libsparse/sparse_read.cpp - android-core - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define _FILE_OFFSET_BITS 64
 #define _LARGEFILE64_SOURCE 1

 #include <algorithm>
 #include <inttypes.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <string>
 #include <unistd.h>

 #include <sparse/sparse.h>

 #include "android-base/stringprintf.h"
 #include "defs.h"
 #include "output_file.h"
 #include "sparse_crc32.h"
 #include "sparse_file.h"
 #include "sparse_format.h"


 #if defined(__APPLE__) && defined(__MACH__)
 #define lseek64 lseek
 #define off64_t off_t
 #endif

 #define SPARSE_HEADER_MAJOR_VER 1
 #define SPARSE_HEADER_LEN       (sizeof(sparse_header_t))
 #define CHUNK_HEADER_LEN (sizeof(chunk_header_t))

 static constexpr int64_t COPY_BUF_SIZE = 1024 * 1024;
 static char *copybuf;

 static std::string ErrorString(int err)
 {
 	if (err == -EOVERFLOW) return "EOF while reading file";
 	if (err == -EINVAL) return "Invalid sparse file format";
 	if (err == -ENOMEM) return "Failed allocation while reading file";
 	return android::base::StringPrintf("Unknown error %d", err);
 }

 static void verbose_error(bool verbose, int err, const char *fmt, ...)
 {
 	if (!verbose) return;

 	std::string msg = ErrorString(err);
 	if (fmt) {
 		msg += " at ";
 		va_list argp;
 		va_start(argp, fmt);
 		android::base::StringAppendV(&msg, fmt, argp);
 		va_end(argp);
 	}
 	sparse_print_verbose("%s\n", msg.c_str());
 }

 static int process_raw_chunk(struct sparse_file *s, unsigned int chunk_size,
 		int fd, int64_t offset, unsigned int blocks, unsigned int block,
 		uint32_t *crc32)
 {
 	int ret;
 	int chunk;
 	int64_t len = blocks * s->block_size;

 	if (chunk_size % s->block_size != 0) {
 		return -EINVAL;
 	}

 	if (chunk_size / s->block_size != blocks) {
 		return -EINVAL;
 	}

 	ret = sparse_file_add_fd(s, fd, offset, len, block);
 	if (ret < 0) {
 		return ret;
 	}

 	if (crc32) {
 		while (len) {
 			chunk = std::min(len, COPY_BUF_SIZE);
 			ret = read_all(fd, copybuf, chunk);
 			if (ret < 0) {
 				return ret;
 			}
 			*crc32 = sparse_crc32(*crc32, copybuf, chunk);
 			len -= chunk;
 		}
 	} else {
 		lseek64(fd, len, SEEK_CUR);
 	}

 	return 0;
 }

 static int process_fill_chunk(struct sparse_file *s, unsigned int chunk_size,
 		int fd, unsigned int blocks, unsigned int block, uint32_t *crc32)
 {
 	int ret;
 	int chunk;
 	int64_t len = (int64_t)blocks * s->block_size;
 	uint32_t fill_val;
 	uint32_t *fillbuf;
 	unsigned int i;

 	if (chunk_size != sizeof(fill_val)) {
 		return -EINVAL;
 	}

 	ret = read_all(fd, &fill_val, sizeof(fill_val));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = sparse_file_add_fill(s, fill_val, len, block);
 	if (ret < 0) {
 		return ret;
 	}

 	if (crc32) {
 		/* Fill copy_buf with the fill value */
 		fillbuf = (uint32_t *)copybuf;
 		for (i = 0; i < (COPY_BUF_SIZE / sizeof(fill_val)); i++) {
 			fillbuf[i] = fill_val;
 		}

 		while (len) {
 			chunk = std::min(len, COPY_BUF_SIZE);
 			*crc32 = sparse_crc32(*crc32, copybuf, chunk);
 			len -= chunk;
 		}
 	}

 	return 0;
 }

 static int process_skip_chunk(struct sparse_file *s, unsigned int chunk_size,
 		int fd __unused, unsigned int blocks,
 		unsigned int block __unused, uint32_t *crc32)
 {
 	if (chunk_size != 0) {
 		return -EINVAL;
 	}

 	if (crc32) {
 	        int64_t len = (int64_t)blocks * s->block_size;
 		memset(copybuf, 0, COPY_BUF_SIZE);

 		while (len) {
 			int chunk = std::min(len, COPY_BUF_SIZE);
 			*crc32 = sparse_crc32(*crc32, copybuf, chunk);
 			len -= chunk;
 		}
 	}

