priv: move shared consts to hive-sh4re; WriteNspawnFlags uses Vec<String> + per-flag validation

hive-c0re/src/priv_client.rs

@@ -59,10 +59,10 @@ pub async fn list_containers() -> Result<String> {
     Ok(stdout)
 }
 
-pub async fn write_nspawn_flags(container: &str, extra_nspawn_flags: &str) -> Result<()> {
+pub async fn write_nspawn_flags(container: &str, extra_nspawn_flags: &[&str]) -> Result<()> {
     ok(call(&PrivRequest::WriteNspawnFlags {
         container: container.to_owned(),
-        extra_nspawn_flags: extra_nspawn_flags.to_owned(),
+        extra_nspawn_flags: extra_nspawn_flags.iter().map(|s| s.to_string()).collect(),
     }).await?)
 }
 

hive-priv/src/main.rs

@@ -20,27 +20,14 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context as _, Result, bail};
-use hive_sh4re::priv_proto::{PRIV_SOCK, PrivRequest, PrivResponse};
+use hive_sh4re::priv_proto::{AGENT_PREFIX, MANAGER_NAME, META_DIR, PRIV_SOCK, SIBLING_CONTAINERS, PrivRequest, PrivResponse};
 use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::{UnixListener, UnixStream};
 use tokio::process::Command;
 
-/// Sub-agent container prefix (mirrors `lifecycle::AGENT_PREFIX`).
-const AGENT_PREFIX: &str = "h-";
-
-/// Manager container name (mirrors `lifecycle::MANAGER_NAME`).
-const MANAGER_NAME: &str = "root";
-
-/// Sibling service containers managed by hive-c0re.
-const SIBLING_CONTAINERS: &[&str] = &["hive-forge", "hive-matrix", "hive-gateway"];
-
 /// Root of the per-agent unix-socket dirs on the host.
 const SOCKET_DIR_ROOT: &str = "/run/hive-agent";
 
-/// Host path of the meta flake (mirrors `meta::meta_dir()`).
-/// The flake ref for agent `<name>` is `{META_DIR}#{name}`.
-const META_DIR: &str = "/var/lib/hyperhive/meta";
-
 #[tokio::main]
 async fn main() -> Result<()> {
     tracing_subscriber::fmt()
@@ -188,6 +175,9 @@ async fn exec(req: PrivRequest) -> Result<(String, String)> {
 
         PrivRequest::WriteNspawnFlags { ref container, ref extra_nspawn_flags } => {
             validate_container_system_name(container)?;
+            for flag in extra_nspawn_flags {
+                validate_nspawn_flag(flag)?;
+            }
             write_nspawn_flags(container, extra_nspawn_flags)?;
             Ok((String::new(), String::new()))
         }
@@ -362,11 +352,22 @@ fn agent_flake_ref(name: &str) -> String {
     format!("{META_DIR}#{name}")
 }
 
+/// Validate one nspawn flag entry: must be non-empty and contain no
+/// ASCII whitespace or null bytes. Whitespace would split the entry
+/// into multiple flags when the start script expands
+/// `$EXTRA_NSPAWN_FLAGS` unquoted.
+fn validate_nspawn_flag(flag: &str) -> Result<()> {
+    if flag.is_empty() || flag.bytes().any(|b| b == 0 || b.is_ascii_whitespace()) {
+        bail!("invalid nspawn flag {flag:?}: must be non-empty and contain no whitespace or null bytes");
+    }
+    Ok(())
+}
+
 /// Update `/etc/nixos-containers/<container>.conf`: strips network-isolation
 /// vars (`PRIVATE_NETWORK`, `HOST_ADDRESS*`, `LOCAL_ADDRESS*`, `HOST_BRIDGE`,
 /// `EXTRA_NSPAWN_FLAGS`), forces `PRIVATE_NETWORK=0` and blank network vars,
 /// then appends `EXTRA_NSPAWN_FLAGS="<flags>"`.
-fn write_nspawn_flags(container: &str, extra_nspawn_flags: &str) -> Result<()> {
+fn write_nspawn_flags(container: &str, extra_nspawn_flags: &[String]) -> Result<()> {
     let path = format!("/etc/nixos-containers/{container}.conf");
     let original = std::fs::read_to_string(&path)
         .with_context(|| format!("read {path}"))?;
@@ -393,6 +394,7 @@ fn write_nspawn_flags(container: &str, extra_nspawn_flags: &str) -> Result<()> {
     out.push_str("HOST_ADDRESS6=\n");
     out.push_str("LOCAL_ADDRESS6=\n");
     out.push_str("HOST_BRIDGE=\n");
-    out.push_str(&format!("EXTRA_NSPAWN_FLAGS=\"{extra_nspawn_flags}\"\n"));
+    let flags_joined = extra_nspawn_flags.join(" ");
+    out.push_str(&format!("EXTRA_NSPAWN_FLAGS=\"{flags_joined}\"\n"));
     std::fs::write(&path, out).with_context(|| format!("write {path}"))
 }

hive-sh4re/src/priv_proto.rs

@@ -8,6 +8,20 @@ use serde::{Deserialize, Serialize};
 /// Default socket path for the privileged helper.
 pub const PRIV_SOCK: &str = "/run/hive/priv.sock";
 
+/// Manager container name. Used by `hive-priv` to skip the `h-` prefix
+/// and by `hive-c0re` for identity checks.
+pub const MANAGER_NAME: &str = "root";
+
+/// Sub-agent container prefix. System container name = `h-<agent_name>`.
+pub const AGENT_PREFIX: &str = "h-";
+
+/// Sibling service containers managed by hive-c0re.
+pub const SIBLING_CONTAINERS: &[&str] = &["hive-forge", "hive-matrix", "hive-gateway"];
+
+/// Host path of the meta flake. The flake ref for agent `<name>` is
+/// `{META_DIR}#{name}`, derived by `hive-priv` — never passed over the wire.
+pub const META_DIR: &str = "/var/lib/hyperhive/meta";
+
 /// A request to the privileged helper.
 ///
 /// Wire format: one JSON object per line over `/run/hive/priv.sock`.
@@ -46,8 +60,9 @@ pub enum PrivRequest {
 
     /// Update `/etc/nixos-containers/<container>.conf`: strip network-isolation
     /// vars, force `PRIVATE_NETWORK=0`, and set `EXTRA_NSPAWN_FLAGS`.
-    /// Written by `lifecycle::set_nspawn_flags`.
+    /// Each entry in `extra_nspawn_flags` is one flag (e.g. `"--bind=/path"`);
-    WriteNspawnFlags { container: String, extra_nspawn_flags: String },
+    /// hive-priv validates and space-joins them. Written by `lifecycle::set_nspawn_flags`.
+    WriteNspawnFlags { container: String, extra_nspawn_flags: Vec<String> },
 
     /// Write `/run/systemd/system/container@<container>.service.d/hyperhive-limits.conf`
     /// with `[Service]\nMemoryMax=<memory_max>\nCPUQuota=<cpu_quota>\n`.