Add stream I/O abstraction library

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

14 files changed, 1119 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 8492596..d21a3ba 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -26,6 +26,7 @@ include lib/lz4/Makemodule.am
 include lib/sqfs/Makemodule.am
 
 if BUILD_TOOLS
+include lib/fstream/Makemodule.am
 include lib/fstree/Makemodule.am
 include lib/common/Makemodule.am
 include lib/tar/Makemodule.am
diff --git a/include/compat.h b/include/compat.h
index ee47ef9..343dcf5 100644
--- a/include/compat.h
+++ b/include/compat.h
@@ -163,6 +163,8 @@ int fchownat(int dirfd, const char *path, int uid, int gid, int flags);
 int fchmodat(int dirfd, const char *path, int mode, int flags);
 
 int chdir(const char *path);
+
+void w32_perror(const char *str);
 #else
 #include <sys/types.h>
 #include <sys/stat.h>
diff --git a/include/fstream.h b/include/fstream.h
new file mode 100644
index 0000000..cc562ca
--- /dev/null
+++ b/include/fstream.h
@@ -0,0 +1,252 @@
+/* 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"
+
+/**
+ * @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,
+};
+
+#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 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, ...);
+
+/**
+ * @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);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* FSTREAM_H */
diff --git a/lib/compat/Makemodule.am b/lib/compat/Makemodule.am
index 7137f2c..c1be522 100644
--- a/lib/compat/Makemodule.am
+++ b/lib/compat/Makemodule.am
@@ -2,5 +2,6 @@ libcompat_a_SOURCES = lib/compat/getline.c lib/compat/getsubopt.c
 libcompat_a_SOURCES += lib/compat/strndup.c lib/compat/mockups.c
 libcompat_a_SOURCES += lib/compat/chdir.c include/compat.h
 libcompat_a_SOURCES += lib/compat/path_to_windows.c
+libcompat_a_SOURCES += lib/compat/w32_perror.c
 
 noinst_LIBRARIES += libcompat.a
diff --git a/lib/compat/w32_perror.c b/lib/compat/w32_perror.c
new file mode 100644
index 0000000..1268501
--- /dev/null
+++ b/lib/compat/w32_perror.c
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * w32_perror.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+#include "compat.h"
+
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+void w32_perror(const char *str)
+{
+	DWORD nStatus = GetLastError();
+	LPVOID msg = NULL;
+
+	FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+		       FORMAT_MESSAGE_FROM_SYSTEM |
+		       FORMAT_MESSAGE_IGNORE_INSERTS,
+		       NULL, nStatus,
+		       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+		       (LPTSTR)&msg, 0, NULL);
+
+	fprintf(stderr, "%s: %s\n", str, (const char *)msg);
+
+	if (msg != NULL)
+		LocalFree(msg);
+}
+#endif
diff --git a/lib/fstream/Makemodule.am b/lib/fstream/Makemodule.am
new file mode 100644
index 0000000..27e4701
--- /dev/null
+++ b/lib/fstream/Makemodule.am
@@ -0,0 +1,17 @@
+libfstream_a_SOURCES = include/fstream.h
+libfstream_a_SOURCES += lib/fstream/internal.h
+libfstream_a_SOURCES += lib/fstream/ostream.c lib/fstream/printf.c
+libfstream_a_SOURCES += lib/fstream/istream.c
+libfstream_a_CFLAGS = $(AM_CFLAGS) $(ZLIB_CFLAGS) $(XZ_CFLAGS)
+libfstream_a_CPPFLAGS = $(AM_CPPFLAGS)
+
+if WINDOWS
+libfstream_a_SOURCES += lib/fstream/win32/ostream.c
+libfstream_a_SOURCES += lib/fstream/win32/istream.c
+libfstream_a_CFLAGS += -DWINVER=0x0600 -D_WIN32_WINNT=0x0600
+else
+libfstream_a_SOURCES += lib/fstream/unix/ostream.c
+libfstream_a_SOURCES += lib/fstream/unix/istream.c
+endif
+
+noinst_LIBRARIES += libfstream.a
diff --git a/lib/fstream/internal.h b/lib/fstream/internal.h
new file mode 100644
index 0000000..e8b0c07
--- /dev/null
+++ b/lib/fstream/internal.h
@@ -0,0 +1,25 @@
+/* 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 "fstream.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+
+#define BUFSZ (262144)
+
+#endif /* INTERNAL_H */
diff --git a/lib/fstream/istream.c b/lib/fstream/istream.c
new file mode 100644
index 0000000..6318a23
--- /dev/null
+++ b/lib/fstream/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/fstream/ostream.c b/lib/fstream/ostream.c
new file mode 100644
index 0000000..afe76e8
--- /dev/null
+++ b/lib/fstream/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/fstream/printf.c b/lib/fstream/printf.c
new file mode 100644
index 0000000..3850487
--- /dev/null
+++ b/lib/fstream/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/fstream/unix/istream.c b/lib/fstream/unix/istream.c
new file mode 100644
index 0000000..5898141
--- /dev/null
+++ b/lib/fstream/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/fstream/unix/ostream.c b/lib/fstream/unix/ostream.c
new file mode 100644
index 0000000..dac675f
--- /dev/null
+++ b/lib/fstream/unix/ostream.c
@@ -0,0 +1,152 @@
+/* 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;
+} 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;
+
+	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;
+
+			perror(file->path);
+			return -1;
+		}
+
+		size -= ret;
+		data = (const char *)data + ret;
+	}
+
+	return 0;
+}
+
+static int file_append_sparse(ostream_t *strm, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	if (lseek(file->fd, size, SEEK_CUR) == (off_t)-1) {
+		perror(file->path);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int file_flush(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	if (fsync(file->fd) != 0) {
+		perror(file->path);
+		return -1;
+	}
+
+	return 0;
+}
+
+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/fstream/win32/istream.c b/lib/fstream/win32/istream.c
new file mode 100644
index 0000000..96c9f1c
--- /dev/null
+++ b/lib/fstream/win32/istream.c
@@ -0,0 +1,120 @@
+/* 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)) {
+			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;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	file->hnd = CreateFile(path, GENERIC_READ, FILE_SHARE_READ, NULL,
+			       OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+
+	if (file->hnd == INVALID_HANDLE_VALUE) {
+		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) {
+		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/fstream/win32/ostream.c b/lib/fstream/win32/ostream.c
new file mode 100644
index 0000000..e593f7e
--- /dev/null
+++ b/lib/fstream/win32/ostream.c
@@ -0,0 +1,189 @@
+/* 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) != 0) {
+		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;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	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 = CreateFile(path, access_flags, 0, NULL, creation_mode,
+			       FILE_ATTRIBUTE_NORMAL, NULL);
+
+	if (file->hnd == INVALID_HANDLE_VALUE) {
+		w32_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)
+{
+	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;
+}