Merge pull request #2412 from stephentoub/driveinfo_drivetype_unix

Fix DriveInfo.DriveType to not throw on Unix

Author: stephentoub

src/Common/src/Interop/Unix/libc/Interop.mountpoints.cs

@@ -4,8 +4,6 @@
 using System;
 using System.Runtime.InteropServices;
 
-using uid_t = System.UInt32;
-
 internal static partial class Interop
 {
     internal static partial class libc
@@ -33,26 +31,40 @@ internal static partial class libc
         private static unsafe extern int get_statfs(string path, out statfs buffer);
 
         /// <summary>
-        /// Gets a statfs struct for a given mount point
+        /// Attempts to get a statfs struct for a given mount point.
         /// </summary>
-        /// <param name="name">The drive name to retrieve the statfs data for</param>
-        /// <returns>Returns </returns>
-        internal static unsafe statfs GetStatFsForDriveName(string name)
+        /// <param name="name">The drive name to retrieve the statfs data for.</param>
+        /// <param name="data">The data retrieved from the mount point.</param>
+        /// <returns>Returns true if data was filled with the results; otherwise, false.</returns>
+        internal static bool TryGetStatFsForDriveName(string name, out statfs data, out int errno)
         {
-            statfs data = default(statfs);
-            int result = get_statfs(name,  out data);
-            if (result < 0)
+            data = default(statfs);
+            errno = 0;
+            if (get_statfs(name, out data) < 0)
             {
-                int errno = Marshal.GetLastWin32Error();
-                if (errno == Interop.Errors.ENOENT)
-                    throw new System.IO.DriveNotFoundException(SR.Format(SR.IO_DriveNotFound_Drive, name)); // match Win32 exception
-                else
-                    throw Interop.GetExceptionForIoErrno(errno, isDirectory: true);
+                errno = Marshal.GetLastWin32Error();
+                return false;
             }
-            else
+            return true;
+        }
+
+        /// <summary>
+        /// Gets a statfs struct for a given mount point
+        /// </summary>
+        /// <param name="name">The drive name to retrieve the statfs data for.</param>
+        /// <returns>Returns the statfs.</returns>
+        internal static statfs GetStatFsForDriveName(string name)
+        {
+            statfs data;
+            int errno;
+            if (!TryGetStatFsForDriveName(name, out data, out errno))
             {
-                return data;
+                throw errno == Errors.ENOENT ?
+                    new System.IO.DriveNotFoundException(SR.Format(SR.IO_DriveNotFound_Drive, name)) : // match Win32 exception
+                    GetExceptionForIoErrno(errno, isDirectory: true);
             }
+            return data;
         }
+
     }
 }

src/System.IO.FileSystem.DriveInfo/src/System/IO/DriveInfo.Unix.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using System.Runtime.InteropServices;
 using System.Security;
 
 namespace System.IO
@@ -26,8 +25,25 @@ public DriveType DriveType
             [SecuritySafeCritical]
             get
             {
-                Interop.libc.statfs data = Interop.libc.GetStatFsForDriveName(Name);
-                return GetDriveType(Interop.libc.GetMountPointFsType(data));
+                Interop.libc.statfs data;
+                int errno;
+                if (Interop.libc.TryGetStatFsForDriveName(Name, out data, out errno))
+                {
+                    return GetDriveType(Interop.libc.GetMountPointFsType(data));
+                }
+
+                // This is one of the few properties that doesn't throw on failure,
+                // instead returning a value from the enum.
+                switch (errno)
+                {
+                    case Interop.Errors.ELOOP:
+                    case Interop.Errors.ENAMETOOLONG:
+                    case Interop.Errors.ENOENT:
+                    case Interop.Errors.ENOTDIR:
+                        return DriveType.NoRootDirectory;
+                    default:
+                        return DriveType.Unknown;
+                }
             }
         }
 

src/System.IO.FileSystem.DriveInfo/tests/DriveInfo.Unix.Tests.cs

@@ -30,6 +30,13 @@ public void TestGetDrives()
             Assert.True(drives.Length > 0, "Expected at least one drive");
             Assert.All(drives, d => Assert.NotNull(d));
             Assert.Contains(drives, d => d.Name == "/");
+            Assert.All(drives, d =>
+            {
+                // None of these should throw
+                DriveType dt = d.DriveType;
+                bool isReady = d.IsReady;
+                DirectoryInfo di = d.RootDirectory;
+            });
         }
 
         [Fact]
@@ -38,9 +45,9 @@ public void TestInvalidDriveName()
         {
             var invalidDrive = new DriveInfo("NonExistentDriveName");
             Assert.Throws<DriveNotFoundException>(() => { var df = invalidDrive.DriveFormat; });
-            Assert.Throws<DriveNotFoundException>(() => { var size = invalidDrive.DriveType; });
             Assert.Throws<DriveNotFoundException>(() => { var size = invalidDrive.TotalFreeSpace; });
             Assert.Throws<DriveNotFoundException>(() => { var size = invalidDrive.TotalSize; });
+            Assert.Equal(DriveType.NoRootDirectory, invalidDrive.DriveType);
         }
 
         [Fact]