Make ShareableBitmapHaiku not depend on SharedMemoryHaiku

This lets us use UNIX's or Haiku's implementation of shared memory.
SharedMemoryHaiku is not fully implemented at present and this
allows us to avoid using it.

Unfortunately, we lose the method of uniquely identifying bitmaps that
we used previously, since the previous method relies on Haiku's
implementation of shared memory to store the id. This will have to be
implemented in some way in the future.

Author: Zardshard

Source/WebCore/platform/graphics/haiku/HaikuUtilities.cpp

@@ -28,44 +28,16 @@
 
 #if PLATFORM(HAIKU)
 
-#include "Logging.h"
-
-#include <Bitmap.h>
-#include <optional>
-#include <OS.h>
-#include <wtf/persistence/PersistentDecoder.h>
-#include <wtf/text/Base64.h>
-#include <wtf/text/WTFString.h>
+#include "NotImplemented.h"
 
 namespace WebCore{
 
 uintptr_t getBitmapUniqueID(BBitmap* bitmap)
 {
     // Gets a unique identifier to a bitmap that is same across processes.
-    // This version gets the id from the id attached to the image's area's name
-    // by SharedMemory::allocate
-
-    area_id area = bitmap->Area();
-
-    area_info info;
-    status_t status = get_area_info(area, &info);
-
-    std::optional<uint64_t> decodedID;
-    if (status == B_OK) {
-        auto base64Data = WTF::String::fromLatin1(&info.name[7]);
-        auto data = WTF::base64Decode(base64Data);
-        WTF::Persistence::Decoder decoder({ data->data(), data->size() });
-        decoder >> decodedID;
-    }
-
-    if (decodedID) {
-        // FIXME: This code is untested. This can be remove once tested.
-        LOG(Compositing, "Found image ID %ld", *decodedID);
-        return *decodedID;
-    } else {
-        LOG(Compositing, "Failed to find image id for BBitmap. Falling back to 0");
-        return 0;
-    }
+    debugger("getBitmapUniqueID needs to be implemented");
+    notImplemented();
+    return 0;
 }
 
 } // namespace WebCore

Source/WebCore/platform/graphics/haiku/ShareableBitmapHaiku.cpp

@@ -71,14 +71,37 @@ void ShareableBitmap::paint(GraphicsContext& context, float scaleFactor, const I
 
 WebCore::PlatformImagePtr ShareableBitmap::createPlatformImage(WebCore::BackingStoreCopy, WebCore::ShouldInterpolate)
 {
-    // FIXME: This doesn't work with UNIX's implementation of shared memory atm.
-    // Or should we use Haiku's implementation of shared memory instead?
-    // NOTE: getBitmapUniqueID depends on bitmaps always being at offset 0 in
-    // their area.
-    // return WebCore::PlatformImagePtr(new BitmapRef(m_sharedMemory->area(), 0, bounds(), 0, /*m_configuration.platformColorSpace()*/ B_RGBA32, bytesPerRow()));
-
-    debugger("ShareableBitmap::createPlatformImage is unimplemented");
-    return nullptr;
+    // Creates a BBitmap (actually BitmapRef) that reads image data from the
+    // address given by data(). This address is in shared memory. The idea is
+    // that multiple processes can point to the same underlying bitmap data.
+    // One can draw, and the other can display.
+
+    status_t status;
+
+    // Get area id of shared memory
+    void* address = data();
+    area_id area = area_for(address);
+    ASSERT(area >= B_OK);
+
+    // Get offset in area to put our BBitmap
+    area_info areaInfo;
+    status = get_area_info(area, &areaInfo);
+    ASSERT(status == B_OK);
+    ptrdiff_t offset = (ptrdiff_t)address - (ptrdiff_t)areaInfo.address;
+
+#if USE(UNIX_DOMAIN_SOCKETS)
+    // We are on UNIX's implementation of shared memory. UNIX's shared memory
+    // doesn't have B_CLONEABLE_AREA by default. We need it enabled so that the
+    // app server can clone it and manipulate the bitmap.
+    status = set_area_protection(area, B_READ_AREA | B_WRITE_AREA | B_CLONEABLE_AREA);
+    ASSERT(status == B_OK);
+#endif
+
+    // Create the BBitmap
+    WebCore::PlatformImagePtr image = adoptRef(new BitmapRef(
+        area, offset, bounds(), B_BITMAP_ACCEPTS_VIEWS, /*m_configuration.platformColorSpace()*/ B_RGBA32, bytesPerRow()));
+
+    return image;
 }
 
 RefPtr<Image> ShareableBitmap::createImage()

Source/WebCore/platform/haiku/SharedMemoryHaiku.cpp

@@ -42,16 +42,9 @@ namespace WebCore {
 
 RefPtr<SharedMemory> SharedMemory::allocate(size_t size)
 {
-    // Make the area's name include a randomnly generated id so that
-    // identifying whether two areas point to the same memory across processes
-    // is easier. Do not change the format of this string without changing all
-    // of the places that depend on this format. (Hint: check all usages of
-    // get_area_info to see if they use the name)
-    uint64_t id = ((uint64_t) weakRandomNumber<uint32_t>() << 32) | weakRandomNumber<uint32_t>();
-    auto name = makeString("WebKit-", base64Encoded(&id, sizeof(id)));
     void* baseAddress;
 
-    area_id sharedArea = create_area(name.ascii().data(), &baseAddress,
+    area_id sharedArea = create_area("WebKit shared memory", &baseAddress,
         B_ANY_ADDRESS, size, B_NO_LOCK, B_READ_AREA | B_WRITE_AREA | B_CLONEABLE_AREA);
 
     if (sharedArea < 0)