[glib: 1/3] GWin32Mount: Don't use SHGetFileInfoW() for icons

[Philip Withnall <pwithnall src gnome org>]

commit d1c542254fe44bdd6ad43574adb571222465b126
Author: Руслан Ижбулатов <lrn1986 gmail com>
Date:   Tue Mar 30 19:39:20 2021 +0000

    GWin32Mount: Don't use SHGetFileInfoW() for icons
    
    This function can cause significant delays when the mounted volume
    is disconnected or just weird. Use IExtractIconW::GetIconLocation()
    instead.
    
    Theoretically, this should require COM to be initialized, but in my tests
    this code worked just fine without calling CoInitializeEx().

 gio/gwin32mount.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 136 insertions(+), 5 deletions(-)
---
diff --git a/gio/gwin32mount.c b/gio/gwin32mount.c
index 83d8695a1..6388beb11 100644
--- a/gio/gwin32mount.c
+++ b/gio/gwin32mount.c
@@ -25,7 +25,47 @@
 
 #include <string.h>
 #define WIN32_MEAN_AND_LEAN
+#define COBJMACROS
 #include <windows.h>
+#include <shlobj.h>
+#include <shlwapi.h>
+
+/* At the moment of writing IExtractIconW interface in Mingw-w64
+ * is missing IUnknown members in its vtable. Use our own
+ * fixed declaration for now.
+ */
+#undef INTERFACE
+#define INTERFACE IMyExtractIconW
+DECLARE_INTERFACE_(IMyExtractIconW,IUnknown)
+{
+    /*** IUnknown methods ***/
+    STDMETHOD_(HRESULT,QueryInterface)(THIS_ REFIID riid, void** ppvObject) PURE;
+    STDMETHOD_(ULONG,AddRef)(THIS) PURE;
+    STDMETHOD_(ULONG,Release)(THIS) PURE;
+    /*** IMyExtractIconW methods ***/
+    STDMETHOD(GetIconLocation)(THIS_ UINT uFlags, LPWSTR pszIconFile, UINT cchMax, int *piIndex, PUINT 
pwFlags) PURE;
+    STDMETHOD(Extract)(THIS_ LPCWSTR pszFile, UINT nIconIndex, HICON *phiconLarge, HICON *phiconSmall, UINT 
nIconSize) PURE;
+};
+#undef INTERFACE
+
+#if !defined(__cplusplus) || defined(CINTERFACE)
+/*** IUnknown methods ***/
+#define IMyExtractIconW_QueryInterface(p,a,b) (p)->lpVtbl->QueryInterface(p,a,b)
+#define IMyExtractIconW_AddRef(p)             (p)->lpVtbl->AddRef(p)
+#define IMyExtractIconW_Release(p)            (p)->lpVtbl->Release(p)
+/*** IMyExtractIconW methods ***/
+#define IMyExtractIconW_GetIconLocation(p,a,b,c,d,e) (p)->lpVtbl->GetIconLocation(p,a,b,c,d,e)
+#define IMyExtractIconW_Extract(p,a,b,c,d,e)         (p)->lpVtbl->Extract(p,a,b,c,d,e)
+#else
+/*** IUnknown methods ***/
+#define IMyExtractIconW_QueryInterface(p,a,b) (p)->QueryInterface(a,b)
+#define IMyExtractIconW_AddRef(p)             (p)->AddRef()
+#define IMyExtractIconW_Release(p)            (p)->Release()
+/*** IMyExtractIconW methods ***/
+#define IMyExtractIconW_GetIconLocation(p,a,b,c,d,e) (p)->GetIconLocation(p,a,b,c,d,e)
+#define IMyExtractIconW_Extract(p,a,b,c,d,e)         (p)->Extract(p,a,b,c,d,e)
+#endif
+
 
 #include <glib.h>
 #include "gwin32volumemonitor.h"
@@ -210,6 +250,92 @@ _win32_drive_type_to_icon (int type, gboolean use_symbolic)
   }
 }
 