 	return 0;
 }

 static int process_crc32_chunk(int fd, unsigned int chunk_size, uint32_t *crc32)
 {
 	uint32_t file_crc32;
 	int ret;

 	if (chunk_size != sizeof(file_crc32)) {
 		return -EINVAL;
 	}

 	ret = read_all(fd, &file_crc32, sizeof(file_crc32));
 	if (ret < 0) {
 		return ret;
 	}

 	if (crc32 != NULL && file_crc32 != *crc32) {
 		return -EINVAL;
 	}

 	return 0;
 }

 static int process_chunk(struct sparse_file *s, int fd, off64_t offset,
 		unsigned int chunk_hdr_sz, chunk_header_t *chunk_header,
 		unsigned int cur_block, uint32_t *crc_ptr)
 {
 	int ret;
 	unsigned int chunk_data_size;

 	chunk_data_size = chunk_header->total_sz - chunk_hdr_sz;

 	switch (chunk_header->chunk_type) {
 		case CHUNK_TYPE_RAW:
 			ret = process_raw_chunk(s, chunk_data_size, fd, offset,
 					chunk_header->chunk_sz, cur_block, crc_ptr);
 			if (ret < 0) {
 				verbose_error(s->verbose, ret, "data block at %" PRId64, offset);
 				return ret;
 			}
 			return chunk_header->chunk_sz;
 		case CHUNK_TYPE_FILL:
 			ret = process_fill_chunk(s, chunk_data_size, fd,
 					chunk_header->chunk_sz, cur_block, crc_ptr);
 			if (ret < 0) {
 				verbose_error(s->verbose, ret, "fill block at %" PRId64, offset);
 				return ret;
 			}
 			return chunk_header->chunk_sz;
 		case CHUNK_TYPE_DONT_CARE:
 			ret = process_skip_chunk(s, chunk_data_size, fd,
 					chunk_header->chunk_sz, cur_block, crc_ptr);
 			if (chunk_data_size != 0) {
 				if (ret < 0) {
 					verbose_error(s->verbose, ret, "skip block at %" PRId64, offset);
 					return ret;
 				}
 			}
 			return chunk_header->chunk_sz;
 		case CHUNK_TYPE_CRC32:
 			ret = process_crc32_chunk(fd, chunk_data_size, crc_ptr);
 			if (ret < 0) {
 				verbose_error(s->verbose, -EINVAL, "crc block at %" PRId64,
 						offset);
 				return ret;
 			}
 			return 0;
 		default:
 			verbose_error(s->verbose, -EINVAL, "unknown block %04X at %" PRId64,
 					chunk_header->chunk_type, offset);
 	}

 	return 0;
 }

 static int sparse_file_read_sparse(struct sparse_file *s, int fd, bool crc)
 {
 	int ret;
 	unsigned int i;
 	sparse_header_t sparse_header;
 	chunk_header_t chunk_header;
 	uint32_t crc32 = 0;
 	uint32_t *crc_ptr = 0;
 	unsigned int cur_block = 0;
 	off64_t offset;

 	if (!copybuf) {
 		copybuf = (char *)malloc(COPY_BUF_SIZE);
 	}

 	if (!copybuf) {
 		return -ENOMEM;
 	}

 	if (crc) {
 		crc_ptr = &crc32;
 	}

 	ret = read_all(fd, &sparse_header, sizeof(sparse_header));
 	if (ret < 0) {
 		return ret;
 	}

 	if (sparse_header.magic != SPARSE_HEADER_MAGIC) {
 		return -EINVAL;
 	}

 	if (sparse_header.major_version != SPARSE_HEADER_MAJOR_VER) {
 		return -EINVAL;
 	}

 	if (sparse_header.file_hdr_sz < SPARSE_HEADER_LEN) {
 		return -EINVAL;
 	}

 	if (sparse_header.chunk_hdr_sz < sizeof(chunk_header)) {
 		return -EINVAL;
 	}

 	if (sparse_header.file_hdr_sz > SPARSE_HEADER_LEN) {
 		/* Skip the remaining bytes in a header that is longer than
 		 * we expected.
 		 */
 		lseek64(fd, sparse_header.file_hdr_sz - SPARSE_HEADER_LEN, SEEK_CUR);
 	}

 	for (i = 0; i < sparse_header.total_chunks; i++) {
 		ret = read_all(fd, &chunk_header, sizeof(chunk_header));
 		if (ret < 0) {
 			return ret;
 		}

