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-rw-r--r--otautil/sysutil.cpp203
1 files changed, 203 insertions, 0 deletions
diff --git a/otautil/sysutil.cpp b/otautil/sysutil.cpp
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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 "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();
+}