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Diffstat (limited to 'otautil/sysutil.cpp')
| -rw-r--r-- | otautil/sysutil.cpp | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/otautil/sysutil.cpp b/otautil/sysutil.cpp new file mode 100644 index 000000000..e6385c4e9 --- /dev/null +++ b/otautil/sysutil.cpp @@ -0,0 +1,203 @@ +/* + * 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 "otautil/sysutil.h" + +#include <errno.h> // TEMP_FAILURE_RETRY +#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 = mmap(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 = mmap(next, range_size, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, + static_cast<off_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(); +} |