Inject universal /slim/init instead of requiring container-specific setup

slim now works with any Containerfile by injecting distro-agnostic scripts at build time: - /slim/init: mounts special filesystems, configures networking (static QEMU slirp), sets up cgroup2, timezone, and rootless container prereqs. Parses slim.cmd=<base64> from the kernel cmdline for runtime overrides, otherwise execs /slim/exec. - /slim/exec: generated from the image's CMD/ENTRYPOINT (via podman image inspect), overridable via --cmd at build and run time. Changes: - New src/inject.rs: inspect image config, infer command, generate /slim/exec script, inject /slim/ into mounted rootfs - New src/scripts/slim-init.sh: the universal init script (include_str!) - build.rs: rename --init to --cmd, inject scripts before packing, drop Meta::save, restructure to ensure unmount always runs - qemu.rs: hardcode init=/slim/init, add --cmd (base64 on cmdline), drop Meta::load, add -no-reboot - Remove src/meta.rs and meta.toml (no longer needed) - Cargo.toml: add serde_json + base64, remove unused walkdir + cpio + toml - Example Containerfiles simplified to plain FROM + CMD - New example/test.sh for manual verification - README updated for new workflow
2026-09-08 21:43:56 +02:00
15 changed files with 236 additions and 4980 deletions
@@ -1,4 +0,0 @@
 [submodule "linux"]
 	path = kernel/linux
 	url = https://github.com/torvalds/linux.git
 	shallow = true
@@ -66,37 +66,15 @@ checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
 [[package]]
 name = "base64"
-version = "0.23.1"
+version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac07cdecf99051d9a5238b80f35af32cdeba5b336e55d957b318b50137e18da5"
+checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 [[package]]
 name = "bitflags"
-version = "2.13.2"
+version = "2.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ded4057c258ba199e2d26386d3af3780957ecaee6c4ef4041c6b4b8b97c0b06"
+checksum = "b588b76d00fde79687d7646a9b5bdf3cc0f655e0bbd080335a95d7e96f3587da"
 [[package]]
 name = "boco"
 version = "0.1.0"
 dependencies = [
 "anyhow",
 "base64",
 "clap",
 "flate2",
 "serde",
 "serde_json",
 "tempfile",
 "xdg",
 ]
 [[package]]
 name = "boco-init"
 version = "0.1.0"
 dependencies = [
 "base64",
 "nix",
 ]
 [[package]]
 name = "cfg-if"
@@ -104,12 +82,6 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 [[package]]
 name = "cfg_aliases"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f079e83a288787bcd14a6aea84cee5c87a67c5a3e660c30f557a3d24761b3527"
 [[package]]
 name = "clap"
 version = "4.6.6"
@@ -183,13 +155,12 @@ checksum = "da7c62ceae207dd37ea5b845da6a0696c799f85e97da1ab5b7910be3c1c80223"
 [[package]]
 name = "flate2"
-version = "1.1.10"
+version = "1.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6e634e2e0ebac1ee034020da1ca582e17ffe4e0f5e985823721e168928136dcb"
+checksum = "843fba2746e448b37e26a819579957415c8cef339bf08564fe8b7ddbd959573c"
 dependencies = [
 "crc32fast",
 "miniz_oxide",
 "zlib-rs",
 ]
 [[package]]
@@ -241,26 +212,14 @@ checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 [[package]]
 name = "miniz_oxide"
-version = "0.9.1"
+version = "0.8.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b63fbc4a50860e98e7b2aa7804ded1db5cbc3aff9193adaff57a6931bf7c4b4c"
+checksum = "1fa76a2c86f704bdb222d66965fb3d63269ce38518b83cb0575fca855ebb6316"
 dependencies = [
 "adler2",
 "simd-adler32",
 ]
 [[package]]
 name = "nix"
 version = "0.31.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf20d2fde8ff38632c426f1165ed7436270b44f199fc55284c38276f9db47c3d"
 dependencies = [
 "bitflags",
 "cfg-if",
 "cfg_aliases",
 "libc",
 ]
 [[package]]
 name = "once_cell"
 version = "1.21.4"
@@ -359,6 +318,20 @@ version = "0.3.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3a219298ac11a56ea9a6d2120044824d6f01aeb034955e7af7bc16858527deea"
 [[package]]
 name = "slim"
 version = "0.1.0"
 dependencies = [
 "anyhow",
 "base64",
 "clap",
 "flate2",
 "serde",
 "serde_json",
 "tempfile",
 "xdg",
 ]
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -367,9 +340,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 [[package]]
 name = "syn"
-version = "3.0.5"
+version = "3.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "12df2e0110f65b775f769bb17ef989067a1d931b2eb822bd4346631eeada89f9"
+checksum = "e6275cddf4610d1775e6d1fe9469b2e77d0f39fd98fb7450901b821e0c53649f"
 dependencies = [
 "proc-macro2",
 "quote",
@@ -422,12 +395,6 @@ version = "3.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2fb433233f2df9344722454bc7e96465c9d03bff9d77c248f9e7523fe79585b5"
 [[package]]
 name = "zlib-rs"
 version = "0.6.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34b31d188d9d685a4f9c7b46d6e36631b07058d2cfe190267adce54dc230bf12"
 [[package]]
 name = "zmij"
 version = "1.0.23"
@@ -1,19 +1,11 @@
 [workspace]
 members = [".", "init"]
 [profile.release]
 opt-level = "z"
 lto = true
 strip = true
 [package]
-name = "boco"
+name = "slim"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 anyhow = "1.0.104"
-base64 = "0.23"
+base64 = "0.22"
 clap = { version = "4.6.6", features = ["derive"] }
 flate2 = "1.1.9"
 serde = { version = "1.0.229", features = ["derive"] }
@@ -1,41 +1,32 @@
-# boco
+# slim
-Turn container images into bootable VMs
+Turning containers into bootable VMs
 ## Example
 ```Dockerfile
 # ./example/alpine/Containerfile
 FROM alpine:latest
 CMD ["/bin/sh"]
 ```
 ```sh
 # Build the container
-podman build ./example/alpine -t boco-alpine
+podman build ./example/alpine -t slim-alpine
-# Make the container bootable. boco injects a custom init program,
+# Make the container bootable. slim injects /slim/init and /slim/exec,
 # then packs the rootfs as a qcow2 disk.
-boco build qcow2 boco-alpine
+slim build qcow2 slim-alpine
-# Boot the image using QEMU, and drop into /bin/sh.
+# Boot the image using QEMU. The container's CMD runs automatically.
