libsquashfs: merge windows & unix file I/O primitives

By adding additional close/duplicate primitives, the remaining, mostly
identical istream/ostream/file code is mostly identical between Windows
and Unix and be merged, mostly without stitches.

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

9 files changed, 412 insertions, 769 deletions

diff --git a/lib/sqfs/Makemodule.am b/lib/sqfs/Makemodule.am
index 83ca478..c722f16 100644
--- a/lib/sqfs/Makemodule.am
+++ b/lib/sqfs/Makemodule.am
@@ -30,7 +30,8 @@ libsquashfs_la_SOURCES = $(LIBSQFS_HEARDS) lib/sqfs/src/id_table.c \
 	lib/sqfs/src/block_processor/block_processor.c \
 	lib/sqfs/src/block_processor/backend.c \
 	lib/sqfs/src/frag_table.c lib/sqfs/src/block_writer.c \
-	lib/sqfs/src/misc.c lib/sqfs/src/istream.c
+	lib/sqfs/src/misc.c lib/sqfs/src/istream.c lib/sqfs/src/io/istream.c \
+	lib/sqfs/src/io/ostream.c lib/sqfs/src/io/file.c
 libsquashfs_la_CPPFLAGS = $(AM_CPPFLAGS)
 libsquashfs_la_LDFLAGS = $(AM_LDFLAGS) -version-info $(LIBSQUASHFS_SO_VERSION)
 libsquashfs_la_CFLAGS = $(AM_CFLAGS) $(PTHREAD_CFLAGS) $(ZLIB_CFLAGS)
@@ -57,15 +58,13 @@ libsquashfs_la_SOURCES += lib/util/src/mempool.c include/util/mempool.h
 endif
 
 if WINDOWS
-libsquashfs_la_SOURCES += lib/sqfs/src/win32/io_file.c \
-		lib/sqfs/src/win32/ostream.c lib/sqfs/src/win32/istream.c
+libsquashfs_la_SOURCES += lib/sqfs/src/io/win32.c
 
 libsquashfs_la_CFLAGS += -DWINVER=0x0600 -D_WIN32_WINNT=0x0600
 libsquashfs_la_CFLAGS += -Wc,-static-libgcc
 libsquashfs_la_LDFLAGS += -no-undefined -avoid-version
 else
-libsquashfs_la_SOURCES += lib/sqfs/src/unix/io_file.c \
-		lib/sqfs/src/unix/ostream.c lib/sqfs/src/unix/istream.c
+libsquashfs_la_SOURCES += lib/sqfs/src/io/unix.c
 endif
 
 if HAVE_PTHREAD
diff --git a/lib/sqfs/src/unix/io_file.c b/lib/sqfs/src/io/file.c
index f9b602a..881730d 100644
--- a/lib/sqfs/src/unix/io_file.c
+++ b/lib/sqfs/src/io/file.c
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: LGPL-3.0-or-later */
 /*
- * io_file.c
+ * file.c
  *
  * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
  */
@@ -11,13 +11,32 @@
 #include "sqfs/error.h"
 #include "compat.h"
 
-#include <sys/stat.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
+
+#if defined(_WIN32) || defined(__WINDOWS__)
+static int get_file_size(HANDLE fd, sqfs_u64 *out)
+{
+	LARGE_INTEGER size;
+	if (!GetFileSizeEx(fd, &size))
+		return -1;
+	*out = size.QuadPart;
+	return 0;
+}
+#else
+#include <sys/stat.h>
+#include <unistd.h>
 #include <errno.h>
-#include <fcntl.h>
 
+static int get_file_size(int fd, sqfs_u64 *out)
+{
+	struct stat sb;
+	if (fstat(fd, &sb))
+		return -1;
+	*out = sb.st_size;
+	return 0;
+}
+#endif
 
 typedef struct {
 	sqfs_file_t base;
@@ -34,7 +53,7 @@ static void stdio_destroy(sqfs_object_t *base)
 {
 	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
 
-	close(file->fd);
+	sqfs_close_native_file(file->fd);
 	free(file);
 }
 
@@ -43,10 +62,13 @@ static sqfs_object_t *stdio_copy(const sqfs_object_t *base)
 	const sqfs_file_stdio_t *file = (const sqfs_file_stdio_t *)base;
 	sqfs_file_stdio_t *copy;
 	size_t size;
-	int err;
 
 	if (!file->readonly) {
+#if defined(_WIN32) || defined(__WINDOWS__)
+		SetLastError(ERROR_NOT_SUPPORTED);
+#else
 		errno = ENOTSUP;
+#endif
 		return NULL;
 	}
 
@@ -57,17 +79,77 @@ static sqfs_object_t *stdio_copy(const sqfs_object_t *base)
 
 	memcpy(copy, file, size);
 
-	copy->fd = dup(file->fd);
-	if (copy->fd < 0) {
-		err = errno;
+	if (sqfs_duplicate_native_file(file->fd, &copy->fd)) {
+		os_error_t error = get_os_error_state();
 		free(copy);
 		copy = NULL;
-		errno = err;
+		set_os_error_state(error);
 	}
 
