sync: store the num_fences from first SYNC_IOC_FILE_INFO
Fixes a bug with the signal time of devices using the
modern sync file interface. The bug only affects kernels running
an Android kernel 4.9 and later.
b/63395253
Test: tests/sync_test.cpp
Change-Id: I6fb00bcb8e16a3268c357153edd8e35a44546caa
diff --git a/libsync/sync.c b/libsync/sync.c
index baeccda..0950082 100644
--- a/libsync/sync.c
+++ b/libsync/sync.c
@@ -217,6 +217,8 @@
local_info.num_fences * sizeof(struct sync_fence_info));
if (!info)
return NULL;
+
+ info->num_fences = local_info.num_fences;
info->sync_fence_info = (__u64)(uintptr_t)(info + 1);
err = ioctl(fd, SYNC_IOC_FILE_INFO, info);