Bind to explicit major version of libgpiod (#2120)

src/System.Device.Gpio/Interop/Unix/SafeChipHandle.cs

@@ -17,9 +17,9 @@ internal class SafeChipHandle : SafeHandle
 
     protected override bool ReleaseHandle()
     {
-        Interop.libgpiod.gpiod_chip_close(handle);
+        Interop.Libgpiod.gpiod_chip_close(handle);
         return true;
     }
 
-    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.libgpiod.InvalidHandleValue;
+    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.Libgpiod.InvalidHandleValue;
 }

src/System.Device.Gpio/Interop/Unix/SafeChipIteratorHandle.cs

@@ -17,9 +17,9 @@ internal class SafeChipIteratorHandle : SafeHandle
 
     protected override bool ReleaseHandle()
     {
-        Interop.libgpiod.gpiod_chip_iter_free(handle);
+        Interop.Libgpiod.gpiod_chip_iter_free(handle);
         return true;
     }
 
-    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.libgpiod.InvalidHandleValue;
+    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.Libgpiod.InvalidHandleValue;
 }

src/System.Device.Gpio/Interop/Unix/SafeLineHandle.cs

@@ -20,17 +20,17 @@ internal class SafeLineHandle : SafeHandle
     protected override bool ReleaseHandle()
     {
         // Contrary to intuition, this does not invalidate the handle (see comment on declaration)
-        Interop.libgpiod.gpiod_line_release(handle);
+        Interop.Libgpiod.gpiod_line_release(handle);
         return true;
     }
 
     /// <summary>
-    /// Release the lock on the line handle. <see cref="Interop.libgpiod.gpiod_line_release"/>
+    /// Release the lock on the line handle. <see cref="Interop.Libgpiod.gpiod_line_release"/>
     /// </summary>
     public void ReleaseLock()
     {
         ReleaseHandle();
     }
 
-    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.libgpiod.InvalidHandleValue;
+    public override bool IsInvalid => handle == IntPtr.Zero || handle == Interop.Libgpiod.InvalidHandleValue;
 }

src/System.Device.Gpio/Interop/Unix/libgpiod/Interop.libgpiod.cs

@@ -8,15 +8,48 @@
 using System;
 using System.Device.Gpio;
 using System.Runtime.InteropServices;
+#if NET6_0_OR_GREATER
+using System.Runtime.Loader;
+using System.Reflection;
+#endif
 // Since this is only used on Linux, and in C on Linux sizeof(long) == sizeof(void*) this is a valid alias.
 using NativeLong = System.IntPtr;
 
 internal partial class Interop
 {
-    internal partial class libgpiod
+    internal static partial class Libgpiod
     {
+#if NET6_0_OR_GREATER
+        private const string LibgpiodLibrary = "libgpiod.so.2";
+#else
         private const string LibgpiodLibrary = "libgpiod";
-        internal static IntPtr InvalidHandleValue = new IntPtr(-1);
+#endif
+        internal static IntPtr InvalidHandleValue;
+
+        static Libgpiod()
+        {
+            InvalidHandleValue = new IntPtr(-1);
+#if NET6_0_OR_GREATER
+            Assembly currentAssembly = typeof(Libgpiod).Assembly;
+
+            AssemblyLoadContext.GetLoadContext(currentAssembly)!.ResolvingUnmanagedDll += (assembly, libgpiodName) =>
+            {
+                if (assembly != currentAssembly || libgpiodName != LibgpiodLibrary)
+                {
+                    return IntPtr.Zero;
+                }
+
+                // If loading the 2.x libgpiod failed, we may be running in a Linux distribution that has the 1.x
+                // version installed, so we try to load that instead.
+                if (NativeLibrary.TryLoad("libgpiod.so.1", out IntPtr handle))
+                {
+                    return handle;
+                }
+
+                return IntPtr.Zero;
+            };
+#endif
+        }
 
         /// <summary>
         /// Release all resources allocated for the gpiochip iterator and close the most recently opened gpiochip(if any).