 	return (sqfs_object_t *)copy;
 }
 
+#if defined(_WIN32) || defined(__WINDOWS__)
+static int stdio_read_at(sqfs_file_t *base, sqfs_u64 offset,
+			 void *buffer, size_t size)
+{
+	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
+	DWORD actually_read;
+	int ret;
+
+	if (offset >= file->size)
+		return SQFS_ERROR_OUT_OF_BOUNDS;
+
+	if (size == 0)
+		return 0;
+
+	if ((offset + size - 1) >= file->size)
+		return SQFS_ERROR_OUT_OF_BOUNDS;
+
+	ret = sqfs_seek_native_file(file->fd, offset, SQFS_FILE_SEEK_START);
+	if (ret)
+		return ret;
+
+	while (size > 0) {
+		if (!ReadFile(file->fd, buffer, size, &actually_read, NULL))
+			return SQFS_ERROR_IO;
+
+		size -= actually_read;
+		buffer = (char *)buffer + actually_read;
+	}
+
+	return 0;
+}
+
+static int stdio_write_at(sqfs_file_t *base, sqfs_u64 offset,
+			  const void *buffer, size_t size)
+{
+	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
+	DWORD actually_read;
+	int ret;
+
+	if (size == 0)
+		return 0;
+
+	ret = sqfs_seek_native_file(file->fd, offset, SQFS_FILE_SEEK_START);
+	if (ret)
+		return ret;
+
+	while (size > 0) {
+		if (!WriteFile(file->fd, buffer, size, &actually_read, NULL))
+			return SQFS_ERROR_IO;
+
+		size -= actually_read;
+		buffer = (char *)buffer + actually_read;
+		offset += actually_read;
+
+		if (offset > file->size)
+			file->size = offset;
+	}
+
+	return 0;
+}
+#else
 static int stdio_read_at(sqfs_file_t *base, sqfs_u64 offset,
 			 void *buffer, size_t size)
 {
@@ -122,6 +204,7 @@ static int stdio_write_at(sqfs_file_t *base, sqfs_u64 offset,
 
 	return 0;
 }
+#endif
 
 static sqfs_u64 stdio_get_size(const sqfs_file_t *base)
 {
@@ -133,9 +216,12 @@ static sqfs_u64 stdio_get_size(const sqfs_file_t *base)
 static int stdio_truncate(sqfs_file_t *base, sqfs_u64 size)
 {
 	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
+	int ret;
 
-	if (ftruncate(file->fd, size))
-		return SQFS_ERROR_IO;
+	ret = sqfs_seek_native_file(file->fd, size, SQFS_FILE_SEEK_START |
+				    SQFS_FILE_SEEK_TRUNCATE);
+	if (ret)
+		return ret;
 
 	file->size = size;
 	return 0;
@@ -146,53 +232,24 @@ static const char *stdio_get_filename(sqfs_file_t *file)
 	return ((sqfs_file_stdio_t *)file)->name;
 }
 
-int sqfs_open_native_file(sqfs_file_handle_t *out, const char *filename,
-			  sqfs_u32 flags)
-{
-	int open_mode;
-
-	*out = -1;
-
-	if (flags & ~SQFS_FILE_OPEN_ALL_FLAGS)
-		return SQFS_ERROR_UNSUPPORTED;
-
-	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
-		open_mode = O_RDONLY;
-	} else {
-		open_mode = O_CREAT | O_RDWR;
-
-		if (flags & SQFS_FILE_OPEN_OVERWRITE) {
-			open_mode |= O_TRUNC;
-		} else {
-			open_mode |= O_EXCL;
-		}
-	}
-
-	*out = open(filename, open_mode, 0644);
-
-	return (*out < 0) ? SQFS_ERROR_IO : 0;
-}
-
 sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 {
+	bool file_opened = false;
 	sqfs_file_stdio_t *file;
 	size_t size, namelen;
 	sqfs_file_t *base;
-	struct stat sb;
-	int temp;
+	os_error_t err;
 
 	namelen = strlen(filename);
 	size = sizeof(*file) + 1;
 
-	if (SZ_ADD_OV(size, namelen, &size)) {
-		errno = EOVERFLOW;
-		return NULL;
-	}
+	if (SZ_ADD_OV(size, namelen, &size))
+		goto fail_no_mem;
 
 	file = calloc(1, size);
 	base = (sqfs_file_t *)file;
 	if (file == NULL)
-		return NULL;
+		goto fail_no_mem;
 
 	sqfs_object_init(file, stdio_destroy, stdio_copy);
 	memcpy(file->name, filename, namelen);
@@ -200,10 +257,10 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 	if (sqfs_open_native_file(&file->fd, filename, flags))
 		goto fail;
 
-	if (fstat(file->fd, &sb))
+	file_opened = true;
+	if (get_file_size(file->fd, &file->size))
 		goto fail;
 
-	file->size = sb.st_size;
 	file->readonly = (flags & SQFS_FILE_OPEN_READ_ONLY) != 0;
 
 	base->read_at = stdio_read_at;
@@ -213,10 +270,17 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 	base->get_filename = stdio_get_filename;
 	return base;
 fail:
-	temp = errno;
-	if (file->fd >= 0)
-		close(file->fd);
+	err = get_os_error_state();
+	if (file_opened)
+		sqfs_close_native_file(file->fd);
 	free(file);
-	errno = temp;
+	set_os_error_state(err);
+	return NULL;
+fail_no_mem:
+#if defined(_WIN32) || defined(__WINDOWS__)
+	SetLastError(ERROR_NOT_ENOUGH_MEMORY);
+#else
+	errno = ENOMEM;
+#endif
 	return NULL;
 }
diff --git a/lib/sqfs/src/unix/istream.c b/lib/sqfs/src/io/istream.c
index a0a3469..c3399fe 100644
--- a/lib/sqfs/src/unix/istream.c
+++ b/lib/sqfs/src/io/istream.c
@@ -9,20 +9,40 @@
 
 #include "sqfs/io.h"
 #include "sqfs/error.h"
+#include "compat.h"
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <assert.h>
 #include <errno.h>
-#include <fcntl.h>
+
+#if defined(_WIN32) || defined(__WINDOWS__)
+static SSIZE_T read(HANDLE fd, void *ptr, size_t size)
+{
+	DWORD ret;
+
+	if (!ReadFile(fd, ptr, size, &ret, NULL)) {
+		os_error_t error = get_os_error_state();
+		set_os_error_state(error);
+
+		if (error.w32_errno == ERROR_HANDLE_EOF ||
+		    error.w32_errno == ERROR_BROKEN_PIPE) {
+			return 0;
+		}
+
+		return -1;
+	}
+
+	return ret;
+}
+#endif
 
