Use libc directly instead of Mono.Posix

DepotDownloader/ContentDownloader.cs

@@ -4,10 +4,10 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Net;
+using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
 using SteamKit2;
-using Mono.Unix;
 
 namespace DepotDownloader
 {
@@ -1185,27 +1185,17 @@ namespace DepotDownloader
 
             if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
             {
-                const FileAccessPermissions execute = FileAccessPermissions.UserExecute | FileAccessPermissions.GroupExecute | FileAccessPermissions.OtherExecute;
-
-                var unixFile = UnixFileSystemInfo.GetFileSystemEntry(fileFinalPath);
-
                 if (file.Flags.HasFlag(EDepotFileFlag.Executable) && (oldManifestFile == null || !oldManifestFile.Flags.HasFlag(EDepotFileFlag.Executable)))
                 {
-                    if (!unixFile.FileAccessPermissions.HasFlag(execute))
-                    {
-                        unixFile.FileAccessPermissions |= execute;
-                    }
+                    UnixUtilities.SetExecute(fileFinalPath, true);
                 }
                 else if (oldManifestFile != null && oldManifestFile.Flags.HasFlag(EDepotFileFlag.Executable))
                 {
-                    if (unixFile.FileAccessPermissions.HasFlag(execute))
-                    {
-                        unixFile.FileAccessPermissions &= ~execute;
-                    }
+                    UnixUtilities.SetExecute(fileFinalPath, false);
                 }
             }
 
-            FileStreamData fileStreamData = new FileStreamData
+            var fileStreamData = new FileStreamData
             {
                 fileStream = fs,
                 fileLock = new SemaphoreSlim(1),

DepotDownloader/DepotDownloader.csproj

@@ -13,6 +13,5 @@
   <ItemGroup>
     <PackageReference Include="protobuf-net" Version="3.0.101" />
     <PackageReference Include="SteamKit2" Version="2.4.0-Alpha.2" />
-    <PackageReference Include="Mono.Posix.NETStandard" Version="1.0.0" />
   </ItemGroup>
 </Project>

DepotDownloader/UnixUtilities.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace DepotDownloader
+{
+    public static class UnixUtilities
+    {
+        [Flags]
+        private enum FilePermissions : uint
+        {
+            S_ISUID = 0x0800, // Set user ID on execution
+            S_ISGID = 0x0400, // Set group ID on execution
+            S_ISVTX = 0x0200, // Save swapped text after use (sticky).
+            S_IRUSR = 0x0100, // Read by owner
+            S_IWUSR = 0x0080, // Write by owner
+            S_IXUSR = 0x0040, // Execute by owner
+            S_IRGRP = 0x0020, // Read by group
+            S_IWGRP = 0x0010, // Write by group
+            S_IXGRP = 0x0008, // Execute by group
+            S_IROTH = 0x0004, // Read by other
+            S_IWOTH = 0x0002, // Write by other
+            S_IXOTH = 0x0001, // Execute by other
+
+            S_IRWXU = S_IRUSR | S_IWUSR | S_IXUSR,
+            S_IRWXG = S_IRGRP | S_IWGRP | S_IXGRP,
+            S_IRWXO = S_IROTH | S_IWOTH | S_IXOTH,
+            ACCESSPERMS = S_IRWXU | S_IRWXG | S_IRWXO, // 0777
+            ALLPERMS = S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO, // 07777
+            DEFFILEMODE = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH, // 0666
+            EXECUTE = S_IXGRP | S_IXUSR | S_IXOTH,
+
+            // Device types
+            S_IFMT = 0xF000, // Bits which determine file type
+            S_IFDIR = 0x4000, // Directory
+            S_IFCHR = 0x2000, // Character device
+            S_IFBLK = 0x6000, // Block device
+            S_IFREG = 0x8000, // Regular file
+            S_IFIFO = 0x1000, // FIFO
+            S_IFLNK = 0xA000, // Symbolic link
+            S_IFSOCK = 0xC000, // Socket
+        }
+
+        [StructLayout(LayoutKind.Explicit, Size = 144)]
+        private readonly struct Stat
+        {
+            [FieldOffset(sizeof(ulong) * 3)]
+            public readonly FilePermissions st_mode;
+        }
+
+        [DllImport("libc", SetLastError = true)]
+        private static extern int stat(string path, out Stat stat);
+
+        [DllImport("libc", SetLastError = true)]
+        private static extern int chmod(string path, FilePermissions mode);
+
+        [DllImport("libc", CallingConvention = CallingConvention.Cdecl, SetLastError = true)]
+        private static extern IntPtr strerror(int errno);
+
+        private static void ThrowIf(int i)
+        {
+            if (i == -1)
+            {
+                var errno = Marshal.GetLastWin32Error();
+                throw new Exception(Marshal.PtrToStringAnsi(strerror(errno)));
+            }
+        }
+
+        public static void SetExecute(string path, bool value)
+        {
+            ThrowIf(UnixUtilities.stat(path, out var stat));
+
+            if (stat.st_mode.HasFlag(FilePermissions.EXECUTE) != value)
+            {
+                ThrowIf(chmod(path, value
+                    ? stat.st_mode | FilePermissions.EXECUTE
+                    : stat.st_mode & ~FilePermissions.EXECUTE));
+            }
+        }
+    }
+}