Android support for non-rooted phones

.github/workflows/rust.yml

@@ -28,11 +28,24 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Install toolchain
-      uses: actions-rs/toolchain@v1
+      uses: dtolnay/rust-toolchain@stable
       with:
         toolchain: ${{ matrix.rust }}
         override: true
     - name: Build
       run: cargo build --verbose
     - name: Run tests
       run: cargo test --verbose
+
+  build_android:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install toolchain
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        targets: 'aarch64-linux-android, armv7-linux-androideabi'
+    - name: build
+      run: |
+        cargo build --target aarch64-linux-android --all-features
+        cargo build --target armv7-linux-androideabi --all-features

Cargo.toml

@@ -21,7 +21,7 @@ slab = "0.4.9"
 env_logger = "0.10.0"
 futures-lite = "1.13.0"
 
-[target.'cfg(target_os="linux")'.dependencies]
+[target.'cfg(any(target_os="linux", target_os="android"))'.dependencies]
 rustix = { version = "0.38.17", features = ["fs", "event", "net"] }
 libc = "0.2.155"
 

src/device.rs

@@ -1,7 +1,3 @@
-use std::{io::ErrorKind, sync::Arc, time::Duration};
-
-use log::error;
-
 use crate::{
     descriptors::{
         decode_string_descriptor, validate_string_descriptor, ActiveConfigurationError,
@@ -14,6 +10,8 @@ use crate::{
     },
     DeviceInfo, Error,
 };
+use log::error;
+use std::{io::ErrorKind, sync::Arc, time::Duration};
 
 /// An opened USB device.
 ///
@@ -46,6 +44,14 @@ impl Device {
         Ok(Device { backend })
     }
 
+    /// Wraps a device that is already open.
+    #[cfg(any(target_os = "android", target_os = "linux"))]
+    pub fn from_fd(fd: std::os::fd::OwnedFd) -> Result<Device, Error> {
+        Ok(Device {
+            backend: platform::Device::from_fd(fd)?,
+        })
+    }
+
     /// Open an interface of the device and claim it for exclusive use.
     pub fn claim_interface(&self, interface: u8) -> Result<Interface, Error> {
         let backend = self.backend.claim_interface(interface)?;
@@ -242,7 +248,7 @@ impl Device {
     ///   and use the interface handle to submit transfers.
     /// * On Linux, this takes a device-wide lock, so if you have multiple threads, you
     ///   are better off using the async methods.
-    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[cfg(any(target_os = "linux", target_os = "macos", target_os = "android"))]
     pub fn control_in_blocking(
         &self,
         control: Control,
@@ -260,7 +266,7 @@ impl Device {
     ///   and use the interface handle to submit transfers.
     /// * On Linux, this takes a device-wide lock, so if you have multiple threads, you
     ///   are better off using the async methods.
-    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[cfg(any(target_os = "linux", target_os = "macos", target_os = "android"))]
     pub fn control_out_blocking(
         &self,
         control: Control,
@@ -296,7 +302,7 @@ impl Device {
     ///
     /// * Not supported on Windows. You must [claim an interface][`Device::claim_interface`]
     ///   and use the interface handle to submit transfers.
-    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[cfg(any(target_os = "linux", target_os = "macos", target_os = "android"))]
     pub fn control_in(&self, data: ControlIn) -> TransferFuture<ControlIn> {
         let mut t = self.backend.make_control_transfer();
         t.submit::<ControlIn>(data);
@@ -329,7 +335,7 @@ impl Device {
     ///
     /// * Not supported on Windows. You must [claim an interface][`Device::claim_interface`]
     ///   and use the interface handle to submit transfers.
-    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[cfg(any(target_os = "linux", target_os = "macos", target_os = "android"))]
     pub fn control_out(&self, data: ControlOut) -> TransferFuture<ControlOut> {
         let mut t = self.backend.make_control_transfer();
         t.submit::<ControlOut>(data);

src/enumeration.rs

@@ -1,7 +1,7 @@
 #[cfg(target_os = "windows")]
 use std::ffi::{OsStr, OsString};
 
-#[cfg(target_os = "linux")]
+#[cfg(any(target_os = "linux", target_os = "android"))]
 use crate::platform::SysfsPath;
 
 use crate::{Device, Error};
@@ -22,10 +22,10 @@ pub struct DeviceId(pub(crate) crate::platform::DeviceId);
 ///     * macOS: `registry_id`, `location_id`
 #[derive(Clone)]
 pub struct DeviceInfo {
-    #[cfg(target_os = "linux")]
+    #[cfg(any(target_os = "linux", target_os = "android"))]
     pub(crate) path: SysfsPath,
 