 		if (sparse_header.chunk_hdr_sz > CHUNK_HEADER_LEN) {
 			/* Skip the remaining bytes in a header that is longer than
 			 * we expected.
 			 */
 			lseek64(fd, sparse_header.chunk_hdr_sz - CHUNK_HEADER_LEN, SEEK_CUR);
 		}

 		offset = lseek64(fd, 0, SEEK_CUR);

 		ret = process_chunk(s, fd, offset, sparse_header.chunk_hdr_sz, &chunk_header,
 				cur_block, crc_ptr);
 		if (ret < 0) {
 			return ret;
 		}

 		cur_block += ret;
 	}

 	if (sparse_header.total_blks != cur_block) {
 		return -EINVAL;
 	}

 	return 0;
 }

 static int sparse_file_read_normal(struct sparse_file *s, int fd)
 {
 	int ret;
 	uint32_t *buf = (uint32_t *)malloc(s->block_size);
 	unsigned int block = 0;
 	int64_t remain = s->len;
 	int64_t offset = 0;
 	unsigned int to_read;
 	unsigned int i;
 	bool sparse_block;

 	if (!buf) {
 		return -ENOMEM;
 	}

 	while (remain > 0) {
 		to_read = std::min(remain, (int64_t)(s->block_size));
 		ret = read_all(fd, buf, to_read);
 		if (ret < 0) {
 			error("failed to read sparse file");
 			free(buf);
 			return ret;
 		}

 		if (to_read == s->block_size) {
 			sparse_block = true;
 			for (i = 1; i < s->block_size / sizeof(uint32_t); i++) {
 				if (buf[0] != buf[i]) {
 					sparse_block = false;
 					break;
 				}
 			}
 		} else {
 			sparse_block = false;
 		}

 		if (sparse_block) {
 			/* TODO: add flag to use skip instead of fill for buf[0] == 0 */
 			sparse_file_add_fill(s, buf[0], to_read, block);
 		} else {
 			sparse_file_add_fd(s, fd, offset, to_read, block);
 		}

 		remain -= to_read;
 		offset += to_read;
 		block++;
 	}

 	free(buf);
 	return 0;
 }

 int sparse_file_read(struct sparse_file *s, int fd, bool sparse, bool crc)
 {
 	if (crc && !sparse) {
 		return -EINVAL;
 	}

 	if (sparse) {
 		return sparse_file_read_sparse(s, fd, crc);
 	} else {
 		return sparse_file_read_normal(s, fd);
 	}
 }

 struct sparse_file *sparse_file_import(int fd, bool verbose, bool crc)
 {
 	int ret;
 	sparse_header_t sparse_header;
 	int64_t len;
 	struct sparse_file *s;

 	ret = read_all(fd, &sparse_header, sizeof(sparse_header));
 	if (ret < 0) {
 		verbose_error(verbose, ret, "header");
 		return NULL;
 	}

 	if (sparse_header.magic != SPARSE_HEADER_MAGIC) {
 		verbose_error(verbose, -EINVAL, "header magic");
 		return NULL;
 	}

 	if (sparse_header.major_version != SPARSE_HEADER_MAJOR_VER) {
 		verbose_error(verbose, -EINVAL, "header major version");
 		return NULL;
 	}

 	if (sparse_header.file_hdr_sz < SPARSE_HEADER_LEN) {
 		return NULL;
 	}

 	if (sparse_header.chunk_hdr_sz < sizeof(chunk_header_t)) {
 		return NULL;
 	}

 	len = (int64_t)sparse_header.total_blks * sparse_header.blk_sz;
 	s = sparse_file_new(sparse_header.blk_sz, len);
 	if (!s) {
 		verbose_error(verbose, -EINVAL, NULL);
 		return NULL;
 	}

 	ret = lseek64(fd, 0, SEEK_SET);
 	if (ret < 0) {
 		verbose_error(verbose, ret, "seeking");
 		sparse_file_destroy(s);
 		return NULL;
 	}

 	s->verbose = verbose;

 	ret = sparse_file_read(s, fd, true, crc);
 	if (ret < 0) {
 		sparse_file_destroy(s);
 		return NULL;
 	}

 	return s;
 }

 struct sparse_file *sparse_file_import_auto(int fd, bool crc, bool verbose)
 {
 	struct sparse_file *s;
 	int64_t len;
 	int ret;

 	s = sparse_file_import(fd, verbose, crc);
 	if (s) {
 		return s;
 	}

 	len = lseek64(fd, 0, SEEK_END);
 	if (len < 0) {
 		return NULL;
 	}

 	lseek64(fd, 0, SEEK_SET);

 	s = sparse_file_new(4096, len);
 	if (!s) {
 		return NULL;
 	}

 	ret = sparse_file_read_normal(s, fd);
 	if (ret < 0) {
 		sparse_file_destroy(s);
 		return NULL;
 	}

 	return s;
 }
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define _FILE_OFFSET_BITS 64
	#define _LARGEFILE64_SOURCE 1