-boco boot boco-alpine
+slim run slim-alpine
 # Override the command at runtime (base64-encoded on the kernel cmdline):
 slim run slim-alpine --cmd '/bin/sh'
 # Override the command at build time (baked into /slim/exec):
 slim build qcow2 slim-alpine --cmd '/bin/sh'
 # Cleanup
-boco image rm boco-alpine
+slim image rm slim-alpine
-podman image rm boco-alpine
+podman image rm slim-alpine
 ```
 Can also be used to boot a more traditional systemd-based VM:
 ```Dockerfile
 FROM archlinux:latest
 # This works! Although you should probably add a user or some services.
 CMD ["/sbin/init"]
 ```
 ## Kernel
-boco boots VMs using a shared kernel at `$XDG_DATA_HOME/boco/registry/vmlinuz`.
+slim boots VMs using a shared kernel at `$XDG_DATA_HOME/slim-rs/registry/vmlinuz`.
-Place a suitable x86 bzImage there before running `boco boot`.
+Place a suitable x86 bzImage there before running `slim run`.
@@ -1,12 +1,11 @@
 #!/bin/bash
-# Test script for boco - boots containers and verifies CMD inference/override.
+# Test script for slim - boots containers and verifies CMD inference/override.
 # Requires: podman, qemu-system-x86_64, KVM, curl, and a kernel at
-# $XDG_DATA_HOME/boco/registry/vmlinuz.
+# $XDG_DATA_HOME/slim-rs/registry/vmlinuz.
 set -u
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
-TARGET_DIR="${CARGO_TARGET_DIR:-$SCRIPT_DIR/../target}"
+SLIM_BIN="$SCRIPT_DIR/../target/debug/slim"
 BOCO_BIN="$TARGET_DIR/debug/boco"
 TIMEOUT=120
 pass=0
@@ -34,7 +33,7 @@ check_output() {
 }
 cleanup() {
-    "$BOCO_BIN" image rm "$1" >/dev/null 2>&1 || true
+    "$SLIM_BIN" image rm "$1" >/dev/null 2>&1 || true
    podman image rm "$2" >/dev/null 2>&1 || true
 }
@@ -54,10 +53,10 @@ FROM $from
 $extra_setup
 CMD ["/bin/sh", "-c", "echo CMD_INFERRED_OK; wget -q -O /dev/null http://1.1.1.1 2>/dev/null && echo CONN_OK; wget -q -O /dev/null http://example.org 2>/dev/null && echo DNS_OK; poweroff -f"]
 EOF
-    img="boco-test-$distro-infer"
+    img="slim-test-$distro-infer"
    if podman build -t "$img" -f "$work/Containerfile.infer" >/dev/null 2>&1; then
-        "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1
+        "$SLIM_BIN" build qcow2 "$img" >/dev/null 2>&1
-        output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" 2>&1 || true)
+        output=$(timeout "$TIMEOUT" "$SLIM_BIN" run "$img" 2>&1 || true)
        check_output "$output" "CMD_INFERRED_OK" "$distro CMD-inferred"
        check_output "$output" "CONN_OK" "$distro connect to 1.1.1.1"
        check_output "$output" "DNS_OK" "$distro DNS lookup"
@@ -66,34 +65,34 @@ EOF
    fi
    cleanup "$img" "$img"
-    # === Test 2: boco boot --cmd override ===
+    # === Test 2: slim run --cmd override ===
-    echo "-- Test 2: boco boot --cmd override"
+    echo "-- Test 2: slim run --cmd override"
    cat > "$work/Containerfile.run" <<EOF
 FROM $from
 $extra_setup
 CMD ["/bin/sh", "-c", "echo SHOULD_NOT_APPEAR; poweroff -f"]
 EOF
-    img="boco-test-$distro-run"
+    img="slim-test-$distro-run"
    if podman build -t "$img" -f "$work/Containerfile.run" >/dev/null 2>&1; then
-        "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1
+        "$SLIM_BIN" build qcow2 "$img" >/dev/null 2>&1
-        output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" --cmd 'echo RUN_OVERRIDE_OK; poweroff -f' 2>&1 || true)
+        output=$(timeout "$TIMEOUT" "$SLIM_BIN" run "$img" --cmd 'echo RUN_OVERRIDE_OK; poweroff -f' 2>&1 || true)
-        check_output "$output" "RUN_OVERRIDE_OK" "$distro boot --cmd override"
+        check_output "$output" "RUN_OVERRIDE_OK" "$distro run --cmd override"
    else
-        report fail "$distro boot --cmd override (podman build failed)"
+        report fail "$distro run --cmd override (podman build failed)"
    fi
    cleanup "$img" "$img"
-    # === Test 3: boco build --cmd override ===
+    # === Test 3: slim build --cmd override ===
-    echo "-- Test 3: boco build --cmd override"
+    echo "-- Test 3: slim build --cmd override"
    cat > "$work/Containerfile.build" <<EOF
 FROM $from
 $extra_setup
 CMD ["/bin/sh", "-c", "echo SHOULD_NOT_APPEAR; poweroff -f"]
 EOF
-    img="boco-test-$distro-build"
+    img="slim-test-$distro-build"
    if podman build -t "$img" -f "$work/Containerfile.build" >/dev/null 2>&1; then
-        "$BOCO_BIN" build qcow2 "$img" --cmd 'echo BUILD_OVERRIDE_OK; poweroff -f' >/dev/null 2>&1
+        "$SLIM_BIN" build qcow2 "$img" --cmd 'echo BUILD_OVERRIDE_OK; poweroff -f' >/dev/null 2>&1
-        output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" 2>&1 || true)
+        output=$(timeout "$TIMEOUT" "$SLIM_BIN" run "$img" 2>&1 || true)
        check_output "$output" "BUILD_OVERRIDE_OK" "$distro build --cmd override"
    else
        report fail "$distro build --cmd override (podman build failed)"
@@ -103,140 +102,10 @@ EOF
    rm -rf "$work"
 }
 test_user() {
    echo "=== Testing USER directive ==="
    work="$(mktemp -d)"
    img="boco-test-user"
    cat > "$work/Containerfile" <<'EOF'
 FROM alpine:latest
 RUN adduser -D -u 1500 testuser
 USER testuser
 CMD ["/bin/sh", "-c", "echo USER_BUILD_OK:$(id -u):$(whoami); poweroff -f"]
 EOF
    echo "-- Building container image with USER directive..."
    if ! podman build --network=none -t "$img" -f "$work/Containerfile" >/dev/null 2>&1; then
        report fail "USER directive (podman build failed)"
        rm -rf "$work"
        return
    fi
    echo "-- Test 1: build-time CMD runs as USER"
    "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1
    output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" 2>&1 || true)
    check_output "$output" "USER_BUILD_OK:1500:testuser" "USER build-time CMD runs as testuser"
    echo "-- Test 2: boot --cmd override runs as USER"
    output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" --cmd 'echo USER_RUN_OK:$(id -u):$(whoami); poweroff -f' 2>&1 || true)
    check_output "$output" "USER_RUN_OK:1500:testuser" "USER boot --cmd override runs as testuser"
    cleanup "$img" "$img"
    rm -rf "$work"
 }
 test_mount() {
    echo "=== Testing --mount (9p shares) ==="
    work="$(mktemp -d)"
    # --- Image 1: no WORKINGDIR, test host:guest and multi-mount ---
    img="boco-test-mount"
    share_dir="$work/share"
    share_dir2="$work/share2"
    guest_dir="/mnt/guest"
    guest_dir2="/mnt/guest2"
    mkdir -p "$share_dir" "$share_dir2"
    echo "hello from host" > "$share_dir/testfile.txt"
    echo "second share" > "$share_dir2/testfile2.txt"
    cat > "$work/Containerfile" <<'EOF'
 FROM alpine:latest
 CMD ["/bin/sh", "-c", "poweroff -f"]
 EOF
    echo "-- Building container image (no WORKINGDIR)..."
