commit deef1856788ff83bcd474d0410ea27417e9774c8
author Ivan Lozano <ivanlozano@google.com> Mon Dec 04 16:09:10 2017 -0800
committer Ivan Lozano <ivanlozano@google.com> Tue Dec 19 16:16:13 2017 -0800
tree a6176e6fab0869362c88309020aa7c9373297924
parent 240201e27b1722009907a31983825668f2416ec2

Fix integer sanitizer in FastMixerDumpState.

Prevent FastMixerDumpState::dump(int) from throwing a runtime error on
integer sanitized builds.

 runtime error: unsigned integer overflow: 3912 - 36680 cannot be
 represented in type 'unsigned int'

The overflow looks intentional, so this refactors the code to use
the builtin overflow function.

Bug: 30969751
Test: Compiled and device boots.
Change-Id: Ic84a1bd08839fe1af7f3b5318cd8d6ccee777443
Merged-In: Ic84a1bd08839fe1af7f3b5318cd8d6ccee777443

services/audioflinger/FastMixerDumpState.cpp

diff --git a/services/audioflinger/FastMixerDumpState.cpp b/services/audioflinger/FastMixerDumpState.cpp
index 6475f22..2e4fb8c 100644
--- a/services/audioflinger/FastMixerDumpState.cpp
+++ b/services/audioflinger/FastMixerDumpState.cpp
@@ -78,7 +78,12 @@
     uint32_t bounds = mBounds;
     uint32_t newestOpen = bounds & 0xFFFF;
     uint32_t oldestClosed = bounds >> 16;
-    uint32_t n = (newestOpen - oldestClosed) & 0xFFFF;
+
+    //uint32_t n = (newestOpen - oldestClosed) & 0xFFFF;
+    uint32_t n;
+    __builtin_sub_overflow(newestOpen, oldestClosed, &n);
+    n = n & 0xFFFF;
+
     if (n > mSamplingN) {
         ALOGE("too many samples %u", n);
         n = mSamplingN;