UserspaceEmulator: Add the chdir syscall

DevTools/UserspaceEmulator/Emulator.cpp

@@ -251,6 +251,8 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
     dbgprintf("Syscall: %s (%x)\n", Syscall::to_string((Syscall::Function)function), function);
 #endif
     switch (function) {
+    case SC_chdir:
+        return virt$chdir(arg1, arg2);
     case SC_access:
         return virt$access(arg1, arg2, arg3);
     case SC_waitid:
@@ -1338,4 +1340,10 @@ int Emulator::virt$waitid(FlatPtr params_addr)
     return rc;
 }
 
+int Emulator::virt$chdir(FlatPtr path, size_t path_length)
+{
+    auto host_path = mmu().copy_buffer_from_vm(path, path_length);
+    return syscall(SC_chdir, host_path.data(), host_path.size());
+}
+
 }

DevTools/UserspaceEmulator/Emulator.h

@@ -137,6 +137,7 @@ private:
     void virt$exit(int);
     ssize_t virt$getrandom(FlatPtr buffer, size_t buffer_size, unsigned int flags);
     int virt$sleep(unsigned);
+    int virt$chdir(FlatPtr, size_t);
     int virt$getpgrp();
     int virt$getpgid(pid_t);
     int virt$setpgid(pid_t pid, pid_t pgid);