platform_system_core/libsparse/sparse_read.cpp

/*
 * 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);
}

class SparseFileSource {
public:
	/* Seeks the source ahead by the given offset. */
	virtual void Seek(int64_t offset) = 0;

	/* Return the current offset. */
	virtual int64_t GetOffset() = 0;

	/* Set the current offset. Return 0 if successful. */
	virtual int SetOffset(int64_t offset) = 0;

	/* Adds the given length from the current offset of the source to the file at the given
	 * block. Return 0 if successful. */
	virtual int AddToSparseFile(struct sparse_file *s, int64_t len, unsigned int block) = 0;

	/* Get data of fixed size from the current offset and seek len bytes.
	 * Return 0 if successful. */
	virtual int ReadValue(void *ptr, int len) = 0;

	/* Find the crc32 of the next len bytes and seek ahead len bytes. Return 0 if successful. */
	virtual int GetCrc32(uint32_t *crc32, int64_t len) = 0;

	virtual ~SparseFileSource() {};
};

class SparseFileFdSource : public SparseFileSource {
private:
	int fd;
public:
	SparseFileFdSource(int fd) : fd(fd) {}
	~SparseFileFdSource() override {}

	void Seek(int64_t off) override {
		lseek64(fd, off, SEEK_CUR);
	}

	int64_t GetOffset() override {
		return lseek64(fd, 0, SEEK_CUR);
	}

	int SetOffset(int64_t offset) override {
		return lseek64(fd, offset, SEEK_SET) == offset ? 0 : -errno;
	}

	int AddToSparseFile(struct sparse_file *s, int64_t len, unsigned int block) override {
		return sparse_file_add_fd(s, fd, GetOffset(), len, block);
	}

	int ReadValue(void *ptr, int len) override {
		return read_all(fd, ptr, len);
	}

	int GetCrc32(uint32_t *crc32, int64_t len) override {
		int chunk;
		int ret;
		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;
		}
		return 0;
	}
};

class SparseFileBufSource : public SparseFileSource {
private:
	char *buf;
	int64_t offset;
public:
	SparseFileBufSource(char *buf) : buf(buf), offset(0) {}
	~SparseFileBufSource() override {}

	void Seek(int64_t off) override {
		buf += off;
		offset += off;
	}

	int64_t GetOffset() override {
		return offset;
	}

	int SetOffset(int64_t off) override {
		buf += off - offset;
		offset = off;
		return 0;
	}

	int AddToSparseFile(struct sparse_file *s, int64_t len, unsigned int block) override {
		return sparse_file_add_data(s, buf, len, block);
	}

	int ReadValue(void *ptr, int len) override {
		memcpy(ptr, buf, len);
		Seek(len);
		return 0;
	}

	int GetCrc32(uint32_t *crc32, int64_t len) override {
		*crc32 = sparse_crc32(*crc32, buf, len);
		Seek(len);
		return 0;
	}
};

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,
		SparseFileSource *source, unsigned int blocks, unsigned int block,
		uint32_t *crc32)
{
	int ret;
	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 = source->AddToSparseFile(s, len, block);
	if (ret < 0) {
		return ret;
	}

	if (crc32) {
		ret = source->GetCrc32(crc32, len);
		if (ret < 0) {
			return ret;
		}
	} else {
		source->Seek(len);
	}

	return 0;
}

static int process_fill_chunk(struct sparse_file *s, unsigned int chunk_size,
		SparseFileSource *source, 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 = source->ReadValue(&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,
		SparseFileSource *source __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(SparseFileSource *source, unsigned int chunk_size, uint32_t *crc32)
{
	uint32_t file_crc32;

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

	int ret = source->ReadValue(&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, SparseFileSource *source,
		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;
	int64_t offset = source->GetOffset();

	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, source,
					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, source,
					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, source,
					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(source, 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, SparseFileSource *source, 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;

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

	if (!copybuf) {
		return -ENOMEM;
	}

	if (crc) {
		crc_ptr = &crc32;
	}

	ret = source->ReadValue(&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.
		 */
		source->Seek(sparse_header.file_hdr_sz - SPARSE_HEADER_LEN);
	}

	for (i = 0; i < sparse_header.total_chunks; i++) {
		ret = source->ReadValue(&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.
			 */
			source->Seek(sparse_header.chunk_hdr_sz - CHUNK_HEADER_LEN);
		}

		ret = process_chunk(s, source, 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) {
		SparseFileFdSource source(fd);
		return sparse_file_read_sparse(s, &source, crc);
	} else {
		return sparse_file_read_normal(s, fd);
	}
}

int sparse_file_read_buf(struct sparse_file *s, char *buf, bool crc)
{
	SparseFileBufSource source(buf);
	return sparse_file_read_sparse(s, &source, crc);
}

static struct sparse_file *sparse_file_import_source(SparseFileSource *source, bool verbose, bool crc)
{
	int ret;
	sparse_header_t sparse_header;
	int64_t len;
	struct sparse_file *s;

	ret = source->ReadValue(&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 = source->SetOffset(0);
	if (ret < 0) {
		verbose_error(verbose, ret, "seeking");
		sparse_file_destroy(s);
		return NULL;
	}

	s->verbose = verbose;

	ret = sparse_file_read_sparse(s, source, crc);
	if (ret < 0) {
		sparse_file_destroy(s);
		return NULL;
	}

	return s;
}

struct sparse_file *sparse_file_import(int fd, bool verbose, bool crc) {
	SparseFileFdSource source(fd);
	return sparse_file_import_source(&source, verbose, crc);
}

struct sparse_file *sparse_file_import_buf(char* buf, bool verbose, bool crc) {
	SparseFileBufSource source(buf);
	return sparse_file_import_source(&source, verbose, crc);
}

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;
}