Add get/set reserved bytes to C bindings (#2171)

- Exposes the API to the `Connection` struct
- Adds `libsql_set_reserved_bytes` and `libsql_get_reserved_bytes` to
`libsql.h`

Author: levydsa

bindings/c/include/libsql.h

@@ -107,6 +107,10 @@ int libsql_load_extension(libsql_connection_t conn,
                           const char *entry_point,
                           const char **out_err_msg);
 
+int libsql_set_reserved_bytes(libsql_connection_t conn, int32_t reserved_bytes, const char **out_err_msg);
+
+int libsql_get_reserved_bytes(libsql_connection_t conn, int32_t *reserved_bytes, const char **out_err_msg);
+
 int libsql_reset(libsql_connection_t conn, const char **out_err_msg);
 
 void libsql_disconnect(libsql_connection_t conn);

bindings/c/src/lib.rs

@@ -549,6 +549,45 @@ pub unsafe extern "C" fn libsql_load_extension(
     0
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn libsql_set_reserved_bytes(
+    conn: libsql_connection_t,
+    reserved_bytes: i32,
+    out_err_msg: *mut *const std::ffi::c_char,
+) -> std::ffi::c_int {
+    if conn.is_null() {
+        set_err_msg("Null connection".to_string(), out_err_msg);
+        return 1;
+    }
+    let conn = conn.get_ref();
+    if let Err(err) = conn.set_reserved_bytes(reserved_bytes) {
+        set_err_msg(err.to_string(), out_err_msg);
+        return 1;
+    }
+    0
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn libsql_get_reserved_bytes(
+    conn: libsql_connection_t,
+    reserved_bytes: *mut i32,
+    out_err_msg: *mut *const std::ffi::c_char,
+) -> std::ffi::c_int {
+    if conn.is_null() {
+        set_err_msg("Null connection".to_string(), out_err_msg);
+        return 1;
+    }
+    let conn = conn.get_ref();
+    match conn.get_reserved_bytes() {
+        Ok(v) => *reserved_bytes = v,
+        Err(err) => {
+            set_err_msg(err.to_string(), out_err_msg);
+            return 1;
+        }
+    }
+    0
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn libsql_reset(
     conn: libsql_connection_t,

libsql/src/connection.rs

@@ -39,6 +39,14 @@ pub(crate) trait Conn {
 
     async fn reset(&self);
 
+    fn set_reserved_bytes(&self, _reserved_bytes: i32) -> Result<()> {
+        Err(crate::Error::ReservedBytesNotSupported)
+    }
+
+    fn get_reserved_bytes(&self) -> Result<i32> {
+        Err(crate::Error::ReservedBytesNotSupported)
+    }
+
     fn enable_load_extension(&self, _onoff: bool) -> Result<()> {
         Err(crate::Error::LoadExtensionNotSupported)
     }
@@ -230,6 +238,14 @@ impl Connection {
         self.conn.reset().await
     }
 
+    pub fn set_reserved_bytes(&self, reserved_bytes: i32) -> Result<()> {
+        self.conn.set_reserved_bytes(reserved_bytes)
+    }
+
+    pub fn get_reserved_bytes(&self) -> Result<i32> {
+        self.conn.get_reserved_bytes()
+    }
+
     /// Enable loading SQLite extensions from SQL queries and Rust API.
     ///
     /// See [`load_extension`](Connection::load_extension) documentation for more details.

libsql/src/errors.rs

@@ -61,6 +61,8 @@ pub enum Error {
     Sync(crate::BoxError),
     #[error("WAL frame insert conflict")]
     WalConflict,
+    #[error("Reserved bytes not supported")]
+    ReservedBytesNotSupported,
 }
 
 #[cfg(feature = "hrana")]

libsql/src/local/impls.rs

@@ -81,6 +81,14 @@ impl Conn for LibsqlConnection {
 
     async fn reset(&self) {}
 
+    fn set_reserved_bytes(&self, reserved_bytes: i32) -> Result<()> {
+        self.conn.set_reserved_bytes(reserved_bytes)
+    }
+
+    fn get_reserved_bytes(&self) -> Result<i32> {
+        self.conn.get_reserved_bytes()
+    }
+
     fn enable_load_extension(&self, onoff: bool) -> Result<()> {
         self.conn.enable_load_extension(onoff)
     }

libsql/src/replication/connection.rs

@@ -542,6 +542,14 @@ impl Conn for RemoteConnection {
     }
 
     async fn reset(&self) {}
+
+    fn set_reserved_bytes(&self, reserved_bytes: i32) -> Result<()> {
+        self.local.set_reserved_bytes(reserved_bytes)
+    }
+
+    fn get_reserved_bytes(&self) -> Result<i32> {
+        self.local.get_reserved_bytes()
+    }
 }
 
 pub struct ColumnMeta {

libsql/src/sync/connection.rs

@@ -189,4 +189,12 @@ impl Conn for SyncedConnection {
     }
 
     async fn reset(&self) {}
+
+    fn set_reserved_bytes(&self, reserved_bytes: i32) -> Result<()> {
+        self.local.set_reserved_bytes(reserved_bytes)
+    }
+
+    fn get_reserved_bytes(&self) -> Result<i32> {
+        self.local.get_reserved_bytes()
+    }
 }