priv: WriteNspawnFlags takes Vec<BindMount> instead of raw flag strings

hive-c0re/src/priv_client.rs

@@ -7,7 +7,7 @@
 //! a persistent connection.
 
 use anyhow::{Context as _, Result, bail};
-use hive_sh4re::priv_proto::{PRIV_SOCK, PrivRequest, PrivResponse};
+use hive_sh4re::priv_proto::{PRIV_SOCK, BindMount, PrivRequest, PrivResponse};
 use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::UnixStream;
 
@@ -59,13 +59,15 @@ 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, binds: &[BindMount]) -> Result<()> {
     ok(call(&PrivRequest::WriteNspawnFlags {
         container: container.to_owned(),
-        extra_nspawn_flags: extra_nspawn_flags.iter().map(|s| s.to_string()).collect(),
+        binds: binds.to_vec(),
     }).await?)
 }
 
+pub use hive_sh4re::priv_proto::BindMount;
+
 pub async fn write_resource_limits(
     container: &str,
     memory_max: &str,

hive-priv/src/main.rs

@@ -20,7 +20,7 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context as _, Result, bail};
-use hive_sh4re::priv_proto::{AGENT_PREFIX, MANAGER_NAME, META_DIR, PRIV_SOCK, SIBLING_CONTAINERS, PrivRequest, PrivResponse};
+use hive_sh4re::priv_proto::{AGENT_PREFIX, MANAGER_NAME, META_DIR, PRIV_SOCK, SIBLING_CONTAINERS, BindMount, PrivRequest, PrivResponse};
 use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::{UnixListener, UnixStream};
 use tokio::process::Command;
@@ -173,12 +173,13 @@ async fn exec(req: PrivRequest) -> Result<(String, String)> {
 
         PrivRequest::ListContainers => container_run(&["list"]).await,
 
-        PrivRequest::WriteNspawnFlags { ref container, ref extra_nspawn_flags } => {
+        PrivRequest::WriteNspawnFlags { ref container, ref binds } => {
             validate_container_system_name(container)?;
-            for flag in extra_nspawn_flags {
-                validate_nspawn_flag(flag)?;
+            for bind in binds {
+                validate_bind_path(&bind.host_path)?;
+                validate_bind_path(&bind.container_path)?;
             }
-            write_nspawn_flags(container, extra_nspawn_flags)?;
+            write_nspawn_flags(container, binds)?;
             Ok((String::new(), String::new()))
         }
 
@@ -352,17 +353,15 @@ 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 (would split the entry when the start script
-/// expands `$EXTRA_NSPAWN_FLAGS` unquoted), double-quotes (would
-/// break the `EXTRA_NSPAWN_FLAGS="..."` conf line), or null bytes.
-fn validate_nspawn_flag(flag: &str) -> Result<()> {
-    if flag.is_empty()
-        || flag.bytes().any(|b| b == 0 || b == b'"' || b.is_ascii_whitespace())
+/// Validate a bind-mount path: must be absolute, non-empty, and contain
+/// no newlines, null bytes, or double-quotes (which would break the
+/// `EXTRA_NSPAWN_FLAGS="..."` conf line format).
+fn validate_bind_path(path: &str) -> Result<()> {
+    if path.is_empty()
+        || !path.starts_with('/')
+        || path.bytes().any(|b| b == 0 || b == b'\n' || b == b'"')
     {
-        bail!(
-            "invalid nspawn flag {flag:?}: must be non-empty and contain no whitespace, double-quotes, or null bytes"
-        );
+        bail!("invalid bind path {path:?}: must be an absolute path with no newlines, null bytes, or double-quotes");
     }
     Ok(())
 }
@@ -371,7 +370,7 @@ fn validate_nspawn_flag(flag: &str) -> Result<()> {
 /// 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: &[String]) -> Result<()> {
+fn write_nspawn_flags(container: &str, binds: &[BindMount]) -> Result<()> {
     let path = format!("/etc/nixos-containers/{container}.conf");
     let original = std::fs::read_to_string(&path)
         .with_context(|| format!("read {path}"))?;
@@ -398,7 +397,11 @@ fn write_nspawn_flags(container: &str, extra_nspawn_flags: &[String]) -> Result<
     out.push_str("HOST_ADDRESS6=\n");
     out.push_str("LOCAL_ADDRESS6=\n");
     out.push_str("HOST_BRIDGE=\n");
-    let flags_joined = extra_nspawn_flags.join(" ");
+    let flags: Vec<String> = binds.iter().map(|b| {
+        let flag = if b.read_only { "--bind-ro" } else { "--bind" };
+        format!("{flag}={}:{}", b.host_path, b.container_path)
+    }).collect();
+    let flags_joined = 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

@@ -22,6 +22,16 @@ pub const SIBLING_CONTAINERS: &[&str] = &["hive-forge", "hive-matrix", "hive-gat
 /// `{META_DIR}#{name}`, derived by `hive-priv` — never passed over the wire.
 pub const META_DIR: &str = "/var/lib/hyperhive/meta";
 
+/// One bind-mount entry for `WriteNspawnFlags`.
+/// hive-priv constructs `--bind=<host_path>:<container_path>` (or `--bind-ro=`)
+/// and validates both paths before writing the conf file.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BindMount {
+    pub host_path: String,
+    pub container_path: String,
+    pub read_only: bool,
+}
+
 /// A request to the privileged helper.
 ///
 /// Wire format: one JSON object per line over `/run/hive/priv.sock`.
@@ -59,10 +69,9 @@ pub enum PrivRequest {
     // --- Config file writes ---
 
     /// Update `/etc/nixos-containers/<container>.conf`: strip network-isolation
-    /// vars, force `PRIVATE_NETWORK=0`, and set `EXTRA_NSPAWN_FLAGS`.
-    /// Each entry in `extra_nspawn_flags` is one flag (e.g. `"--bind=/path"`);
-    /// hive-priv validates and space-joins them. Written by `lifecycle::set_nspawn_flags`.
-    WriteNspawnFlags { container: String, extra_nspawn_flags: Vec<String> },
+    /// vars, force `PRIVATE_NETWORK=0`, and set `EXTRA_NSPAWN_FLAGS` from the
+    /// provided bind-mount list. Written by `lifecycle::set_nspawn_flags`.
+    WriteNspawnFlags { container: String, binds: Vec<BindMount> },
 
     /// Write `/run/systemd/system/container@<container>.service.d/hyperhive-limits.conf`
     /// with `[Service]\nMemoryMax=<memory_max>\nCPUQuota=<cpu_quota>\n`.