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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #define _FILE_OFFSET_BITS 64
     18 #define _LARGEFILE64_SOURCE 1
     19 
     20 #include <fcntl.h>
     21 #include <limits.h>
     22 #include <stdbool.h>
     23 #include <stddef.h>
     24 #include <stdlib.h>
     25 #include <string.h>
     26 #include <sys/stat.h>
     27 #include <sys/types.h>
     28 #include <unistd.h>
     29 #include <zlib.h>
     30 
     31 #include "output_file.h"
     32 #include "sparse_format.h"
     33 #include "sparse_crc32.h"
     34 
     35 #ifndef USE_MINGW
     36 #include <sys/mman.h>
     37 #define O_BINARY 0
     38 #else
     39 #define ftruncate64 ftruncate
     40 #endif
     41 
     42 #if defined(__APPLE__) && defined(__MACH__)
     43 #define lseek64 lseek
     44 #define ftruncate64 ftruncate
     45 #define mmap64 mmap
     46 #define off64_t off_t
     47 #endif
     48 
     49 #ifdef __BIONIC__
     50 extern void*  __mmap2(void *, size_t, int, int, int, off_t);
     51 static inline void *mmap64(void *addr, size_t length, int prot, int flags,
     52         int fd, off64_t offset)
     53 {
     54     return __mmap2(addr, length, prot, flags, fd, offset >> 12);
     55 }
     56 #endif
     57 
     58 #define min(a, b) \
     59 	({ typeof(a) _a = (a); typeof(b) _b = (b); (_a < _b) ? _a : _b; })
     60 
     61 #define SPARSE_HEADER_MAJOR_VER 1
     62 #define SPARSE_HEADER_MINOR_VER 0
     63 #define SPARSE_HEADER_LEN       (sizeof(sparse_header_t))
     64 #define CHUNK_HEADER_LEN (sizeof(chunk_header_t))
     65 
     66 #define container_of(inner, outer_t, elem) \
     67 	((outer_t *)((char *)inner - offsetof(outer_t, elem)))
     68 
     69 struct output_file_ops {
     70 	int (*open)(struct output_file *, int fd);
     71 	int (*skip)(struct output_file *, int64_t);
     72 	int (*pad)(struct output_file *, int64_t);
     73 	int (*write)(struct output_file *, void *, int);
     74 	void (*close)(struct output_file *);
     75 };
     76 
     77 struct sparse_file_ops {
     78 	int (*write_data_chunk)(struct output_file *out, unsigned int len,
     79 			void *data);
     80 	int (*write_fill_chunk)(struct output_file *out, unsigned int len,
     81 			uint32_t fill_val);
     82 	int (*write_skip_chunk)(struct output_file *out, int64_t len);
     83 	int (*write_end_chunk)(struct output_file *out);
     84 };
     85 
     86 struct output_file {
     87 	int64_t cur_out_ptr;
     88 	unsigned int chunk_cnt;
     89 	uint32_t crc32;
     90 	struct output_file_ops *ops;
     91 	struct sparse_file_ops *sparse_ops;
     92 	int use_crc;
     93 	unsigned int block_size;
     94 	int64_t len;
     95 	char *zero_buf;
     96 	uint32_t *fill_buf;
     97 	char *buf;
     98 };
     99 
    100 struct output_file_gz {
    101 	struct output_file out;
    102 	gzFile gz_fd;
    103 };
    104 
    105 #define to_output_file_gz(_o) \
    106 	container_of((_o), struct output_file_gz, out)
    107 
    108 struct output_file_normal {
    109 	struct output_file out;
    110 	int fd;
    111 };
    112 
    113 #define to_output_file_normal(_o) \
    114 	container_of((_o), struct output_file_normal, out)
    115 
    116 struct output_file_callback {
    117 	struct output_file out;
    118 	void *priv;
    119 	int (*write)(void *priv, const void *buf, int len);
    120 };
    121 
    122 #define to_output_file_callback(_o) \
    123 	container_of((_o), struct output_file_callback, out)
    124 
    125 static int file_open(struct output_file *out, int fd)
    126 {
    127 	struct output_file_normal *outn = to_output_file_normal(out);
    128 