	#include <algorithm>
	#include <inttypes.h>
	#include <fcntl.h>
	#include <stdarg.h>
	#include <stdint.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <string>
	#include <unistd.h>

	#include <sparse/sparse.h>

	#include "android-base/stringprintf.h"
	#include "defs.h"
	#include "output_file.h"
	#include "sparse_crc32.h"
	#include "sparse_file.h"
	#include "sparse_format.h"


	#if defined(__APPLE__) && defined(__MACH__)
	#define lseek64 lseek
	#define off64_t off_t
	#endif

	#define SPARSE_HEADER_MAJOR_VER 1
	#define SPARSE_HEADER_LEN (sizeof(sparse_header_t))
	#define CHUNK_HEADER_LEN (sizeof(chunk_header_t))

	static constexpr int64_t COPY_BUF_SIZE = 1024 * 1024;
	static char *copybuf;

	static std::string ErrorString(int err)
	{
	if (err == -EOVERFLOW) return "EOF while reading file";
	if (err == -EINVAL) return "Invalid sparse file format";
	if (err == -ENOMEM) return "Failed allocation while reading file";
	return android::base::StringPrintf("Unknown error %d", err);
	}

	static void verbose_error(bool verbose, int err, const char *fmt, ...)
	{
	if (!verbose) return;

	std::string msg = ErrorString(err);
	if (fmt) {
	msg += " at ";
	va_list argp;
	va_start(argp, fmt);
	android::base::StringAppendV(&msg, fmt, argp);
	va_end(argp);
	}
	sparse_print_verbose("%s\n", msg.c_str());
	}

	static int process_raw_chunk(struct sparse_file *s, unsigned int chunk_size,
	int fd, int64_t offset, unsigned int blocks, unsigned int block,
	uint32_t *crc32)
	{
	int ret;
	int chunk;
	int64_t len = blocks * s->block_size;

	if (chunk_size % s->block_size != 0) {
	return -EINVAL;
	}

	if (chunk_size / s->block_size != blocks) {
	return -EINVAL;
	}

	ret = sparse_file_add_fd(s, fd, offset, len, block);
	if (ret < 0) {
	return ret;
	}

	if (crc32) {
	while (len) {
	chunk = std::min(len, COPY_BUF_SIZE);
	ret = read_all(fd, copybuf, chunk);
	if (ret < 0) {
	return ret;
	}
	crc32 = sparse_crc32(crc32, copybuf, chunk);
	len -= chunk;
	}
	} else {
	lseek64(fd, len, SEEK_CUR);
	}

	return 0;
	}

	static int process_fill_chunk(struct sparse_file *s, unsigned int chunk_size,
	int fd, unsigned int blocks, unsigned int block, uint32_t *crc32)
	{
	int ret;
	int chunk;
	int64_t len = (int64_t)blocks * s->block_size;
	uint32_t fill_val;
	uint32_t *fillbuf;
	unsigned int i;

	if (chunk_size != sizeof(fill_val)) {
	return -EINVAL;
	}

	ret = read_all(fd, &fill_val, sizeof(fill_val));
	if (ret < 0) {
	return ret;
	}

	ret = sparse_file_add_fill(s, fill_val, len, block);
	if (ret < 0) {
	return ret;
	}

	if (crc32) {
	/* Fill copy_buf with the fill value */
	fillbuf = (uint32_t *)copybuf;
	for (i = 0; i < (COPY_BUF_SIZE / sizeof(fill_val)); i++) {
	fillbuf[i] = fill_val;
	}

	while (len) {
	chunk = std::min(len, COPY_BUF_SIZE);
	crc32 = sparse_crc32(crc32, copybuf, chunk);
	len -= chunk;
	}
	}

	return 0;
	}

	static int process_skip_chunk(struct sparse_file *s, unsigned int chunk_size,
	int fd __unused, unsigned int blocks,
	unsigned int block __unused, uint32_t *crc32)
	{
	if (chunk_size != 0) {
	return -EINVAL;
	}