 #define BUFSZ (131072)
 
 typedef struct {
 	sqfs_istream_t base;
 	char *path;
-	int fd;
+	sqfs_file_handle_t fd;
 
 	bool eof;
 	size_t buffer_offset;
@@ -56,8 +76,10 @@ static int precache(sqfs_istream_t *strm)
 		}
 
 		if (ret < 0) {
+#if !defined(_WIN32) && !defined(__WINDOWS__)
 			if (errno == EINTR)
 				continue;
+#endif
 			return SQFS_ERROR_IO;
 		}
 
@@ -107,7 +129,7 @@ static void file_destroy(sqfs_object_t *obj)
 {
 	file_istream_t *file = (file_istream_t *)obj;
 
-	close(file->fd);
+	sqfs_close_native_file(file->fd);
 	free(file->path);
 	free(file);
 }
@@ -117,6 +139,7 @@ int sqfs_istream_open_handle(sqfs_istream_t **out, const char *path,
 {
 	file_istream_t *file;
 	sqfs_istream_t *strm;
+	int ret;
 
 	if (flags & ~(SQFS_FILE_OPEN_ALL_FLAGS))
 		return SQFS_ERROR_UNSUPPORTED;
@@ -130,21 +153,21 @@ int sqfs_istream_open_handle(sqfs_istream_t **out, const char *path,
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		int temp = errno;
+		os_error_t err = get_os_error_state();
 		free(file);
-		errno = temp;
+		set_os_error_state(err);
 		return SQFS_ERROR_ALLOC;
 	}
 
-	file->fd = dup(fd);
-	if (file->fd < 0) {
-		int temp = errno;
+	ret = sqfs_duplicate_native_file(fd, &file->fd);
+	if (ret) {
+		os_error_t err = get_os_error_state();
 		free(file->path);
 		free(file);
-		errno = temp;
-		return SQFS_ERROR_IO;
+		set_os_error_state(err);
+		return ret;
 	}
-	close(fd);
+	sqfs_close_native_file(fd);
 
 	strm->get_buffered_data = file_get_buffered_data;
 	strm->advance_buffer = file_advance_buffer;
@@ -171,9 +194,9 @@ int sqfs_istream_open_file(sqfs_istream_t **out, const char *path,
 
 	ret = sqfs_istream_open_handle(out, path, fd, flags);
 	if (ret != 0) {
-		int temp = errno;
-		close(fd);
-		errno = temp;
+		os_error_t err = get_os_error_state();
+		sqfs_close_native_file(fd);
+		set_os_error_state(err);
 	}
 
 	return ret;
diff --git a/lib/sqfs/src/unix/ostream.c b/lib/sqfs/src/io/ostream.c
index efdc3cd..ba8e29a 100644
--- a/lib/sqfs/src/unix/ostream.c
+++ b/lib/sqfs/src/io/ostream.c
@@ -9,26 +9,30 @@
 
 #include "sqfs/io.h"
 #include "sqfs/error.h"
+#include "compat.h"
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <errno.h>
-#include <fcntl.h>
 
 typedef struct {
 	sqfs_ostream_t base;
 	char *path;
-	int flags;
-	int fd;
+	sqfs_u32 flags;
+	sqfs_file_handle_t fd;
 
-	off_t sparse_count;
-	off_t size;
+	sqfs_u64 sparse_count;
+	sqfs_u64 size;
 } file_ostream_t;
 
 static int write_all(file_ostream_t *file, const sqfs_u8 *data, size_t size)
 {
 	while (size > 0) {
+#if defined(_WIN32) || defined(__WINDOWS__)
+		DWORD ret;
+		if (!WriteFile(file->fd, data, size, &ret, NULL))
+			return SQFS_ERROR_IO;
+#else
 		ssize_t ret = write(file->fd, data, size);
 
 		if (ret == 0) {
@@ -41,7 +45,7 @@ static int write_all(file_ostream_t *file, const sqfs_u8 *data, size_t size)
 				continue;
 			return SQFS_ERROR_IO;
 		}
-
+#endif
 		file->size += ret;
 		size -= ret;
 		data += ret;
@@ -66,14 +70,14 @@ static int realize_sparse(file_ostream_t *file)
 			return SQFS_ERROR_ALLOC;
 
 		while (file->sparse_count > 0) {
-			diff = file->sparse_count > (off_t)bufsz ?
-				bufsz : (size_t)file->sparse_count;
+			diff = file->sparse_count > bufsz ?
+				bufsz : file->sparse_count;
 
 			ret = write_all(file, buffer, diff);
 			if (ret) {
-				int temp = errno;
+				os_error_t err = get_os_error_state();
 				free(buffer);
-				errno = temp;
+				set_os_error_state(err);
 				return ret;
 			}
 
@@ -82,11 +86,11 @@ static int realize_sparse(file_ostream_t *file)
 
 		free(buffer);
 	} else {
-		if (lseek(file->fd, file->sparse_count, SEEK_CUR) == (off_t)-1)
-			return SQFS_ERROR_IO;
-
-		if (ftruncate(file->fd, file->size) != 0)
-			return SQFS_ERROR_IO;
+		ret = sqfs_seek_native_file(file->fd, file->sparse_count,
+					    SQFS_FILE_SEEK_CURRENT |
+					    SQFS_FILE_SEEK_TRUNCATE);
+		if (ret)
+			return ret;
 
 		file->sparse_count = 0;
 	}
@@ -121,11 +125,13 @@ static int file_flush(sqfs_ostream_t *strm)
 	if (ret)
 		return ret;
 
-	if (fsync(file->fd) != 0) {
-		if (errno != EINVAL)
-			return SQFS_ERROR_IO;
-	}
-
+#if defined(_WIN32) || defined(__WINDOWS__)
+	if (!FlushFileBuffers(file->fd))
+		return SQFS_ERROR_IO;
+#else
+	if (fsync(file->fd) != 0 && errno != EINVAL)
+		return SQFS_ERROR_IO;
+#endif
 	return 0;
 }
 
