feat: prefer symlinks over generating files for openxr active runtime json file

src/file_builders/active_runtime_json.rs

@@ -1,18 +1,17 @@
 use crate::{
-    paths::{get_backup_dir, SYSTEM_PREFIX},
+    paths::SYSTEM_PREFIX,
     profile::Profile,
-    util::{
-        file_utils::{copy_file, deserialize_file, get_writer, set_file_readonly},
-        steam_library_folder::SteamLibraryFolder,
-    },
+    util::file_utils::{deserialize_file, get_writer, set_file_readonly},
     xdg::XDG,
 };
+use anyhow::bail;
 use serde::{Deserialize, Serialize};
 use std::{
-    fs::remove_file,
+    fs::{remove_file, rename},
+    os::unix::fs::symlink,
     path::{Path, PathBuf},
 };
-use tracing::error;
+use tracing::{info, warn};
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct ActiveRuntimeInnerRuntime {
@@ -38,46 +37,6 @@ fn get_active_runtime_json_path() -> PathBuf {
     get_openxr_conf_dir().join("1/active_runtime.json")
 }
 
-pub fn is_steam(active_runtime: &ActiveRuntime) -> bool {
-    matches!(active_runtime.runtime.valve_runtime_is_steamvr, Some(true))
-}
-
-pub const STEAMVR_STEAM_APPID: u32 = 250820;
-
-pub fn find_steam_openxr_json() -> Option<PathBuf> {
-    match SteamLibraryFolder::get_folders() {
-        Ok(libraryfolders) => libraryfolders
-            .iter()
-            .find(|(_, folder)| folder.apps.contains_key(&STEAMVR_STEAM_APPID))
-            .map(|(_, folder)| {
-                PathBuf::from(&folder.path).join("steamapps/common/SteamVR/steamxr_linux64.json")
-            }),
-        Err(e) => {
-            error!("unable to find steam openxr json: unable to load steam libraryfolders: {e}");
-            None
-        }
-    }
-}
-
-fn get_backup_steam_active_runtime_path() -> PathBuf {
-    get_backup_dir().join("active_runtime.json.steam.bak")
-}
-
-fn get_backed_up_steam_active_runtime() -> Option<ActiveRuntime> {
-    get_active_runtime_from_path(&get_backup_steam_active_runtime_path())
-}
-
-fn backup_steam_active_runtime() {
-    if let Some(ar) = get_current_active_runtime() {
-        if is_steam(&ar) {
-            copy_file(
-                &get_active_runtime_json_path(),
-                &get_backup_steam_active_runtime_path(),
-            );
-        }
-    }
-}
-
 fn get_active_runtime_from_path(path: &Path) -> Option<ActiveRuntime> {
     deserialize_file(path)
 }
@@ -99,29 +58,6 @@ pub fn dump_current_active_runtime(active_runtime: &ActiveRuntime) -> anyhow::Re
     dump_active_runtime_to_path(active_runtime, &get_active_runtime_json_path())
 }
 
-fn build_steam_active_runtime() -> ActiveRuntime {
-    if let Some(backup) = get_backed_up_steam_active_runtime() {
-        return backup;
-    }
-    ActiveRuntime {
-        file_format_version: "1.0.0".into(),
-        runtime: ActiveRuntimeInnerRuntime {
-            valve_runtime_is_steamvr: Some(true),
-            libmonado_path: None,
-            library_path: XDG
-                .get_data_home()
-                .join("Steam/steamapps/common/SteamVR/bin/linux64/vrclient.so"),
-            name: Some("SteamVR".into()),
-        },
-    }
-}
-
-pub fn set_current_active_runtime_to_steam() -> anyhow::Result<()> {
-    set_file_readonly(&get_active_runtime_json_path(), false)?;
-    dump_current_active_runtime(&build_steam_active_runtime())?;
-    Ok(())
-}
-
 pub fn build_profile_active_runtime(profile: &Profile) -> anyhow::Result<ActiveRuntime> {
     let Some(libopenxr_path) = profile.libopenxr_so() else {
         anyhow::bail!(
@@ -158,18 +94,66 @@ fn relativize_active_runtime_lib_path(ar: &ActiveRuntime, path: &Path) -> Active
     res
 }
 
