diff --git a/libs/vsutil/src/file.rs b/libs/vsutil/src/file.rs
new file mode 100644
index 0000000..4adaae1
--- /dev/null
+++ b/libs/vsutil/src/file.rs
@@ -0,0 +1,28 @@
+// Copyright 2023, 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.
+
+//! Functions to process files.
+
+use binder::{self, ExceptionCode, ParcelFileDescriptor, Status};
+use std::fs::File;
+
+/// Converts a `&ParcelFileDescriptor` to a `File` by cloning the file.
+pub fn clone_file(fd: &ParcelFileDescriptor) -> binder::Result<File> {
+    fd.as_ref().try_clone().map_err(|e| {
+        Status::new_exception_str(
+            ExceptionCode::BAD_PARCELABLE,
+            Some(format!("Failed to clone File from ParcelFileDescriptor: {:?}", e)),
+        )
+    })
+}
diff --git a/libs/vsutil/src/lib.rs b/libs/vsutil/src/lib.rs
new file mode 100644
index 0000000..cac888a
--- /dev/null
+++ b/libs/vsutil/src/lib.rs
@@ -0,0 +1,22 @@
+// Copyright 2023, 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.
+
+//! This library provides utility functions used by both various
+//! Virtualization services.
+
+mod file;
+mod partition;
+
+pub use file::clone_file;
+pub use partition::init_writable_partition;
diff --git a/libs/vsutil/src/partition.rs b/libs/vsutil/src/partition.rs
new file mode 100644
index 0000000..a4e72de
--- /dev/null
+++ b/libs/vsutil/src/partition.rs
@@ -0,0 +1,93 @@
+// Copyright 2023, 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.
+
+//! Functions to process partitions.
+
+use crate::file::clone_file;
+use android_system_virtualizationservice::aidl::android::system::virtualizationservice::{
+    PartitionType::PartitionType,
+};
+use binder::{self, ExceptionCode, ParcelFileDescriptor, Status};
+use disk::QcowFile;
+use std::io::{Error, ErrorKind, Write};
+
+/// crosvm requires all partitions to be a multiple of 4KiB.
+const PARTITION_GRANULE_BYTES: u64 = 4096;
+
+/// Initialize an empty partition image of the given size to be used as a writable partition.
+pub fn init_writable_partition(
+    image_fd: &ParcelFileDescriptor,
+    size_bytes: i64,
+    partition_type: PartitionType,
+) -> binder::Result<()> {
+    let size_bytes = size_bytes.try_into().map_err(|e| {
+        Status::new_exception_str(
+            ExceptionCode::ILLEGAL_ARGUMENT,
+            Some(format!("Invalid size {}: {:?}", size_bytes, e)),
+        )
+    })?;
+    let size_bytes = round_up(size_bytes, PARTITION_GRANULE_BYTES);
+    let image = clone_file(image_fd)?;
+    // initialize the file. Any data in the file will be erased.
+    image.set_len(0).map_err(|e| {
+        Status::new_service_specific_error_str(-1, Some(format!("Failed to reset a file: {:?}", e)))
+    })?;
+    let mut part = QcowFile::new(image, size_bytes).map_err(|e| {
+        Status::new_service_specific_error_str(
+            -1,
+            Some(format!("Failed to create QCOW2 image: {:?}", e)),
+        )
+    })?;
+
+    match partition_type {
+        PartitionType::RAW => Ok(()),
+        PartitionType::ANDROID_VM_INSTANCE => format_as_android_vm_instance(&mut part),
+        PartitionType::ENCRYPTEDSTORE => format_as_encryptedstore(&mut part),
+        _ => Err(Error::new(
+            ErrorKind::Unsupported,
+            format!("Unsupported partition type {:?}", partition_type),
+        )),
+    }
+    .map_err(|e| {
+        Status::new_service_specific_error_str(
+            -1,
+            Some(format!("Failed to initialize partition as {:?}: {:?}", partition_type, e)),
+        )
+    })
+}
+
+fn round_up(input: u64, granule: u64) -> u64 {
+    if granule == 0 {
+        return input;
+    }
+    // If the input is absurdly large we round down instead of up; it's going to fail anyway.
+    let result = input.checked_add(granule - 1).unwrap_or(input);
+    (result / granule) * granule
+}
+
+fn format_as_android_vm_instance(part: &mut dyn Write) -> std::io::Result<()> {
+    const ANDROID_VM_INSTANCE_MAGIC: &str = "Android-VM-instance";
+    const ANDROID_VM_INSTANCE_VERSION: u16 = 1;
+
+    part.write_all(ANDROID_VM_INSTANCE_MAGIC.as_bytes())?;
+    part.write_all(&ANDROID_VM_INSTANCE_VERSION.to_le_bytes())?;
+    part.flush()
+}
+
+fn format_as_encryptedstore(part: &mut dyn Write) -> std::io::Result<()> {
+    const UNFORMATTED_STORAGE_MAGIC: &str = "UNFORMATTED-STORAGE";
+
+    part.write_all(UNFORMATTED_STORAGE_MAGIC.as_bytes())?;
+    part.flush()
+}