fs_mgr/fs_mgr_slotselect.cpp

/*
 * Copyright (C) 2015 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 <stdio.h>

#include <string>

#include "fs_mgr.h"
#include "fs_mgr_priv.h"

// Returns "_a" or "_b" based on androidboot.slot_suffix in kernel cmdline, or an empty string
// if that parameter does not exist.
std::string fs_mgr_get_slot_suffix() {
    std::string ab_suffix;

    fs_mgr_get_boot_config("slot_suffix", &ab_suffix);
    return ab_suffix;
}

// Updates |fstab| for slot_suffix. Returns true on success, false on error.
bool fs_mgr_update_for_slotselect(struct fstab *fstab) {
    int n;
    std::string ab_suffix;

    for (n = 0; n < fstab->num_entries; n++) {
        fstab_rec& record = fstab->recs[n];
        if (record.fs_mgr_flags & MF_SLOTSELECT) {
            if (ab_suffix.empty()) {
                ab_suffix = fs_mgr_get_slot_suffix();
                // Return false if failed to get ab_suffix when MF_SLOTSELECT is specified.
                if (ab_suffix.empty()) return false;
            }

            char* new_blk_device;
            if (asprintf(&new_blk_device, "%s%s", record.blk_device, ab_suffix.c_str()) <= 0) {
                return false;
            }
            free(record.blk_device);
            record.blk_device = new_blk_device;

            char* new_partition_name;
            if (record.logical_partition_name) {
                if (asprintf(&new_partition_name, "%s%s", record.logical_partition_name,
                             ab_suffix.c_str()) <= 0) {
                    return false;
                }
                free(record.logical_partition_name);
                record.logical_partition_name = new_partition_name;
            }
        }
    }
    return true;
}