    129 	outn->fd = fd;
    130 	return 0;
    131 }
    132 
    133 static int file_skip(struct output_file *out, int64_t cnt)
    134 {
    135 	off64_t ret;
    136 	struct output_file_normal *outn = to_output_file_normal(out);
    137 
    138 	ret = lseek64(outn->fd, cnt, SEEK_CUR);
    139 	if (ret < 0) {
    140 		error_errno("lseek64");
    141 		return -1;
    142 	}
    143 	return 0;
    144 }
    145 
    146 static int file_pad(struct output_file *out, int64_t len)
    147 {
    148 	int ret;
    149 	struct output_file_normal *outn = to_output_file_normal(out);
    150 
    151 	ret = ftruncate64(outn->fd, len);
    152 	if (ret < 0) {
    153 		return -errno;
    154 	}
    155 
    156 	return 0;
    157 }
    158 
    159 static int file_write(struct output_file *out, void *data, int len)
    160 {
    161 	int ret;
    162 	struct output_file_normal *outn = to_output_file_normal(out);
    163 
    164 	ret = write(outn->fd, data, len);
    165 	if (ret < 0) {
    166 		error_errno("write");
    167 		return -1;
    168 	} else if (ret < len) {
    169 		error("incomplete write");
    170 		return -1;
    171 	}
    172 
    173 	return 0;
    174 }
    175 
    176 static void file_close(struct output_file *out)
    177 {
    178 	struct output_file_normal *outn = to_output_file_normal(out);
    179 
    180 	free(outn);
    181 }
    182 
    183 static struct output_file_ops file_ops = {
    184 	.open = file_open,
    185 	.skip = file_skip,
    186 	.pad = file_pad,
    187 	.write = file_write,
    188 	.close = file_close,
    189 };
    190 
    191 static int gz_file_open(struct output_file *out, int fd)
    192 {
    193 	struct output_file_gz *outgz = to_output_file_gz(out);
    194 
    195 	outgz->gz_fd = gzdopen(fd, "wb9");
    196 	if (!outgz->gz_fd) {
    197 		error_errno("gzopen");
    198 		return -errno;
    199 	}
    200 
    201 	return 0;
    202 }
    203 
    204 
    205 static int gz_file_skip(struct output_file *out, int64_t cnt)
    206 {
    207 	off64_t ret;
    208 	struct output_file_gz *outgz = to_output_file_gz(out);
    209 
    210 	ret = gzseek(outgz->gz_fd, cnt, SEEK_CUR);
    211 	if (ret < 0) {
    212 		error_errno("gzseek");
    213 		return -1;
    214 	}
    215 	return 0;
    216 }
    217 
    218 static int gz_file_pad(struct output_file *out, int64_t len)
    219 {
    220 	off64_t ret;
    221 	struct output_file_gz *outgz = to_output_file_gz(out);
    222 
    223 	ret = gztell(outgz->gz_fd);
    224 	if (ret < 0) {
    225 		return -1;
    226 	}
    227 
    228 	if (ret >= len) {
    229 		return 0;
    230 	}
    231 
    232 	ret = gzseek(outgz->gz_fd, len - 1, SEEK_SET);
    233 	if (ret < 0) {
    234 		return -1;
    235 	}
    236 
    237 	gzwrite(outgz->gz_fd, "", 1);
    238 
    239 	return 0;
    240 }
    241 
    242 static int gz_file_write(struct output_file *out, void *data, int len)
    243 {
    244 	int ret;
    245 	struct output_file_gz *outgz = to_output_file_gz(out);
    246 
    247 	ret = gzwrite(outgz->gz_fd, data, len);
    248 	if (ret < 0) {
    249 		error_errno("gzwrite");
    250 		return -1;
    251 	} else if (ret < len) {
    252 		error("incomplete gzwrite");
    253 		return -1;
    254 	}
    255 
    256 	return 0;
    257 }
    258 
    259 static void gz_file_close(struct output_file *out)
    260 {
    261 	struct output_file_gz *outgz = to_output_file_gz(out);
    262 
    263 	gzclose(outgz->gz_fd);
    264 	free(outgz);
    265 }
    266 
    267 static struct output_file_ops gz_file_ops = {
    268 	.open = gz_file_open,
    269 	.skip = gz_file_skip,
    270 	.pad = gz_file_pad,
    271 	.write = gz_file_write,
