Fixed: Replaced mono symlink resolve logic to better handle errors.

src/NzbDrone.Common/Disk/DiskProviderBase.cs

@@ -383,12 +383,20 @@ namespace NzbDrone.Common.Disk
 
         public virtual IMount GetMount(string path)
         {
-            var mounts = GetMounts();
+            try
+            {
+                var mounts = GetMounts();
 
-            return mounts.Where(drive => drive.RootDirectory.PathEquals(path) ||
-                                         drive.RootDirectory.IsParentPath(path))
-                      .OrderByDescending(drive => drive.RootDirectory.Length)
-                      .FirstOrDefault();
+                return mounts.Where(drive => drive.RootDirectory.PathEquals(path) ||
+                                             drive.RootDirectory.IsParentPath(path))
+                          .OrderByDescending(drive => drive.RootDirectory.Length)
+                          .FirstOrDefault();
+            }
+            catch (Exception ex)
+            {
+                Logger.DebugException(string.Format("Failed to get mount for path {0}", path), ex);
+                return null;
+            }
         }
 
         protected List<IMount> GetDriveInfoMounts()

src/NzbDrone.Mono/DiskProvider.cs

@@ -16,10 +16,19 @@ namespace NzbDrone.Mono
         private static readonly Logger Logger = NzbDroneLogger.GetLogger(typeof(DiskProvider));
 
         private readonly IProcMountProvider _procMountProvider;
+        private readonly ISymbolicLinkResolver _symLinkResolver;
 
-        public DiskProvider(IProcMountProvider procMountProvider)
+        public DiskProvider(IProcMountProvider procMountProvider, ISymbolicLinkResolver symLinkResolver)
         {
             _procMountProvider = procMountProvider;
+            _symLinkResolver = symLinkResolver;
+        }
+
+        public override IMount GetMount(string path)
+        {
+            path = _symLinkResolver.GetCompleteRealPath(path);
+
+            return base.GetMount(path);
         }
 
         public override long? GetAvailableSpace(string path)

src/NzbDrone.Mono/NzbDrone.Mono.csproj

@@ -74,6 +74,7 @@
     <Compile Include="ProcMount.cs" />
     <Compile Include="ProcMountProvider.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="SymbolicLinkResolver.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\NzbDrone.Common\NzbDrone.Common.csproj">

src/NzbDrone.Mono/ProcMountProvider.cs

@@ -2,11 +2,9 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Text;
 using NLog;
 using NzbDrone.Common.Disk;
 using NzbDrone.Common.Extensions;
-using Mono.Unix;
 
 namespace NzbDrone.Mono
 {

src/NzbDrone.Mono/SymbolicLinkResolver.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Text;
+using Mono.Unix;
+using Mono.Unix.Native;
+using NLog;
+
+namespace NzbDrone.Mono
+{
+    public interface ISymbolicLinkResolver
+    {
+        string GetCompleteRealPath(string path);
+    }
+
+    // Mono's own implementation doesn't handle exceptions very well.
+    // All of this code was copied from mono with minor changes.
+    public class SymbolicLinkResolver : ISymbolicLinkResolver
+    {
+        private readonly Logger _logger;
+
+        public SymbolicLinkResolver(Logger logger)
+        {
+            _logger = logger;
+        }
+
+        public string GetCompleteRealPath(string path)
+        {
+            if (path == null) return null;
+
+            try
+            {
+                string[] dirs;
+                int lastIndex;
+                GetPathComponents(path, out dirs, out lastIndex);
+
+                var realPath = new StringBuilder();
+                if (dirs.Length > 0)
+                {
+                    var dir = UnixPath.IsPathRooted(path) ? "/" : "";
+                    dir += dirs[0];
+                    realPath.Append(GetRealPath(dir));
+                }
+                for (var i = 1; i < lastIndex; ++i)
+                {
+                    realPath.Append("/").Append(dirs[i]);
+                    var realSubPath = GetRealPath(realPath.ToString());
+                    realPath.Remove(0, realPath.Length);
+                    realPath.Append(realSubPath);
+                }
+                return realPath.ToString();
+            }
+            catch (Exception ex)
+            {
+                _logger.DebugException(string.Format("Failed to check for symlinks in the path {0}", path), ex);
+                return path;
+            }
+        }
+
+
+        private static void GetPathComponents(string path, out string[] components, out int lastIndex)
+        {
+            var dirs = path.Split(UnixPath.DirectorySeparatorChar);
+            var target = 0;
+            for (var i = 0; i < dirs.Length; ++i)
+            {
+                if (dirs[i] == "." || dirs[i] == string.Empty)
+                {
+                    continue;
+                }
+
+                if (dirs[i] == "..")
+                {
+                    if (target != 0)
+                    {
+                        target--;
+                    }
+                    else
+                    {
+                        target++;
+                    }
+                }
+                else
+                {
+                    dirs[target++] = dirs[i];
+                }
+            }
+            components = dirs;
+            lastIndex = target;
+        }
+
+        public string GetRealPath(string path)
+        {
+            do
+            {
+                var link = UnixPath.TryReadLink(path);
+
+                if (link == null)
+                {
+                    var errno = Stdlib.GetLastError();
+                    if (errno != Errno.EINVAL)
+                    {
+                        _logger.Trace("Checking path {0} for symlink returned error {1}, assuming it's not a symlink.", path, errno);
+                    }
+
+                    return path;
+                }
+
+                if (UnixPath.IsPathRooted(link))
+                {
+                    path = link;
+                }
+                else
+                {
+                    path = UnixPath.GetDirectoryName(path) + UnixPath.DirectorySeparatorChar + link;
+                    path = UnixPath.GetCanonicalPath(path);
+                }
+            } while (true);
+        } 
+
+    }
+}