You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ecli.rs
    path of file: ./repos/tikv/components/encryption/export/examples
    
    the code of the file until where you have to start completion: // Copyright 2020 TiKV Project Authors. Licensed under Apache-2.0.

use std::io::{Read, Write};

use azure::STORAGE_VENDOR_NAME_AZURE;
pub use cloud::kms::Config as CloudConfig;
use encryption::GcpConfig;
use encryption_export::{create_cloud_backend, AzureConfig, Backend, Error, KmsConfig, Result};
use file_system::{File, OpenOptions};
use gcp::ST
    
fn process() -> Result<()> {
    let opt: Opt = Opt::from_args();

    let mut file = File::open(&opt.file)?;
    let mut content = Vec::new();
    file.read_to_end(&mut content)?;

    let credential_file = opt.credential_file.as_ref();
    let backend = match &opt.command {
        Command::Aws(cmd) => create_aws_backend(cmd, credential_file)?,
        Command::Azure(cmd) => create_azure_backend(cmd, credential_file)?,
        Command::Gcp(cmd) => create_gcp_backend(cmd, credential_file)?,
    };

    let output = match opt.operation {
        Operation::Encrypt => {
            let ciphertext = backend.encrypt(&content)?;
            ciphertext.write_to_bytes()?
        }
        Operation::Decrypt => {
            let mut encrypted_content = EncryptedContent::default();
            encrypted_content.merge_from_bytes(&content)?;
            backend.decrypt(&encrypted_content)?
        }
    };

    let mut file = OpenOptions::new()
        .create(true)
        .write(true)
        .open(&opt.output)?;
    file.write_all(&output)?;
    Ok(())
}