这个是glibc的实现：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | /** 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. */voidabort (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：
1 2 3 4 5 6 7 8 | #include <u.h>#include <libc.h>voidabort(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！
评论 ()
