commit d3c230b5c9ba6e242c0a6b290a185517f2c118e8
author Alistair Delva <adelva@google.com> Thu May 14 16:35:03 2020 -0700
committer Alistair Delva <adelva@google.com> Sat May 16 00:02:21 2020 +0000
tree 72871c26a94983bbdeaa0b185907f642f940f030
parent b6e2c14ed133b6882c38daddd24791a032f655d5

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
Merged-In: Ieae805d08fddd0124a397636f04d99194a9ef7e5

VolumeManager.cpp

diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index f860eef..9f151ea 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -78,6 +78,7 @@
 using android::vold::CreateDir;
 using android::vold::DeleteDirContents;
 using android::vold::DeleteDirContentsAndDir;
+using android::vold::IsVirtioBlkDevice;
 using android::vold::Symlink;
 using android::vold::Unlink;
 using android::vold::UnmountTree;
@@ -94,8 +95,6 @@
 static const unsigned int kSizeVirtualDisk = 536870912;
 
 static const unsigned int kMajorBlockMmc = 179;
-static const unsigned int kMajorBlockExperimentalMin = 240;
-static const unsigned int kMajorBlockExperimentalMax = 254;
 
 VolumeManager* VolumeManager::sInstance = NULL;
 
@@ -214,12 +213,10 @@
             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;