@@ -133,7 +139,7 @@ static void file_destroy(sqfs_object_t *obj)
 {
 	file_ostream_t *file = (file_ostream_t *)obj;
 
-	close(file->fd);
+	sqfs_close_native_file(file->fd);
 	free(file->path);
 	free(file);
 }
@@ -146,10 +152,16 @@ static const char *file_get_filename(sqfs_ostream_t *strm)
 int sqfs_ostream_open_handle(sqfs_ostream_t **out, const char *path,
 			     sqfs_file_handle_t fd, sqfs_u32 flags)
 {
-	file_ostream_t *file = calloc(1, sizeof(*file));
-	sqfs_ostream_t *strm = (sqfs_ostream_t *)file;
+	file_ostream_t *file;
+	sqfs_ostream_t *strm;
+	int ret;
 
 	*out = NULL;
+	if (flags & ~(SQFS_FILE_OPEN_ALL_FLAGS))
+		return SQFS_ERROR_UNSUPPORTED;
+
+	file = calloc(1, sizeof(*file));
+	strm = (sqfs_ostream_t *)file;
 	if (file == NULL)
 		return SQFS_ERROR_ALLOC;
 
@@ -157,22 +169,22 @@ int sqfs_ostream_open_handle(sqfs_ostream_t **out, const char *path,
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		int temp = errno;
+		os_error_t err = get_os_error_state();
 		free(file);
-		errno = temp;
+		set_os_error_state(err);
 		return SQFS_ERROR_ALLOC;
 	}
 
-	file->fd = dup(fd);
-	if (file->fd < 0) {
-		int temp = errno;
+	ret = sqfs_duplicate_native_file(fd, &file->fd);
+	if (ret) {
+		os_error_t err = get_os_error_state();
 		free(file->path);
 		free(file);
-		errno = temp;
-		return SQFS_ERROR_IO;
+		set_os_error_state(err);
+		return ret;
 	}
 
-	close(fd);
+	sqfs_close_native_file(fd);
 
 	file->flags = flags;
 	strm->append = file_append;
@@ -199,9 +211,9 @@ int sqfs_ostream_open_file(sqfs_ostream_t **out, const char *path,
 
 	ret = sqfs_ostream_open_handle(out, path, fd, flags);
 	if (ret) {
-		int temp = errno;
-		close(fd);
-		errno = temp;
+		os_error_t err = get_os_error_state();
+		sqfs_close_native_file(fd);
+		set_os_error_state(err);
 		return ret;
 	}
 