src/System.Device.Gpio/System/Device/Gpio/Drivers/LibGpiodDriver.cs

@@ -31,7 +31,7 @@ public class LibGpiodDriver : UnixDriver
     // for use the bias flags we need libgpiod version 1.5 or later
     private static bool IsLibgpiodVersion1_5orHigher()
     {
-        IntPtr libgpiodVersionPtr = Interop.libgpiod.gpiod_version_string();
+        IntPtr libgpiodVersionPtr = Interop.Libgpiod.gpiod_version_string();
         string? libgpiodVersionMatch = Marshal.PtrToStringAnsi(libgpiodVersionPtr);
 
         if (libgpiodVersionMatch is object)
@@ -69,13 +69,13 @@ public class LibGpiodDriver : UnixDriver
         try
         {
             _pinNumberLock = new object();
-            _chip = Interop.libgpiod.gpiod_chip_open_by_number(gpioChip);
+            _chip = Interop.Libgpiod.gpiod_chip_open_by_number(gpioChip);
             if (_chip == null)
             {
                 throw ExceptionHelper.GetIOException(ExceptionResource.NoChipFound, Marshal.GetLastWin32Error());
             }
 
-            _pinCount = Interop.libgpiod.gpiod_chip_num_lines(_chip);
+            _pinCount = Interop.Libgpiod.gpiod_chip_num_lines(_chip);
             _pinNumberToEventHandler = new ConcurrentDictionary<int, LibGpiodDriverEventHandler>();
             _pinNumberToSafeLineHandle = new ConcurrentDictionary<int, SafeLineHandle>();
             _pinValue = new ConcurrentDictionary<int, PinValue>();
@@ -115,10 +115,10 @@ public class LibGpiodDriver : UnixDriver
         {
             _pinNumberToSafeLineHandle.TryGetValue(pinNumber, out SafeLineHandle? pinHandle);
 
-            if (pinHandle is null || (pinHandle is object && !Interop.libgpiod.gpiod_line_is_free(pinHandle)))
+            if (pinHandle is null || (pinHandle is object && !Interop.Libgpiod.gpiod_line_is_free(pinHandle)))
             {
                 pinHandle?.Dispose();
-                pinHandle = Interop.libgpiod.gpiod_chip_get_line(_chip, pinNumber);
+                pinHandle = Interop.Libgpiod.gpiod_chip_get_line(_chip, pinNumber);
                 _pinNumberToSafeLineHandle[pinNumber] = pinHandle;
             }
 
@@ -184,13 +184,13 @@ public class LibGpiodDriver : UnixDriver
                 return;
             }
 
-            SafeLineHandle pinHandle = Interop.libgpiod.gpiod_chip_get_line(_chip, pinNumber);
+            SafeLineHandle pinHandle = Interop.Libgpiod.gpiod_chip_get_line(_chip, pinNumber);
             if (pinHandle == null)
             {
                 throw ExceptionHelper.GetIOException(ExceptionResource.OpenPinError, Marshal.GetLastWin32Error());
             }
 
-            int mode = Interop.libgpiod.gpiod_line_direction(pinHandle);
+            int mode = Interop.Libgpiod.gpiod_line_direction(pinHandle);
             if (mode == 1)
             {
                 pinHandle.PinMode = PinMode.Input;
@@ -202,7 +202,7 @@ public class LibGpiodDriver : UnixDriver
 
             if (s_isLibgpiodVersion1_5orHigher && pinHandle.PinMode == PinMode.Input)
             {
-                int bias = Interop.libgpiod.gpiod_line_bias(pinHandle);
+                int bias = Interop.Libgpiod.gpiod_line_bias(pinHandle);
                 if (bias == (int)RequestFlag.GPIOD_LINE_REQUEST_FLAG_BIAS_PULL_DOWN)
                 {
                     pinHandle.PinMode = PinMode.InputPullDown;
@@ -226,7 +226,7 @@ public class LibGpiodDriver : UnixDriver
     {
         if (_pinNumberToSafeLineHandle.TryGetValue(pinNumber, out SafeLineHandle? pinHandle))
         {
-            int result = Interop.libgpiod.gpiod_line_get_value(pinHandle);
+            int result = Interop.Libgpiod.gpiod_line_get_value(pinHandle);
             if (result == -1)
             {
                 throw ExceptionHelper.GetIOException(ExceptionResource.ReadPinError, Marshal.GetLastWin32Error(), pinNumber);
@@ -271,12 +271,12 @@ public class LibGpiodDriver : UnixDriver
             pinHandle.ReleaseLock();
             int requestResult = mode switch
             {
-                PinMode.Input => Interop.libgpiod.gpiod_line_request_input(pinHandle, s_consumerName),
-                PinMode.InputPullDown => Interop.libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
+                PinMode.Input => Interop.Libgpiod.gpiod_line_request_input(pinHandle, s_consumerName),
+                PinMode.InputPullDown => Interop.Libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
                         (int)RequestFlag.GPIOD_LINE_REQUEST_FLAG_BIAS_PULL_DOWN),
-                PinMode.InputPullUp => Interop.libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
+                PinMode.InputPullUp => Interop.Libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
                         (int)RequestFlag.GPIOD_LINE_REQUEST_FLAG_BIAS_PULL_UP),
-                PinMode.Output => Interop.libgpiod.gpiod_line_request_output(pinHandle, s_consumerName, 0),
+                PinMode.Output => Interop.Libgpiod.gpiod_line_request_output(pinHandle, s_consumerName, 0),
                 _ => -1,
             };
 