    272 	.close = gz_file_close,
    273 };
    274 
    275 static int callback_file_open(struct output_file *out, int fd)
    276 {
    277 	return 0;
    278 }
    279 
    280 static int callback_file_skip(struct output_file *out, int64_t off)
    281 {
    282 	struct output_file_callback *outc = to_output_file_callback(out);
    283 	int to_write;
    284 	int ret;
    285 
    286 	while (off > 0) {
    287 		to_write = min(off, (int64_t)INT_MAX);
    288 		ret = outc->write(outc->priv, NULL, to_write);
    289 		if (ret < 0) {
    290 			return ret;
    291 		}
    292 		off -= to_write;
    293 	}
    294 
    295 	return 0;
    296 }
    297 
    298 static int callback_file_pad(struct output_file *out, int64_t len)
    299 {
    300 	return -1;
    301 }
    302 
    303 static int callback_file_write(struct output_file *out, void *data, int len)
    304 {
    305 	int ret;
    306 	struct output_file_callback *outc = to_output_file_callback(out);
    307 
    308 	return outc->write(outc->priv, data, len);
    309 }
    310 
    311 static void callback_file_close(struct output_file *out)
    312 {
    313 	struct output_file_callback *outc = to_output_file_callback(out);
    314 
    315 	free(outc);
    316 }
    317 
    318 static struct output_file_ops callback_file_ops = {
    319 	.open = callback_file_open,
    320 	.skip = callback_file_skip,
    321 	.pad = callback_file_pad,
    322 	.write = callback_file_write,
    323 	.close = callback_file_close,
    324 };
    325 
    326 int read_all(int fd, void *buf, size_t len)
    327 {
    328 	size_t total = 0;
    329 	int ret;
    330 	char *ptr = buf;
    331 
    332 	while (total < len) {
    333 		ret = read(fd, ptr, len - total);
    334 
    335 		if (ret < 0)
    336 			return -errno;
    337 
    338 		if (ret == 0)
    339 			return -EINVAL;
    340 
    341 		ptr += ret;
    342 		total += ret;
    343 	}
    344 
    345 	return 0;
    346 }
    347 
    348 static int write_sparse_skip_chunk(struct output_file *out, int64_t skip_len)
    349 {
    350 	chunk_header_t chunk_header;
    351 	int ret, chunk;
    352 
    353 	if (skip_len % out->block_size) {
    354 		error("don't care size %llu is not a multiple of the block size %u",
    355 				skip_len, out->block_size);
    356 		return -1;
    357 	}
    358 
    359 	/* We are skipping data, so emit a don't care chunk. */
    360 	chunk_header.chunk_type = CHUNK_TYPE_DONT_CARE;
    361 	chunk_header.reserved1 = 0;
    362 	chunk_header.chunk_sz = skip_len / out->block_size;
    363 	chunk_header.total_sz = CHUNK_HEADER_LEN;
    364 	ret = out->ops->write(out, &chunk_header, sizeof(chunk_header));
    365 	if (ret < 0)
    366 		return -1;
    367 
    368 	out->cur_out_ptr += skip_len;
    369 	out->chunk_cnt++;
    370 
    371 	return 0;
    372 }
    373 
    374 static int write_sparse_fill_chunk(struct output_file *out, unsigned int len,
    375 		uint32_t fill_val)
    376 {
    377 	chunk_header_t chunk_header;
    378 	int rnd_up_len, zero_len, count;
    379 	int ret;
    380 	unsigned int i;
    381 
    382 	/* Round up the fill length to a multiple of the block size */
    383 	rnd_up_len = ALIGN(len, out->block_size);
    384 
    385 	/* Finally we can safely emit a chunk of data */
    386 	chunk_header.chunk_type = CHUNK_TYPE_FILL;
    387 	chunk_header.reserved1 = 0;
    388 	chunk_header.chunk_sz = rnd_up_len / out->block_size;
    389 	chunk_header.total_sz = CHUNK_HEADER_LEN + sizeof(fill_val);
    390 	ret = out->ops->write(out, &chunk_header, sizeof(chunk_header));
    391 
    392 	if (ret < 0)
    393 		return -1;
    394 	ret = out->ops->write(out, &fill_val, sizeof(fill_val));
