aboutsummaryrefslogtreecommitdiff
path: root/include/sqfs/io.h
blob: 91343d60c9c89b2e93e03926eef0e8d145c358a3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
 * io.h - This file is part of libsquashfs
 *
 * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
#ifndef SQFS_IO_H
#define SQFS_IO_H

#include "sqfs/predef.h"

/**
 * @file io.h
 *
 * @brief Contains low-level interfaces for abstracting file I/O
 *
 * The @ref sqfs_file_t interface abstracts I/O on a random-acces read/write
 * file, @ref sqfs_ostream_t represents a buffered, sequential, append only
 * data stream, @ref sqfs_istream_t represents a buffered, sequential, read only
 * data stream.
 */

/**
 * @typedef sqfs_file_handle_t
 *
 * @brief Native handle type for file I/O
 */

#if defined(_WIN32) || defined(__WINDOWS__)
#include <handleapi.h>

typedef HANDLE sqfs_file_handle_t;
#else
typedef int sqfs_file_handle_t;
#endif

/**
 * @enum SQFS_FILE_OPEN_FLAGS
 *
 * @brief Flags for file I/O related data structures and functions
 */
typedef enum {
	/**
	 * @brief If set, access the file for reading only
	 *
	 * If not set, the file is expected to have a zero size after opening
	 * which can be grown with successive writes to end of the file.
	 *
	 * Opening an existing file with this flag cleared results in failure,
	 * unless the @ref SQFS_FILE_OPEN_OVERWRITE flag is also set.
	 */
	SQFS_FILE_OPEN_READ_ONLY = 0x01,

	/**
	 * @brief If the read only flag is not set, overwrite any
	 *        existing file.
	 *
	 * If the file alrady exists, it is truncated to zero bytes size and
	 * overwritten.
	 */
	SQFS_FILE_OPEN_OVERWRITE = 0x02,

	/**
	 * @brief If set, do not try to apply any character set transformations
	 *        to the file path.
	 *
	 * This flag currently only affects the Windows implementation. On
	 * Unix-like systems, the path is always passed to the OS API as-is
	 * and this flag has no effect.
	 *
	 * On Windows, the file paths are converted from UTF-8 to UTF-16 and
	 * then passed on to the wide-char API. If this flag is set, the path
	 * is used as-is and passed on to the 8-bit ANSI API instead, letting
	 * the OS decide how to convert and interpret the path.
	 */
	SQFS_FILE_OPEN_NO_CHARSET_XFRM = 0x04,

	/**
	 * @brief Do not use sparse file I/O APIs, always fill in zero bytes
	 *
	 * This flag currently has no effect on @ref sqfs_file_t, it changes
	 * the behavior of @ref sqfs_ostream_t when appending sparse data.
	 */
	SQFS_FILE_OPEN_NO_SPARSE = 0x08,

	SQFS_FILE_OPEN_ALL_FLAGS = 0x0F,
} SQFS_FILE_OPEN_FLAGS;

/**
 * @enum SQFS_FILE_SEEK_FLAGS
 *
 * @brief Controls the behavior of @ref sqfs_seek_native_file
 */
typedef enum {
	SQFS_FILE_SEEK_CURRENT = 0x00,
	SQFS_FILE_SEEK_START = 0x01,
	SQFS_FILE_SEEK_END = 0x02,
	SQFS_FILE_SEEK_TRUNCATE = 0x10,

	SQFS_FILE_SEEK_TYPE_MASK = 0x03,
	SQFS_FILE_SEEK_FLAG_MASK = 0x10,
} SQFS_FILE_SEEK_FLAGS;

/**
 * @interface sqfs_file_t
 *
 * @extends sqfs_object_t
 *
 * @brief Abstracts file I/O to make it easy to embedd SquashFS.
 *
 * Files are only copyable if they are read only, i.e. if a file has been
 * opened with write access, @ref sqfs_copy will always return NULL. The
 * other data types inside libsquashfs assume this to hold for all
 * implementations of this interface.
 */
struct sqfs_file_t {
	sqfs_object_t base;

	/**
	 * @brief Read a chunk of data from an absolute position.
	 *
	 * @param file A pointer to the file object.
	 * @param offset An absolute offset to read data from.
	 * @param buffer A pointer to a buffer to copy the data to.
	 * @param size The number of bytes to read from the file.
	 *
	 * @return Zero on success, an @ref SQFS_ERROR identifier on failure
	 *         that the data structures in libsquashfs that use this return
	 *         directly to the caller.
	 */
	int (*read_at)(sqfs_file_t *file, sqfs_u64 offset,
		       void *buffer, size_t size);