    if ! podman build --network=none -t "$img" -f "$work/Containerfile" >/dev/null 2>&1; then
        report fail "--mount (podman build failed)"
        rm -rf "$work"
        return
    fi
    echo "-- Building boco VM..."
    if ! "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1; then
        report fail "--mount (boco build failed)"
        cleanup "$img" "$img"
        rm -rf "$work"
        return
    fi
    share_canon=$(readlink -f "$share_dir")
    share_canon2=$(readlink -f "$share_dir2")
    echo "-- Test 1: --mount host:guest (absolute guest path, multi-mount)..."
    output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" \
        --mount "${share_dir}:${guest_dir}" \
        --mount "${share_dir2}:${guest_dir2}" \
        --cmd "for f in /sys/bus/virtio/drivers/9pnet_virtio/virtio*/mount_tag; do [ -f \"\$f\" ] && echo \"\$f: \$(tr -d '\\0' < \"\$f\")\"; done; mount -v; cat ${guest_dir}/testfile.txt 2>/dev/null || echo NO_FILE; cat ${guest_dir2}/testfile2.txt 2>/dev/null || echo NO_FILE2; echo MOUNT_VERIFY_DONE; poweroff -f" \
        2>&1 || true)
    check_output "$output" "mount_tag: boco0" "--mount 9p share detected"
    check_output "$output" "mount_tag: boco1" "--mount second 9p share detected"
    check_output "$output" "type 9p" "--mount 9p filesystem in mount list"
    check_output "$output" "hello from host" "--mount file accessible at guest path"
    check_output "$output" "second share" "--mount second file accessible at guest path"
    check_output "$output" "MOUNT_VERIFY_DONE" "--mount VM ran to completion"
    cleanup "$img" "$img"
    # --- Image 2: with WORKINGDIR, test relative guest path ---
    img="boco-test-mount-wd"
    share_dir3="$work/share3"
    mkdir -p "$share_dir3"
    echo "relative share" > "$share_dir3/relfile.txt"
    cat > "$work/Containerfile.wd" <<'EOF'
 FROM alpine:latest
 WORKDIR /app
 CMD ["/bin/sh", "-c", "poweroff -f"]
 EOF
    echo "-- Building container image (WORKINGDIR /app)..."
    if ! podman build --network=none -t "$img" -f "$work/Containerfile.wd" >/dev/null 2>&1; then
        report fail "--mount relative (podman build failed)"
        rm -rf "$work"
        return
    fi
    echo "-- Building boco VM..."
    if ! "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1; then
        report fail "--mount relative (boco build failed)"
        cleanup "$img" "$img"
        rm -rf "$work"
        return
    fi
    echo "-- Test 2: --mount host:relative-guest (resolved against WORKINGDIR)..."
    output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" \
        --mount "${share_dir3}:data" \
        --cmd "mount -v; cat /app/data/relfile.txt 2>/dev/null || echo NO_REL_FILE; echo REL_VERIFY_DONE; poweroff -f" \
        2>&1 || true)
    check_output "$output" "type 9p" "--mount relative 9p filesystem in mount list"
    check_output "$output" "relative share" "--mount relative file accessible at WORKINGDIR/data"
    check_output "$output" "REL_VERIFY_DONE" "--mount relative VM ran to completion"
    cleanup "$img" "$img"
    rm -rf "$work"
 }
 test_service() {
    echo "=== Testing nextcloud service ==="
-    img="boco-test-nextcloud"
+    img="slim-test-nextcloud"
    host_port=18080
    work="$(mktemp -d)"
@@ -252,16 +121,16 @@ EOF
        return
    fi
-    echo "-- Building boco VM..."
+    echo "-- Building slim VM..."
-    if ! "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1; then
+    if ! "$SLIM_BIN" build qcow2 "$img" >/dev/null 2>&1; then
-        report fail "nextcloud service (boco build failed)"
+        report fail "nextcloud service (slim build failed)"
        cleanup "$img" "$img"
        rm -rf "$work"
        return
    fi
    echo "-- Booting VM with port forward (host :${host_port} -> guest :80)..."
-    setsid timeout 300 "$BOCO_BIN" boot "$img" \
+    setsid timeout 300 "$SLIM_BIN" run "$img" \
        --forward "tcp:0.0.0.0:${host_port}-:80" \
        --memory 2048M >/dev/null 2>&1 &
    vm_pid=$!
@@ -295,75 +164,14 @@ EOF
    rm -rf "$work"
 }
-test_systemd() {
+echo "Building slim..."
    echo "=== Testing systemd as init ==="
    work="$(mktemp -d)"
    img="boco-test-systemd"
    cat > "$work/boco-test.service" <<'SVC'
 [Unit]
 Description=boco systemd test
 After=multi-user.target
 [Service]
 Type=oneshot
 ExecStart=/bin/sh -c "echo SYSTEMD_TEST_OK > /dev/console; sleep 1; systemctl poweroff"
 [Install]
 WantedBy=multi-user.target
 SVC
    cat > "$work/Containerfile" <<EOF
 FROM archlinux:latest
 COPY boco-test.service /etc/systemd/system/boco-test.service
 RUN mkdir -p /etc/systemd/system/multi-user.target.wants && \
    ln -sf /etc/systemd/system/boco-test.service \
       /etc/systemd/system/multi-user.target.wants/boco-test.service
 CMD ["/sbin/init"]
 EOF
    echo "-- Building container image with systemd..."
    if ! podman build -t "$img" "$work" >/dev/null 2>&1; then
        report fail "systemd as init (podman build failed)"
        rm -rf "$work"
        return
    fi
    echo "-- Building boco VM..."
    if ! "$BOCO_BIN" build qcow2 "$img" >/dev/null 2>&1; then
        report fail "systemd as init (boco build failed)"
        cleanup "$img" "$img"
        rm -rf "$work"
        return
    fi
    echo "-- Booting VM (systemd as PID 1)..."
    output=$(timeout "$TIMEOUT" "$BOCO_BIN" boot "$img" 2>&1 || true)
    check_output "$output" "SYSTEMD_TEST_OK" "systemd boots and runs service"
    check_output "$output" "reboot: Power down" "systemd shuts down cleanly"
    cleanup "$img" "$img"
    rm -rf "$work"
 }
 echo "Building boco..."
