Update registered_vfs function (#114)

* Update `registered_vfs` function

* Add document about vfs has been registered

Author: Spxg

src/vfs/relaxed_idb.rs

@@ -1,4 +1,5 @@
 //! relaxed-idb vfs implementation
+//!
 //! **The `relaxed-idb` feature is required, and it is not recommended to use in a production environment.**
 //!
 //! ```rust
@@ -900,26 +901,27 @@ impl RelaxedIdbUtil {
 
 /// Register `relaxed-idb` vfs and return a utility object which can be used
 /// to perform basic administration of the file pool
+///
+/// If the vfs corresponding to `options.vfs_name` has been registered,
+/// only return a utility object.
 pub async fn install(options: &RelaxedIdbCfg, default_vfs: bool) -> Result<RelaxedIdbUtil> {
     static REGISTER_GUARD: tokio::sync::Mutex<()> = tokio::sync::Mutex::const_new(());
     let _guard = REGISTER_GUARD.lock().await;
 
-    let pool = match registered_vfs(&options.vfs_name) {
-        Ok(vfs) => unsafe { RelaxedIdbStore::app_data(vfs) },
-        Err(RegisterVfsError::VfsNotRegistered) => {
-            let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
-            let pool = RelaxedIdb::new(options, tx).await?;
-            let vfs = register_vfs::<RelaxedIdbIoMethods, RelaxedIdbVfs>(
-                &options.vfs_name,
-                pool,
-                default_vfs,
-            )?;
-
-            let app_data = unsafe { RelaxedIdbStore::app_data(vfs) };
-            wasm_bindgen_futures::spawn_local(app_data.commit_loop(rx));
-            app_data
-        }
-        Err(vfs_error) => return Err(RelaxedIdbError::Vfs(vfs_error)),
+    let pool = if let Some(vfs) = registered_vfs(&options.vfs_name)? {
+        unsafe { RelaxedIdbStore::app_data(vfs) }
+    } else {
+        let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
+        let pool = RelaxedIdb::new(options, tx).await?;
+        let vfs = register_vfs::<RelaxedIdbIoMethods, RelaxedIdbVfs>(
+            &options.vfs_name,
+            pool,
+            default_vfs,
+        )?;
+
+        let app_data = unsafe { RelaxedIdbStore::app_data(vfs) };
+        wasm_bindgen_futures::spawn_local(app_data.commit_loop(rx));
+        app_data
     };
 
     Ok(RelaxedIdbUtil { pool })

src/vfs/sahpool.rs

@@ -790,21 +790,23 @@ impl OpfsSAHPoolUtil {
 
 /// Register `opfs-sahpool` vfs and return a utility object which can be used
 /// to perform basic administration of the file pool
+///
+/// If the vfs corresponding to `options.vfs_name` has been registered,
+/// only return a utility object.
 pub async fn install(options: &OpfsSAHPoolCfg, default_vfs: bool) -> Result<OpfsSAHPoolUtil> {
     static REGISTER_GUARD: tokio::sync::Mutex<()> = tokio::sync::Mutex::const_new(());
     let _guard = REGISTER_GUARD.lock().await;
 
-    let vfs = match registered_vfs(&options.vfs_name) {
-        Ok(vfs) => vfs,
-        Err(RegisterVfsError::VfsNotRegistered) => {
-            register_vfs::<SyncAccessHandleIoMethods, SyncAccessHandleVfs>(
-                &options.vfs_name,
-                OpfsSAHPool::new(options).await?,
-                default_vfs,
-            )?
-        }
-        Err(vfs_error) => return Err(OpfsSAHError::Vfs(vfs_error)),
+    let vfs = if let Some(vfs) = registered_vfs(&options.vfs_name)? {
+        vfs
+    } else {
+        register_vfs::<SyncAccessHandleIoMethods, SyncAccessHandleVfs>(
+            &options.vfs_name,
+            OpfsSAHPool::new(options).await?,
+            default_vfs,
+        )?
     };
+
     let pool = unsafe { SyncAccessHandleStore::app_data(vfs) };
 
     Ok(OpfsSAHPoolUtil { pool })

src/vfs/utils.rs

@@ -323,28 +323,15 @@ impl SQLiteVfsFile {
 pub enum RegisterVfsError {
     #[error("An error occurred converting the given vfs name to a CStr")]
     ToCStr,
-    #[error("Vfs has already been registered")]
-    VfsAlreadyRegistered,
-    #[error("Vfs is not registered")]
-    VfsNotRegistered,
     #[error("An error occurred while registering vfs with sqlite")]
     RegisterVfs,
 }
 
 /// Check whether vfs is registered and get vfs pointer
-pub fn registered_vfs(vfs_name: &str) -> Result<*mut sqlite3_vfs, RegisterVfsError> {
+pub fn registered_vfs(vfs_name: &str) -> Result<Option<*mut sqlite3_vfs>, RegisterVfsError> {
     let name = CString::new(vfs_name).map_err(|_| RegisterVfsError::ToCStr)?;
-    let name_ptr = name.into_raw();
-    let vfs = unsafe {
-        let vfs = sqlite3_vfs_find(name_ptr);
-        drop(CString::from_raw(name_ptr));
-        vfs
-    };
-    if vfs.is_null() {
-        Err(RegisterVfsError::VfsNotRegistered)
-    } else {
-        Ok(vfs)
-    }
+    let vfs = unsafe { sqlite3_vfs_find(name.as_ptr()) };
+    Ok((!vfs.is_null()).then_some(vfs))
 }
 
 /// Register vfs general method
@@ -356,15 +343,7 @@ pub fn register_vfs<IO: SQLiteIoMethods, V: SQLiteVfs<IO>>(
     let name = CString::new(vfs_name).map_err(|_| RegisterVfsError::ToCStr)?;
     let name_ptr = name.into_raw();
 
-    unsafe {
-        if !sqlite3_vfs_find(name_ptr).is_null() {
-            drop(CString::from_raw(name_ptr));
-            return Err(RegisterVfsError::VfsAlreadyRegistered);
-        }
-    }
-
     let app_data = VfsAppData::new(app_data).leak();
-
     let vfs = Box::leak(Box::new(V::vfs(name_ptr, app_data.cast())));
     let ret = unsafe { sqlite3_vfs_register(vfs, i32::from(default_vfs)) };