diff --git a/roots.cpp b/roots.cpp
new file mode 100644
index 0000000..9345cb0
--- /dev/null
+++ b/roots.cpp
@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) 2007 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 <errno.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <ctype.h>
+
+#include "mtdutils/mtdutils.h"
+#include "mtdutils/mounts.h"
+#include "roots.h"
+#include "common.h"
+#include "make_ext4fs.h"
+
+static int num_volumes = 0;
+static Volume* device_volumes = NULL;
+
+static int parse_options(char* options, Volume* volume) {
+    char* option;
+    while ((option = strtok(options, ","))) {
+        options = NULL;
+
+        if (strncmp(option, "length=", 7) == 0) {
+            volume->length = strtoll(option+7, NULL, 10);
+        } else {
+            LOGE("bad option \"%s\"\n", option);
+            return -1;
+        }
+    }
+    return 0;
+}
+
+void load_volume_table() {
+    int alloc = 2;
+    device_volumes = (Volume*)malloc(alloc * sizeof(Volume));
+
+    // Insert an entry for /tmp, which is the ramdisk and is always mounted.
+    device_volumes[0].mount_point = "/tmp";
+    device_volumes[0].fs_type = "ramdisk";
+    device_volumes[0].device = NULL;
+    device_volumes[0].device2 = NULL;
+    device_volumes[0].length = 0;
+    num_volumes = 1;
+
+    FILE* fstab = fopen("/etc/recovery.fstab", "r");
+    if (fstab == NULL) {
+        LOGE("failed to open /etc/recovery.fstab (%s)\n", strerror(errno));
+        return;
+    }
+
+    char buffer[1024];
+    int i;
+    while (fgets(buffer, sizeof(buffer)-1, fstab)) {
+        for (i = 0; buffer[i] && isspace(buffer[i]); ++i);
+        if (buffer[i] == '\0' || buffer[i] == '#') continue;
+
+        char* original = strdup(buffer);
+
+        char* mount_point = strtok(buffer+i, " \t\n");
+        char* fs_type = strtok(NULL, " \t\n");
+        char* device = strtok(NULL, " \t\n");
+        // lines may optionally have a second device, to use if
+        // mounting the first one fails.
+        char* options = NULL;
+        char* device2 = strtok(NULL, " \t\n");
+        if (device2) {
+            if (device2[0] == '/') {
+                options = strtok(NULL, " \t\n");
+            } else {
+                options = device2;
+                device2 = NULL;
+            }
+        }
+
+        if (mount_point && fs_type && device) {
+            while (num_volumes >= alloc) {
+                alloc *= 2;
+                device_volumes = (Volume*)realloc(device_volumes, alloc*sizeof(Volume));
+            }
+            device_volumes[num_volumes].mount_point = strdup(mount_point);
+            device_volumes[num_volumes].fs_type = strdup(fs_type);
+            device_volumes[num_volumes].device = strdup(device);
+            device_volumes[num_volumes].device2 =
+                device2 ? strdup(device2) : NULL;
+
+            device_volumes[num_volumes].length = 0;
+            if (parse_options(options, device_volumes + num_volumes) != 0) {
+                LOGE("skipping malformed recovery.fstab line: %s\n", original);
+            } else {
+                ++num_volumes;
+            }
+        } else {
+            LOGE("skipping malformed recovery.fstab line: %s\n", original);
+        }
+        free(original);
+    }
+
+    fclose(fstab);
+
+    printf("recovery filesystem table\n");
+    printf("=========================\n");
+    for (i = 0; i < num_volumes; ++i) {
+        Volume* v = &device_volumes[i];
+        printf("  %d %s %s %s %s %lld\n", i, v->mount_point, v->fs_type,
+               v->device, v->device2, v->length);
+    }
+    printf("\n");
+}
+
+Volume* volume_for_path(const char* path) {
+    int i;
+    for (i = 0; i < num_volumes; ++i) {
+        Volume* v = device_volumes+i;
+        int len = strlen(v->mount_point);
+        if (strncmp(path, v->mount_point, len) == 0 &&
+            (path[len] == '\0' || path[len] == '/')) {
+            return v;
+        }
+    }
+    return NULL;
+}
+
+int ensure_path_mounted(const char* path) {
+    Volume* v = volume_for_path(path);
+    if (v == NULL) {
+        LOGE("unknown volume for path [%s]\n", path);
+        return -1;
+    }
+    if (strcmp(v->fs_type, "ramdisk") == 0) {
+        // the ramdisk is always mounted.
