/blog/ekd123

这个是glibc的实现：

/** Copyright (C) 1991,93,95,96,97,98,2001,02 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <bits/libc-lock.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/** Try to get a machine dependent instruction which will make the
   program crash.  This is used in case everything else fails.  */
#include <abort-instr.h>
#ifndef ABORT_INSTRUCTION
/** No such instruction is available.  */
# define ABORT_INSTRUCTION
#endif

#ifdef USE_IN_LIBIO
# include <libio/libioP.h>
# define fflush(s) _IO_flush_all_lockp (0)
#endif

/** We must avoid to run in circles.  Therefore we remember how far we
   already got.  */
static int stage;

/** We should be prepared for multiple threads trying to run abort.  */
__libc_lock_define_initialized_recursive (static, lock);


/** Cause an abnormal program termination with core-dump.  */
void
abort (void)
{
  struct sigaction act;
  sigset_t sigs;

  /** First acquire the lock.  */
  __libc_lock_lock_recursive (lock);

  /** Now it's for sure we are alone.  But recursive calls are possible.  */

  /** Unlock SIGABRT.  */
  if (stage == 0)
    {
      ++stage;
      if (__sigemptyset (&sigs) == 0 &&
	  __sigaddset (&sigs, SIGABRT) == 0)
	__sigprocmask (SIG_UNBLOCK, &sigs, (sigset_t *) NULL);
    }

  /** Flush all streams.  We cannot close them now because the user
     might have registered a handler for SIGABRT.  */
  if (stage == 1)
    {
      ++stage;
      fflush (NULL);
    }

  /** Send signal which possibly calls a user handler.  */
  if (stage == 2)
    {
      /** This stage is special: we must allow repeated calls of
	 `abort' when a user defined handler for SIGABRT is installed.
	 This is risky since the `raise' implementation might also
	 fail but I don't see another possibility.  */
      int save_stage = stage;

      stage = 0;
      __libc_lock_unlock_recursive (lock);

      raise (SIGABRT);

      __libc_lock_lock_recursive (lock);
      stage = save_stage + 1;
    }

  /** There was a handler installed.  Now remove it.  */
  if (stage == 3)
    {
      ++stage;
      memset (&act, '\0', sizeof (struct sigaction));
      act.sa_handler = SIG_DFL;
      __sigfillset (&act.sa_mask);
      act.sa_flags = 0;
      __sigaction (SIGABRT, &act, NULL);
    }

  /** Now close the streams which also flushes the output the user
     defined handler might has produced.  */
  if (stage == 4)
    {
      ++stage;
      __fcloseall ();
    }

  /** Try again.  */
  if (stage == 5)
    {
      ++stage;
      raise (SIGABRT);
    }

  /** Now try to abort using the system specific command.  */
  if (stage == 6)
    {
      ++stage;
      ABORT_INSTRUCTION;
    }

  /** If we can't signal ourselves and the abort instruction failed, exit.  */
  if (stage == 7)
    {
      ++stage;
      _exit (127);
    }

  /** If even this fails try to use the provided instruction to crash
     or otherwise make sure we never return.  */
  while (1)
    /** Try for ever and ever.  */
    ABORT_INSTRUCTION;
}
libc_hidden_def (abort)

我实在想用“又臭又长”来形容……哪个人看得懂，估计可以去维护Linux内核代码了。

也许。。。你觉得这是玩笑，可他是真的，这是来自Plan 9的abort实现：

#include <u.h>
#include <libc.h>
void
abort(void)
{
	while(*(int*)0)
		;
}

哈哈，简洁啊，巧妙啊！我觉得直接 *(int*)0 一下也可以，不过加个while或许能提升干掉的成功率。

唉，没办法，智商不够，还看不懂Linux的代码（glibc都这样了，何况linux内核？），只能去Plan 9看看啦！