winmm/mmio: Add extra handling for unbuffered MMIO handles

gistfile1.diff

From c877ba08ee19b8b5f38ea4f37ce345208d158eba Mon Sep 17 00:00:00 2001
From: Cloudef <mailRoxas@gmail.com>
Date: Sun, 6 Nov 2011 18:57:57 +0200
Subject: winmm/mmio: Add extra handling for unbuffered MMIO handles

On non buffered mmioSeek, set the lBufOffset accordingly.
On non buffered mmioRead, seek to beginning of the file and return 0 meaning that the file ended.

I don't know if this just reveals bad programming in application,
or that native winmm likes to try handle code when it's wrongly used..

Fixes crashing on unbuffered cases.
---
 dlls/winmm/mmio.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/dlls/winmm/mmio.c b/dlls/winmm/mmio.c
index 8c49826..0d4f6f6 100644
--- a/dlls/winmm/mmio.c
+++ b/dlls/winmm/mmio.c
@@ -765,7 +765,13 @@ LONG WINAPI mmioRead(HMMIO hmmio, HPSTR pch, LONG cch)

     /* unbuffered case first */
     if (!wm->info.pchBuffer)
-	return send_message(wm->ioProc, &wm->info, MMIOM_READ, (LPARAM)pch, cch, FALSE);
+    {
+       /* check end of file, should return always 0 or error */
+       if (wm->info.lDiskOffset + cch > wm->dwFileSize)
+          return send_message(wm->ioProc, &wm->info, MMIOM_SEEK, 0, SEEK_SET, FALSE);
+       else
+          return send_message(wm->ioProc, &wm->info, MMIOM_READ, (LPARAM)pch, cch, FALSE);
+    }

     /* first try from current buffer */
     if (wm->info.pchNext != wm->info.pchEndRead) {
@@ -869,6 +872,6 @@ LONG WINAPI mmioSeek(HMMIO hmmio, LONG lOffset, INT iOrigin)
     /* not buffered, direct seek on file */
     if (!wm->info.pchBuffer)
-	return send_message(wm->ioProc, &wm->info, MMIOM_SEEK, lOffset, iOrigin, FALSE);
+       return wm->info.lBufOffset = send_message(wm->ioProc, &wm->info, MMIOM_SEEK, lOffset, iOrigin, FALSE);

     switch (iOrigin) {
     case SEEK_SET:
--
1.7.7.2