An aarch64 ptrace-based system call intercepter for the Raspberry Pi version of ADOM, allowing you to run it in Termux on Android without it getting SECCOMP killed by the kernel

syscall-intercept.c

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>

#include <asm-generic/unistd.h>

#include <sys/procfs.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/user.h>
#include <sys/wait.h>

#include <elf.h>

int main(int argc, char* argv[]){
  setenv("TERM", "xterm", 1);
  setenv("TERMINFO", "/data/data/com.termux/files/usr/share/terminfo", 1);

  pid_t pid = fork();

  if(pid == -1){
    fprintf(stderr, "Failed to fork: %s", strerror(errno));
    exit(1);
  } else if (pid == 0){
    ptrace(PTRACE_TRACEME, 0, 0, 0);
    execvp("/data/data/com.termux/files/home/compspace/adom/adom.bin", argv);
  }

  waitpid(pid, 0, 0);
  ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_EXITKILL);

  while(1){
    ptrace(PTRACE_SYSCALL, pid, 0, 0);
    if(waitpid(pid, 0, 0) < 1){
      exit(0);
    }

    struct user_regs_struct regs;
    struct iovec iovec;

    iovec.iov_base = &regs;
    iovec.iov_len = sizeof(regs);

    ptrace(PTRACE_GETREGSET, pid, NT_ARM_VFP, &iovec);

    int blocked = 0;

    if(regs.regs[0] == __NR_setuid){
      blocked = 1;
      regs.regs[0] = -1;
      ptrace(PTRACE_SETREGSET, pid, 0, &regs);
    }

    ptrace(PTRACE_SYSCALL, pid, 0, 0);
    waitpid(pid, 0, 0);

    if(blocked){
      regs.regs[0] = -EPERM;
      ptrace(PTRACE_SETREGSET, pid, 0, &regs);
    }
  }
}