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// Licensed under the Apache License, Version 2.0 // <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option. // All files in the project carrying such notice may not be copied, modified, or distributed // except according to those terms. //! Utilities and wrappers for Microsoft COM interfaces in Windows. //! //! This works with the `Class` and `Interface` traits from the `winapi` crate. use std::marker::PhantomData; use std::mem; use std::ops::Deref; use std::ptr::{self, null_mut, NonNull}; use std::rc::Rc; use std::slice; use winapi::shared::minwindef::LPVOID; use winapi::shared::{ winerror::HRESULT, wtypesbase::{CLSCTX, CLSCTX_INPROC_SERVER, CLSCTX_LOCAL_SERVER}, }; use winapi::um::{ combaseapi::{CoCreateInstance, CoInitializeEx, CoTaskMemFree, CoUninitialize}, objbase::{COINIT_APARTMENTTHREADED, COINIT_MULTITHREADED}, unknwnbase::IUnknown, }; use winapi::{Class, Interface}; use check_succeeded; use error::{succeeded_or_err, HResult, ResultExt}; /// Wrap COM interfaces sanely /// /// Originally from [wio-rs](https://github.com/retep998/wio-rs) `ComPtr` #[repr(transparent)] pub struct ComRef<T>(NonNull<T>) where T: Interface; impl<T> ComRef<T> where T: Interface, { /// Creates a `ComRef` to wrap a raw pointer. /// It takes ownership over the pointer which means it does __not__ call `AddRef`. /// `T` __must__ be a COM interface that inherits from `IUnknown`. pub unsafe fn from_raw(ptr: NonNull<T>) -> ComRef<T> { ComRef(ptr) } /// Casts up the inheritance chain pub fn up<U>(self) -> ComRef<U> where T: Deref<Target = U>, U: Interface, { unsafe { ComRef::from_raw(NonNull::new(self.into_raw().as_ptr() as *mut U).unwrap()) } } /// Extracts the raw pointer. /// You are now responsible for releasing it yourself. pub fn into_raw(self) -> NonNull<T> { let p = self.0; mem::forget(self); p } fn as_unknown(&self) -> &IUnknown { unsafe { &*(self.as_raw_ptr() as *mut IUnknown) } } /// Get another interface via `QueryInterface`. /// /// If the call to `QueryInterface` fails or the resulting interface is null, return an error. pub fn cast<U>(&self) -> Result<ComRef<U>, HResult> where U: Interface, { let mut obj = null_mut(); let hr = succeeded_or_err(unsafe { self.as_unknown().QueryInterface(&U::uuidof(), &mut obj) })?; NonNull::new(obj as *mut U) .map(|obj| unsafe { ComRef::from_raw(obj) }) .ok_or_else(|| HResult::new(hr).function("IUnknown::QueryInterface")) } /// Obtains the raw pointer without transferring ownership. /// /// Do __not__ release this pointer because it is still owned by the `ComRef`. /// /// Do __not__ use this pointer beyond the lifetime of the `ComRef`. pub fn as_raw(&self) -> NonNull<T> { self.0 } /// Obtains the raw pointer without transferring ownership. /// /// Do __not__ release this pointer because it is still owned by the `ComRef`. /// /// Do __not__ use this pointer beyond the lifetime of the `ComRef`. pub fn as_raw_ptr(&self) -> *mut T { self.0.as_ptr() } } impl<T> Deref for ComRef<T> where T: Interface, { type Target = T; fn deref(&self) -> &T { unsafe { &*self.as_raw_ptr() } } } impl<T> Clone for ComRef<T> where T: Interface, { fn clone(&self) -> Self { unsafe { self.as_unknown().AddRef(); ComRef::from_raw(self.as_raw()) } } } impl<T> Drop for ComRef<T> where T: Interface, { fn drop(&mut self) { unsafe { self.as_unknown().Release(); } } } /// A scope for automatic COM initialization and deinitialization. /// /// Functions that need COM initialized can take a `&ComApartmentScope` argument and be sure that /// it is so. It's recommended to use a thread local for this through the /// [`INIT_MTA`](constant.INIT_MTA.html) or [`INIT_STA`](constant.INIT_STA.html) statics. #[derive(Debug, Default)] pub struct ComApartmentScope { /// PhantomData used in lieu of unstable impl !Send + !Sync. /// It must be dropped on the same thread it was created on so it can't be Send, /// and references are meant to indicate that COM has been inited on the current thread so it /// can't be Sync. _do_not_send: PhantomData<Rc<()>>, } impl ComApartmentScope { /// This thread should be the sole occupant of a single thread apartment pub fn init_sta() -> Result<Self, HResult> { unsafe { check_succeeded!(CoInitializeEx(ptr::null_mut(), COINIT_APARTMENTTHREADED)) }?; Ok(Default::default()) } /// This thread should join the process's multithreaded apartment pub fn init_mta() -> Result<Self, HResult> { unsafe { check_succeeded!