Expand virtio_block check to other virtual devicesHEADq10.0

The Android Emulator isn't the only virtual device the virtio-block
detection code is useful for, and those platforms might not set any
discriminating properties to indicate that they are virtual.

Rework the virtio-block major detection to use /proc/devices instead
of hardcoding the assumption that any virtual platform can have
virtio-block at any experimental major; the new code permits only the
exact experimental major assigned to virtio-block.

The new code runs everywhere, but it will only run once and could be
expanded later to detect dynamic or experimental majors.

Bug: 156286088
Change-Id: Ieae805d08fddd0124a397636f04d99194a9ef7e5
Merged-In: Ieae805d08fddd0124a397636f04d99194a9ef7e5
(cherry picked from commit d3c230b5c9ba6e242c0a6b290a185517f2c118e8)

1 files changed, 2 insertions, 2 deletions

diff --git a/Utils.h b/Utils.h
index af4e401..661443b 100644
--- a/Utils.h
+++ b/Utils.h
@@ -133,8 +133,8 @@ status_t RestoreconRecursive(const std::string& path);
 // TODO: promote to android::base
 bool Readlinkat(int dirfd, const std::string& path, std::string* result);
 
-/* Checks if Android is running in QEMU */
-bool IsRunningInEmulator();
+// Handles dynamic major assignment for virtio-block
+bool IsVirtioBlkDevice(unsigned int major);
 
 status_t UnmountTreeWithPrefix(const std::string& prefix);
 status_t UnmountTree(const std::string& mountPoint);