imm32: Resize the composition string if the driver requested so.

dlls/imm32/ime.c

@@ -457,9 +457,8 @@ BOOL WINAPI ImeProcessKey( HIMC himc, UINT vkey, LPARAM lparam, BYTE *state )
 
 UINT WINAPI ImeToAsciiEx( UINT vkey, UINT vsc, BYTE *state, TRANSMSGLIST *msgs, UINT flags, HIMC himc )
 {
-    struct ime_driver_call_params params = {.himc = himc, .state = state};
     COMPOSITIONSTRING *compstr;
-    UINT count = 0;
+    UINT size, count = 0;
     INPUTCONTEXT *ctx;
     NTSTATUS status;
 
@@ -468,10 +467,23 @@ UINT WINAPI ImeToAsciiEx( UINT vkey, UINT vsc, BYTE *state, TRANSMSGLIST *msgs,
 
     if (!(ctx = ImmLockIMC( himc ))) return 0;
     if (!(compstr = ImmLockIMCC( ctx->hCompStr ))) goto done;
+    size = compstr->dwSize;
+
+    do
+    {
+        struct ime_driver_call_params params = {.himc = himc, .state = state};
+        HIMCC himcc;
+
+        ImmUnlockIMCC( ctx->hCompStr );
+        if (!(himcc = ImmReSizeIMCC( ctx->hCompStr, size ))) goto done;
+        if (!(compstr = ImmLockIMCC( (ctx->hCompStr = himcc) ))) goto done;
 
         params.compstr = compstr;
         status = NtUserMessageCall( ctx->hWnd, WINE_IME_TO_ASCII_EX, vkey, vsc, &params,
                                     NtUserImeDriverCall, FALSE );
+        size = compstr->dwSize;
+    } while (status == STATUS_BUFFER_TOO_SMALL);
+
     if (status) WARN( "WINE_IME_TO_ASCII_EX returned status %#lx\n", status );
 
     ImmUnlockIMCC( ctx->hCompStr );

dlls/imm32/imm_private.h

@@ -19,6 +19,8 @@
 #include <stdarg.h>
 #include <stddef.h>
 
+#include "ntstatus.h"
+#define WIN32_NO_STATUS
 #include "windef.h"
 #include "winbase.h"
 #include "wingdi.h"