    395 	if (ret < 0)
    396 		return -1;
    397 
    398 	if (out->use_crc) {
    399 		count = out->block_size / sizeof(uint32_t);
    400 		while (count--)
    401 			out->crc32 = sparse_crc32(out->crc32, &fill_val, sizeof(uint32_t));
    402 	}
    403 
    404 	out->cur_out_ptr += rnd_up_len;
    405 	out->chunk_cnt++;
    406 
    407 	return 0;
    408 }
    409 
    410 static int write_sparse_data_chunk(struct output_file *out, unsigned int len,
    411 		void *data)
    412 {
    413 	chunk_header_t chunk_header;
    414 	int rnd_up_len, zero_len;
    415 	int ret;
    416 
    417 	/* Round up the data length to a multiple of the block size */
    418 	rnd_up_len = ALIGN(len, out->block_size);
    419 	zero_len = rnd_up_len - len;
    420 
    421 	/* Finally we can safely emit a chunk of data */
    422 	chunk_header.chunk_type = CHUNK_TYPE_RAW;
    423 	chunk_header.reserved1 = 0;
    424 	chunk_header.chunk_sz = rnd_up_len / out->block_size;
    425 	chunk_header.total_sz = CHUNK_HEADER_LEN + rnd_up_len;
    426 	ret = out->ops->write(out, &chunk_header, sizeof(chunk_header));
    427 
    428 	if (ret < 0)
    429 		return -1;
    430 	ret = out->ops->write(out, data, len);
    431 	if (ret < 0)
    432 		return -1;
    433 	if (zero_len) {
    434 		ret = out->ops->write(out, out->zero_buf, zero_len);
    435 		if (ret < 0)
    436 			return -1;
    437 	}
    438 
    439 	if (out->use_crc) {
    440 		out->crc32 = sparse_crc32(out->crc32, data, len);
    441 		if (zero_len)
    442 			out->crc32 = sparse_crc32(out->crc32, out->zero_buf, zero_len);
    443 	}
    444 
    445 	out->cur_out_ptr += rnd_up_len;
    446 	out->chunk_cnt++;
    447 
    448 	return 0;
    449 }
    450 
    451 int write_sparse_end_chunk(struct output_file *out)
    452 {
    453 	chunk_header_t chunk_header;
    454 	int ret;
    455 
    456 	if (out->use_crc) {
    457 		chunk_header.chunk_type = CHUNK_TYPE_CRC32;
    458 		chunk_header.reserved1 = 0;
    459 		chunk_header.chunk_sz = 0;
    460 		chunk_header.total_sz = CHUNK_HEADER_LEN + 4;
    461 
    462 		ret = out->ops->write(out, &chunk_header, sizeof(chunk_header));
    463 		if (ret < 0) {
    464 			return ret;
    465 		}
    466 		out->ops->write(out, &out->crc32, 4);
    467 		if (ret < 0) {
    468 			return ret;
    469 		}
    470 
    471 		out->chunk_cnt++;
    472 	}
    473 
    474 	return 0;
    475 }
    476 
    477 static struct sparse_file_ops sparse_file_ops = {
    478 		.write_data_chunk = write_sparse_data_chunk,
    479 		.write_fill_chunk = write_sparse_fill_chunk,
    480 		.write_skip_chunk = write_sparse_skip_chunk,
    481 		.write_end_chunk = write_sparse_end_chunk,
    482 };
    483 
    484 static int write_normal_data_chunk(struct output_file *out, unsigned int len,
    485 		void *data)
    486 {
    487 	int ret;
    488 	unsigned int rnd_up_len = ALIGN(len, out->block_size);
    489 
    490 	ret = out->ops->write(out, data, len);
    491 	if (ret < 0) {
    492 		return ret;
    493 	}
    494 
    495 	if (rnd_up_len > len) {
    496 		ret = out->ops->skip(out, rnd_up_len - len);
    497 	}
    498 
    499 	return ret;
    500 }
    501 
    502 static int write_normal_fill_chunk(struct output_file *out, unsigned int len,
    503 		uint32_t fill_val)
    504 {
    505 	int ret;
    506 	unsigned int i;
    507 	unsigned int write_len;
    508 
    509 	/* Initialize fill_buf with the fill_val */
    510 	for (i = 0; i < out->block_size / sizeof(uint32_t); i++) {
    511 		out->fill_buf[i] = fill_val;
    512 	}
    513 
    514 	while (len) {
    515 		write_len = min(len, out->block_size);