 cargo build 2>&1
 cargo build --release -p boco-init --target x86_64-unknown-linux-musl 2>&1
 cp "$TARGET_DIR/x86_64-unknown-linux-musl/release/boco-init" \
   "${XDG_DATA_HOME:-$HOME/.local/share}/boco/boco-init"
 test_distro "alpine" "alpine:latest" ""
 test_distro "archlinux" "archlinux:latest" "RUN pacman -Sy --noconfirm iproute2 wget; pacman -Sc --noconfirm"
 test_user
 test_mount
 test_service
 test_systemd
 echo ""
 echo "=== Results: $pass passed, $fail failed ==="
 [ "$fail" -eq 0 ]
@@ -1,8 +0,0 @@
 [package]
 name = "boco-init"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 base64 = "0.23"
 nix = { version = "0.31", features = ["mount", "fs", "process", "user", "reboot"] }
@@ -1,429 +0,0 @@
 //! boco universal init.
 //!
 //! Injected by `boco build` at /boco/init and invoked via init=/boco/init.
 //! Sets up devices, filesystems, networking, and 9p shares, then execs the
 //! container's CMD/ENTRYPOINT (or a runtime override) with execvp so the
 //! command becomes PID 1 directly.
 use base64::Engine;
 use nix::mount::{MsFlags, mount};
 use nix::sys::reboot::{RebootMode, reboot};
 use nix::sys::stat::{Mode, SFlag, makedev, mknod};
 use nix::sys::wait::waitpid;
 use nix::unistd::{ForkResult, Gid, Uid, User, execvp, fork, setgid, setuid};
 use std::env;
 use std::ffi::CString;
 use std::fs;
 use std::os::unix::fs::PermissionsExt;
 use std::path::Path;
 use std::process::Command;
 fn warn(msg: &str) {
    eprintln!("boco-init: {msg}");
 }
 /// Run a fallible operation, logging on error.
 fn try_io<F, T>(label: &str, f: F)
 where
    F: FnOnce() -> std::io::Result<T>,
 {
    if let Err(e) = f() {
        warn(&format!("{label}: {e}"));
    }
 }
 /// Run a command, logging on error or non-zero exit.
 fn try_cmd(label: &str, cmd: &mut Command) {
    match cmd.status() {
        Ok(status) => {
            if !status.success() {
                warn(&format!("{label}: exited with {status}"));
            }
        }
        Err(e) => warn(&format!("{label}: {e}")),
    }
 }
 /// The kernel passes a minimal environment to init. Set a default PATH
 /// so that `ip` and other tools can be found by name.
 fn ensure_path() {
    if env::var("PATH").is_err() {
        // SAFETY: we are single-threaded before fork/exec.
        unsafe {
            env::set_var(
                "PATH",
                "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
            );
        }
    }
 }
 fn find_in_path(prog: &str) -> Option<String> {
    let path = env::var("PATH").ok()?;
    for dir in path.split(':') {
        let candidate = format!("{dir}/{prog}");
        if Path::new(&candidate).exists() {
            return Some(candidate);
        }
    }
    None
 }
 fn try_mount(
    source: Option<&str>,
    target: &str,
    fstype: Option<&str>,
    flags: MsFlags,
    data: Option<&str>,
 ) {
    if let Err(e) = mount(source, target, fstype, flags, data) {
        warn(&format!("mount {target}: {e}"));
    }
 }
 fn setup_filesystems() {
    if !Path::new("/dev/console").exists() {
        try_io("mknod /dev/console", || {
            mknod(
                "/dev/console",
                SFlag::S_IFCHR,
                Mode::S_IRUSR | Mode::S_IWUSR,
                makedev(5, 1),
            )
            .map_err(std::io::Error::from)
        });
    }
    let dirs = [
        "/proc",
        "/sys",
        "/dev/pts",
        "/dev/shm",
        "/run",
        "/tmp",
        "/sys/fs/cgroup",
    ];
    for d in &dirs {
        try_io(&format!("mkdir {d}"), || fs::create_dir_all(d));
    }
    try_mount(Some("proc"), "/proc", Some("proc"), MsFlags::empty(), None);
    try_mount(Some("sysfs"), "/sys", Some("sysfs"), MsFlags::empty(), None);
    try_mount(
        Some("devpts"),
        "/dev/pts",
        Some("devpts"),
        MsFlags::empty(),
        None,
    );
    try_mount(
        Some("tmpfs"),
        "/dev/shm",
        Some("tmpfs"),
        MsFlags::empty(),
        None,
    );
    try_mount(
        Some("tmpfs"),
        "/run",
        Some("tmpfs"),
        MsFlags::empty(),
        Some("mode=755"),
    );
    try_mount(
        Some("tmpfs"),
        "/tmp",
        Some("tmpfs"),
        MsFlags::empty(),
        Some("mode=1777"),
    );
    // cgroup2
    try_mount(
        Some("cgroup2"),
        "/sys/fs/cgroup",
        Some("cgroup2"),
        MsFlags::empty(),
        None,
    );
    if let Ok(controllers) = fs::read_to_string("/sys/fs/cgroup/cgroup.controllers") {
        for c in controllers.split_whitespace() {
            try_io("write cgroup.subtree_control", || {
                fs::write("/sys/fs/cgroup/cgroup.subtree_control", format!("+{c}"))
            });
        }
    }
 }
 fn setup_rootless_prereqs() {
    // make-rshared /
    if let Err(e) =
        mount::<str, str, str, str>(None, "/", None, MsFlags::MS_REC | MsFlags::MS_SHARED, None)
    {
        warn(&format!("make-rshared /: {e}"));
    }
    // chmod u+s newuidmap newgidmap
    for bin in &["/usr/bin/newuidmap", "/usr/bin/newgidmap"] {
        match fs::metadata(bin) {
            Ok(meta) => {
                let mut perms = meta.permissions();
                perms.set_mode(perms.mode() | 0o4000);
                try_io(&format!("chmod u+s {bin}"), || {
                    fs::set_permissions(bin, perms)
                });
            }
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
            Err(e) => warn(&format!("stat {bin}: {e}")),
        }
    }
 }
 fn setup_timezone() {
    try_io("symlink timezone", || {
        std::os::unix::fs::symlink("/usr/share/zoneinfo/Europe/Stockholm", "/etc/localtime")
    });
 }
 fn setup_networking() {
    let ip = find_in_path("ip").unwrap_or_else(|| "/sbin/ip".to_string());
    try_cmd(
        "ip link set lo up",
        Command::new(&ip).args(["link", "set", "lo", "up"]),
    );
    try_cmd(
        "ip link set eth0 up",
        Command::new(&ip).args(["link", "set", "eth0", "up"]),
    );
    try_cmd(
        "ip addr add 10.0.2.15/24 dev eth0",
        Command::new(&ip).args(["addr", "add", "10.0.2.15/24", "dev", "eth0"]),
    );
    try_cmd(
        "ip route add default via 10.0.2.2",
        Command::new(&ip).args(["route", "add", "default", "via", "10.0.2.2"]),
    );
    try_io("write /etc/resolv.conf", || {
        fs::write("/etc/resolv.conf", "nameserver 10.0.2.3\n")
    });
 }
 fn setup_9p_shares(workdir: &str) {
    let cmdline = match fs::read_to_string("/proc/cmdline") {
        Ok(c) => c,
        Err(e) => {
            warn(&format!("read /proc/cmdline: {e}"));
            return;
        }
    };
    let b64 = base64::engine::general_purpose::STANDARD;