	/**
	 * @brief Write a chunk of data at an absolute position.
	 *
	 * @param file A pointer to the file object.
	 * @param offset An absolute offset to write data to.
	 * @param buffer A pointer to a buffer to write to the file.
	 * @param size The number of bytes to write from the buffer.
	 *
	 * @return Zero on success, an @ref SQFS_ERROR identifier on failure
	 *         that the data structures in libsquashfs that use this return
	 *         directly to the caller.
	 */
	int (*write_at)(sqfs_file_t *file, sqfs_u64 offset,
			const void *buffer, size_t size);

	/**
	 * @brief Get the number of bytes currently stored in the file.
	 *
	 * @param file A pointer to the file object.
	 */
	sqfs_u64 (*get_size)(const sqfs_file_t *file);

	/**
	 * @brief Extend or shrink a file to a specified size.
	 *
	 * @param file A pointer to the file object.
	 * @param size The new capacity of the file in bytes.
	 *
	 * @return Zero on success, an @ref SQFS_ERROR identifier on failure
	 *         that the data structures in libsquashfs that use this return
	 *         directly to the caller.
	 */
	int (*truncate)(sqfs_file_t *file, sqfs_u64 size);

	/**
	 * @brief Get the original name of the file used for opening it.
	 *
	 * @param file A pointer to the file object.
	 *
	 * @return A pointer to a string representing the file name.
	 */
	const char *(*get_filename)(sqfs_file_t *file);
};

/**
 * @interface sqfs_istream_t
 *
 * @extends sqfs_object_t
 *
 * @brief A sequential, read-only data stream.
 */
struct sqfs_istream_t {
	sqfs_object_t base;

	/**
	 * @brief Peek into the data buffered in an istream
	 *
	 * If the internal buffer is empty, the function tries to fetch more,
	 * which can block. It returns a positive return code if there is no
	 * more data to be read, a negative error code if reading failed. Since
	 * this and other functions can alter the buffer pointer and contents,
	 * do not store the pointers returned here across function calls.
	 *
	 * Higher level functions like @ref sqfs_istream_read (providing a
	 * Unix read() style API) are built on top of this primitive.
	 *
	 * @param strm A pointer to an sqfs_istream_t implementation.
	 * @param out Returns a pointer into an internal buffer on success.
	 * @param size Returns the number of bytes available in the buffer.
	 * @param want A number of bytes that the reader would like to have.
	 *             If there is less than this available, the implementation
	 *             can choose to do a blocking precache.
	 *
	 * @return Zero on success, a negative error code on failure,
	 *         a postive number on EOF.
	 */
	int (*get_buffered_data)(sqfs_istream_t *strm, const sqfs_u8 **out,
				 size_t *size, size_t want);

	/**
	 * @brief Mark a section of the internal buffer of an istream as used
	 *
	 * This marks the first `count` bytes of the internal buffer as used,
	 * forcing get_buffered_data to return data afterwards and potentially
	 * try to load more data.
	 *
	 * @param strm A pointer to an sqfs_istream_t implementation.
	 * @param count The number of bytes used up.
	 */
	void (*advance_buffer)(sqfs_istream_t *strm, size_t count);

	/**
	 * @brief Get the underlying filename of an input stream.
	 *
	 * @param strm The input stream to get the filename from.
	 *
	 * @return A string holding the underlying filename.
	 */
	const char *(*get_filename)(sqfs_istream_t *strm);
};

/**
 * @interface sqfs_ostream_t
 *
 * @extends sqfs_object_t
 *
 * @brief An append-only data stream.
 */
struct sqfs_ostream_t {
	sqfs_object_t base;

	/**
	 * @brief Append a block of data to an output stream.
	 *
	 * @param strm A pointer to an output stream.
	 * @param data A pointer to the data block to append. If NULL,
	 *             synthesize a chunk of zero bytes.
	 * @param size The number of bytes to append.
	 *
	 * @return Zero on success, -1 on failure.
	 */
	int (*append)(sqfs_ostream_t *strm, const void *data, size_t size);

	/**
	 * @brief Process all pending, buffered data and flush it to disk.
	 *
	 * 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.
	 */
	int (*flush)(sqfs_ostream_t *strm);

	/**
	 * @brief Get the underlying filename of a output stream.
	 *
	 * @param strm The output stream to get the filename from.
	 *
	 * @return A string holding the underlying filename.
	 */
	const char *(*get_filename)(sqfs_ostream_t *strm);
};

