Add support for volatile registry keys in OpenOptions (#3632)

Co-authored-by: Kenny Kerr <kenny@kennykerr.ca>

Author: Copilot

crates/libs/registry/src/bindings.rs

@@ -72,6 +72,7 @@ pub const REG_EXPAND_SZ: REG_VALUE_TYPE = 2u32;
 pub const REG_MULTI_SZ: REG_VALUE_TYPE = 7u32;
 pub type REG_OPEN_CREATE_OPTIONS = u32;
 pub const REG_OPTION_NON_VOLATILE: REG_OPEN_CREATE_OPTIONS = 0u32;
+pub const REG_OPTION_VOLATILE: REG_OPEN_CREATE_OPTIONS = 1u32;
 pub const REG_QWORD: REG_VALUE_TYPE = 11u32;
 pub type REG_SAM_FLAGS = u32;
 pub const REG_SZ: REG_VALUE_TYPE = 1u32;

crates/libs/registry/src/open_options.rs

@@ -7,6 +7,7 @@ pub struct OpenOptions<'a> {
     access: u32,
     create: bool,
     transaction: Option<&'a Transaction>,
+    options: u32,
 }
 
 impl<'a> OpenOptions<'a> {
@@ -16,6 +17,7 @@ impl<'a> OpenOptions<'a> {
             access: 0,
             create: false,
             transaction: None,
+            options: REG_OPTION_NON_VOLATILE,
         }
     }
 
@@ -49,6 +51,12 @@ impl<'a> OpenOptions<'a> {
         self
     }
 
+    /// Sets the option to create a volatile registry key that is not preserved when the system restarts.
+    pub fn volatile(&mut self) -> &mut Self {
+        self.options |= REG_OPTION_VOLATILE;
+        self
+    }
+
     /// Opens a registry key with the options provided by `self`.
     pub fn open<T: AsRef<str>>(&self, path: T) -> Result<Key> {
         let mut handle = null_mut();
@@ -61,7 +69,7 @@ impl<'a> OpenOptions<'a> {
                         pcwstr(path).as_ptr(),
                         0,
                         null(),
-                        REG_OPTION_NON_VOLATILE,
+                        self.options,
                         self.access,
                         null(),
                         &mut handle,
@@ -86,7 +94,7 @@ impl<'a> OpenOptions<'a> {
                     pcwstr(path).as_ptr(),
                     0,
                     null(),
-                    REG_OPTION_NON_VOLATILE,
+                    self.options,
                     self.access,
                     null(),
                     &mut handle,

crates/tests/libs/registry/tests/volatile.rs

@@ -0,0 +1,23 @@
+use windows_registry::*;
+
+#[test]
+fn volatile_key() {
+    let test_key = "software\\windows-rs\\tests\\volatile";
+    _ = CURRENT_USER.remove_tree(test_key);
+
+    // Create a volatile key - this key will not persist when the system restarts
+    let key = CURRENT_USER
+        .options()
+        .create()
+        .volatile()
+        .read()
+        .write()
+        .open(test_key)
+        .unwrap();
+
+    // Write some data to the volatile key
+    key.set_u64("test_value", 12345u64).unwrap();
+
+    // Verify we can read the data
+    assert_eq!(key.get_u64("test_value").unwrap(), 12345u64);
+}

crates/tools/bindings/src/registry.txt

@@ -24,6 +24,7 @@
     REG_EXPAND_SZ
     REG_MULTI_SZ
     REG_OPTION_NON_VOLATILE
+    REG_OPTION_VOLATILE
     REG_QWORD
     REG_SZ
     RegCloseKey