-    #[cfg(target_os = "linux")]
+    #[cfg(any(target_os = "linux", target_os = "android"))]
     pub(crate) busnum: u8,
 
     #[cfg(target_os = "windows")]
@@ -83,7 +83,7 @@ impl DeviceInfo {
             DeviceId(self.devinst)
         }
 
-        #[cfg(target_os = "linux")]
+        #[cfg(any(target_os = "linux", target_os = "android"))]
         {
             DeviceId(crate::platform::DeviceId {
                 bus: self.busnum,
@@ -114,7 +114,7 @@ impl DeviceInfo {
     /// *(Linux-only)* Bus number.
     ///
     /// On Linux, the `bus_id` is an integer and this provides the value as `u8`.
-    #[cfg(target_os = "linux")]
+    #[cfg(any(target_os = "linux", target_os = "android"))]
     pub fn busnum(&self) -> u8 {
         self.busnum
     }
@@ -314,6 +314,9 @@ impl std::fmt::Debug for DeviceInfo {
         #[cfg(target_os = "linux")]
         {
             s.field("sysfs_path", &self.path);
+        }
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        {
             s.field("busnum", &self.busnum);
         }
 

src/platform/linux_usbfs/device.rs

@@ -1,3 +1,4 @@
+use std::io::{ErrorKind, Seek};
 use std::{ffi::c_void, time::Duration};
 use std::{
     fs::File,
@@ -24,7 +25,9 @@ use super::{
     usbfs::{self, Urb},
     SysfsPath,
 };
+use crate::descriptors::Configuration;
 use crate::platform::linux_usbfs::events::Watch;
+use crate::transfer::{ControlType, Recipient};
 use crate::{
     descriptors::{parse_concatenated_config_descriptors, DESCRIPTOR_LEN_DEVICE},
     transfer::{
@@ -54,13 +57,39 @@ impl LinuxDevice {
         let fd = rustix::fs::open(&path, OFlags::RDWR | OFlags::CLOEXEC, Mode::empty())
             .inspect_err(|e| warn!("Failed to open device {path:?}: {e}"))?;
 
+        let inner = Self::create_inner(fd, Some(d.path.clone()), Some(active_config));
+        if inner.is_ok() {
+            debug!("Opened device bus={busnum} addr={devnum}",);
+        }
+        inner
+    }
+
+    pub(crate) fn from_fd(fd: OwnedFd) -> Result<Arc<LinuxDevice>, Error> {
+        debug!("Wrapping fd {} as usbfs device", fd.as_raw_fd());
+
+        Self::create_inner(fd, None, None)
+    }
+
+    pub(crate) fn create_inner(
+        fd: OwnedFd,
+        sysfs: Option<SysfsPath>,
+        active_config: Option<u8>,
+    ) -> Result<Arc<LinuxDevice>, Error> {
         let descriptors = {
             let mut file = unsafe { ManuallyDrop::new(File::from_raw_fd(fd.as_raw_fd())) };
+            // NOTE: Seek required on android
+            file.seek(std::io::SeekFrom::Start(0))?;
             let mut buf = Vec::new();
             file.read_to_end(&mut buf)?;
             buf
         };
 
+        let active_config = if let Some(active_config) = active_config {
+            active_config
+        } else {
+            Self::get_config(&descriptors, &fd)?
+        };
+
         // because there's no Arc::try_new_cyclic
         let mut events_err = None;
         let arc = Arc::new_cyclic(|weak| {
@@ -71,11 +100,14 @@ impl LinuxDevice {
             );
             let events_id = *res.as_ref().unwrap_or(&usize::MAX);
             events_err = res.err();
+            if events_err.is_none() {
+                debug!("Opened device fd={} with id {}", fd.as_raw_fd(), events_id,);
+            }
             LinuxDevice {
                 fd,
                 events_id,
                 descriptors,
-                sysfs: Some(d.path.clone()),
+                sysfs,
                 active_config: AtomicU8::new(active_config),
             }
         });
@@ -84,10 +116,6 @@ impl LinuxDevice {
             error!("Failed to initialize event loop: {err}");
             Err(err)
         } else {
-            debug!(
-                "Opened device bus={busnum} addr={devnum} with id {}",
-                arc.events_id
-            );
             Ok(arc)
         }
     }
@@ -262,13 +290,15 @@ impl LinuxDevice {
         }))
     }
 
+    #[cfg(target_os = "linux")]
     pub(crate) fn detach_kernel_driver(
         self: &Arc<Self>,
         interface_number: u8,
     ) -> Result<(), Error> {
         usbfs::detach_kernel_driver(&self.fd, interface_number).map_err(|e| e.into())
     }
 
