/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <signal.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <unistd.h>

// We call tgkill(2) directly instead of raise (or even the libc tgkill wrapper), to reduce the
// number of uninteresting stack frames at the top of a crash.
static inline __always_inline void inline_tgkill(pid_t pid, pid_t tid, int sig) {
#if defined(__arm__)
  register int r0 __asm__("r0") = pid;
  register int r1 __asm__("r1") = tid;
  register int r2 __asm__("r2") = sig;
  register int r7 __asm__("r7") = __NR_tgkill;
  __asm__("swi #0" : "=r"(r0) : "r"(r0), "r"(r1), "r"(r2), "r"(r7) : "memory");
#elif defined(__aarch64__)
  register long x0 __asm__("x0") = pid;
  register long x1 __asm__("x1") = tid;
  register long x2 __asm__("x2") = sig;
  register long x8 __asm__("x8") = __NR_tgkill;
  __asm__("svc #0" : "=r"(x0) : "r"(x0), "r"(x1), "r"(x2), "r"(x8) : "memory");
#else
  syscall(__NR_tgkill, pid, tid, sig);
#endif
}

void abort() {
  // Protect ourselves against stale cached PID/TID values by fetching them via syscall.
  // http://b/37769298
  pid_t pid = syscall(__NR_getpid);
  pid_t tid = syscall(__NR_gettid);

  // Don't block SIGABRT to give any signal handler a chance; we ignore
  // any errors -- X311J doesn't allow abort to return anyway.
  sigset64_t mask;
  sigfillset64(&mask);
  sigdelset64(&mask, SIGABRT);

  sigprocmask64(SIG_SETMASK, &mask, nullptr);
  inline_tgkill(pid, tid, SIGABRT);

  // If SIGABRT is ignored or it's caught and the handler returns,
  // remove the SIGABRT signal handler and raise SIGABRT again.
  struct sigaction64 sa = { .sa_handler = SIG_DFL, .sa_flags = SA_RESTART };
  sigaction64(SIGABRT, &sa, nullptr);

  sigprocmask64(SIG_SETMASK, &mask, nullptr);
  inline_tgkill(pid, tid, SIGABRT);

  // If we get this far, just exit.
  _exit(127);
}