    for tok in cmdline.split_whitespace() {
        if let Some(rest) = tok.strip_prefix("boco.mount=") {
            let Some((tag, dest_b64)) = rest.split_once(':') else {
                continue;
            };
            let dest = match b64.decode(dest_b64) {
                Ok(bytes) => match String::from_utf8(bytes) {
                    Ok(s) => s,
                    Err(e) => {
                        warn(&format!("9p: invalid UTF-8 in guest path: {e}"));
                        continue;
                    }
                },
                Err(e) => {
                    warn(&format!("9p: base64 decode failed: {e}"));
                    continue;
                }
            };
            // Resolve relative guest paths against WORKINGDIR
            let dest = if dest.starts_with('/') {
                dest
            } else {
                format!("{}/{}", workdir, dest)
            };
            try_io(&format!("mkdir {dest}"), || fs::create_dir_all(&dest));
            try_mount(
                Some(tag),
                &dest,
                Some("9p"),
                MsFlags::empty(),
                Some("trans=virtio,version=9p2000.L"),
            );
        }
    }
 }
 fn read_file_opt(path: &str) -> Option<String> {
    fs::read_to_string(path)
        .ok()
        .filter(|s| !s.trim().is_empty())
 }
 fn split_null_delimited(data: &[u8]) -> Vec<String> {
    data.split(|&b| b == 0)
        .filter(|s| !s.is_empty())
        .map(|s| String::from_utf8_lossy(s).into_owned())
        .collect()
 }
 fn read_argv() -> Vec<String> {
    // Check for runtime override: boco.cmd=<base64(null-delimited argv)>
    let b64 = base64::engine::general_purpose::STANDARD;
    if let Ok(cmdline) = fs::read_to_string("/proc/cmdline") {
        for tok in cmdline.split_whitespace() {
            if let Some(rest) = tok.strip_prefix("boco.cmd=")
                && let Ok(decoded) = b64.decode(rest)
            {
                let argv = split_null_delimited(&decoded);
                if !argv.is_empty() {
                    return argv;
                }
            }
        }
    }
    // Fall back to build-time argv from /boco/exec
    match fs::read("/boco/exec") {
        Ok(data) => {
            let argv = split_null_delimited(&data);
            if !argv.is_empty() {
                return argv;
            }
        }
        Err(e) => warn(&format!("read /boco/exec: {e}")),
    }
    warn("no command found, falling back to /bin/sh");
    vec!["/bin/sh".to_string()]
 }
 fn apply_env() {
    if let Ok(data) = fs::read("/boco/env") {
        for entry in split_null_delimited(&data) {
            if let Some((key, val)) = entry.split_once('=') {
                // SAFETY: we are single-threaded before fork/exec.
                unsafe { env::set_var(key, val) };
            }
        }
    }
 }
 fn apply_workdir() {
    if let Some(dir) = read_file_opt("/boco/workdir") {
        try_io("set working directory", || env::set_current_dir(&dir));
    }
 }
 struct UserSpec {
    uid: Uid,
    gid: Gid,
 }
 fn resolve_user(spec: &str) -> Option<UserSpec> {
    let (user_part, gid_part) = match spec.split_once(':') {
        Some((u, g)) => (u, Some(g)),
        None => (spec, None),
    };
    let (uid, default_gid) = if let Ok(numeric) = user_part.parse::<u32>() {
        let user = User::from_uid(Uid::from_raw(numeric)).ok().flatten();
        let gid = user
            .as_ref()
            .map(|u| u.gid)
            .unwrap_or(Gid::from_raw(numeric));
        (Uid::from_raw(numeric), gid)
    } else {
        let user = User::from_name(user_part).ok().flatten()?;
        (user.uid, user.gid)
    };
    let gid = match gid_part {
        Some(g) => match g.parse::<u32>() {
            Ok(n) => Gid::from_raw(n),
            Err(_) => default_gid,
        },
        None => default_gid,
    };
    Some(UserSpec { uid, gid })
 }
 fn exec_command(argv: &[String], user: Option<UserSpec>) -> ! {
    let cstrings: Vec<CString> = argv
        .iter()
        .map(|s| CString::new(s.as_str()).unwrap_or_default())
        .collect();
    let c_prog = cstrings[0].clone();
    let c_refs: Vec<&CString> = cstrings.iter().collect();
    match user {
        None => {
            // No privilege drop: exec directly, PID 1 becomes the command.
            let Err(e) = execvp(&c_prog, &c_refs);
            warn(&format!("execvp {}: {e}", argv[0]));
            let _ = reboot(RebootMode::RB_POWER_OFF);
            std::process::exit(1);
        }
        Some(user) => {
            // Drop privileges in a child so PID 1 (root) can poweroff afterwards.
            match unsafe { fork() } {
                Ok(ForkResult::Child) => {
                    // setgid before setuid to avoid losing privileges
                    if let Err(e) = setgid(user.gid) {
                        warn(&format!("setgid: {e}"));
                    }
                    if let Err(e) = setuid(user.uid) {
                        warn(&format!("setuid: {e}"));
                    }
                    let Err(e) = execvp(&c_prog, &c_refs);
                    warn(&format!("execvp {}: {e}", argv[0]));
                    std::process::exit(127);
                }
                Ok(ForkResult::Parent { child }) => {
                    let _ = waitpid(child, None);
                    let _ = reboot(RebootMode::RB_POWER_OFF);
                    std::process::exit(0);
                }
                Err(e) => {
                    warn(&format!("fork: {e}"));
                    let _ = reboot(RebootMode::RB_POWER_OFF);
                    std::process::exit(1);
                }
            }
        }
    }
 }
 fn main() {
    ensure_path();
    // === Devices & special filesystems ===
    setup_filesystems();
    // === Rootless container prerequisites (best-effort) ===
    setup_rootless_prereqs();
    // === Timezone ===
    setup_timezone();
    // === Networking ===
    setup_networking();
    // === 9p shares ===
    let workdir = read_file_opt("/boco/workdir").unwrap_or_default();
    setup_9p_shares(&workdir);
    // === Environment & working directory ===
    apply_env();
    apply_workdir();
    // === Resolve user for privilege drop ===
    let user = read_file_opt("/boco/user").and_then(|spec| resolve_user(&spec));
    // === Execute the configured command ===
    let argv = read_argv();
    exec_command(&argv, user);
 }
@@ -1,4 +1,4 @@
-//! Build: mount a podman image, inject /boco/ scripts, and pack the rootfs
+//! Build: mount a podman image, inject /slim/ scripts, and pack the rootfs
 //! as a gzipped cpio initrd or qcow2 disk in the registry.
