Changeset 21302 for trunk/src/kernel32/mmapview.cpp

Timestamp:

Jun 18, 2009, 11:53:26 AM (16 years ago)

Author:

ydario

Message:

Kernel32 updates.

File:

• trunk/src/kernel32/mmapview.cpp (modified) (5 diffs)

trunk/src/kernel32/mmapview.cpp

@@ -106 +106 @@
         if(mfAccess & MEMMAP_ACCESS_COPYONWRITE) 
         {
+            //A copy on write view is a private copy of the memory map
+            //The pages reflect the state of the original map until they are
+            //modified.
+            //We use guard pages to track access to the COW view.
+            pMapView = VirtualAlloc(0, size, MEM_COMMIT, PAGE_READWRITE|PAGE_GUARD);
+            if(pMapView == NULL) {
+                dprintf(("VirtualAlloc FAILED"));
             SetLastError(ERROR_NOT_ENOUGH_MEMORY);
             errorState = 1;
             return;
+        }
         }
         else 
@@ -118 +126 @@
         }
     }
+    //Allocate bitmap for all pages of a COW view to track which pages are 
+    //shared and which are private (copy on write -> private page)
+    if(fdwAccess == FILE_MAP_COPY) 
+    {
+        DWORD nrPages = mSize >> PAGE_SHIFT;
+        if(mSize & 0xFFF)
+           nrPages++;
+
+        int sizebitmap = nrPages/8 + 1;
+
+        pCOWBitmap = (char *)malloc(sizebitmap);
+        if(pCOWBitmap) {
+            memset(pCOWBitmap, 0, sizebitmap);
+        }
+        else DebugInt3();
+    }
 
     dprintf(("Win32MemMapView::Win32MemMapView: created %x (alias for %x), size %d", pMapView, viewaddr, size));
@@ -245 +269 @@
 //       PAGEVIEW_READONLY      -> set page flags to readonly
 //       PAGEVIEW_VIEW          -> set page flags to view default
+//       PAGEVIEW_GUARD         -> set page flags of COW view to GUARD
 //
 // Returns:
@@ -264 +289 @@
         ( (flags == PAGEVIEW_GUARD) && !(mfAccess & MEMMAP_ACCESS_COPYONWRITE) ) ) 
     {
+        //PAGEVIEW_GUARD only applies to COW views
         //PAGEVIEW_VIEW/READONLY does not apply to COW views
         return TRUE; 
@@ -289 +315 @@
             accessAttr |= PAG_WRITE;
         }
-    }
-
+        if(flags == PAGEVIEW_GUARD) {
+            accessAttr |= PAG_GUARD;
+        }
+    }
+
+    if(flags == PAGEVIEW_GUARD || (mfAccess & MEMMAP_ACCESS_COPYONWRITE)) 
     {
+        DWORD startpage = (offset - mOffset) >> PAGE_SHIFT;
+        DWORD nrPages = size >> PAGE_SHIFT;
+        if(size & 0xFFF)
+           nrPages++;
+
+        //COW views need special treatment. If we are told to change any flags
+        //of the COW pages, then only the shared pages must be changed.
+        //So check each page if it is still shared.
+        for(int i=startpage;i<startpage+nrPages;i++) 
+    {
+            if(!isCOWPage(i)) 
+            {//page is still shared, so set the guard flag
+                rc = OSLibDosSetMem((char *)pMapView+(offset - mOffset), PAGE_SIZE, accessAttr);
+                if(rc) {
+                    dprintf(("Win32MemMapView::changePageFlags: OSLibDosSetMem %x %x %x failed with %d", (char *)pMapView+(offset - mOffset), size, accessAttr, rc));
+                    return FALSE;
+                }
+            }
+            offset += PAGE_SIZE;
+        }
+    }
+    else {
         rc = OSLibDosSetMem((char *)pMapView+(offset - mOffset), size, accessAttr);
         if(rc) {