+/* mount_path doesn't need to end with a path separator.
+   mount_path must use backslashes as path separators, not slashes.
+   IShellFolder::ParseDisplayName() takes non-const string as input,
+   so mount_path can't be a const string.
+   result_name and result_index must not be NULL.
+   Returns TRUE when result_name is set (free with g_free),
+   FALSE otherwise.
+ */
+static gboolean
+get_icon_name_index (wchar_t  *mount_path,
+                     wchar_t **result_name,
+                     int      *result_index)
+{
+  IShellFolder *desktop;
+  PIDLIST_RELATIVE volume;
+  IShellFolder *volume_parent;
+  PCUITEMID_CHILD volume_relative;
+  IMyExtractIconW *eicon;
+  int icon_index;
+  UINT icon_flags;
+  wchar_t *name_buffer;
+  gsize name_buffer_size;
+  gsize arbitrary_reasonable_limit = 5000;
+  gboolean result = FALSE;
+
+  *result_name = NULL;
+
+  /* Get the desktop folder object reference */
+  if (!SUCCEEDED (SHGetDesktopFolder (&desktop)))
+    return FALSE;
+
+  /* Construct the volume IDList relative to desktop */
+  if (SUCCEEDED (IShellFolder_ParseDisplayName (desktop, NULL, NULL, mount_path, NULL, &volume, NULL)))
+    {
+      /* Get the parent of the volume (transfer-full) and the IDList relative to parent (transfer-none) */
+      if (SUCCEEDED (SHBindToParent (volume, &IID_IShellFolder, (void **) &volume_parent, &volume_relative)))
+        {
+          /* Get a reference to IExtractIcon object for the volume */
+          if (SUCCEEDED (IShellFolder_GetUIObjectOf (volume_parent, NULL, 1, (LPCITEMIDLIST *) 
&volume_relative, &IID_IExtractIconW, NULL, (void **) &eicon)))
+            {
+              gboolean keep_going = TRUE;
+              name_buffer = NULL;
+              name_buffer_size = MAX_PATH / 2;
+              while (keep_going)
+                {
+                  name_buffer_size *= 2;
+                  name_buffer = g_renew (wchar_t, name_buffer, name_buffer_size);
+                  name_buffer[name_buffer_size - 1] = 0x1; /* sentinel */
+                  keep_going = FALSE;
+
+                  /* Try to get the icon location */
+                  if (SUCCEEDED (IMyExtractIconW_GetIconLocation (eicon, GIL_FORSHELL, name_buffer, 
name_buffer_size, &icon_index, &icon_flags)))
+                    {
+                      if (name_buffer[name_buffer_size - 1] != 0x1)
+                        {
+                          if (name_buffer_size < arbitrary_reasonable_limit)
+                            {
+                              /* Buffer was too small, keep going */
+                              keep_going = TRUE;
+                              continue;
+                            }
+                          /* Else stop trying */
+                        }
+                      /* name_buffer might not contain a name */
+                      else if ((icon_flags & GIL_NOTFILENAME) != GIL_NOTFILENAME)
+                        {
+                          *result_name = g_steal_pointer (&name_buffer);
+                          *result_index = icon_index;
+                          result = TRUE;
+                        }
+                    }
+                }
+
+              g_free (name_buffer);
+              IMyExtractIconW_Release (eicon);
+            }
+          IShellFolder_Release (volume_parent);
+        }
+      CoTaskMemFree (volume);
+    }
+
+  IShellFolder_Release (desktop);
+
+  return result;
+}
+
 static GIcon *
 g_win32_mount_get_icon (GMount *mount)
 {
@@ -220,15 +346,20 @@ g_win32_mount_get_icon (GMount *mount)
   /* lazy creation */
   if (!win32_mount->icon)
     {
-      SHFILEINFOW shfi;
+      wchar_t *icon_path;
+      int icon_index;
+      wchar_t *p;
       wchar_t *wfn = g_utf8_to_utf16 (win32_mount->mount_path, -1, NULL, NULL, NULL);
 
-      if (SHGetFileInfoW (wfn, 0, &shfi, sizeof (shfi), SHGFI_ICONLOCATION))
+      for (p = wfn; p != NULL && *p != 0; p++)
+        if (*p == L'/')
+          *p = L'\\';
+
+      if (get_icon_name_index (wfn, &icon_path, &icon_index))
         {
-         gchar *name = g_utf16_to_utf8 (shfi.szDisplayName, -1, NULL, NULL, NULL);
-         gchar *id = g_strdup_printf ("%s,%i", name, shfi.iIcon);
+         gchar *id = g_strdup_printf ("%S,%i", icon_path, icon_index);
+         g_free (icon_path);
          win32_mount->icon = g_themed_icon_new (id);
-         g_free (name);
          g_free (id);
        }
       else