+        return 0;
+    }
+
+    int result;
+    result = scan_mounted_volumes();
+    if (result < 0) {
+        LOGE("failed to scan mounted volumes\n");
+        return -1;
+    }
+
+    const MountedVolume* mv =
+        find_mounted_volume_by_mount_point(v->mount_point);
+    if (mv) {
+        // volume is already mounted
+        return 0;
+    }
+
+    mkdir(v->mount_point, 0755);  // in case it doesn't already exist
+
+    if (strcmp(v->fs_type, "yaffs2") == 0) {
+        // mount an MTD partition as a YAFFS2 filesystem.
+        mtd_scan_partitions();
+        const MtdPartition* partition;
+        partition = mtd_find_partition_by_name(v->device);
+        if (partition == NULL) {
+            LOGE("failed to find \"%s\" partition to mount at \"%s\"\n",
+                 v->device, v->mount_point);
+            return -1;
+        }
+        return mtd_mount_partition(partition, v->mount_point, v->fs_type, 0);
+    } else if (strcmp(v->fs_type, "ext4") == 0 ||
+               strcmp(v->fs_type, "vfat") == 0) {
+        result = mount(v->device, v->mount_point, v->fs_type,
+                       MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
+        if (result == 0) return 0;
+
+        if (v->device2) {
+            LOGW("failed to mount %s (%s); trying %s\n",
+                 v->device, strerror(errno), v->device2);
+            result = mount(v->device2, v->mount_point, v->fs_type,
+                           MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
+            if (result == 0) return 0;
+        }
+
+        LOGE("failed to mount %s (%s)\n", v->mount_point, strerror(errno));
+        return -1;
+    }
+
+    LOGE("unknown fs_type \"%s\" for %s\n", v->fs_type, v->mount_point);
+    return -1;
+}
+
+int ensure_path_unmounted(const char* path) {
+    Volume* v = volume_for_path(path);
+    if (v == NULL) {
+        LOGE("unknown volume for path [%s]\n", path);
+        return -1;
+    }
+    if (strcmp(v->fs_type, "ramdisk") == 0) {
+        // the ramdisk is always mounted; you can't unmount it.
+        return -1;
+    }
+
+    int result;
+    result = scan_mounted_volumes();
+    if (result < 0) {
+        LOGE("failed to scan mounted volumes\n");
+        return -1;
+    }
+
+    const MountedVolume* mv =
+        find_mounted_volume_by_mount_point(v->mount_point);
+    if (mv == NULL) {
+        // volume is already unmounted
+        return 0;
+    }
+
+    return unmount_mounted_volume(mv);
+}
+
+int format_volume(const char* volume) {
+    Volume* v = volume_for_path(volume);
+    if (v == NULL) {
+        LOGE("unknown volume \"%s\"\n", volume);
+        return -1;
+    }
+    if (strcmp(v->fs_type, "ramdisk") == 0) {
+        // you can't format the ramdisk.
+        LOGE("can't format_volume \"%s\"", volume);
+        return -1;
+    }
+    if (strcmp(v->mount_point, volume) != 0) {
+        LOGE("can't give path \"%s\" to format_volume\n", volume);
+        return -1;
+    }
+
+    if (ensure_path_unmounted(volume) != 0) {
+        LOGE("format_volume failed to unmount \"%s\"\n", v->mount_point);
+        return -1;
+    }
+
+    if (strcmp(v->fs_type, "yaffs2") == 0 || strcmp(v->fs_type, "mtd") == 0) {
+        mtd_scan_partitions();
+        const MtdPartition* partition = mtd_find_partition_by_name(v->device);
+        if (partition == NULL) {
+            LOGE("format_volume: no MTD partition \"%s\"\n", v->device);
+            return -1;
+        }
+
+        MtdWriteContext *write = mtd_write_partition(partition);
+        if (write == NULL) {
+            LOGW("format_volume: can't open MTD \"%s\"\n", v->device);
+            return -1;
+        } else if (mtd_erase_blocks(write, -1) == (off_t) -1) {
+            LOGW("format_volume: can't erase MTD \"%s\"\n", v->device);
+            mtd_write_close(write);
+            return -1;
+        } else if (mtd_write_close(write)) {
+            LOGW("format_volume: can't close MTD \"%s\"\n", v->device);
+            return -1;
+        }
+        return 0;
+    }
+
+    if (strcmp(v->fs_type, "ext4") == 0) {
+        int result = make_ext4fs(v->device, v->length);
+        if (result != 0) {
+            LOGE("format_volume: make_extf4fs failed on %s\n", v->device);
+            return -1;
+        }
+        return 0;
+    }
+
+    LOGE("format_volume: fs_type \"%s\" unsupported\n", v->fs_type);
+    return -1;
+}