+    #[cfg(target_os = "linux")]
     pub(crate) fn attach_kernel_driver(
         self: &Arc<Self>,
         interface_number: u8,
@@ -303,6 +333,78 @@ impl LinuxDevice {
             }
         }
     }
+
+    fn get_config(descriptors: &[u8], fd: &OwnedFd) -> Result<u8, Error> {
+        const REQUEST_GET_CONFIGURATION: u8 = 0x08;
+
+        let mut dst = [0u8; 1];
+
+        let control = Control {
+            control_type: ControlType::Standard,
+            recipient: Recipient::Device,
+            request: REQUEST_GET_CONFIGURATION,
+            value: 0,
+            index: 0,
+        };
+
+        let r = usbfs::control(
+            &fd,
+            usbfs::CtrlTransfer {
+                bRequestType: control.request_type(Direction::In),
+                bRequest: control.request,
+                wValue: control.value,
+                wIndex: control.index,
+                wLength: dst.len() as u16,
+                timeout: Duration::from_millis(50)
+                    .as_millis()
+                    .try_into()
+                    .expect("timeout must fit in u32 ms"),
+                data: &mut dst[0] as *mut u8 as *mut c_void,
+            },
+        );
+
+        match r {
+            Ok(n) => {
+                if n == dst.len() {
+                    let active_config = dst[0];
+                    debug!("Obtained active configuration for fd {} from GET_CONFIGURATION request: {active_config}", fd.as_raw_fd());
+                    return Ok(active_config);
+                } else {
+                    warn!("GET_CONFIGURATION request returned incorrect length: {n}, expected 1",);
+                }
+            }
+            Err(e) => {
+                warn!(
+                    "GET_CONFIGURATION request failed: {:?}",
+                    errno_to_transfer_error(e)
+                );
+            }
+        }
+
+        if descriptors.len() < DESCRIPTOR_LEN_DEVICE as usize {
+            warn!(
+                "Descriptors for device fd {} too short to use fallback configuration",
+                fd.as_raw_fd()
+            );
+            return Err(ErrorKind::Other.into());
+        }
+
+        // Assume the current configuration is the first one
+        // See: https://github.com/libusb/libusb/blob/467b6a8896daea3d104958bf0887312c5d14d150/libusb/os/linux_usbfs.c#L865
+        let mut descriptors =
+            parse_concatenated_config_descriptors(&descriptors[DESCRIPTOR_LEN_DEVICE as usize..])
+                .map(Configuration::new);
+
+        if let Some(config) = descriptors.next() {
+            return Ok(config.configuration_value());
+        }
+
+        error!(
+            "No available configurations for device fd {}",
+            fd.as_raw_fd()
+        );
+        return Err(ErrorKind::Other.into());
+    }
 }
 
 impl Drop for LinuxDevice {

src/platform/linux_usbfs/usbfs.rs

@@ -95,7 +95,8 @@ mod opcodes {
 pub fn detach_kernel_driver<Fd: AsFd>(fd: Fd, interface: u8) -> io::Result<()> {
     let command = UsbFsIoctl {
         interface: interface.into(),
-        ioctl_code: opcodes::nested::USBDEVFS_DISCONNECT::OPCODE.raw(),
+        // NOTE: Cast needed since on android this type is i32 vs u32 on linux
+        ioctl_code: opcodes::nested::USBDEVFS_DISCONNECT::OPCODE.raw() as _,
         data: std::ptr::null_mut(),
     };
     unsafe {
@@ -107,7 +108,7 @@ pub fn detach_kernel_driver<Fd: AsFd>(fd: Fd, interface: u8) -> io::Result<()> {
 pub fn attach_kernel_driver<Fd: AsFd>(fd: Fd, interface: u8) -> io::Result<()> {
     let command = UsbFsIoctl {
         interface: interface.into(),
-        ioctl_code: opcodes::nested::USBDEVFS_CONNECT::OPCODE.raw(),
+        ioctl_code: opcodes::nested::USBDEVFS_CONNECT::OPCODE.raw() as _,
         data: std::ptr::null_mut(),
     };
     unsafe {

src/platform/mod.rs

@@ -1,7 +1,7 @@
-#[cfg(target_os = "linux")]
+#[cfg(any(target_os = "linux", target_os = "android"))]
 mod linux_usbfs;
 
-#[cfg(target_os = "linux")]
+#[cfg(any(target_os = "linux", target_os = "android"))]
 pub use linux_usbfs::*;
 
 #[cfg(target_os = "windows")]