Support commandline completion

To enable, run: `source <(COMPLETE=bash cfsrun)`. Or packagers could
use this to generate a bash completion script at build time.

Signed-off-by: Alexander Larsson <alexl@redhat.com>

Author: alexlarsson

Cargo.lock

@@ -12,6 +12,7 @@ path = "src/main.rs"
 [dependencies]
 anyhow = { version = "1.0", default-features = false }
 clap = { version = "4.5", default-features = false, features = ["std", "help", "usage", "derive"] }
+clap_complete = { version = "4.5", default-features = false, features = ["unstable-dynamic"] }
 composefs = { workspace = true }
 composefs-fuse = { workspace = true }
 composefs-oci = { workspace = true }

composefs-run/Cargo.toml

@@ -10,7 +10,7 @@ mod userns;
 use std::path::PathBuf;
 
 use anyhow::{Context, Result, ensure};
-use clap::Parser;
+use clap::{CommandFactory, Parser};
 use composefs::fsverity::{FsVerityHashValue, Sha256HashValue, Sha512HashValue};
 use composefs::repository::{Repository, read_repo_algorithm};
 use composefs_oci::OciDigest;
@@ -411,6 +411,8 @@ pub(crate) struct Cli {
 }
 
 fn main() -> Result<()> {
+    clap_complete::CompleteEnv::with_factory(Cli::command).complete();
+
     match std::env::args().nth(1).as_deref() {
         Some("--internal-cleanup") => return run::cleanup(),
         Some("--internal-fuse-serve") => {