+const ACTIVE_RUNTIME_BAK: &str = "active_runtime.json.envision.bak";
+
 pub fn set_current_active_runtime_to_profile(profile: &Profile) -> anyhow::Result<()> {
     let dest = get_active_runtime_json_path();
-    set_file_readonly(&dest, false)?;
-    backup_steam_active_runtime();
-    let pfx = profile.clone().prefix;
-    let mut ar = build_profile_active_runtime(profile)?;
-    // hack: relativize libopenxr_monado.so path for system installs
-    if pfx == PathBuf::from(SYSTEM_PREFIX) {
-        ar = relativize_active_runtime_lib_path(&ar, &dest);
+    if dest.is_dir() {
+        bail!("{} is a directory", dest.to_string_lossy());
     }
-    dump_current_active_runtime(&ar)?;
-    set_file_readonly(&dest, true)?;
+    if !dest.is_symlink() {
+        set_file_readonly(&dest, false)?;
+    }
+    if dest.is_file() || dest.is_symlink() {
+        rename(&dest, dest.parent().unwrap().join(ACTIVE_RUNTIME_BAK))?;
+    } else {
+        info!("no active_runtime.json file to backup")
+    }
+
+    let profile_openxr_json = profile.openxr_json_path();
+    if profile_openxr_json.is_file() {
+        symlink(profile_openxr_json, &dest)?;
+    } else {
+        warn!("profile openxr json file doesn't exist");
+        // fallback: build the file from scratch
+        let pfx = profile.clone().prefix;
+        let mut ar = build_profile_active_runtime(profile)?;
+        // hack: relativize libopenxr_monado.so path for system installs
+        if pfx == PathBuf::from(SYSTEM_PREFIX) {
+            ar = relativize_active_runtime_lib_path(&ar, &dest);
+        }
+        dump_current_active_runtime(&ar)?;
+        set_file_readonly(&dest, true)?;
+    }
+    Ok(())
+}
+
+pub fn remove_current_active_runtime() -> anyhow::Result<()> {
+    let dest = get_active_runtime_json_path();
+    if dest.is_dir() {
+        bail!("{} is a directory", dest.to_string_lossy());
+    }
+    if !dest.exists() {
+        info!("no current active_runtime.json to remove")
+    }
+    Ok(remove_file(dest)?)
+}
+
+pub fn restore_active_runtime_backup() -> anyhow::Result<()> {
+    let dest = get_active_runtime_json_path();
+    let bak = dest.parent().unwrap().join(ACTIVE_RUNTIME_BAK);
+    if bak.is_file() || bak.is_symlink() {
+        if dest.is_dir() {
+            bail!("{} is a directory", dest.to_string_lossy());
+        }
+        if !dest.is_symlink() {
+            set_file_readonly(&dest, false)?;
+        }
+        rename(&bak, &dest)?;
+    } else {
+        info!("{ACTIVE_RUNTIME_BAK} does not exist, nothing to restore");
+    }
+
     Ok(())
 }
 

src/main.rs

@@ -1,7 +1,7 @@
 use anyhow::Result;
 use constants::{resources, APP_ID, APP_NAME, GETTEXT_PACKAGE, LOCALE_DIR, RESOURCES_BASE_PATH};
 use file_builders::{
-    active_runtime_json::{get_current_active_runtime, set_current_active_runtime_to_steam},
+    active_runtime_json::restore_active_runtime_backup,
     openvrpaths_vrpath::{get_current_openvrpaths, set_current_openvrpaths_to_steam},
 };
 use gettextrs::LocaleCategory;
@@ -48,14 +48,9 @@ pub mod xdg;
 pub mod xr_devices;
 
 fn restore_steam_xr_files() {
-    let active_runtime = get_current_active_runtime();
     let openvrpaths = get_current_openvrpaths();
-    if let Some(ar) = active_runtime {
-        if !file_builders::active_runtime_json::is_steam(&ar) {
-            if let Err(e) = set_current_active_runtime_to_steam() {
-                warn!("failed to restore active runtime to steam: {e}");
-            }
-        }
+    if let Err(e) = restore_active_runtime_backup() {
+        warn!("failed to restore active runtime to steam: {e}");
     }
     if let Some(ovrp) = openvrpaths {
         if !file_builders::openvrpaths_vrpath::is_steam(&ovrp) {

