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Ryujinx/Ryujinx.Memory/MemoryManagementUnix.cs

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using Mono.Unix.Native;
using System;
using System.Collections.Concurrent;
namespace Ryujinx.Memory
{
static class MemoryManagementUnix
{
private static readonly ConcurrentDictionary<IntPtr, ulong> _allocations = new ConcurrentDictionary<IntPtr, ulong>();
public static IntPtr Allocate(ulong size)
{
return AllocateInternal(size, MmapProts.PROT_READ | MmapProts.PROT_WRITE);
}
public static IntPtr Reserve(ulong size)
{
return AllocateInternal(size, MmapProts.PROT_NONE);
}
private static IntPtr AllocateInternal(ulong size, MmapProts prot)
{
const MmapFlags flags = MmapFlags.MAP_PRIVATE | MmapFlags.MAP_ANONYMOUS;
IntPtr ptr = Syscall.mmap(IntPtr.Zero, size, prot, flags, -1, 0);
if (ptr == new IntPtr(-1L))
{
throw new OutOfMemoryException();
}
if (!_allocations.TryAdd(ptr, size))
{
// This should be impossible, kernel shouldn't return an already mapped address.
throw new InvalidOperationException();
}
return ptr;
}
public static bool Commit(IntPtr address, ulong size)
{
return Syscall.mprotect(address, size, MmapProts.PROT_READ | MmapProts.PROT_WRITE) == 0;
}
public static bool Reprotect(IntPtr address, ulong size, MemoryPermission permission)
{
return Syscall.mprotect(address, size, GetProtection(permission)) == 0;
}
private static MmapProts GetProtection(MemoryPermission permission)
{
return permission switch
{
MemoryPermission.None => MmapProts.PROT_NONE,
MemoryPermission.Read => MmapProts.PROT_READ,
MemoryPermission.ReadAndWrite => MmapProts.PROT_READ | MmapProts.PROT_WRITE,
MemoryPermission.ReadAndExecute => MmapProts.PROT_READ | MmapProts.PROT_EXEC,
MemoryPermission.ReadWriteExecute => MmapProts.PROT_READ | MmapProts.PROT_WRITE | MmapProts.PROT_EXEC,
MemoryPermission.Execute => MmapProts.PROT_EXEC,
_ => throw new MemoryProtectionException(permission)
};
}
public static bool Free(IntPtr address)
{
if (_allocations.TryRemove(address, out ulong size))
{
return Syscall.munmap(address, size) == 0;
}
return false;
}
}
}