UserspaceEmulator: Add SC_rmdir syscall

Author: https://github.com/bcoles
Commit: https://github.com/SerenityOS/serenity/commit/1eccd78e3a8
Pull-request: https://github.com/SerenityOS/serenity/pull/5790

Userland/DevTools/UserspaceEmulator/Emulator.h

@@ -123,6 +123,7 @@ private:
     int virt$pipe(FlatPtr pipefd, int flags);
     int virt$close(int);
     int virt$mkdir(FlatPtr path, size_t path_length, mode_t mode);
+    int virt$rmdir(FlatPtr path, size_t path_length);
     int virt$unlink(FlatPtr path, size_t path_length);
     int virt$get_process_name(FlatPtr buffer, int size);
     int virt$set_process_name(FlatPtr buffer, int size);

Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp

@@ -134,6 +134,8 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
         return virt$fstat(arg1, arg2);
     case SC_mkdir:
         return virt$mkdir(arg1, arg2, arg3);
+    case SC_rmdir:
+        return virt$rmdir(arg1, arg2);
     case SC_unlink:
         return virt$unlink(arg1, arg2);
     case SC_write:
@@ -306,6 +308,12 @@ int Emulator::virt$mkdir(FlatPtr path, size_t path_length, mode_t mode)
     return syscall(SC_mkdir, buffer.data(), buffer.size(), mode);
 }
 
+int Emulator::virt$rmdir(FlatPtr path, size_t path_length)
+{
+    auto buffer = mmu().copy_buffer_from_vm(path, path_length);
+    return syscall(SC_rmdir, buffer.data(), buffer.size());
+}
+
 int Emulator::virt$unlink(FlatPtr path, size_t path_length)
 {
     auto buffer = mmu().copy_buffer_from_vm(path, path_length);