    516 		ret = out->ops->write(out, out->fill_buf, write_len);
    517 		if (ret < 0) {
    518 			return ret;
    519 		}
    520 
    521 		len -= write_len;
    522 	}
    523 
    524 	return 0;
    525 }
    526 
    527 static int write_normal_skip_chunk(struct output_file *out, int64_t len)
    528 {
    529 	return out->ops->skip(out, len);
    530 }
    531 
    532 int write_normal_end_chunk(struct output_file *out)
    533 {
    534 	return out->ops->pad(out, out->len);
    535 }
    536 
    537 static struct sparse_file_ops normal_file_ops = {
    538 		.write_data_chunk = write_normal_data_chunk,
    539 		.write_fill_chunk = write_normal_fill_chunk,
    540 		.write_skip_chunk = write_normal_skip_chunk,
    541 		.write_end_chunk = write_normal_end_chunk,
    542 };
    543 
    544 void output_file_close(struct output_file *out)
    545 {
    546 	int ret;
    547 
    548 	out->sparse_ops->write_end_chunk(out);
    549 	out->ops->close(out);
    550 }
    551 
    552 static int output_file_init(struct output_file *out, int block_size,
    553 		int64_t len, bool sparse, int chunks, bool crc)
    554 {
    555 	int ret;
    556 
    557 	out->len = len;
    558 	out->block_size = block_size;
    559 	out->cur_out_ptr = 0ll;
    560 	out->chunk_cnt = 0;
    561 	out->crc32 = 0;
    562 	out->use_crc = crc;
    563 
    564 	out->zero_buf = calloc(block_size, 1);
    565 	if (!out->zero_buf) {
    566 		error_errno("malloc zero_buf");
    567 		return -ENOMEM;
    568 	}
    569 
    570 	out->fill_buf = calloc(block_size, 1);
    571 	if (!out->fill_buf) {
    572 		error_errno("malloc fill_buf");
    573 		ret = -ENOMEM;
    574 		goto err_fill_buf;
    575 	}
    576 
    577 	if (sparse) {
    578 		out->sparse_ops = &sparse_file_ops;
    579 	} else {
    580 		out->sparse_ops = &normal_file_ops;
    581 	}
    582 
    583 	if (sparse) {
    584 		sparse_header_t sparse_header = {
    585 				.magic = SPARSE_HEADER_MAGIC,
    586 				.major_version = SPARSE_HEADER_MAJOR_VER,
    587 				.minor_version = SPARSE_HEADER_MINOR_VER,
    588 				.file_hdr_sz = SPARSE_HEADER_LEN,
    589 				.chunk_hdr_sz = CHUNK_HEADER_LEN,
    590 				.blk_sz = out->block_size,
    591 				.total_blks = out->len / out->block_size,
    592 				.total_chunks = chunks,
    593 				.image_checksum = 0
    594 		};
    595 
    596 		if (out->use_crc) {
    597 			sparse_header.total_chunks++;
    598 		}
    599 
    600 		ret = out->ops->write(out, &sparse_header, sizeof(sparse_header));
    601 		if (ret < 0) {
    602 			goto err_write;
    603 		}
    604 	}
    605 
    606 	return 0;
    607 
    608 err_write:
    609 	free(out->fill_buf);
    610 err_fill_buf:
    611 	free(out->zero_buf);
    612 	return ret;
    613 }
    614 
    615 static struct output_file *output_file_new_gz(void)
    616 {
    617 	struct output_file_gz *outgz = calloc(1, sizeof(struct output_file_gz));
    618 	if (!outgz) {
    619 		error_errno("malloc struct outgz");
    620 		return NULL;
    621 	}
    622 
    623 	outgz->out.ops = &gz_file_ops;
    624 
    625 	return &outgz->out;
    626 }
    627 
    628 static struct output_file *output_file_new_normal(void)
    629 {
    630 	struct output_file_normal *outn = calloc(1, sizeof(struct output_file_normal));
    631 	if (!outn) {
    632 		error_errno("malloc struct outn");
    633 		return NULL;
    634 	}
    635 
    636 	outn->out.ops = &file_ops;
    637 
    638 	return &outn->out;
    639 }
    640 
    641 struct output_file *output_file_open_callback(int (*write)(void *, const void *, int),
    642 		void *priv, unsigned int block_size, int64_t len, int gz, int sparse,
