1 files changed, 156 insertions, 0 deletions
diff --git a/bootctrl/BootControlShared.cpp b/bootctrl/BootControlShared.cpp
new file mode 100644
index 0000000..193ddea
--- /dev/null
+++ b/bootctrl/BootControlShared.cpp
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2019 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 LOG_TAG "bootcontrolhal"
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <bootloader_message/bootloader_message.h>
+
+#include "BootControlShared.h"
+
+namespace android {
+namespace hardware {
+namespace boot {
+namespace V1_1 {
+namespace implementation {
+
+using android::base::unique_fd;
+using android::hardware::boot::V1_1::MergeStatus;
+
+constexpr off_t kBootloaderControlOffset = offsetof(bootloader_message_ab, slot_suffix);
+
+static uint32_t CRC32(const uint8_t *buf, size_t size) {
+    static uint32_t crc_table[256];
+
+    // Compute the CRC-32 table only once.
+    if (!crc_table[1]) {
+        for (uint32_t i = 0; i < 256; ++i) {
+            uint32_t crc = i;
+            for (uint32_t j = 0; j < 8; ++j) {
+                uint32_t mask = -(crc & 1);
+                crc = (crc >> 1) ^ (0xEDB88320 & mask);
+            }
+            crc_table[i] = crc;
+        }
+    }
+
+    uint32_t ret = -1;
+    for (size_t i = 0; i < size; ++i) {
+        ret = (ret >> 8) ^ crc_table[(ret ^ buf[i]) & 0xFF];
+    }
+
+    return ~ret;
+}
+
+uint32_t ComputeChecksum(const bootloader_control *boot_ctrl) {
+    return CRC32(reinterpret_cast<const uint8_t *>(boot_ctrl),
+                 offsetof(bootloader_control, crc32_le));
+}
+
+static bool LoadUpdateState(const std::string &misc_device, bootloader_control *buffer) {
+    unique_fd fd(open(misc_device.c_str(), O_RDONLY));
+    if (fd < 0) {
+        PLOG(ERROR) << "failed to open " << misc_device;
+        return false;
+    }
+    if (lseek(fd, kBootloaderControlOffset, SEEK_SET) != kBootloaderControlOffset) {
+        PLOG(ERROR) << "failed to lseek " << misc_device;
+        return false;
+    }
+    if (!android::base::ReadFully(fd, buffer, sizeof(bootloader_control))) {
+        PLOG(ERROR) << "failed to read " << misc_device;
+        return false;
+    }
+    return true;
+}
+
+static bool SaveUpdateState(const std::string &misc_device, bootloader_control *buffer) {
+    unique_fd fd(open(misc_device.c_str(), O_WRONLY | O_SYNC));
+    if (fd < 0) {
+        PLOG(ERROR) << "failed to open " << misc_device;
+        return false;
+    }
+    if (lseek(fd, kBootloaderControlOffset, SEEK_SET) != kBootloaderControlOffset) {
+        PLOG(ERROR) << "failed to lseek " << misc_device;
+        return false;
+    }
+
+    buffer->crc32_le = ComputeChecksum(buffer);
+    if (!android::base::WriteFully(fd, buffer, sizeof(bootloader_control))) {
+        PLOG(ERROR) << "failed to write " << misc_device;
+        return false;
+    }
+    return true;
+}
+
+BootControlShared::BootControlShared() {
+    std::string err;
+    misc_device_ = get_bootloader_message_blk_device(&err);
+    if (misc_device_.empty()) {
+        LOG(FATAL) << "Unable to locate misc device: " << err;
+    }
+
+    bootloader_control control;
+    if (!LoadUpdateState(misc_device_, &control)) {
+        LOG(FATAL) << "Unable to read update state from misc partition";
+    }
+    uint32_t computed_crc32 = ComputeChecksum(&control);
+
+    bool initialize = false;
+    if (computed_crc32 != control.crc32_le) {
+        LOG(WARNING) << "Invalid boot control found, expected CRC32 0x" << std::hex
+                     << computed_crc32 << " but found 0x" << std::hex << control.crc32_le;
+        initialize = true;
+    } else if (control.magic != BOOT_CTRL_MAGIC) {
+        LOG(WARNING) << "Invalid boot control magic, " << std::hex << control.magic;
+        initialize = true;
+    }
+    if (initialize) {
+        LOG(WARNING) << "Re-initializing misc.";
+
+        // We only use the |merge_status| field of this structure.
+        memset(&control, 0, sizeof(control));
+        control.magic = BOOT_CTRL_MAGIC;
+        control.version = BOOT_CTRL_VERSION;
+        control.merge_status = static_cast<uint8_t>(MergeStatus::NONE);
+        SaveUpdateState(misc_device_, &control);
+    }
+}
+
+Return<bool> BootControlShared::setSnapshotMergeStatus(MergeStatus status) {
+    bootloader_control control;
+    if (!LoadUpdateState(misc_device_, &control)) {
+        return false;
+    }
+    control.merge_status = static_cast<uint8_t>(status);
+    return SaveUpdateState(misc_device_, &control);
+}
+
+Return<MergeStatus> BootControlShared::getSnapshotMergeStatus() {
+    bootloader_control control;
+    if (!LoadUpdateState(misc_device_, &control)) {
+        return MergeStatus::UNKNOWN;
+    }
+    return static_cast<MergeStatus>(control.merge_status);
+}
+
+}  // namespace implementation
+}  // namespace V1_1
+}  // namespace boot
+}  // namespace hardware
+}  // namespace android