Move units and default-target processing to Rust

More oxidation.

rust/src/composepost.rs

@@ -125,6 +125,60 @@ pub(crate) fn compose_postprocess_final(rootfs_dfd: i32) -> CxxResult<()> {
     Ok(tasks.par_iter().try_for_each(|f| f(&rootfs_dfd))?)
 }
 
+#[context("Handling treefile 'units'")]
+fn compose_postprocess_units(rootfs_dfd: &openat::Dir, treefile: &mut Treefile) -> Result<()> {
+    let multiuser_wants = Path::new("usr/etc/systemd/system/multi-user.target.wants");
+
+    let mut created = false;
+    for unit in treefile.parsed.units.iter().flatten() {
+        if !created {
+            rootfs_dfd.ensure_dir_all(multiuser_wants, 0o755)?;
+            created = true;
+        }
+
+        let dest = multiuser_wants.join(unit);
+        if rootfs_dfd.exists(&dest)? {
+            continue;
+        }
+
+        println!("Adding {} to multi-user.target.wants", unit);
+
+        let target = format!("/usr/lib/systemd/system/{}", unit);
+        rootfs_dfd.symlink(&dest, &target)?;
+    }
+    Ok(())
+}
+
+#[context("Handling treefile 'default-target'")]
+fn compose_postprocess_default_target(rootfs_dfd: &openat::Dir, target: &str) -> Result<()> {
+    /* This used to be in /etc, but doing it in /usr makes more sense, as it's
+     * part of the OS defaults. This was changed in particular to work with
+     * ConditionFirstBoot= which runs `systemctl preset-all`:
+     * https://github.com/projectatomic/rpm-ostree/pull/1425
+     */
+    let default_target_path = "usr/lib/systemd/system/default.target";
+    rootfs_dfd.remove_file_optional(default_target_path)?;
+    let dest = format!("/usr/lib/systemd/system/{}", target);
+    rootfs_dfd.symlink(default_target_path, dest)?;
+
+    Ok(())
+}
+
+#[context("Handling targets")]
+pub(crate) fn compose_postprocess_targets(
+    rootfs_dfd: i32,
+    treefile: &mut Treefile,
+) -> CxxResult<()> {
+    let rootfs_dfd = crate::ffiutil::ffi_view_openat_dir(rootfs_dfd);
+
+    compose_postprocess_units(&rootfs_dfd, treefile)?;
+    if let Some(t) = treefile.parsed.default_target.as_deref() {
+        compose_postprocess_default_target(&rootfs_dfd, t)?;
+    }
+
+    Ok(())
+}
+
 /// The treefile format has two kinds of postprocessing scripts;
 /// there's a single `postprocess-script` as well as inline (anonymous)
 /// scripts.  This function executes both kinds in bwrap containers.

rust/src/lib.rs

@@ -88,6 +88,7 @@ pub mod ffi {
     // composepost.rs
     extern "Rust" {
         fn composepost_nsswitch_altfiles(rootfs_dfd: i32) -> Result<()>;
+        fn compose_postprocess_targets(rootfs_dfd: i32, treefile: &mut Treefile) -> Result<()>;
         fn compose_postprocess(
             rootfs_dfd: i32,
             treefile: &mut Treefile,

rust/src/treefile.rs

@@ -1012,10 +1012,10 @@ pub(crate) struct TreeComposeConfig {
 
     // systemd
     #[serde(skip_serializing_if = "Option::is_none")]
-    units: Option<Vec<String>>,
+    pub(crate) units: Option<Vec<String>>,
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(rename = "default-target")]
-    default_target: Option<String>,
+    pub(crate) default_target: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(rename = "machineid-compat")]
     // Defaults to `true`

src/libpriv/rpmostree-postprocess.cxx

@@ -1213,74 +1213,9 @@ rpmostree_treefile_postprocessing (int            rootfs_fd,
   if (!rename_if_exists (rootfs_fd, "etc", rootfs_fd, "usr/etc", error))
     return FALSE;
 
-  JsonArray *units = NULL;
+  rpmostreecxx::compose_postprocess_targets(rootfs_fd, treefile_rs);
-  if (json_object_has_member (treefile, "units"))
-    units = json_object_get_array_member (treefile, "units");
 
   guint len;
-  if (units)
-    len = json_array_get_length (units);
-  else
-    len = 0;
-
-  {
-    glnx_autofd int multiuser_wants_dfd = -1;
-
-    if (!glnx_shutil_mkdir_p_at (rootfs_fd, "usr/etc/systemd/system/multi-user.target.wants", 0755,
-                                 cancellable, error))
-      return FALSE;
-    if (!glnx_opendirat (rootfs_fd, "usr/etc/systemd/system/multi-user.target.wants", TRUE,
-                         &multiuser_wants_dfd, error))
-      return FALSE;
-
-    for (guint i = 0; i < len; i++)
-      {
-        const char *unitname = _rpmostree_jsonutil_array_require_string_element (units, i, error);
-        g_autofree char *symlink_target = NULL;
-        struct stat stbuf;
-
-        if (!unitname)
-          return FALSE;
-
-        symlink_target = g_strconcat ("/usr/lib/systemd/system/", unitname, NULL);
-
-        if (fstatat (multiuser_wants_dfd, unitname, &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
-          {
-            if (errno != ENOENT)
-              return glnx_throw_errno_prefix (error, "fstatat(%s)", unitname);
-          }
-        else
-          continue;
-
-        g_print ("Adding %s to multi-user.target.wants\n", unitname);
-
-        if (symlinkat (symlink_target, multiuser_wants_dfd, unitname) < 0)
-          return glnx_throw_errno_prefix (error, "symlinkat(%s)", unitname);
-      }
-  }
-
-  const char *default_target = NULL;
-  if (!_rpmostree_jsonutil_object_get_optional_string_member (treefile, "default-target",
-                                                              &default_target, error))
-    return FALSE;
-
-  if (default_target != NULL)
-    {
-      g_autofree char *dest_default_target_path =
-        g_strconcat ("/usr/lib/systemd/system/", default_target, NULL);
-
-      /* This used to be in /etc, but doing it in /usr makes more sense, as it's
-       * part of the OS defaults. This was changed in particular to work with
-       * ConditionFirstBoot= which runs `systemctl preset-all`:
-       * https://github.com/projectatomic/rpm-ostree/pull/1425
-       */
-      static const char default_target_path[] = "usr/lib/systemd/system/default.target";
-      (void) unlinkat (rootfs_fd, default_target_path, 0);
-
-      if (symlinkat (dest_default_target_path, rootfs_fd, default_target_path) < 0)
-        return glnx_throw_errno_prefix (error, "symlinkat(%s)", default_target_path);
-    }
-
   JsonArray *remove = NULL;
   if (json_object_has_member (treefile, "remove-files"))
     {