 use anyhow::{Context, Result, bail};
@@ -41,7 +41,7 @@ pub(crate) fn build(
    }: BuildCmd,
 ) -> Result<()> {
    let image = &name;
-    let container = format!("boco-build-{}", image.replace(':', "-"));
+    let container = format!("slim-build-{}", image.replace(':', "-"));
    let mount_path = mount_container(image, &container)?;
    println!("Mounted at: {}", mount_path.display());
@@ -75,18 +75,12 @@ fn build_inner(
    cmd: Option<String>,
 ) -> Result<()> {
    let config = inject::inspect_config(image)?;
-    let argv = match cmd {
+    let command = cmd.unwrap_or_else(|| inject::infer_command(&config));
-        Some(s) => vec!["/bin/sh".into(), "-c".into(), s],
+    let env = inject::env(&config);
-        None => inject::infer_argv(&config),
+    let working_dir = inject::working_dir(&config);
-    };
+    let exec_script = inject::build_exec_script(&command, &env, working_dir);
-    inject::inject(
+    inject::inject(mount_path, &exec_script)?;
-        mount_path,
+    println!("Injected /slim/ (init + exec)");
        &argv,
        &config.env,
        config.user.as_deref(),
        config.working_dir.as_deref(),
    )?;
    println!("Injected /boco/ (init + exec)");
    match kind {
        ImageKind::Initrd => build_initrd(image, mount_path),
@@ -1,6 +1,5 @@
-//! Inject: inspect a podman image's config, infer the default command argv,
+//! Inject: inspect a podman image's config, infer the default command, and
-//! and inject the boco init binary + null-delimited argv/env files into the
+//! inject distro-agnostic /slim/ scripts (init + exec) into the mounted rootfs.
 //! mounted rootfs.
 use anyhow::{Context, Result, anyhow};
 use serde::Deserialize;
@@ -8,21 +7,20 @@ use std::fs;
 use std::path::Path;
 use crate::command::cmd;
-use crate::registry::init_binary_path;
+
 const SLIM_INIT: &str = include_str!("scripts/slim-init.sh");
 #[derive(Debug, Default, Deserialize)]
 #[serde(rename_all = "PascalCase")]
 pub struct Config {
    #[serde(default)]
-    pub cmd: Vec<String>,
+    cmd: Option<Vec<String>>,
    #[serde(default)]
-    pub entrypoint: Vec<String>,
+    entrypoint: Option<Vec<String>>,
    #[serde(default)]
-    pub env: Vec<String>,
+    env: Option<Vec<String>>,
    #[serde(default)]
-    pub working_dir: Option<String>,
+    working_dir: Option<String>,
    #[serde(default)]
    pub user: Option<String>,
 }
 pub fn inspect_config(image: &str) -> Result<Config> {
@@ -39,77 +37,98 @@ pub fn inspect_config(image: &str) -> Result<Config> {
    Ok(config)
 }
-/// Infer the command argv from the image config.
+/// Infer the command string from the image config.
 ///
 /// Concatenates ENTRYPOINT + CMD (Docker semantics). If neither is present,
-/// falls back to `["/bin/sh"]`.
+/// falls back to `/bin/sh`.
-pub fn infer_argv(config: &Config) -> Vec<String> {
+pub fn infer_command(config: &Config) -> String {
-    let parts: Vec<String> = config
+    let entrypoint = config.entrypoint.as_deref().filter(|e| !e.is_empty());
-        .entrypoint
+    let cmd = config.cmd.as_deref().filter(|c| !c.is_empty());
        .iter()
        .chain(config.cmd.iter())
        .cloned()
        .collect();
-    if parts.is_empty() {
+    let parts: Vec<String> = match (entrypoint, cmd) {
-        vec!["/bin/sh".into()]
+        (Some(ep), Some(c)) => {
            let mut parts = ep.to_vec();
            parts.extend(c.iter().cloned());
            parts
        }
        (Some(ep), None) => ep.to_vec(),
        (None, Some(c)) => c.to_vec(),
        (None, None) => vec!["/bin/sh".to_string()],
    };
    if parts.len() == 3 && (parts[0] == "/bin/sh" || parts[0] == "sh") && parts[1] == "-c" {
        parts[2].clone()
    } else {
-        parts
+        shell_join(&parts)
    }
 }
-/// Join items as null-delimited bytes.
+pub fn env(config: &Config) -> Vec<String> {
-pub fn null_delimited(items: &[String]) -> Vec<u8> {
+    config.env.clone().unwrap_or_default()
-    let mut data = Vec::new();
+}
-    for item in items {
+
-        data.extend_from_slice(item.as_bytes());
+pub fn working_dir(config: &Config) -> Option<&str> {
-        data.push(0);
+    config.working_dir.as_deref()
 }
 fn shell_escape(s: &str) -> String {
    format!("'{}'", s.replace('\'', "'\\''"))
 }
 fn shell_join(parts: &[String]) -> String {
    parts
        .iter()
        .map(|p| shell_escape(p))
        .collect::<Vec<_>>()
        .join(" ")
 }
 /// Generate the /slim/exec script from a command string, env vars, and working dir.
 pub fn build_exec_script(command: &str, env: &[String], working_dir: Option<&str>) -> String {
    let mut lines = String::from("#!/bin/sh\n");
    if let Some(dir) = working_dir.filter(|d| !d.is_empty()) {
        lines.push_str(&format!("cd {} 2>/dev/null\n", shell_escape(dir)));
    }
-    data
+    for var in env {
        if let Some((key, val)) = var.split_once('=') {
            lines.push_str(&format!(
                "export {}={}\n",
                shell_escape(key),
                shell_escape(val)
            ));
        }
    }
    lines.push_str(&format!("exec /bin/sh -c {}\n", shell_escape(command)));
    lines
 }
-/// Install `content` into the mounted rootfs at `<mount>/boco/<name>` with
+/// Inject /slim/init and /slim/exec into a mounted container image rootfs.
-/// the given mode.
