composefs-backend: Check for /var symlink before creating to fix issue with bootc switch on other distros.

Coauthored-by: Tulip Blossom <[email protected]>
Signed-off-by: Kyle Gospodnetich <[email protected]>

Author: KyleGospo

crates/lib/src/bootc_composefs/state.rs

@@ -123,13 +123,16 @@ pub(crate) fn write_composefs_state(
 
     let actual_var_path = root_path.join(SHARED_VAR_PATH);
     create_dir_all(&actual_var_path)?;
-
-    symlink(
-        path_relative_to(state_path.as_std_path(), actual_var_path.as_std_path())
-            .context("Getting var symlink path")?,
-        state_path.join("var"),
-    )
-    .context("Failed to create symlink for /var")?;
+    
+    let var_symlink_target = path_relative_to(state_path.as_std_path(), actual_var_path.as_std_path())
+        .context("Getting var symlink path")?;
+    
+    let var_symlink_path = state_path.join("var");
+    
+    if !var_symlink_path.exists() {
+        symlink(&var_symlink_target, &var_symlink_path)
+            .context("Failed to create symlink for /var")?;
+    }
 
     let ImageReference {
         image: image_name,