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/*
* Copyright 2006 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.
*/
#include "SysUtil.h"
#include <fcntl.h>
#include <stdint.h> // SIZE_MAX
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
bool MemMapping::MapFD(int fd) {
struct stat sb;
if (fstat(fd, &sb) == -1) {
PLOG(ERROR) << "fstat(" << fd << ") failed";
return false;
}
void* memPtr = mmap(nullptr, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (memPtr == MAP_FAILED) {
PLOG(ERROR) << "mmap(" << sb.st_size << ", R, PRIVATE, " << fd << ", 0) failed";
return false;
}
addr = static_cast<unsigned char*>(memPtr);
length = sb.st_size;
ranges_.clear();
ranges_.emplace_back(MappedRange{ memPtr, static_cast<size_t>(sb.st_size) });
return true;
}
// A "block map" which looks like this (from uncrypt/uncrypt.cpp):
//
// /dev/block/platform/msm_sdcc.1/by-name/userdata # block device
// 49652 4096 # file size in bytes, block size
// 3 # count of block ranges
// 1000 1008 # block range 0
// 2100 2102 # ... block range 1
// 30 33 # ... block range 2
//
// Each block range represents a half-open interval; the line "30 33" reprents the blocks
// [30, 31, 32].
bool MemMapping::MapBlockFile(const std::string& filename) {
std::string content;
if (!android::base::ReadFileToString(filename, &content)) {
PLOG(ERROR) << "Failed to read " << filename;
return false;
}
std::vector<std::string> lines = android::base::Split(android::base::Trim(content), "\n");
if (lines.size() < 4) {
LOG(ERROR) << "Block map file is too short: " << lines.size();
return false;
}
size_t size;
size_t blksize;
if (sscanf(lines[1].c_str(), "%zu %zu", &size, &blksize) != 2) {
LOG(ERROR) << "Failed to parse file size and block size: " << lines[1];
return false;
}
size_t range_count;
if (sscanf(lines[2].c_str(), "%zu", &range_count) != 1) {
LOG(ERROR) << "Failed to parse block map header: " << lines[2];
return false;
}
size_t blocks;
if (blksize != 0) {
blocks = ((size - 1) / blksize) + 1;
}
if (size == 0 || blksize == 0 || blocks > SIZE_MAX / blksize || range_count == 0 ||
lines.size() != 3 + range_count) {
LOG(ERROR) << "Invalid data in block map file: size " << size << ", blksize " << blksize
<< ", range_count " << range_count << ", lines " << lines.size();
return false;
}
// Reserve enough contiguous address space for the whole file.
void* reserve = mmap64(nullptr, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (reserve == MAP_FAILED) {
PLOG(ERROR) << "failed to reserve address space";
return false;
}
const std::string& block_dev = lines[0];
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(block_dev.c_str(), O_RDONLY)));
if (fd == -1) {
PLOG(ERROR) << "failed to open block device " << block_dev;
munmap(reserve, blocks * blksize);
return false;
}
ranges_.clear();
unsigned char* next = static_cast<unsigned char*>(reserve);
size_t remaining_size = blocks * blksize;
bool success = true;
for (size_t i = 0; i < range_count; ++i) {
const std::string& line = lines[i + 3];
size_t start, end;
if (sscanf(line.c_str(), "%zu %zu\n", &start, &end) != 2) {
LOG(ERROR) << "failed to parse range " << i << ": " << line;
success = false;
break;
}
size_t range_size = (end - start) * blksize;
if (end <= start || (end - start) > SIZE_MAX / blksize || range_size > remaining_size) {
LOG(ERROR) << "Invalid range: " << start << " " << end;
success = false;
break;
}
void* range_start = mmap64(next, range_size, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd,
static_cast<off64_t>(start) * blksize);
if (range_start == MAP_FAILED) {
PLOG(ERROR) << "failed to map range " << i << ": " << line;
success = false;
break;
}
ranges_.emplace_back(MappedRange{ range_start, range_size });
next += range_size;
remaining_size -= range_size;
}
if (success && remaining_size != 0) {
LOG(ERROR) << "Invalid ranges: remaining_size " << remaining_size;
success = false;
}
if (!success) {
munmap(reserve, blocks * blksize);
return false;
}
addr = static_cast<unsigned char*>(reserve);
length = size;
LOG(INFO) << "mmapped " << range_count << " ranges";
return true;
}
bool MemMapping::MapFile(const std::string& fn) {
if (fn.empty()) {
LOG(ERROR) << "Empty filename";
return false;
}
if (fn[0] == '@') {
// Block map file "@/cache/recovery/block.map".
if (!MapBlockFile(fn.substr(1))) {
LOG(ERROR) << "Map of '" << fn << "' failed";
return false;
}
} else {
// This is a regular file.
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(fn.c_str(), O_RDONLY)));
if (fd == -1) {
PLOG(ERROR) << "Unable to open '" << fn << "'";
return false;
}
if (!MapFD(fd)) {
LOG(ERROR) << "Map of '" << fn << "' failed";
return false;
}
}
return true;
}
MemMapping::~MemMapping() {
for (const auto& range : ranges_) {
if (munmap(range.addr, range.length) == -1) {
PLOG(ERROR) << "Failed to munmap(" << range.addr << ", " << range.length << ")";
}
};
ranges_.clear();
}
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