distrib/libsparse/src/sparse_read.c - emulator-unstable-refactoring - 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 _GNU_SOURCE
 #define _FILE_OFFSET_BITS 64
 #define _LARGEFILE64_SOURCE 1

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

 #include <sparse/sparse.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))

 #define COPY_BUF_SIZE (1024U*1024U)
 static char *copybuf;

 #define min(a, b) \
 	({ typeof(a) _a = (a); typeof(b) _b = (b); (_a < _b) ? _a : _b; })

 static void verbose_error(bool verbose, int err, const char *fmt, ...)
 {
 	char *s = "";
 	char *at = "";
 	if (fmt) {
 		va_list argp;
 		int size;

 		va_start(argp, fmt);
 		size = vsnprintf(NULL, 0, fmt, argp);
 		va_end(argp);

 		if (size < 0) {
 			return;
 		}

 		at = malloc(size + 1);
 		if (at == NULL) {
 			return;
 		}

 		va_start(argp, fmt);
 		vsnprintf(at, size, fmt, argp);
 		va_end(argp);
 		at[size] = 0;
 		s = " at ";
 	}
 	if (verbose) {
 #ifndef USE_MINGW
 		if (err == -EOVERFLOW) {
 			sparse_print_verbose("EOF while reading file%s%s\n", s, at);
 		} else
 #endif
 		if (err == -EINVAL) {
 			sparse_print_verbose("Invalid sparse file format%s%s\n", s, at);
 		} else if (err == -ENOMEM) {
 			sparse_print_verbose("Failed allocation while reading file%s%s\n",
 					s, at);
 		} else {
 			sparse_print_verbose("Unknown error %d%s%s\n", err, s, at);
 		}
 	}
 	if (fmt) {
 		free(at);
 	}
 }

 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;
 	unsigned int 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 = 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 = 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 = 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 (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 %lld", 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 %lld", 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 %lld", 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 %lld",
 						offset);
 				return ret;
 			}
 			return 0;
 		default:
 			verbose_error(s->verbose, -EINVAL, "unknown block %04X at %lld",
 					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 = 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 = 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 = min(remain, s->block_size);
 		ret = read_all(fd, buf, to_read);
 		if (ret < 0) {
 			error("failed to read sparse file");
 			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++;
 	}

 	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)
 {
 	struct sparse_file *s;
 	int64_t len;
 	int ret;

 	s = sparse_file_import(fd, true, 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 _GNU_SOURCE
	#define _FILE_OFFSET_BITS 64
	#define _LARGEFILE64_SOURCE 1

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

	#include <sparse/sparse.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))

	#define COPY_BUF_SIZE (1024U*1024U)
	static char *copybuf;

	#define min(a, b) \
	({ typeof(a) _a = (a); typeof(b) _b = (b); (_a < _b) ? _a : _b; })

	static void verbose_error(bool verbose, int err, const char *fmt, ...)
	{
	char *s = "";
	char *at = "";
	if (fmt) {
	va_list argp;
	int size;

	va_start(argp, fmt);
	size = vsnprintf(NULL, 0, fmt, argp);
	va_end(argp);

	if (size < 0) {
	return;
	}

	at = malloc(size + 1);
	if (at == NULL) {
	return;
	}

	va_start(argp, fmt);
	vsnprintf(at, size, fmt, argp);
	va_end(argp);
	at[size] = 0;
	s = " at ";
	}
	if (verbose) {
	#ifndef USE_MINGW
	if (err == -EOVERFLOW) {
	sparse_print_verbose("EOF while reading file%s%s\n", s, at);
	} else
	#endif
	if (err == -EINVAL) {
	sparse_print_verbose("Invalid sparse file format%s%s\n", s, at);
	} else if (err == -ENOMEM) {
	sparse_print_verbose("Failed allocation while reading file%s%s\n",
	s, at);
	} else {
	sparse_print_verbose("Unknown error %d%s%s\n", err, s, at);
	}
	}
	if (fmt) {
	free(at);
	}
	}

	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;
	unsigned int 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 = 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 = 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 = 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 (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 %lld", 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 %lld", 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 %lld", 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 %lld",
	offset);
	return ret;
	}
	return 0;
	default:
	verbose_error(s->verbose, -EINVAL, "unknown block %04X at %lld",
	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 = 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 = 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 = min(remain, s->block_size);
	ret = read_all(fd, buf, to_read);
	if (ret < 0) {
	error("failed to read sparse file");
	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++;
	}

	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)
	{
	struct sparse_file *s;
	int64_t len;
	int ret;

	s = sparse_file_import(fd, true, 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;
	}