src/profile.rs

@@ -47,6 +47,13 @@ impl XRServiceType {
         }
     }
 
+    pub fn openxr_json_rel_path(&self) -> &'static str {
+        match self {
+            Self::Monado => "share/openxr/1/openxr_monado.json",
+            Self::Wivrn => "share/openxr/1/openxr_wivrn.json",
+        }
+    }
+
     pub fn ipc_file_path(&self) -> PathBuf {
         XDG.get_runtime_directory()
             .expect("XDG runtime directory is not available")
@@ -586,6 +593,12 @@ impl Profile {
         missing_deps.dedup(); // dedup only works if sorted, hence the above
         missing_deps
     }
+
+    /// the file that will become active_runtime.json, as installed in the
+    /// prefix
+    pub fn openxr_json_path(&self) -> PathBuf {
+        self.prefix.join(self.xrservice_type.openxr_json_rel_path())
+    }
 }
 
 pub fn prepare_ld_library_path(prefix: &Path) -> String {

src/ui/app.rs

@@ -26,7 +26,8 @@ use crate::{
     depcheck::common::dep_pkexec,
     file_builders::{
         active_runtime_json::{
-            set_current_active_runtime_to_profile, set_current_active_runtime_to_steam,
+            remove_current_active_runtime, restore_active_runtime_backup,
+            set_current_active_runtime_to_profile,
         },
         openvrpaths_vrpath::{
             set_current_openvrpaths_to_profile, set_current_openvrpaths_to_steam,
@@ -250,9 +251,16 @@ impl App {
 
     pub fn restore_openxr_openvr_files(&self) {
         restore_runtime_entrypoint();
-        if let Err(e) = set_current_active_runtime_to_steam() {
+        if let Err(e) = remove_current_active_runtime() {
             alert(
-                "Could not restore Steam active runtime",
+                "Could not remove profile active runtime",
+                Some(&format!("{e}")),
+                Some(&self.app_win.clone().upcast::<gtk::Window>()),
+            );
+        }
+        if let Err(e) = restore_active_runtime_backup() {
+            alert(
+                "Could not restore previous active runtime",
                 Some(&format!("{e}")),
                 Some(&self.app_win.clone().upcast::<gtk::Window>()),
             );

src/util/file_utils.rs

@@ -57,7 +57,13 @@ pub fn deserialize_file<T: serde::de::DeserializeOwned>(path: &Path) -> Option<T
     }
 }
 
-pub fn set_file_readonly(path: &Path, readonly: bool) -> Result<(), std::io::Error> {
+pub fn set_file_readonly(path: &Path, readonly: bool) -> anyhow::Result<()> {
+    if path.is_symlink() {
+        bail!(
+            "path {} is a symlink, trying to change its write permission will only change the original file",
+            path.to_string_lossy()
+        );
+    }
     if !path.is_file() {
         debug!(
             "trying to set readonly on a file that does not exist: {}",
@@ -69,7 +75,7 @@ pub fn set_file_readonly(path: &Path, readonly: bool) -> Result<(), std::io::Err
         .expect("Could not get metadata for file")
         .permissions();
     perms.set_readonly(readonly);
-    fs::set_permissions(path, perms)
+    Ok(fs::set_permissions(path, perms)?)
 }
 
 pub fn setcap_cap_sys_nice_eip_cmd(profile: &Profile) -> Vec<String> {
@@ -104,8 +110,10 @@ pub fn copy_file(source: &Path, dest: &Path) {
                 .unwrap_or_else(|_| panic!("Failed to create dir {}", parent.to_str().unwrap()));
         }
     }
-    set_file_readonly(dest, false)
-        .unwrap_or_else(|_| panic!("Failed to set file {} as rw", dest.to_string_lossy()));
+    if !dest.is_symlink() {
+        set_file_readonly(dest, false)
+            .unwrap_or_else(|_| panic!("Failed to set file {} as rw", dest.to_string_lossy()));
+    }
     copy(source, dest).unwrap_or_else(|e| {
         panic!(
             "Failed to copy {} to {}: {e}",