diff --git a/lib/sqfs/src/io/unix.c b/lib/sqfs/src/io/unix.c
new file mode 100644
index 0000000..45af2ce
--- /dev/null
+++ b/lib/sqfs/src/io/unix.c
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * unix.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#define SQFS_BUILDING_DLL
+#include "config.h"
+
+#include "sqfs/io.h"
+#include "sqfs/error.h"
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+int sqfs_open_native_file(sqfs_file_handle_t *out, const char *filename,
+			  sqfs_u32 flags)
+{
+	int open_mode;
+
+	*out = -1;
+
+	if (flags & ~SQFS_FILE_OPEN_ALL_FLAGS)
+		return SQFS_ERROR_UNSUPPORTED;
+
+	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
+		open_mode = O_RDONLY;
+	} else {
+		open_mode = O_CREAT | O_RDWR;
+
+		if (flags & SQFS_FILE_OPEN_OVERWRITE) {
+			open_mode |= O_TRUNC;
+		} else {
+			open_mode |= O_EXCL;
+		}
+	}
+
+	*out = open(filename, open_mode, 0644);
+
+	return (*out < 0) ? SQFS_ERROR_IO : 0;
+}
+
+void sqfs_close_native_file(sqfs_file_handle_t fd)
+{
+	while (close(fd) != 0 && errno == EINTR)
+		;
+}
+
+int sqfs_duplicate_native_file(sqfs_file_handle_t in, sqfs_file_handle_t *out)
+{
+	*out = dup(in);
+	return (*out < 0) ? SQFS_ERROR_IO : 0;
+}
+
+int sqfs_seek_native_file(sqfs_file_handle_t fd,
+			  sqfs_s64 offset, sqfs_u32 flags)
+{
+	int whence;
+	off_t off;
+
+	switch (flags & SQFS_FILE_SEEK_TYPE_MASK) {
+	case SQFS_FILE_SEEK_START:   whence = SEEK_SET; break;
+	case SQFS_FILE_SEEK_CURRENT: whence = SEEK_CUR; break;
+	case SQFS_FILE_SEEK_END:     whence = SEEK_END; break;
+	default:                     return SQFS_ERROR_UNSUPPORTED;
+	}
+
+	if (flags & ~(SQFS_FILE_SEEK_FLAG_MASK | SQFS_FILE_SEEK_TYPE_MASK))
+		return SQFS_ERROR_UNSUPPORTED;
+
+	off = lseek(fd, offset, whence);
+	if (off == ((off_t)-1)) {
+		if (errno == ESPIPE)
+			return SQFS_ERROR_UNSUPPORTED;
+		return SQFS_ERROR_IO;
+	}
+
+	if (flags & SQFS_FILE_SEEK_TRUNCATE) {
+		while (ftruncate(fd, off) != 0) {
+			if (errno != EINTR)
+				return SQFS_ERROR_IO;
+		}
+	}
+
+	return 0;
+}
diff --git a/lib/sqfs/src/io/win32.c b/lib/sqfs/src/io/win32.c
new file mode 100644
index 0000000..decfd23
--- /dev/null
+++ b/lib/sqfs/src/io/win32.c
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * win32.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#define SQFS_BUILDING_DLL
+#include "config.h"
+
+#include "sqfs/io.h"
+#include "sqfs/error.h"
+#include "compat.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+int sqfs_open_native_file(sqfs_file_handle_t *out, const char *filename,
+			  sqfs_u32 flags)
+{
+	int access_flags, creation_mode, share_mode;
+	WCHAR *wpath = NULL;
+	os_error_t err;
+	DWORD length;
+
+	*out = INVALID_HANDLE_VALUE;
+
+	if (flags & ~SQFS_FILE_OPEN_ALL_FLAGS) {
+		SetLastError(ERROR_INVALID_PARAMETER);
+		return SQFS_ERROR_UNSUPPORTED;
+	}
+
+	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
+		access_flags = GENERIC_READ;
+		creation_mode = OPEN_EXISTING;
+		share_mode = FILE_SHARE_READ;
+	} else {
+		access_flags = GENERIC_READ | GENERIC_WRITE;
+		share_mode = 0;
+
+		if (flags & SQFS_FILE_OPEN_OVERWRITE) {
+			creation_mode = CREATE_ALWAYS;
+		} else {
+			creation_mode = CREATE_NEW;
+		}
+	}
+
+	if (flags & SQFS_FILE_OPEN_NO_CHARSET_XFRM) {
+		*out = CreateFileA(filename, access_flags, share_mode, NULL,
+				   creation_mode, FILE_ATTRIBUTE_NORMAL, NULL);
+	} else {
+		length = MultiByteToWideChar(CP_UTF8, 0, filename, -1, NULL, 0);
+		if (length <= 0)
+			return SQFS_ERROR_INTERNAL;
+
+		wpath = calloc(sizeof(wpath[0]), length + 1);
+		if (wpath == NULL) {
+			SetLastError(ERROR_NOT_ENOUGH_MEMORY);
+			return SQFS_ERROR_ALLOC;
+		}
+
+		MultiByteToWideChar(CP_UTF8, 0, filename, -1,
+				    wpath, length + 1);
+		wpath[length] = '\0';
+
+		*out = CreateFileW(wpath, access_flags, share_mode, NULL,
+				   creation_mode, FILE_ATTRIBUTE_NORMAL,
+				   NULL);
+
+		err = get_os_error_state();
+		free(wpath);
+		set_os_error_state(err);
+	}
+
+	return (*out == INVALID_HANDLE_VALUE) ? SQFS_ERROR_IO : 0;
+}
+
+void sqfs_close_native_file(sqfs_file_handle_t hnd)
+{
+	CloseHandle(hnd);
+}
+
+int sqfs_duplicate_native_file(sqfs_file_handle_t in, sqfs_file_handle_t *out)
+{
+	HANDLE hProc = GetCurrentProcess();
+	BOOL ret = DuplicateHandle(hProc, in, hProc, out, 0,
+				   FALSE, DUPLICATE_SAME_ACCESS);
+
+	return ret ? 0 : SQFS_ERROR_IO;
+}
+
+int sqfs_seek_native_file(sqfs_file_handle_t fd,
+			  sqfs_s64 offset, sqfs_u32 flags)
+{
+	LARGE_INTEGER pos;
+	DWORD whence;
+
+	switch (type & SQFS_FILE_SEEK_TYPE_MASK) {
+	case SQFS_FILE_SEEK_START:   whence = FILE_BEGIN; break;
+	case SQFS_FILE_SEEK_CURRENT: whence = FILE_CURRENT; break;
+	case SQFS_FILE_SEEK_END:     whence = FILE_END; break;
+	default:                     return SQFS_ERROR_UNSUPPORTED;
+	}
+
+	if (flags & ~(SQFS_FILE_SEEK_FLAG_MASK | SQFS_FILE_SEEK_TYPE_MASK))
+		return SQFS_ERROR_UNSUPPORTED;
+
+	if (GetFileType(fd) != FILE_TYPE_DISK)
