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Patches/MemoryLinux.cs

@@ -0,0 +1,221 @@
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace WeaponPaints;
+
+public static class MemoryLinux
+{
+    // Based on https://github.com/Source2ZE/CS2Fixes/blob/main/src/utils/plat_unix.cpp
+    static int ParseProt(string s)
+    {
+        int prot = 0;
+
+        foreach (var c in s)
+        {
+            switch (c)
+            {
+                case '-':
+                    break;
+                case 'r':
+                    prot |= NativeMethods.PROT_READ;
+                    break;
+                case 'w':
+                    prot |= NativeMethods.PROT_WRITE;
+                    break;
+                case 'x':
+                    prot |= NativeMethods.PROT_EXEC;
+                    break;
+                case 's':
+                    break;
+                case 'p':
+                    break;
+                default:
+                    break;
+            }
+        }
+
+        return prot;
+    }
+
+    static int GetProt(IntPtr pAddr, uint nSize)
+    {
+        using (var f = File.OpenRead("/proc/self/maps"))
+        using (var reader = new StreamReader(f))
+        {
+            while (!reader.EndOfStream)
+            {
+                var line = reader.ReadLine();
+                if (line == null)
+                    continue;
+
+                var parts = line.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
+                if (parts.Length < 5)
+                    continue;
+
+                var range = parts[0];
+                var prot = parts[1];
+
+                var startEnd = range.Split('-');
+                if (startEnd.Length != 2)
+                    continue;
+
+                var start = Convert.ToUInt64(startEnd[0], 16);
+                var end = Convert.ToUInt64(startEnd[1], 16);
+
+                if (start < (ulong)pAddr && end > (ulong)pAddr + nSize)
+                {
+                    return ParseProt(prot);
+                }
+            }
+        }
+
+        return 0;
+    }
+
+    public static void PatchBytesAtAddress(IntPtr pPatchAddress, byte[] pPatch, int iPatchSize)
+    {
+        if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) return;
+        
+        var oldProt = GetProt(pPatchAddress, (uint)iPatchSize);
+
+        var pageSize = (ulong)NativeMethods.sysconf(NativeMethods._SC_PAGESIZE);
+        var alignAddr = (IntPtr)((long)pPatchAddress & ~(long)(pageSize - 1));
+
+        var end = (IntPtr)((long)pPatchAddress + iPatchSize);
+        var alignSize = (ulong)((long)end - (long)alignAddr);
+
+        var result = NativeMethods.mprotect(alignAddr, alignSize, NativeMethods.PROT_READ | NativeMethods.PROT_WRITE);
+
+        Marshal.Copy(pPatch, 0, pPatchAddress, iPatchSize);
+
+        result = NativeMethods.mprotect(alignAddr, alignSize, oldProt);
+    }
+    
+    private static byte[]? ReadProcessMemory(int pid, long address, int size)
+    {
+        if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) return null;
+        
+        byte[] buffer = new byte[size];
+
+        NativeMethods.Iovec local = new NativeMethods.Iovec
+        {
+            iov_base = Marshal.UnsafeAddrOfPinnedArrayElement(buffer, 0),
+            iov_len = new IntPtr(size)
+        };
+
+        NativeMethods.Iovec remote = new NativeMethods.Iovec
+        {
+            iov_base = new IntPtr(address),
+            iov_len = new IntPtr(size)
+        };
+
+        long bytesRead = NativeMethods.process_vm_readv(pid, new NativeMethods.Iovec[] { local }, 1, new NativeMethods.Iovec[] { remote }, 1, 0);
+        if (bytesRead == -1)
+        {
+            throw new Exception($"process_vm_readv failed with error {Marshal.GetLastPInvokeError()}");
+        }
+
+        return buffer;
+    }
+    
+    public static byte[]? ReadMemory(IntPtr address, int size)
+    {
+        if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) return null;
+        
+        return ReadProcessMemory(Process.GetCurrentProcess().Id, (long)address, size);
+    }
+
+    #pragma warning disable CS0649 // Field is never assigned to, and will always have its default value
+    #pragma warning disable CS8981 // The type name only contains lower-cased ascii characters. Such names may become reserved for the language.
+    static class NativeMethods
+    {
+        public const int O_RDONLY = 0;
+        public const int PROT_READ = 0x1;
+        public const int PROT_WRITE = 0x2;
+        public const int PROT_EXEC = 0x4;
+        public const int MAP_PRIVATE = 0x2;
+        public const int PT_LOAD = 1;
+        public const int PF_X = 0x1;
+        public const int _SC_PAGESIZE = 30;
+        public const int RTLD_DI_LINKMAP = 2;
+
+        [DllImport("libc")]
+        public static extern int dlinfo(IntPtr handle, int request, out link_map lmap);
+
+        [DllImport("libc")]
+        public static extern int dlclose(IntPtr handle);
+
+        [DllImport("libc")]
+        public static extern int open(string pathname, int flags);
+
+        [DllImport("libc")]
+        public static extern int fstat(int fd, out stat buf);
+
+        [DllImport("libc")]
+        public static extern IntPtr mmap(IntPtr addr, ulong length, int prot, int flags, int fd, ulong offset);
+
+        [DllImport("libc")]
+        public static extern int munmap(IntPtr addr, ulong length);
+
+        [DllImport("libc")]
+        public static extern int mprotect(IntPtr addr, ulong len, int prot);
+
+        [DllImport("libc")]
+        public static extern long sysconf(int name);
+
+        [DllImport("libc")]
+        public static extern long process_vm_readv(int pid, Iovec[] local_iov, ulong liovcnt, Iovec[] remote_iov, ulong riovcnt, ulong flags);
+
+        [StructLayout(LayoutKind.Sequential)]
+        public struct Iovec
+        {
+            public IntPtr iov_base;
+            public IntPtr iov_len;
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        public struct link_map
+        {
+            public IntPtr l_addr;
+            public IntPtr l_name;
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        public struct ElfW
+        {
+            public struct Ehdr
+            {
+                public byte e_shnum;
+                public uint e_shoff;
+                public ushort e_phnum;
+                public uint e_phoff;
+            }
+
+            public struct Phdr
+            {
+                public int p_type;
+                public int p_flags;
+
+                public ulong p_vaddr;
+                public ulong p_filesz;
+            }
+
+            public struct Shdr
+            {
+                public uint sh_name;
+                public uint sh_offset;
+                public uint sh_size;
+                public ulong sh_addr;
+            }
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+
+        public struct stat
+        {
+            public ulong st_size;
+        }
+    }
+    #pragma warning restore CS8981 // The type name only contains lower-cased ascii characters. Such names may become reserved for the language.
+    #pragma warning restore CS0649 // Field is never assigned to, and will always have its default value
+}