libgui: Add generation numbers to BufferQueue

This change allows producers to set a generation number on a
BufferQueue. This number will be embedded in any new GraphicBuffers
created in that BufferQueue, and attempts to attach buffers which have
a different generation number will fail.

It also plumbs the setGenerationNumber method through Surface, with the
additional effect that any buffers attached to the Surface after
setting a new generation number will automatically be updated with the
new number (as opposed to failing, as would happen on through IGBP).

Bug: 20923096
Change-Id: I32bf726b035f99c3e5834beaf76afb9f01adcbc2

1 files changed, 7 insertions, 0 deletions

diff --git a/libs/gui/BufferQueueConsumer.cpp b/libs/gui/BufferQueueConsumer.cpp
index 4174676c76..ae796b14db 100644
--- a/libs/gui/BufferQueueConsumer.cpp
+++ b/libs/gui/BufferQueueConsumer.cpp
@@ -248,6 +248,13 @@ status_t BufferQueueConsumer::attachBuffer(int* outSlot,
         return INVALID_OPERATION;
     }
 
+    if (buffer->getGenerationNumber() != mCore->mGenerationNumber) {
+        BQ_LOGE("attachBuffer: generation number mismatch [buffer %u] "
+                "[queue %u]", buffer->getGenerationNumber(),
+                mCore->mGenerationNumber);
+        return BAD_VALUE;
+    }
+
     // Find a free slot to put the buffer into
     int found = BufferQueueCore::INVALID_BUFFER_SLOT;
     if (!mCore->mFreeSlots.empty()) {