+pub fn inject(mount_path: &Path, exec_script: &str) -> Result<()> {
 fn install_into_rootfs(mount: &str, name: &str, mode: &str, content: &[u8]) -> Result<()> {
    let temp = tempfile::NamedTempFile::new()?;
    fs::write(temp.path(), content)?;
    let src = temp.path().to_str().context("temp path is not UTF-8")?;
    let dest = format!("{mount}/boco/{name}");
    cmd(&[
        "podman", "unshare", "--", "install", "-D", "-m", mode, src, &dest,
    ])?;
    Ok(())
 }
 /// Inject /boco/init (binary), /boco/exec (null-delimited argv), /boco/env
 /// (null-delimited env), and optionally /boco/user and /boco/workdir into a
 /// mounted container image rootfs.
 pub fn inject(
    mount_path: &Path,
    argv: &[String],
    env: &[String],
    user: Option<&str>,
    working_dir: Option<&str>,
 ) -> Result<()> {
    let mount_str = mount_path.to_str().context("mount path is not UTF-8")?;
-    let init_binary = fs::read(init_binary_path()?).context("Failed to read boco-init binary")?;
+    let init_temp = tempfile::NamedTempFile::new()?;
-    let exec_data = null_delimited(argv);
+    let exec_temp = tempfile::NamedTempFile::new()?;
-    let env_data = null_delimited(env);
+    fs::write(init_temp.path(), SLIM_INIT)?;
    fs::write(exec_temp.path(), exec_script)?;
-    install_into_rootfs(mount_str, "init", "755", &init_binary)?;
+    let init_src = init_temp
-    install_into_rootfs(mount_str, "exec", "644", &exec_data)?;
+        .path()
-    if !env_data.is_empty() {
+        .to_str()
-        install_into_rootfs(mount_str, "env", "644", &env_data)?;
+        .context("temp path is not UTF-8")?;
-    }
+    let exec_src = exec_temp
        .path()
        .to_str()
        .context("temp path is not UTF-8")?;
-    if let Some(user) = user.filter(|u| !u.is_empty()) {
+    let init_dest = format!("{mount_str}/slim/init");
-        install_into_rootfs(mount_str, "user", "644", user.as_bytes())?;
+    let exec_dest = format!("{mount_str}/slim/exec");
    }
-    if let Some(dir) = working_dir.filter(|d| !d.is_empty()) {
+    cmd(&[
-        install_into_rootfs(mount_str, "workdir", "644", dir.as_bytes())?;
+        "podman", "unshare", "--", "install", "-D", "-m", "755", init_src, &init_dest,
-    }
+    ])?;
    cmd(&[
        "podman", "unshare", "--", "install", "-D", "-m", "755", exec_src, &exec_dest,
    ])?;
    Ok(())
 }
@@ -9,7 +9,7 @@ mod registry;
 use anyhow::Result;
 use clap::{Parser, Subcommand};
-use crate::{build::BuildCmd, image::ImageCmd, qemu::BootCmd};
+use crate::{build::BuildCmd, image::ImageCmd, qemu::RunCmd};
 #[derive(Parser, Debug)]
 #[command(about = "Turn containers into bootable VMs")]
@@ -23,8 +23,8 @@ enum Commands {
    /// Build initrd from an image (podman image must exist)
    Build(BuildCmd),
    /// Launch a previously built VM via QEMU.
-    Boot(BootCmd),
+    Run(RunCmd),
-    /// List boco images in the registry
+    /// List slim images in the registry
    #[command(subcommand)]
    Image(ImageCmd),
 }
@@ -35,8 +35,8 @@ fn main() -> Result<()> {
        Commands::Build(cmd) => {
            build::build(cmd)?;
        }
-        Commands::Boot(cmd) => {
+        Commands::Run(cmd) => {
-            qemu::boot(cmd)?;
+            qemu::run(cmd)?;
        }
        Commands::Image(cmd) => {
            image::run(cmd)?;
@@ -1,8 +1,8 @@
 //! QEMU: boot a registry entry with qemu-system-x86_64 using direct kernel
 //! boot (-kernel/-initrd or -drive). The kernel is shared across all VMs
-//! at $XDG_DATA_HOME/boco/registry/vmlinuz. A universal /boco/init script (injected
+//! at $XDG_DATA_HOME/slim-rs/registry/vmlinuz. A universal /slim/init script (injected
-//! at build time) handles VM bootstrap; /boco/exec runs the container's
+//! at build time) handles VM bootstrap; /slim/exec runs the container's
-//! CMD/ENTRYPOINT. Runtime overrides are delivered as `boco.cmd=<base64>`
+//! CMD/ENTRYPOINT. Runtime overrides are delivered as `slim.cmd=<base64>`
 //! on the kernel cmdline.
 use anyhow::{Context, Result, bail};
@@ -16,7 +16,7 @@ use crate::{
 };
 #[derive(Args, Debug)]
-pub struct BootCmd {
+pub struct RunCmd {
    /// Image tag / registry subdir name
    name: String,
@@ -29,26 +29,18 @@ pub struct BootCmd {
    forward: Vec<PortForward>,
    /// Override the command to exec in the VM (base64-encoded on the kernel
-    /// cmdline as boco.cmd=<b64>). Overrides the CMD inferred at build time.
+    /// cmdline as slim.cmd=<b64>). Overrides the CMD inferred at build time.
    #[clap(long)]
    cmd: Option<String>,
    /// Share a host directory into the VM via 9p. Format:
    /// `<host-path>` or `<host-path>:<guest-path>`. When the guest path is
    /// omitted, the host path is used. Non-absolute guest paths are
    /// relative to the image's WORKINGDIR. Can be repeated.
    #[clap(long)]
    mount: Vec<String>,
 }
-pub(crate) fn boot(
+pub(crate) fn run(
-    BootCmd {
+    RunCmd {
        name,
        memory,
        forward,
        cmd,
-        mount,
+    }: RunCmd,
    }: BootCmd,
 ) -> Result<()> {
    let reg_dir = registry_dir(&name)?;
    let vmlinuz_path = registry_base_dir()?.join("vmlinuz");
@@ -67,7 +59,7 @@ pub(crate) fn boot(
        "rw".into(),
        "earlyprintk=serial".into(),
        "nokaslr".into(),
-        "init=/boco/init".into(),
+        "init=/slim/init".into(),
        "devtmpfs.mount=1".into(), // Automatically mount /dev at boot
    ];
@@ -81,43 +73,12 @@ pub(crate) fn boot(
        fs_args = vec!["-initrd".to_string(), initrd_str];
        cmdline.push("root=/dev/ram0".into());
    } else {
-        bail!("Registry missing rootfs/initrd for '{name}'. Run `boco build` first.");
+        bail!("Registry missing rootfs/initrd for '{name}'. Run `slim build` first.");
    }
    if let Some(cmd) = &cmd {
-        let argv = ["/bin/sh".to_string(), "-c".to_string(), cmd.clone()];
+        let encoded = base64::engine::general_purpose::STANDARD.encode(cmd.as_bytes());
-        let data: Vec<u8> = argv.join("\0").into_bytes();
+        cmdline.push(format!("slim.cmd={encoded}"));
        let encoded = base64::engine::general_purpose::STANDARD.encode(&data);
        cmdline.push(format!("boco.cmd={encoded}"));
    }
    // Build 9p shares for each --mount.  Tags are short (boco0, boco1, …)
    // because 9p mount_tag has a ~31-byte limit.  The guest destination path
    // is passed on the kernel cmdline as boco.mount=<tag>:<base64(guest_path)>.