+		return SQFS_ERROR_UNSUPPORTED;
+
+	pos.QuadPart = offset;
+	if (!SetFilePointerEx(fd, pos, NULL, whence))
+		return SQFS_ERROR_IO;
+
+	if (flags & SQFS_FILE_SEEK_TRUNCATE) {
+		if (!SetEndOfFile(fd))
+			return SQFS_ERROR_IO;
+	}
+
+	return 0;
+}
diff --git a/lib/sqfs/src/win32/io_file.c b/lib/sqfs/src/win32/io_file.c
deleted file mode 100644
index 4d76b94..0000000
--- a/lib/sqfs/src/win32/io_file.c
+++ /dev/null
@@ -1,271 +0,0 @@
-/* SPDX-License-Identifier: LGPL-3.0-or-later */
-/*
- * io_file.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#define SQFS_BUILDING_DLL
-#include "config.h"
-
-#include "sqfs/io.h"
-#include "sqfs/error.h"
-#include "compat.h"
-
-#include <stdlib.h>
-
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-
-
-typedef struct {
-	sqfs_file_t base;
-
-	bool readonly;
-	sqfs_u64 size;
-	sqfs_file_handle_t fd;
-
-	char name[];
-} sqfs_file_stdio_t;
-
-
-static void stdio_destroy(sqfs_object_t *base)
-{
-	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
-
-	CloseHandle(file->fd);
-	free(file);
-}
-
-static sqfs_object_t *stdio_copy(const sqfs_object_t *base)
-{
-	const sqfs_file_stdio_t *file = (const sqfs_file_stdio_t *)base;
-	sqfs_file_stdio_t *copy;
-	size_t size;
-	BOOL ret;
-
-	if (!file->readonly) {
-		SetLastError(ERROR_NOT_SUPPORTED);
-		return NULL;
-	}
-
-	size = sizeof(*file) + strlen(file->name) + 1;
-	copy = calloc(1, size);
-	if (copy == NULL)
-		return NULL;
-
-	memcpy(copy, file, size);
-
-	ret = DuplicateHandle(GetCurrentProcess(), file->fd,
-			      GetCurrentProcess(), &copy->fd,
-			      0, FALSE, DUPLICATE_SAME_ACCESS);
-
-	if (!ret) {
-		os_error_t err = get_os_error_state();
-		free(copy);
-		set_os_error_state(err);
-		return NULL;
-	}
-
-	return (sqfs_object_t *)copy;
-}
-
-static int stdio_read_at(sqfs_file_t *base, sqfs_u64 offset,
-			 void *buffer, size_t size)
-{
-	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
-	DWORD actually_read;
-	LARGE_INTEGER pos;
-
-	if (offset >= file->size)
-		return SQFS_ERROR_OUT_OF_BOUNDS;
-
-	if (size == 0)
-		return 0;
-
-	if ((offset + size - 1) >= file->size)
-		return SQFS_ERROR_OUT_OF_BOUNDS;
-
-	pos.QuadPart = offset;
-
-	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
-		return SQFS_ERROR_IO;
-
-	while (size > 0) {
-		if (!ReadFile(file->fd, buffer, size, &actually_read, NULL))
-			return SQFS_ERROR_IO;
-
-		size -= actually_read;
-		buffer = (char *)buffer + actually_read;
-	}
-
-	return 0;
-}
-
-static int stdio_write_at(sqfs_file_t *base, sqfs_u64 offset,
-			  const void *buffer, size_t size)
-{
-	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
-	DWORD actually_read;
-	LARGE_INTEGER pos;
-
-	if (size == 0)
-		return 0;
-
-	pos.QuadPart = offset;
-
-	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
-		return SQFS_ERROR_IO;
-
-	while (size > 0) {
-		if (!WriteFile(file->fd, buffer, size, &actually_read, NULL))
-			return SQFS_ERROR_IO;
-
-		size -= actually_read;
-		buffer = (char *)buffer + actually_read;
-		offset += actually_read;
-
-		if (offset > file->size)
-			file->size = offset;
-	}
-
-	return 0;
-}
-
-static sqfs_u64 stdio_get_size(const sqfs_file_t *base)
-{
-	const sqfs_file_stdio_t *file = (const sqfs_file_stdio_t *)base;
-
-	return file->size;
-}
-
-static int stdio_truncate(sqfs_file_t *base, sqfs_u64 size)
-{
-	sqfs_file_stdio_t *file = (sqfs_file_stdio_t *)base;
-	LARGE_INTEGER pos;
-
-	pos.QuadPart = size;
-
-	if (!SetFilePointerEx(file->fd, pos, NULL, FILE_BEGIN))
-		return SQFS_ERROR_IO;
-
-	if (!SetEndOfFile(file->fd))
-		return SQFS_ERROR_IO;
-
-	file->size = size;
-	return 0;
-}
-
-static const char *stdio_get_filename(sqfs_file_t *file)
-{
-	return ((sqfs_file_stdio_t *)file)->name;
-}
-
-int sqfs_open_native_file(sqfs_file_handle_t *out, const char *filename,
-			  sqfs_u32 flags)
-{
-	int access_flags, creation_mode, share_mode;
-	WCHAR *wpath = NULL;
-	os_error_t err;
-	DWORD length;
-
-	*out = INVALID_HANDLE_VALUE;
-
-	if (flags & ~SQFS_FILE_OPEN_ALL_FLAGS) {
-		SetLastError(ERROR_INVALID_PARAMETER);
-		return SQFS_ERROR_UNSUPPORTED;
-	}
-
-	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
-		access_flags = GENERIC_READ;
-		creation_mode = OPEN_EXISTING;
-		share_mode = FILE_SHARE_READ;
-	} else {
-		access_flags = GENERIC_READ | GENERIC_WRITE;
-		share_mode = 0;
-
-		if (flags & SQFS_FILE_OPEN_OVERWRITE) {
-			creation_mode = CREATE_ALWAYS;
-		} else {
-			creation_mode = CREATE_NEW;
-		}
-	}
-
-	if (flags & SQFS_FILE_OPEN_NO_CHARSET_XFRM) {
-		*out = CreateFileA(filename, access_flags, share_mode, NULL,
-				   creation_mode, FILE_ATTRIBUTE_NORMAL, NULL);
-	} else {
-		length = MultiByteToWideChar(CP_UTF8, 0, filename, -1, NULL, 0);
-		if (length <= 0)
-			return SQFS_ERROR_INTERNAL;
-
-		wpath = calloc(sizeof(wpath[0]), length + 1);
-		if (wpath == NULL) {
-			SetLastError(ERROR_NOT_ENOUGH_MEMORY);
-			return SQFS_ERROR_ALLOC;
-		}
-
-		MultiByteToWideChar(CP_UTF8, 0, filename, -1,