(CoInitializeEx(ptr::null_mut(), COINIT_MULTITHREADED)) }?; Ok(Default::default()) } } impl Drop for ComApartmentScope { fn drop(&mut self) { unsafe { CoUninitialize(); } } } thread_local! { // TODO these examples should probably be in convenience functions. /// A single thread apartment scope for the duration of the current thread. /// /// # Example /// ``` /// use comedy::com::{ComApartmentScope, INIT_STA}; /// /// fn do_com_stuff(_com: &ComApartmentScope) { /// } /// /// INIT_STA.with(|com| { /// let com = match com { /// Err(e) => return Err(e.clone()), /// Ok(ref com) => com, /// }; /// do_com_stuff(com); /// Ok(()) /// }).unwrap() /// ``` pub static INIT_STA: Result<ComApartmentScope, HResult> = ComApartmentScope::init_sta(); /// A multithreaded apartment scope for the duration of the current thread. /// /// # Example /// ``` /// use comedy::com::{ComApartmentScope, INIT_MTA}; /// /// fn do_com_stuff(_com: &ComApartmentScope) { /// } /// /// INIT_MTA.with(|com| { /// let com = match com { /// Err(e) => return Err(e.clone()), /// Ok(ref com) => com, /// }; /// do_com_stuff(com); /// Ok(()) /// }).unwrap() /// ``` pub static INIT_MTA: Result<ComApartmentScope, HResult> = ComApartmentScope::init_mta(); } /// Create an instance of a COM class. /// /// This is mostly just a call to `CoCreateInstance` with some error handling. /// The CLSID of the class and the IID of the interface come from the winapi `RIDL` macro, which /// defines `Class` and `Interface` implementations. /// /// [`create_instance_local_server`](fn.create_instance_local_server.html) and /// [`create_instance_inproc_server`](fn.create_instance_inproc_server.html) are convenience /// functions for typical contexts. pub fn create_instance<C, I>(ctx: CLSCTX) -> Result<ComRef<I>, HResult> where C: Class, I: Interface, { get(|interface| unsafe { CoCreateInstance( &C::uuidof(), ptr::null_mut(), // pUnkOuter ctx, &I::uuidof(), interface as *mut *mut _, ) }) .function("CoCreateInstance") } /// Create an instance of a COM class in the current process (`CLSCTX_LOCAL_SERVER`). pub fn create_instance_local_server<C, I>() -> Result<ComRef<I>, HResult> where C: Class, I: Interface, { create_instance::<C, I>(CLSCTX_LOCAL_SERVER) } /// Create an instance of a COM class in a separate process space on the same machine /// (`CLSCTX_INPROC_SERVER`). pub fn create_instance_inproc_server<C, I>() -> Result<ComRef<I>, HResult> where C: Class, I: Interface, { create_instance::<C, I>(CLSCTX_INPROC_SERVER) } /// Call a COM method, returning a `Result`. /// /// An error is returned if the call fails. The error is augmented with the name of the interface /// and method, and the file name and line number of the macro usage. /// /// `QueryInterface` is not used, the receiving interface must already be the given type. /// /// # Example /// /// ```no_run /// # extern crate winapi; /// # /// # use winapi::um::bits::IBackgroundCopyJob; /// # /// # use comedy::com::ComRef; /// # use comedy::{com_call, HResult}; /// # /// fn cancel_job(job: &ComRef<IBackgroundCopyJob>) -> Result<(), HResult> { /// unsafe { /// com_call!(job, IBackgroundCopyJob::Cancel())?; /// } /// Ok(()) /// } /// ``` #[macro_export] macro_rules! com_call { ($obj:expr, $interface:ident :: $method:ident ( $($arg:expr),* )) => {{ use $crate::error::ResultExt; $crate::error::succeeded_or_err({ let obj: &$interface = &*$obj; obj.$method($($arg),*) }).function(concat!(stringify!($interface), "::", stringify!($method))) .file_line(file!(), line!()) }}; // support for trailing comma in method argument list ($obj:expr, $interface:ident :: $method:ident ( $($arg:expr),+ , )) => {{ $crate::com_call!($obj, $interface::$method($($arg),+)) }}; } /// Get an interface pointer that is returned through an output parameter. /// /// If the call returns a failure `HRESULT`, return an error. /// /// /// # Null and Enumerators /// If the method succeeds but the resulting interface pointer is null, this will return an /// `HResult` error with the successful return code. In particular this can happen with /// enumeration interfaces, which return `S_FALSE` when they write less than the requested number /// of results. pub fn get<I, F>(getter: F) -> Result<ComRef<I>, HResult> where I: Interface, F: FnOnce(*mut *mut I) -> HRESULT, { let mut interface: *mut I = ptr::null_mut(); let hr = succeeded_or_err(getter(&mut interface as *mut *mut I))?; NonNull::new(interface) .map(|interface| unsafe { ComRef::from_raw(interface) }) .ok_or_else(|| HResult::new(hr)) } /// Call a COM method, create a [`ComRef`](com/struct.ComRef.html) from an output parameter. /// /// An error is returned if the call fails. The error is augmented with the name of the interface /// and method, and the file name and line number of the macro usage. /// /// # Null