	if (crc32) {
	int64_t len = (int64_t)blocks * s->block_size;
	memset(copybuf, 0, COPY_BUF_SIZE);

	while (len) {
	int chunk = std::min(len, COPY_BUF_SIZE);
	crc32 = sparse_crc32(crc32, copybuf, chunk);
	len -= chunk;
	}
	}

	return 0;
	}

	static int process_crc32_chunk(int fd, unsigned int chunk_size, uint32_t *crc32)
	{
	uint32_t file_crc32;
	int ret;

	if (chunk_size != sizeof(file_crc32)) {
	return -EINVAL;
	}

	ret = read_all(fd, &file_crc32, sizeof(file_crc32));
	if (ret < 0) {
	return ret;
	}

	if (crc32 != NULL && file_crc32 != *crc32) {
	return -EINVAL;
	}

	return 0;
	}

	static int process_chunk(struct sparse_file *s, int fd, off64_t offset,
	unsigned int chunk_hdr_sz, chunk_header_t *chunk_header,
	unsigned int cur_block, uint32_t *crc_ptr)
	{
	int ret;
	unsigned int chunk_data_size;

	chunk_data_size = chunk_header->total_sz - chunk_hdr_sz;

	switch (chunk_header->chunk_type) {
	case CHUNK_TYPE_RAW:
	ret = process_raw_chunk(s, chunk_data_size, fd, offset,
	chunk_header->chunk_sz, cur_block, crc_ptr);
	if (ret < 0) {
	verbose_error(s->verbose, ret, "data block at %" PRId64, offset);
	return ret;
	}
	return chunk_header->chunk_sz;
	case CHUNK_TYPE_FILL:
	ret = process_fill_chunk(s, chunk_data_size, fd,
	chunk_header->chunk_sz, cur_block, crc_ptr);
	if (ret < 0) {
	verbose_error(s->verbose, ret, "fill block at %" PRId64, offset);
	return ret;
	}
	return chunk_header->chunk_sz;
	case CHUNK_TYPE_DONT_CARE:
	ret = process_skip_chunk(s, chunk_data_size, fd,
	chunk_header->chunk_sz, cur_block, crc_ptr);
	if (chunk_data_size != 0) {
	if (ret < 0) {
	verbose_error(s->verbose, ret, "skip block at %" PRId64, offset);
	return ret;
	}
	}
	return chunk_header->chunk_sz;
	case CHUNK_TYPE_CRC32:
	ret = process_crc32_chunk(fd, chunk_data_size, crc_ptr);
	if (ret < 0) {
	verbose_error(s->verbose, -EINVAL, "crc block at %" PRId64,
	offset);
	return ret;
	}
	return 0;
	default:
	verbose_error(s->verbose, -EINVAL, "unknown block %04X at %" PRId64,
	chunk_header->chunk_type, offset);
	}

	return 0;
	}

	static int sparse_file_read_sparse(struct sparse_file *s, int fd, bool crc)
	{
	int ret;
	unsigned int i;
	sparse_header_t sparse_header;
	chunk_header_t chunk_header;
	uint32_t crc32 = 0;
	uint32_t *crc_ptr = 0;
	unsigned int cur_block = 0;
	off64_t offset;

	if (!copybuf) {
	copybuf = (char *)malloc(COPY_BUF_SIZE);
	}

	if (!copybuf) {
	return -ENOMEM;
	}

	if (crc) {
	crc_ptr = &crc32;
	}

	ret = read_all(fd, &sparse_header, sizeof(sparse_header));
	if (ret < 0) {
	return ret;
	}

	if (sparse_header.magic != SPARSE_HEADER_MAGIC) {
	return -EINVAL;
	}

	if (sparse_header.major_version != SPARSE_HEADER_MAJOR_VER) {
	return -EINVAL;
	}

	if (sparse_header.file_hdr_sz < SPARSE_HEADER_LEN) {
	return -EINVAL;
	}

	if (sparse_header.chunk_hdr_sz < sizeof(chunk_header)) {
	return -EINVAL;
	}

	if (sparse_header.file_hdr_sz > SPARSE_HEADER_LEN) {
	/* Skip the remaining bytes in a header that is longer than
	* we expected.
	*/
	lseek64(fd, sparse_header.file_hdr_sz - SPARSE_HEADER_LEN, SEEK_CUR);
	}

	for (i = 0; i < sparse_header.total_chunks; i++) {
	ret = read_all(fd, &chunk_header, sizeof(chunk_header));
	if (ret < 0) {
	return ret;
	}