-				    wpath, length + 1);
-		wpath[length] = '\0';
-
-		*out = CreateFileW(wpath, access_flags, share_mode, NULL,
-				   creation_mode, FILE_ATTRIBUTE_NORMAL,
-				   NULL);
-
-		err = get_os_error_state();
-		free(wpath);
-		set_os_error_state(err);
-	}
-
-	return (*out == INVALID_HANDLE_VALUE) ? SQFS_ERROR_IO : 0;
-}
-
-sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
-{
-	sqfs_file_stdio_t *file;
-	size_t namelen, total;
-	LARGE_INTEGER size;
-	sqfs_file_t *base;
-	os_error_t err;
-
-	namelen = strlen(filename);
-	total = sizeof(*file) + 1;
-
-	if (SZ_ADD_OV(total, namelen, &total)) {
-		SetLastError(ERROR_NOT_ENOUGH_MEMORY);
-		return NULL;
-	}
-
-	file = calloc(1, total);
-	base = (sqfs_file_t *)file;
-	if (file == NULL) {
-		SetLastError(ERROR_NOT_ENOUGH_MEMORY);
-		return NULL;
-	}
-
-	sqfs_object_init(file, stdio_destroy, stdio_copy);
-	memcpy(file->name, filename, namelen);
-
-	if (sqfs_open_native_file(&file->fd, filename, flags))
-		goto fail;
-
-	if (!GetFileSizeEx(file->fd, &size))
-		goto fail;
-
-	file->size = size.QuadPart;
-	file->readonly = (flags & SQFS_FILE_OPEN_READ_ONLY) != 0;
-
-	base->read_at = stdio_read_at;
-	base->write_at = stdio_write_at;
-	base->get_size = stdio_get_size;
-	base->truncate = stdio_truncate;
-	base->get_filename = stdio_get_filename;
-	return base;
-fail:
-	err = get_os_error_state();
-	if (file->fd != INVALID_HANDLE_VALUE)
-		CloseHandle(file->fd);
-	free(file);
-	set_os_error_state(err);
-	return NULL;
-}
diff --git a/lib/sqfs/src/win32/istream.c b/lib/sqfs/src/win32/istream.c
deleted file mode 100644
index aeb3352..0000000
--- a/lib/sqfs/src/win32/istream.c
+++ /dev/null
@@ -1,190 +0,0 @@
-/* SPDX-License-Identifier: LGPL-3.0-or-later */
-/*
- * istream.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#define SQFS_BUILDING_DLL
-#include "config.h"
-
-#include "sqfs/io.h"
-#include "sqfs/error.h"
-
-#define BUFSZ (131072)
-
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-#include <assert.h>
-
-typedef struct {
-	sqfs_istream_t base;
-	char *path;
-	HANDLE hnd;
-
-	bool eof;
-	size_t buffer_offset;
-	size_t buffer_used;
-	sqfs_u8 buffer[BUFSZ];
-} file_istream_t;
-
-static int precache(sqfs_istream_t *strm)
-{
-	file_istream_t *file = (file_istream_t *)strm;
-	DWORD diff, actual;
-
-	if (file->eof)
-		return 0;
-
-	if (file->buffer_offset > 0 &&
-	    file->buffer_offset < file->buffer_used) {
-		memmove(file->buffer, file->buffer + file->buffer_offset,
-			file->buffer_used - file->buffer_offset);
-	}
-
-	file->buffer_used -= file->buffer_offset;
-	file->buffer_offset = 0;
-
-	while (file->buffer_used < sizeof(file->buffer)) {
-		diff = sizeof(file->buffer) - file->buffer_used;
-
-		if (!ReadFile(file->hnd, file->buffer + file->buffer_used,
-			      diff, &actual, NULL)) {
-			os_error_t error = get_os_error_state();
-
-			if (error.w32_errno == ERROR_HANDLE_EOF ||
-			    error.w32_errno == ERROR_BROKEN_PIPE) {
-				file->eof = true;
-				break;
-			}
-
-			set_os_error_state(error);
-			return SQFS_ERROR_IO;
-		}
-
-		if (actual == 0) {
-			file->eof = true;
-			break;
-		}
-
-		file->buffer_used += actual;
-	}
-
-	return 0;
-}
-
-static int file_get_buffered_data(sqfs_istream_t *strm, const sqfs_u8 **out,
-				  size_t *size, size_t want)
-{
-	file_istream_t *file = (file_istream_t *)strm;
-
-	if (want > BUFSZ)
-		want = BUFSZ;
-
-	if (file->buffer_used == 0 ||
-	    (file->buffer_used - file->buffer_offset) < want) {
-		int ret = precache(strm);
-		if (ret)
-			return ret;
-	}
-
-	*out = file->buffer + file->buffer_offset;
-	*size = file->buffer_used - file->buffer_offset;
-	return (file->eof && *size == 0) ? 1 : 0;
-}
-
-static void file_advance_buffer(sqfs_istream_t *strm, size_t count)
-{
-	file_istream_t *file = (file_istream_t *)strm;
-
-	assert(count <= file->buffer_used);
-
-	file->buffer_offset += count;
-
-	assert(file->buffer_offset <= file->buffer_used);
-}
-
-static const char *file_get_filename(sqfs_istream_t *strm)
-{
-	return ((file_istream_t *)strm)->path;
-}
-
-static void file_destroy(sqfs_object_t *obj)
-{
-	file_istream_t *file = (file_istream_t *)obj;
-
-	CloseHandle(file->hnd);
-	free(file->path);
-	free(file);
-}
-
-int sqfs_istream_open_handle(sqfs_istream_t **out, const char *path,
-			     sqfs_file_handle_t hnd, sqfs_u32 flags)
-{
-	file_istream_t *file;
-	sqfs_istream_t *strm;
-	BOOL ret;
-
-	if (flags & ~(SQFS_FILE_OPEN_ALL_FLAGS))
-		return SQFS_ERROR_UNSUPPORTED;
-
-	file = calloc(1, sizeof(*file));
-	strm = (sqfs_istream_t *)file;
-	if (file == NULL)
-		return SQFS_ERROR_ALLOC;
-
-	sqfs_object_init(file, file_destroy, NULL);
-
-	file->path = strdup(path);
-	if (file->path == NULL) {
-		os_error_t err = get_os_error_state();
-		free(file);
-		set_os_error_state(err);
-		return SQFS_ERROR_ALLOC;
-	}
-
-	ret = DuplicateHandle(GetCurrentProcess(), hnd,
-			      GetCurrentProcess(), &file->hnd,
-			      0, FALSE, DUPLICATE_SAME_ACCESS);