    643 		int chunks, int crc)
    644 {
    645 	int ret;
    646 	struct output_file_callback *outc;
    647 
    648 	outc = calloc(1, sizeof(struct output_file_callback));
    649 	if (!outc) {
    650 		error_errno("malloc struct outc");
    651 		return NULL;
    652 	}
    653 
    654 	outc->out.ops = &callback_file_ops;
    655 	outc->priv = priv;
    656 	outc->write = write;
    657 
    658 	ret = output_file_init(&outc->out, block_size, len, sparse, chunks, crc);
    659 	if (ret < 0) {
    660 		free(outc);
    661 		return NULL;
    662 	}
    663 
    664 	return &outc->out;
    665 }
    666 
    667 struct output_file *output_file_open_fd(int fd, unsigned int block_size, int64_t len,
    668 		int gz, int sparse, int chunks, int crc)
    669 {
    670 	int ret;
    671 	struct output_file *out;
    672 
    673 	if (gz) {
    674 		out = output_file_new_gz();
    675 	} else {
    676 		out = output_file_new_normal();
    677 	}
    678 	if (!out) {
    679 		return NULL;
    680 	}
    681 
    682 	out->ops->open(out, fd);
    683 
    684 	ret = output_file_init(out, block_size, len, sparse, chunks, crc);
    685 	if (ret < 0) {
    686 		free(out);
    687 		return NULL;
    688 	}
    689 
    690 	return out;
    691 }
    692 
    693 /* Write a contiguous region of data blocks from a memory buffer */
    694 int write_data_chunk(struct output_file *out, unsigned int len, void *data)
    695 {
    696 	return out->sparse_ops->write_data_chunk(out, len, data);
    697 }
    698 
    699 /* Write a contiguous region of data blocks with a fill value */
    700 int write_fill_chunk(struct output_file *out, unsigned int len,
    701 		uint32_t fill_val)
    702 {
    703 	return out->sparse_ops->write_fill_chunk(out, len, fill_val);
    704 }
    705 
    706 int write_fd_chunk(struct output_file *out, unsigned int len,
    707 		int fd, int64_t offset)
    708 {
    709 	int ret;
    710 	int64_t aligned_offset;
    711 	int aligned_diff;
    712 	int buffer_size;
    713 	char *ptr;
    714 
    715 	aligned_offset = offset & ~(4096 - 1);
    716 	aligned_diff = offset - aligned_offset;
    717 	buffer_size = len + aligned_diff;
    718 
    719 #ifndef USE_MINGW
    720 	char *data = mmap64(NULL, buffer_size, PROT_READ, MAP_SHARED, fd,
    721 			aligned_offset);
    722 	if (data == MAP_FAILED) {
    723 		return -errno;
    724 	}
    725 	ptr = data + aligned_diff;
    726 #else
    727 	off64_t pos;
    728 	char *data = malloc(len);
    729 	if (!data) {
    730 		return -errno;
    731 	}
    732 	pos = lseek64(fd, offset, SEEK_SET);
    733 	if (pos < 0) {
    734 		return -errno;
    735 	}
    736 	ret = read_all(fd, data, len);
    737 	if (ret < 0) {
    738 		return ret;
    739 	}
    740 	ptr = data;
    741 #endif
    742 
    743 	ret = out->sparse_ops->write_data_chunk(out, len, ptr);
    744 
    745 #ifndef USE_MINGW
    746 	munmap(data, buffer_size);
    747 #else
    748 	free(data);
    749 #endif
    750 
    751 	return ret;
    752 }
    753 
    754 /* Write a contiguous region of data blocks from a file */
    755 int write_file_chunk(struct output_file *out, unsigned int len,
    756 		const char *file, int64_t offset)
    757 {
    758 	int ret;
    759 
    760 	int file_fd = open(file, O_RDONLY | O_BINARY);
    761 	if (file_fd < 0) {
    762 		return -errno;
    763 	}
    764 
    765 	ret = write_fd_chunk(out, len, file_fd, offset);
    766 
    767 	close(file_fd);
    768 
    769 	return ret;
    770 }
    771 
    772 int write_skip_chunk(struct output_file *out, int64_t len)
    773 {
    774 	return out->sparse_ops->write_skip_chunk(out, len);
    775 }
    776