	if (sparse_header.chunk_hdr_sz > CHUNK_HEADER_LEN) {
	/* Skip the remaining bytes in a header that is longer than
	* we expected.
	*/
	lseek64(fd, sparse_header.chunk_hdr_sz - CHUNK_HEADER_LEN, SEEK_CUR);
	}

	offset = lseek64(fd, 0, SEEK_CUR);

	ret = process_chunk(s, fd, offset, sparse_header.chunk_hdr_sz, &chunk_header,
	cur_block, crc_ptr);
	if (ret < 0) {
	return ret;
	}

	cur_block += ret;
	}

	if (sparse_header.total_blks != cur_block) {
	return -EINVAL;
	}

	return 0;
	}

	static int sparse_file_read_normal(struct sparse_file *s, int fd)
	{
	int ret;
	uint32_t buf = (uint32_t )malloc(s->block_size);
	unsigned int block = 0;
	int64_t remain = s->len;
	int64_t offset = 0;
	unsigned int to_read;
	unsigned int i;
	bool sparse_block;

	if (!buf) {
	return -ENOMEM;
	}

	while (remain > 0) {
	to_read = std::min(remain, (int64_t)(s->block_size));
	ret = read_all(fd, buf, to_read);
	if (ret < 0) {
	error("failed to read sparse file");
	free(buf);
	return ret;
	}

	if (to_read == s->block_size) {
	sparse_block = true;
	for (i = 1; i < s->block_size / sizeof(uint32_t); i++) {
	if (buf[0] != buf[i]) {
	sparse_block = false;
	break;
	}
	}
	} else {
	sparse_block = false;
	}

	if (sparse_block) {
	/* TODO: add flag to use skip instead of fill for buf[0] == 0 */
	sparse_file_add_fill(s, buf[0], to_read, block);
	} else {
	sparse_file_add_fd(s, fd, offset, to_read, block);
	}

	remain -= to_read;
	offset += to_read;
	block++;
	}

	free(buf);
	return 0;
	}

	int sparse_file_read(struct sparse_file *s, int fd, bool sparse, bool crc)
	{
	if (crc && !sparse) {
	return -EINVAL;
	}

	if (sparse) {
	return sparse_file_read_sparse(s, fd, crc);
	} else {
	return sparse_file_read_normal(s, fd);
	}
	}

	struct sparse_file *sparse_file_import(int fd, bool verbose, bool crc)
	{
	int ret;
	sparse_header_t sparse_header;
	int64_t len;
	struct sparse_file *s;

	ret = read_all(fd, &sparse_header, sizeof(sparse_header));
	if (ret < 0) {
	verbose_error(verbose, ret, "header");
	return NULL;
	}

	if (sparse_header.magic != SPARSE_HEADER_MAGIC) {
	verbose_error(verbose, -EINVAL, "header magic");
	return NULL;
	}

	if (sparse_header.major_version != SPARSE_HEADER_MAJOR_VER) {
	verbose_error(verbose, -EINVAL, "header major version");
	return NULL;
	}

	if (sparse_header.file_hdr_sz < SPARSE_HEADER_LEN) {
	return NULL;
	}

	if (sparse_header.chunk_hdr_sz < sizeof(chunk_header_t)) {
	return NULL;
	}

	len = (int64_t)sparse_header.total_blks * sparse_header.blk_sz;
	s = sparse_file_new(sparse_header.blk_sz, len);
	if (!s) {
	verbose_error(verbose, -EINVAL, NULL);
	return NULL;
	}

	ret = lseek64(fd, 0, SEEK_SET);
	if (ret < 0) {
	verbose_error(verbose, ret, "seeking");
	sparse_file_destroy(s);
	return NULL;
	}

	s->verbose = verbose;

	ret = sparse_file_read(s, fd, true, crc);
	if (ret < 0) {
	sparse_file_destroy(s);
	return NULL;
	}

	return s;
	}

	struct sparse_file *sparse_file_import_auto(int fd, bool crc, bool verbose)
	{
	struct sparse_file *s;
	int64_t len;
	int ret;

	s = sparse_file_import(fd, verbose, crc);
	if (s) {
	return s;
	}

	len = lseek64(fd, 0, SEEK_END);
	if (len < 0) {
	return NULL;
	}

	lseek64(fd, 0, SEEK_SET);

	s = sparse_file_new(4096, len);
	if (!s) {
	return NULL;
	}

	ret = sparse_file_read_normal(s, fd);
	if (ret < 0) {
	sparse_file_destroy(s);
	return NULL;
	}

	return s;
	}