[vlc-devel] [PATCH] dshow: Use MTA and stop leaking thread context out of the module

[Hugo Beauzée-Luyssen]

Fix #16935
---
 modules/access/dshow/dshow.cpp | 44 +++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/modules/access/dshow/dshow.cpp b/modules/access/dshow/dshow.cpp
index d42ec0871e..817584f86d 100644
--- a/modules/access/dshow/dshow.cpp
+++ b/modules/access/dshow/dshow.cpp
@@ -35,6 +35,7 @@
 #include <list>
 #include <string>
 #include <assert.h>
+#include <stdexcept>
 
 #define VLC_MODULE_LICENSE VLC_LICENSE_GPL_2_PLUS
 #include <vlc_common.h>
@@ -299,6 +300,19 @@ vlc_module_begin ()
 
 vlc_module_end ()
 
+struct ComContext
+{
+    ComContext( int mode )
+    {
+        if( !SUCCEEDED( CoInitializeEx( NULL, mode ) ) )
+            throw std::runtime_error( "CoInitializeEx failed" );
+    }
+    ~ComContext()
+    {
+        CoUninitialize();
+    }
+
+};
 
 /*****************************************************************************
  * DirectShow elementary stream descriptor
@@ -392,10 +406,6 @@ static int CommonOpen( vlc_object_t *p_this, access_sys_t *p_sys,
     bool b_use_audio = true;
     bool b_use_video = true;
 
-    /* Initialize OLE/COM */
-    if( FAILED(CoInitializeEx( NULL, COINIT_APARTMENTTHREADED )) )
-        vlc_assert_unreachable();
-
     var_Create( p_this,  CFG_PREFIX "config", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
     var_Create( p_this,  CFG_PREFIX "tuner", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
     psz_val = var_CreateGetString( p_this, CFG_PREFIX "vdev" );
@@ -665,6 +675,8 @@ static int DemuxOpen( vlc_object_t *p_this )
         return VLC_ENOMEM;
     p_demux->p_sys = (demux_sys_t *)p_sys;
 
+    ComContext ctx( COINIT_MULTITHREADED );
+
     if( CommonOpen( p_this, p_sys, true ) != VLC_SUCCESS )
     {
         CommonClose( p_this, p_sys );
@@ -770,6 +782,8 @@ static int AccessOpen( vlc_object_t *p_this )
     if( !p_sys )
         return VLC_ENOMEM;
 
+    ComContext ctx( COINIT_MULTITHREADED );
+
     if( CommonOpen( p_this, p_sys, false ) != VLC_SUCCESS )
     {
         CommonClose( p_this, p_sys );
@@ -804,9 +818,6 @@ static void CommonClose( vlc_object_t *p_this, access_sys_t *p_sys )
 
     DeleteDirectShowGraph( p_this, p_sys );
 
-    /* Uninitialize OLE/COM */
-    CoUninitialize();
-
     vlc_delete_all( p_sys->pp_streams );
 
     vlc_mutex_destroy( &p_sys->lock );
@@ -823,6 +834,8 @@ static void AccessClose( vlc_object_t *p_this )
     access_t     *p_access = (access_t *)p_this;
     access_sys_t *p_sys    = (access_sys_t *)p_access->p_sys;
 
+    ComContext ctx( COINIT_MULTITHREADED );
+
     /* Stop capturing stuff */
     p_sys->p_control->Stop();
 
@@ -837,6 +850,8 @@ static void DemuxClose( vlc_object_t *p_this )
     demux_t      *p_demux = (demux_t *)p_this;
     access_sys_t *p_sys   = (access_sys_t *)p_demux->p_sys;
 
+    ComContext ctx( COINIT_MULTITHREADED );
+
     /* Stop capturing stuff */
     p_sys->p_control->Stop();
 
@@ -1738,6 +1753,8 @@ static size_t EnumDeviceCaps( vlc_object_t *p_this, IBaseFilter *p_filter,
  *****************************************************************************/
 static block_t *ReadCompressed( access_t *p_access, bool *eof )
 {
+    ComContext ctx( COINIT_MULTITHREADED );
+
     access_sys_t   *p_sys = (access_sys_t *)p_access->p_sys;
     /* There must be only 1 elementary stream to produce a valid stream
      * of MPEG or DV data */
@@ -1783,6 +1800,8 @@ out:
  ****************************************************************************/
 static int Demux( demux_t *p_demux )
 {
+    ComContext ctx( COINIT_MULTITHREADED );
+
     access_sys_t *p_sys = (access_sys_t *)p_demux->p_sys;
     int i_found_samples;
 
@@ -2017,11 +2036,12 @@ static int FindDevices( vlc_object_t *p_this, const char *psz_name,
 {
     /* Find list of devices */
     std::list<std::string> list_devices;
-    if( SUCCEEDED(CoInitializeEx( NULL, COINIT_MULTITHREADED ))
-     || SUCCEEDED(CoInitializeEx( NULL, COINIT_APARTMENTTHREADED )) )
+    try
     {
         bool b_audio = !strcmp( psz_name, CFG_PREFIX "adev" );
 
+        ComContext ctx( COINIT_MULTITHREADED );
+
         FindCaptureDevice( p_this, NULL, &list_devices, b_audio );
 
         if( b_audio )
@@ -2031,8 +2051,10 @@ static int FindDevices( vlc_object_t *p_this, const char *psz_name,
             if( !list_vdevs.empty() )
                 AppendAudioEnabledVDevs( p_this, list_devices, list_vdevs );
         }
-
-        CoUninitialize();
+    }
+    catch (const std::runtime_error& ex)
+    {
+        msg_Err( p_this, "Failed fetch devices: %s", ex.what() );
     }
 
     unsigned count = 2 + list_devices.size(), i = 2;
-- 
2.11.0