    // If no guest path is specified, the host path is used as the guest path.
    let mut virtfs_args: Vec<String> = Vec::new();
    for (i, spec) in mount.iter().enumerate() {
        let (host_path, guest_path) = match spec.split_once(':') {
            Some((h, g)) => (h, g),
            None => (spec.as_str(), spec.as_str()),
        };
        let canonical = std::path::Path::new(host_path)
            .canonicalize()
            .with_context(|| format!("Cannot resolve mount path '{host_path}'"))?;
        let host_str = canonical
            .to_str()
            .context("Mount path is not valid UTF-8")?;
        let tag = format!("boco{i}");
        let dest_b64 = base64::engine::general_purpose::STANDARD.encode(guest_path.as_bytes());
        // QEMU's QemuOpts splits on commas — escape literal commas in the
        // path as ",," per QEMU convention.
        let host_escaped = host_str.replace(',', ",,");
        virtfs_args.push("-virtfs".into());
        virtfs_args.push(format!(
            "local,path={host_escaped},mount_tag={tag},security_model=mapped-xattr"
        ));
        cmdline.push(format!("boco.mount={tag}:{dest_b64}"));
    }
    println!("Booting {name} from registry: {}", reg_dir.display());
@@ -140,7 +101,6 @@ pub(crate) fn boot(
        .arg("-kernel")
        .arg(vmlinuz_path.as_os_str())
        .args(&fs_args)
        .args(&virtfs_args)
        .args(["-snapshot"])
        .args(["-no-reboot"])
        .args(["-append", &cmdline])
@@ -1,12 +1,12 @@
 //! Registry: local storage of built VM artifacts under
-//! `$XDG_DATA_HOME/boco/registry/<image>/`.
+//! `$XDG_DATA_HOME/slim-rs/registry/<image>/`.
 use anyhow::{Context, Result, anyhow, bail};
 use std::{fs, io, path::PathBuf};
 /// Validate a user-supplied image name before it is used in a registry path.
 ///
-/// The name becomes a directory under `$XDG_DATA_HOME/boco/registry/`, so
+/// The name becomes a directory under `$XDG_DATA_HOME/slim-rs/registry/`, so
 /// path separators and `.`/`..` would allow escaping that directory.
 /// Allow-list: ASCII alphanumerics plus `.`, `_`, `:`, `-` (covers image
 /// refs like `alpine:3.15`).
@@ -27,17 +27,11 @@ pub(crate) fn validate_image_name(name: &str) -> Result<()> {
 }
 pub(crate) fn registry_base_dir() -> Result<PathBuf> {
-    let base = xdg::BaseDirectories::with_prefix("boco");
+    let base = xdg::BaseDirectories::with_prefix("slim-rs");
    base.create_data_directory("registry")
        .context("Failed to create XDG_DATA_HOME subdirectory")
 }
 pub(crate) fn init_binary_path() -> Result<PathBuf> {
    let base = xdg::BaseDirectories::with_prefix("boco");
    base.get_data_file("boco-init")
        .context("boco-init not found in XDG data dir")
 }
 pub(crate) fn registry_dir(image: &str) -> Result<PathBuf> {
    validate_image_name(image)?;
    let base = registry_base_dir()?;
@@ -62,7 +56,7 @@ mod tests {
    fn accepts_valid_image_names() {
        for name in [
            "alpine:3.15",
-            "boco",
+            "slim",
            "mock-vm",
            "my_vm",
            "a.b.c",
@@ -0,0 +1,54 @@
 #!/bin/sh
 # slim universal init - distro-agnostic VM bootstrap.
 # Injected by `slim build` at /slim/init and invoked via init=/slim/init.
 # === Devices & special filesystems ===
 [ -c /dev/console ] || mknod -m 600 /dev/console c 5 1
 mkdir -p /proc /sys /dev/pts /dev/shm
 mount -t proc proc /proc
 mount -t sysfs sysfs /sys
 mount -t devpts devpts /dev/pts
 mount -t tmpfs tmpfs /dev/shm
 mount -t tmpfs tmpfs /run  -o mode=755
 mount -t tmpfs tmpfs /tmp  -o mode=1777
 # === cgroup2 ===
 mkdir -p /sys/fs/cgroup
 mount -t cgroup2 none /sys/fs/cgroup 2>/dev/null || echo "mount cgroup2 failed"
 # shellcheck disable=SC2013 # word-splitting is intentional: controllers are space-separated
 for c in $(cat /sys/fs/cgroup/cgroup.controllers 2>/dev/null); do
    echo "+$c" > /sys/fs/cgroup/cgroup.subtree_control 2>/dev/null || echo "enable cgroup controller $c failed"
 done
 # === Rootless container prerequisites (best-effort) ===
 mount --make-rshared / 2>/dev/null || echo "make-rshared / failed"
 chmod u+s /usr/bin/newuidmap /usr/bin/newgidmap 2>/dev/null || echo "chmod newuidmap/newgidmap failed"
 # === Timezone ===
 ln -sf /usr/share/zoneinfo/Europe/Stockholm /etc/localtime 2>/dev/null || echo "set timezone failed"
 # === Networking (QEMU slirp: guest 10.0.2.15/24, gw 10.0.2.2, dns 10.0.2.3) ===
 ip link set lo up 2>/dev/null || echo "ip link set lo up failed"
 ip link set eth0 up 2>/dev/null || echo "ip link set eth0 up failed"
 ip addr add 10.0.2.15/24 dev eth0 2>/dev/null || echo "ip addr add eth0 failed"
 ip route add default via 10.0.2.2 2>/dev/null || echo "ip route add default failed"
 echo nameserver 10.0.2.3 > /etc/resolv.conf
 # === Execute the configured command ===
 # If slim.cmd=<base64> is on the kernel cmdline, decode and exec it.
 # Otherwise, exec /slim/exec (generated from the image's CMD/ENTRYPOINT).
 # shellcheck disable=SC2013 # word-splitting is intentional: cmdline tokens are space-separated
 for tok in $(cat /proc/cmdline 2>/dev/null); do
    case "$tok" in
        slim.cmd=*)
            v=${tok#slim.cmd=}
            decoded=$(printf '%s' "$v" | base64 -d 2>/dev/null) \
                || decoded=$(printf '%s' "$v" | openssl base64 -d 2>/dev/null) \
                || echo "base64 decode failed"
            if [ -n "$decoded" ]; then
                exec /bin/sh -c "$decoded"
            fi
            ;;
    esac
 done
 exec /slim/exec