@@ -303,12 +303,12 @@ public class LibGpiodDriver : UnixDriver
             pinHandle.ReleaseLock();
             int requestResult = mode switch
             {
-                PinMode.Input => Interop.libgpiod.gpiod_line_request_input(pinHandle, s_consumerName),
-                PinMode.InputPullDown => Interop.libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
+                PinMode.Input => Interop.Libgpiod.gpiod_line_request_input(pinHandle, s_consumerName),
+                PinMode.InputPullDown => Interop.Libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
                     (int)RequestFlag.GPIOD_LINE_REQUEST_FLAG_BIAS_PULL_DOWN),
-                PinMode.InputPullUp => Interop.libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
+                PinMode.InputPullUp => Interop.Libgpiod.gpiod_line_request_input_flags(pinHandle, s_consumerName,
                     (int)RequestFlag.GPIOD_LINE_REQUEST_FLAG_BIAS_PULL_UP),
-                PinMode.Output => Interop.libgpiod.gpiod_line_request_output(pinHandle, s_consumerName, initialValue == PinValue.High ? 1 : 0),
+                PinMode.Output => Interop.Libgpiod.gpiod_line_request_output(pinHandle, s_consumerName, initialValue == PinValue.High ? 1 : 0),
                 _ => -1,
             };
 
@@ -383,7 +383,7 @@ public class LibGpiodDriver : UnixDriver
                 pin: pinNumber);
         }
 
-        Interop.libgpiod.gpiod_line_set_value(pinHandle, (value == PinValue.High) ? 1 : 0);
+        Interop.Libgpiod.gpiod_line_set_value(pinHandle, (value == PinValue.High) ? 1 : 0);
         _pinValue[pinNumber] = value;
     }
 
@@ -391,7 +391,7 @@ public class LibGpiodDriver : UnixDriver
     public override ComponentInformation QueryComponentInformation()
     {
         var self = new ComponentInformation(this, "LibGpiodDriver");
-        IntPtr libgpiodVersionPtr = Interop.libgpiod.gpiod_version_string();
+        IntPtr libgpiodVersionPtr = Interop.Libgpiod.gpiod_version_string();
         string libgpiodVersion = Marshal.PtrToStringAnsi(libgpiodVersionPtr) ?? string.Empty;
         self.Properties["LibGpiodVersion"] = libgpiodVersion;
         return self;

src/System.Device.Gpio/System/Device/Gpio/LibgpiodDriverEventHandler.cs

@@ -34,7 +34,7 @@ internal sealed class LibGpiodDriverEventHandler : IDisposable
 
     private void SubscribeForEvent(SafeLineHandle pinHandle)
     {
-        int eventSuccess = Interop.libgpiod.gpiod_line_request_both_edges_events(pinHandle, s_consumerName);
+        int eventSuccess = Interop.Libgpiod.gpiod_line_request_both_edges_events(pinHandle, s_consumerName);
 
         if (eventSuccess < 0)
         {
@@ -55,7 +55,7 @@ internal sealed class LibGpiodDriverEventHandler : IDisposable
                     TvNsec = new IntPtr(50_000_000)
                 };
 
-                WaitEventResult waitResult = Interop.libgpiod.gpiod_line_event_wait(pinHandle, ref timeout);
+                WaitEventResult waitResult = Interop.Libgpiod.gpiod_line_event_wait(pinHandle, ref timeout);
                 if (waitResult == WaitEventResult.Error)
                 {
                     var errorCode = Marshal.GetLastWin32Error();
@@ -71,7 +71,7 @@ internal sealed class LibGpiodDriverEventHandler : IDisposable
                 if (waitResult == WaitEventResult.EventOccured)
                 {
                     GpioLineEvent eventResult = new GpioLineEvent();
-                    int checkForEvent = Interop.libgpiod.gpiod_line_event_read(pinHandle, ref eventResult);
+                    int checkForEvent = Interop.Libgpiod.gpiod_line_event_read(pinHandle, ref eventResult);
                     if (checkForEvent == -1)
                     {
                         throw ExceptionHelper.GetIOException(ExceptionResource.EventReadError, Marshal.GetLastWin32Error());