/**
 * @interface sqfs_dir_iterator_t
 *
 * @extends sqfs_object_t
 *
 * @brief An iterator over entries in a filesystem directory.
 */
struct sqfs_dir_iterator_t {
	sqfs_object_t obj;

	/**
	 * @brief Read the next entry and update internal state relating to it
	 *
	 * @param it A pointer to the iterator itself
	 * @param out Returns a pointer to an entry on success. Has to be
	 *            released with @ref sqfs_free().
	 *
	 * @return Zero on success, postivie value if the end of the list was
	 *         reached, negative @ref SQFS_ERROR value on failure.
	 */
	int (*next)(sqfs_dir_iterator_t *it, sqfs_dir_entry_t **out);

	/**
	 * @brief If the last entry was a symlink, extract the target path
	 *
	 * @param it A pointer to the iterator itself.
	 * @param out Returns a pointer to a string on success. Has to be
	 *            released with @ref sqfs_free().
	 *
	 * @return Zero on success, negative @ref SQFS_ERROR value on failure.
	 */
	int (*read_link)(sqfs_dir_iterator_t *it, char **out);

	/**
	 * @brief If the last entry was a directory, open it.
	 *
	 * If next() returned a directory, this can be used to create a brand
	 * new sqfs_dir_iterator_t for it, that is independent of the current
	 * one and returns the sub-directories entries.
	 *
	 * @param it A pointer to the iterator itself.
	 * @param out Returns a pointer to a directory iterator on success.
	 *
	 * @return Zero on success, negative @ref SQFS_ERROR value on failure.
	 */
	int (*open_subdir)(sqfs_dir_iterator_t *it,
			   sqfs_dir_iterator_t **out);

	/**
	 * @brief Skip a sub-hierarchy on a stacked iterator
	 *
	 * If an iterator would ordinarily recurse into a sub-directory,
	 * tell it to skip those entries. On simple, flag iterators like the
	 * one returned by @ref dir_iterator_create, this has no effect.
	 *
	 * @param it A pointer to the iterator itself.
	 */
	void (*ignore_subdir)(sqfs_dir_iterator_t *it);

	/**
	 * @brief If the last entry was a regular file, open it.
	 *
	 * If next() returned a file, this can be used to create an istream
	 * to read from it.
	 *
	 * @param it A pointer to the iterator itself.
	 * @param out Returns a pointer to a @ref sqfs_istream_t on success.
	 *
	 * @return Zero on success, negative @ref SQFS_ERROR value on failure.
	 */
	int (*open_file_ro)(sqfs_dir_iterator_t *it, sqfs_istream_t **out);

	/**
	 * @brief Read extended attributes associated with the current entry
	 *
	 * @param it A pointer to the iterator itself.
	 * @param out Returns a linked list of xattr entries. Has to be
	 *            released with @ref sqfs_xattr_list_free().
	 *
	 * @return Zero on success, negative @ref SQFS_ERROR value on failure.
	 */
	int (*read_xattr)(sqfs_dir_iterator_t *it, sqfs_xattr_t **out);
};

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief Open a native file handle
 *
 * On Unix-like systems, this generates a file descriptor that needs to be
 * closed with close() (or @ref sqfs_native_file_close). If opening fails,
 * errno is preseved.
 *
 * On Windows, a HANDLE is created that needs to be disposed of
 * using CloseHandle(), or alternatively through @ref sqfs_native_file_close.
 * If opening fails, GetLastError() is preseved.
 *
 * On Windows, if @ref SQFS_FILE_OPEN_NO_CHARSET_XFRM is set, the given string
 * is passed to the ANSI API that interprets the string according to the the
 * currently set codepage. If the flag is not present, the string is assumed
 * to be UTF-8,the function internally converts it to UTF-16 and uses the wide
 * char API.
 *
 * @param out Returns a native file handle on success
 * @param filename The path to the file to open
 * @param flags A set of @ref SQFS_FILE_OPEN_FLAGS controlling how the
 *              file is opened.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 *         If an unknown flag was used, @ref SQFS_ERROR_UNSUPPORTED is returned.
 */
SQFS_API int sqfs_native_file_open(sqfs_file_handle_t *out,
				   const char *filename, sqfs_u32 flags);

/**
 * @brief Despose of a file handle returned by @ref sqfs_native_file_open
 *
 * @param fd A native OS file handle
 */
SQFS_API void sqfs_native_file_close(sqfs_file_handle_t fd);

