Skip FUSE request from /dev/fuse if unique=0

APCT log shows that we got FUSE request unique=0 and replying to such
request causes a EINVAL.

The possible reasons of getting unique=0 here are:

 * /dev/fuse actually submits such requests. In this case, not replying
   to such request probabbly safe as the kernel cannot wait corresponding
   response without a unique number. We can observing the kernel code to
   find out what unique=0 actually means.
 * Memory corruption happens and unique number are cleared with zero.
   In this case, if we skip unique=0 request, libappfuse does not reply
   to the kernel request and APCT result will become timeout .

To see which case happens, the CL ScopedLogSeverity to output
verbose logs and lets FuseBridgeLoop skip a request from /dev/fuse if unique=0.

Bug: 62429763
Test: libappfuse_tests
Change-Id: I8c4d532564b690d55573b92260170b0cd68150ab

1 files changed, 1 insertions, 0 deletions

diff --git a/libappfuse/tests/FuseBridgeLoopTest.cc b/libappfuse/tests/FuseBridgeLoopTest.cc
index 51d605136..0a28451bf 100644
--- a/libappfuse/tests/FuseBridgeLoopTest.cc
+++ b/libappfuse/tests/FuseBridgeLoopTest.cc
@@ -67,6 +67,7 @@ class FuseBridgeLoopTest : public ::testing::Test {
     memset(&request_, 0, sizeof(FuseRequest));
     request_.header.opcode = opcode;
     request_.header.len = sizeof(fuse_in_header);
+    request_.header.unique = 1;
     ASSERT_TRUE(request_.Write(dev_sockets_[0]));
 
     memset(&response_, 0, sizeof(FuseResponse));