and Enumerators /// If the method succeeds but the resulting interface pointer is null, this will return an /// `HResult` error with the successful return code. In particular this can happen with /// enumeration interfaces, which return `S_FALSE` when they write less than the requested number /// of results. /// /// # Example /// /// ```no_run /// # extern crate winapi; /// # use winapi::shared::guiddef::GUID; /// # use winapi::um::bits::{IBackgroundCopyManager, IBackgroundCopyJob}; /// # use comedy::com::ComRef; /// # use comedy::{com_call_getter, HResult}; /// /// fn create_job(bcm: &ComRef<IBackgroundCopyManager>, id: &GUID) /// -> Result<ComRef<IBackgroundCopyJob>, HResult> /// { /// unsafe { /// com_call_getter!( /// |job| bcm, /// IBackgroundCopyManager::GetJob(id, job) /// ) /// } /// } /// ``` #[macro_export] macro_rules! com_call_getter { (| $outparam:ident | $obj:expr, $interface:ident :: $method:ident ( $($arg:expr),* )) => {{ use $crate::error::ResultExt; let obj: &$interface = &*$obj; $crate::com::get(|$outparam| { obj.$method($($arg),*) }).function(concat!(stringify!($interface), "::", stringify!($method))) .file_line(file!(), line!()) }}; // support for trailing comma in method argument list (| $outparam:ident | $obj:expr, $interface:ident :: $method:ident ( $($arg:expr),+ , )) => { $crate::com_call_getter!(|$outparam| $obj, $interface::$method($($arg),+)) }; } /// Get a task memory pointer that is returned through an output parameter. /// /// If the call returns a failure `HRESULT`, return an error. /// /// # Null /// If the method succeeds but the resulting pointer is null, this will return an /// `Err(HResult)` with the successful return code. pub fn get_cotaskmem<F, T>(getter: F) -> Result<CoTaskMem<T>, HResult> where F: FnOnce(*mut *mut T) -> HRESULT, { let mut ptr = ptr::null_mut() as *mut T; let hr = succeeded_or_err(getter(&mut ptr))?; NonNull::new(ptr) .map(|ptr| unsafe { CoTaskMem::new(ptr) }) .ok_or_else(|| HResult::new(hr)) } /// Call a COM method, create a [`CoTaskMem`](handle/struct.CoTaskMem.html) from an output /// parameter. /// /// An error is returned if the call fails or if the pointer is null. The error is augmented with /// the name of the interface and method, and the file name and line number of the macro usage. /// /// # Null /// If the method succeeds but the resulting pointer is null, this will return an `HResult` /// error with the successful return code. /// /// # Example /// /// ```no_run /// # extern crate winapi; /// # use winapi::shared::winerror::HRESULT; /// # use winapi::um::bits::IBackgroundCopyManager; /// # use comedy::com::{ComRef, CoTaskMem}; /// # use comedy::{com_call_taskmem_getter, HResult}; /// # /// fn get_error_description(bcm: &ComRef<IBackgroundCopyManager>, lang_id: u32, hr: HRESULT) /// -> Result<CoTaskMem<u16>, HResult> /// { /// unsafe { /// com_call_taskmem_getter!( /// |desc| bcm, /// IBackgroundCopyManager::GetErrorDescription(hr, lang_id, desc) /// ) /// } /// } /// ``` #[macro_export] macro_rules! com_call_taskmem_getter { (| $outparam:ident | $obj:expr, $interface:ident :: $method:ident ( $($arg:expr),* )) => {{ use $crate::error::ResultExt; $crate::com::get_cotaskmem(|$outparam| { $obj.$method($($arg),*) }).function(concat!(stringify!($interface), "::", stringify!($method))) .file_line(file!(), line!()) }}; // support for trailing comma in method argument list (| $outparam:ident | $obj:expr, $interface:ident :: $method:ident ( $($arg:expr),+ , )) => { $crate::com_call_taskmem_getter!(|$outparam| $obj, $interface::$method($($arg),+)) }; } /// A Windows COM task memory pointer that will be automatically freed. // I have only found this useful with strings, so that is the only access provided here by // `as_slice_until_null()`. `Deref<Target=T>` would not be generally useful as task memory // is usually encountered as variable length structures. #[repr(transparent)] #[derive(Debug)] pub struct CoTaskMem<T>(NonNull<T>); impl<T> CoTaskMem<T> { /// Take ownership of COM task memory, which will be freed with `CoTaskMemFree()` upon drop. /// /// # Safety /// /// `p` should be the only copy of the pointer. pub unsafe fn new(p: NonNull<T>) -> CoTaskMem<T> { CoTaskMem(p) } } impl<T> Drop for CoTaskMem<T> { fn drop(&mut self) { unsafe { CoTaskMemFree(self.0.as_ptr() as LPVOID); } } } impl CoTaskMem<u16> { /// Interpret as a null-terminated `u16` array, return as a slice without terminator. pub unsafe fn as_slice_until_null(&self) -> &[u16] { for i in 0.. { if *self.0.as_ptr().offset(i) == 0 { return slice::from_raw_parts(self.0.as_ptr(), i as usize); } } unreachable!() } }