/**
 * @brief Duplicate a file handle returned by @ref sqfs_native_file_open
 *
 * @param in A native OS file handle
 * @param out A new file handle pointing to the same kernel object
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_native_file_duplicate(sqfs_file_handle_t in,
					sqfs_file_handle_t *out);

/**
 * @brief Set the file read/write pointer on a native file handle
 *
 * @param in A native OS file handle
 * @param offset A relative offset to seek to
 * @param flags A combination of @ref SQFS_FILE_SEEK_FLAGS flags
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_native_file_seek(sqfs_file_handle_t hnd,
				   sqfs_s64 offset, sqfs_u32 flags);

/**
 * @brief Try to query the current on-disk size from a native file handle
 *
 * @param hnd A native OS file handle
 * @param out Returns the file size on success
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_native_file_get_size(sqfs_file_handle_t hnd, sqfs_u64 *out);

/**
 * @brief Open a file through the operating systems filesystem API
 *
 * @memberof sqfs_file_t
 *
 * This function basically combines @ref sqfs_native_file_open
 * and @ref sqfs_file_open_handle to conveniently open a file object in
 * one operation
 *
 * @param out Returns a pointer to an @ref sqfs_file_t on success.
 * @param filename The name of the file to open.
 * @param flags A set of @ref SQFS_FILE_OPEN_FLAGS.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_file_open(sqfs_file_t **out, const char *filename,
			    sqfs_u32 flags);

/**
 * @brief Create an @ref sqfs_file_t implementation from a native file handle
 *
 * @memberof sqfs_file_t
 *
 * This function internally creates an instance of a reference implementation
 * of the @ref sqfs_file_t interface that uses the operating systems native
 * API for file I/O.
 *
 * It takes up ownership of the file handle and takes care of cleaning it up.
 * On failure, the handle remains usable, and ownership remains with the caller.
 *
 * @param out Returns a pointer to a file object on success.
 * @param filename The name to associate with the handle.
 * @param fd A native file handle.
 * @param flags A combination of @ref SQFS_FILE_OPEN_FLAGS flags.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR number on failure
 */
SQFS_API int sqfs_file_open_handle(sqfs_file_t **out, const char *filename,
				   sqfs_file_handle_t fd, sqfs_u32 flags);

/**
 * @brief Create an input stream for an OS native file handle.
 *
 * @memberof sqfs_istream_t
 *
 * The functions takes up ownership of the file handle and takes care
 * of cleaning it up. On failure, the handle remains usable, and ownership
 * remains with the caller.
 *
 * @param out Returns a pointer to an input stream on success.
 * @param path The name to associate with the handle.
 * @param fd A native file handle.
 * @param flags A combination of @ref SQFS_FILE_OPEN_FLAGS flags.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR number on failure
 */
SQFS_API
int sqfs_istream_open_handle(sqfs_istream_t **out, const char *path,
			     sqfs_file_handle_t fd, sqfs_u32 flags);

/**
 * @brief Create an output stream that writes to an OS native file handle.
 *
 * @memberof sqfs_ostream_t
 *
 * If the flag SQFS_FILE_OPEN_NO_SPARSE is set, the underlying implementation
 * always writes chunks of zero bytes when passing a NULL pointer to append.
 * Otherwise, it tries to use seek/truncate style APIs to create sparse output
 * files.
 *
 * @param out Returns a pointer to an output stream on success.
 * @param path The name to associate with the handle.
 * @param fd A native file handle.
 * @param flags A combination of @ref SQFS_FILE_OPEN_FLAGS flags.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR number on failure
 */
SQFS_API int sqfs_ostream_open_handle(sqfs_ostream_t **out, const char *path,
				      sqfs_file_handle_t hnd, sqfs_u32 flags);

/**
 * @brief Create an input stream that reads from a file.
 *
 * @memberof sqfs_istream_t
 *
 * The flag @ref SQFS_FILE_OPEN_READ_ONLY is implicitly assumed to be set,
 * since the function constructs a read-only primitive. If either the flags
 * @ref SQFS_FILE_OPEN_OVERWRITE or @ref SQFS_FILE_OPEN_NO_SPARSE are set,
 * an error is returend.
 *
 * @param out Returns a pointer to an input stream on success.
 * @param path A path to the file to open or create.
 * @param flags A combination of @ref SQFS_FILE_OPEN_FLAGS flags.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR number on failure
 */
SQFS_API int sqfs_istream_open_file(sqfs_istream_t **out, const char *path,
				    sqfs_u32 flags);

