H */
diff --git a/include/tar.h b/include/tar.h
index 41be57f..dadc16e 100644
--- a/include/tar.h
+++ b/include/tar.h
@@ -9,7 +9,8 @@
 
 #include "config.h"
 #include "compat.h"
-#include "fstream.h"
+#include "io/istream.h"
+#include "io/ostream.h"
 
 #include <stdbool.h>
 #include <stdint.h>