-	if (!ret) {
-		os_error_t err = get_os_error_state();
-		free(file->path);
-		free(file);
-		set_os_error_state(err);
-		return SQFS_ERROR_IO;
-	}
-
-	CloseHandle(hnd);
-
-	strm->get_buffered_data = file_get_buffered_data;
-	strm->advance_buffer = file_advance_buffer;
-	strm->get_filename = file_get_filename;
-
-	*out = strm;
-	return 0;
-}
-
-int sqfs_istream_open_file(sqfs_istream_t **out, const char *path,
-			   sqfs_u32 flags)
-{
-	sqfs_file_handle_t hnd;
-	int ret;
-
-	flags |= SQFS_FILE_OPEN_READ_ONLY;
-
-	if (flags & (SQFS_FILE_OPEN_OVERWRITE | SQFS_FILE_OPEN_NO_SPARSE))
-		return SQFS_ERROR_ARG_INVALID;
-
-	ret = sqfs_open_native_file(&hnd, path, flags);
-	if (ret)
-		return ret;
-
-	ret = sqfs_istream_open_handle(out, path, hnd, flags);
-	if (ret) {
-		os_error_t err = get_os_error_state();
-		CloseHandle(hnd);
-		set_os_error_state(err);
-		return ret;
-	}
-
-	return 0;
-}
diff --git a/lib/sqfs/src/win32/ostream.c b/lib/sqfs/src/win32/ostream.c
deleted file mode 100644
index 2f85c29..0000000
--- a/lib/sqfs/src/win32/ostream.c
+++ /dev/null
@@ -1,201 +0,0 @@
-/* SPDX-License-Identifier: LGPL-3.0-or-later */
-/*
- * ostream.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#define SQFS_BUILDING_DLL
-#include "config.h"
-
-#include "sqfs/io.h"
-#include "sqfs/error.h"
-
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-
-typedef struct {
-	sqfs_ostream_t base;
-	sqfs_u64 sparse_count;
-	char *path;
-	HANDLE hnd;
-	int flags;
-} file_ostream_t;
-
-static int write_data(file_ostream_t *file, const void *data, size_t size)
-{
-	DWORD diff;
-
-	while (size > 0) {
-		if (!WriteFile(file->hnd, data, size, &diff, NULL))
-			return SQFS_ERROR_IO;
-
-		size -= diff;
-		data = (const char *)data + diff;
-	}
-
-	return 0;
-}
-
-static int realize_sparse(file_ostream_t *file)
-{
-	size_t bufsz, diff;
-	LARGE_INTEGER pos;
-	void *buffer;
-	int ret;
-
-	if (file->sparse_count == 0)
-		return 0;
-
-	if (file->flags & SQFS_FILE_OPEN_NO_SPARSE) {
-		bufsz = file->sparse_count > 1024 ? 1024 : file->sparse_count;
-		buffer = calloc(1, bufsz);
-
-		if (buffer == NULL)
-			return SQFS_ERROR_ALLOC;
-
-		while (file->sparse_count > 0) {
-			diff = file->sparse_count > bufsz ?
-				bufsz : file->sparse_count;
-
-			ret = write_data(file, buffer, diff);
-			if (ret) {
-				os_error_t err = get_os_error_state();
-				free(buffer);
-				set_os_error_state(err);
-				return ret;
-			}
-
-			file->sparse_count -= diff;
-		}
-
-		free(buffer);
-	} else {
-		pos.QuadPart = file->sparse_count;
-
-		if (!SetFilePointerEx(file->hnd, pos, NULL, FILE_CURRENT))
-			return SQFS_ERROR_IO;
-
-		if (!SetEndOfFile(file->hnd))
-			return SQFS_ERROR_IO;
-
-		file->sparse_count = 0;
-	}
-
-	return 0;
-}
-
-static int file_append(sqfs_ostream_t *strm, const void *data, size_t size)
-{
-	file_ostream_t *file = (file_ostream_t *)strm;
-	int ret;
-
-	if (size == 0 || data == NULL) {
-		file->sparse_count += size;
-		return 0;
-	}
-
-	ret = realize_sparse(file);
-	if (ret)
-		return ret;
-
-	return write_data(file, data, size);
-}
-
-static int file_flush(sqfs_ostream_t *strm)
-{
-	file_ostream_t *file = (file_ostream_t *)strm;
-	int ret;
-
-	ret = realize_sparse(file);
-	if (ret)
-		return ret;
-
-	if (!FlushFileBuffers(file->hnd))
-		return SQFS_ERROR_IO;
-
-	return 0;
-}
-
-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(sqfs_ostream_t *strm)
-{
-	return ((file_ostream_t *)strm)->path;
-}
-
-int sqfs_ostream_open_handle(sqfs_ostream_t **out, const char *path,
-			     sqfs_file_handle_t hnd, sqfs_u32 flags)
-{
-	file_ostream_t *file;
-	sqfs_ostream_t *strm;
-	BOOL ret;
-
-	if (flags & ~(SQFS_FILE_OPEN_ALL_FLAGS))
-		return SQFS_ERROR_UNSUPPORTED;
-
-	file = calloc(1, sizeof(*file));
-	strm = (sqfs_ostream_t *)file;
-	if (file == NULL)
-		return SQFS_ERROR_ALLOC;
-
-	sqfs_object_init(file, file_destroy, NULL);
-
-	file->path = strdup(path);
-	if (file->path == NULL) {
-		free(file);
-		return SQFS_ERROR_ALLOC;
-	}
-
-	ret = DuplicateHandle(GetCurrentProcess(), hnd,
-			      GetCurrentProcess(), &file->hnd,
-			      0, FALSE, DUPLICATE_SAME_ACCESS);
-	if (!ret) {
-		os_error_t err = get_os_error_state();
-		free(file->path);
-		free(file);
-		set_os_error_state(err);
-		return SQFS_ERROR_IO;
-	}
-
-	CloseHandle(hnd);
-
-	file->flags = flags;
-	strm->append = file_append;
-	strm->flush = file_flush;
-	strm->get_filename = file_get_filename;
-
-	*out = strm;
-	return 0;
-}
-
-int sqfs_ostream_open_file(sqfs_ostream_t **out, const char *path,
-			   sqfs_u32 flags)
-{
-	sqfs_file_handle_t hnd;
-	int ret;
-
-	*out = NULL;
-	if (flags & SQFS_FILE_OPEN_READ_ONLY)
-		return SQFS_ERROR_ARG_INVALID;
-
-	ret = sqfs_open_native_file(&hnd, path, flags);
-	if (ret)
-		return ret;
-
-	ret = sqfs_ostream_open_handle(out, path, hnd, flags);
-	if (ret) {
-		os_error_t err = get_os_error_state();
-		CloseHandle(hnd);
-		set_os_error_state(err);
-		return SQFS_ERROR_IO;
-	}
-
-	return 0;
-}