/**
 * @brief Create an output stream that writes to a file.
 *
 * @memberof sqfs_ostream_t
 *
 * If the file does not yet exist, it is created. If it does exist this
 * function fails, unless the flag SQFS_FILE_OPEN_OVERWRITE is set, in which
 * case the file is opened and its contents are discarded.
 *
 * If the flag SQFS_FILE_OPEN_NO_SPARSE is set, the underlying implementation
 * always writes chunks of zero bytes when passing a NULL pointer to append.
 * Otherwise, it tries to use seek/truncate style APIs to create sparse output
 * files.
 *
 * @param out Returns a pointer to an output stream on success.
 * @param path A path to the file to open or create.
 * @param flags A combination of @ref SQFS_FILE_OPEN_FLAGS flags.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR number on failure
 */
SQFS_API int sqfs_ostream_open_file(sqfs_ostream_t **out,
				    const char *path, sqfs_u32 flags);

/**
 * @brief Read data from an input stream
 *
 * @memberof sqfs_istream_t
 *
 * This function implements a Unix-style read() function on top of
 * an @ref sqfs_istream_t, taking care of buffer management internally.
 *
 * @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, a
 *         negative @ref SQFS_ERROR code on failure, 0 on end-of-file.
 */
SQFS_API sqfs_s32 sqfs_istream_read(sqfs_istream_t *strm,
				    void *data, size_t size);

/**
 * @brief Skip over a number of bytes in an input stream.
 *
 * @memberof sqfs_istream_t
 *
 * @param strm A pointer to an input stream.
 * @param size The number of bytes to seek forward.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_istream_skip(sqfs_istream_t *strm, sqfs_u64 size);

/**
 * @brief Dump data from an input stream to an output stream
 *
 * @memberof sqfs_istream_t
 *
 * @param in A pointer to an input stream to read from.
 * @param out A pointer to an output stream to append to.
 * @param size The number of bytes to copy over.
 *
 * @return Zero on success, a negative @ref SQFS_ERROR code on failure.
 */
SQFS_API sqfs_s32 sqfs_istream_splice(sqfs_istream_t *in, sqfs_ostream_t *out,
				      sqfs_u32 size);

/**
 * @brief Construct a simple directory iterator given a path
 *
 * @memberof sqfs_dir_iterator_t
 *
 * On systems with encoding aware file I/O (like Windows), the path is
 * interpreted to be UTF-8 encoded and converted to the native system API
 * encoding to open the directory. For each directory entry, the name in
 * the native encoding is converted back to UTF-8 when reading.
 *
 * The implementation returned by this is simple, non-recursive, reporting
 * directory contents as returned by the OS native API, i.e. not sorted,
 * and including the "." and ".." entries.
 *
 * @param path A path to a directory on the file system.
 *
 * @return A pointer to a sqfs_dir_iterator_t implementation on success,
 *         NULL on error (message is printed to stderr).
 */
SQFS_API int sqfs_dir_iterator_create_native(sqfs_dir_iterator_t **out,
					     const char *path,
					     sqfs_u32 flags);

/**
 * @brief Construct a recursive directory iterator
 *
 * @memberof sqfs_dir_iterator_t
 *
 * The recursive directory iterator automatcally enters sub directories
 * and adds the parent path as prefix to the entries. The "." and ".."
 * entries are filtered out.
 *
 * @param out Returns a pointer to a recursive directory iterator
 * @param base The root directory iterator used as base
 *
 * @return Zero on success, an @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_dir_iterator_create_recursive(sqfs_dir_iterator_t **out,
						sqfs_dir_iterator_t *base);

/**
 * @brief Construct a directory iterator that detects hard links
 *
 * @memberof sqfs_dir_iterator_t
 *
 * This creates a directory iterator implementation that returns entries from
 * a wrapped iterator, but detects and filters hard links using the device and
 * inode numbers from the entries. If an entry is observed with the same values
 * than a previous entry, the entry is changed into a link with
 * the @ref SQFS_DIR_ENTRY_FLAG_HARD_LINK flags set and asking for the link
 * target returns the previously seen entry name.
 *
 * @param out Returns a pointer to the hard link filter iterator
 * @param base The directory iterator to wrap internally
 *
 * @return Zero on success, an @ref SQFS_ERROR code on failure.
 */
SQFS_API int sqfs_hard_link_filter_create(sqfs_dir_iterator_t **out,
					  sqfs_dir_iterator_t *base);

#ifdef __cplusplus
}
#endif

#endif /* SQFS_IO_H */