commit ff1fc9bc417c8a4b6bffb2b12ab69a705676c17a
author Alistair Delva <adelva@google.com> Thu May 14 16:35:03 2020 -0700
committer Alistair Delva <adelva@google.com> Fri May 15 17:00:44 2020 -0700
tree 26f269cd503a1fcc0bc9f7eb88be687c95aa8725
parent dbc0da396a7913a896ef14f5134db7fa2e62be4b

Expand virtio_block check to other virtual devices

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

VolumeManager.cpp

diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index c0d0e77..f64f5f6 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -83,6 +83,7 @@
 using android::vold::DeleteDirContentsAndDir;
 using android::vold::EnsureDirExists;
 using android::vold::IsFilesystemSupported;
+using android::vold::IsVirtioBlkDevice;
 using android::vold::PrepareAndroidDirs;
 using android::vold::PrepareAppDirFromRoot;
 using android::vold::PrivateVolume;
@@ -103,8 +104,6 @@
 static const unsigned int kSizeVirtualDisk = 536870912;
 
 static const unsigned int kMajorBlockMmc = 179;
-static const unsigned int kMajorBlockExperimentalMin = 240;
-static const unsigned int kMajorBlockExperimentalMax = 254;
 
 using ScanProcCallback = bool(*)(uid_t uid, pid_t pid, int nsFd, const char* name, void* params);
 
@@ -231,12 +230,10 @@
             for (const auto& source : mDiskSources) {
                 if (source->matches(eventPath)) {
                     // For now, assume that MMC and virtio-blk (the latter is
-                    // emulator-specific; see Disk.cpp for details) devices are SD,
-                    // and that everything else is USB
+                    // specific to virtual platforms; see Utils.cpp for details)
+                    // devices are SD, and that everything else is USB
                     int flags = source->getFlags();
-                    if (major == kMajorBlockMmc || (android::vold::IsRunningInEmulator() &&
-                                                    major >= (int)kMajorBlockExperimentalMin &&
-                                                    major <= (int)kMajorBlockExperimentalMax)) {
+                    if (major == kMajorBlockMmc || IsVirtioBlkDevice(major)) {
                         flags |= android::vold::Disk::Flags::kSd;
                     } else {
                         flags |= android::vold::Disk::Flags::kUsb;