/* Copyright 2012 The ChromiumOS Authors

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#include <signal.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "signal_handler.h"

#include "util.h"

/*

 * si_syscall was added in glibc-2.17+, but Android still uses glibc-2.15

 * for its prebuilt binary host toolchains.  Add a compat hack for it.

 */

static int get_si_syscall(const siginfo_t *info)

{

#if defined(si_syscall)

  return info->si_syscall;

#else

  typedef struct {

    void *ip;

    int nr;

    unsigned int arch;

  } local_siginfo_t;

  union {

    const siginfo_t *info;

    const local_siginfo_t *local_info;

  } local_info = {

      .info = info,

  };

  return local_info.local_info->nr;

#endif

}

void log_sigsys_handler(int sig attribute_unused, siginfo_t *info,

      void *void_context attribute_unused)

{

  const char *syscall_name;

  int nr = get_si_syscall(info);

  syscall_name = lookup_syscall_name(nr);

  if (syscall_name)

    die("blocked syscall: %s", syscall_name);

  else

    die("blocked syscall: %d", nr);

  /*

   * We trapped on a syscall that should have killed the process.

   * This should never ever return, but we're paranoid.

   */

  for (;;)

    _exit(1);

}

int install_sigsys_handler()

{

  int ret = 0;

  struct sigaction act;

  sigset_t mask;

  memset(&act, 0, sizeof(act));

  act.sa_sigaction = &log_sigsys_handler;

  act.sa_flags = SA_SIGINFO;

  sigemptyset(&mask);

  sigaddset(&mask, SIGSYS);

  ret = sigaction(SIGSYS, &act, NULL);

  if (ret < 0)

    return ret;

  ret = sigprocmask(SIG_UNBLOCK, &mask, NULL);

  if (ret < 0)

    return ret;

  return 0;

}