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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2020-09-04 18:26:16 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2020-09-16 09:34:35 +0200
commit1e255d0f6c472bb3c710aea1ea8dc5d27c0fba4a (patch)
tree0ba8dfc243a00ef955da973b1615a95498579525 /lib/fstream
parentb96f0fc154feef531be76034bf6e38925636146f (diff)
Add stream I/O abstraction library
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib/fstream')
-rw-r--r--lib/fstream/Makemodule.am17
-rw-r--r--lib/fstream/internal.h25
-rw-r--r--lib/fstream/istream.c91
-rw-r--r--lib/fstream/ostream.c84
-rw-r--r--lib/fstream/printf.c30
-rw-r--r--lib/fstream/unix/istream.c124
-rw-r--r--lib/fstream/unix/ostream.c152
-rw-r--r--lib/fstream/win32/istream.c120
-rw-r--r--lib/fstream/win32/ostream.c189
9 files changed, 832 insertions, 0 deletions
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;
+}