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df6b9cdb0c
It's a bad idea to have a global event loop in a client application as that will cause an initialization-order fiasco in ASAN. Therefore, LibC now has a flag "s_global_initializers_ran" which is false until _entry in crt0 runs, which in turn only gets called after all the global initializers were actually executed. The EventLoop constructor checks the flag and crashes the program if it is being called as a global constructor. A note next to the VERIFY_NOT_REACHED() informs the developer of these things and how we usually instantiate event loops. The upshot of this is that global event loops will cause a crash before any undefined behavior is hit.
62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Types.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/internals.h>
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#include <unistd.h>
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#ifndef _DYNAMIC_LOADER
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extern "C" {
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extern size_t __stack_chk_guard;
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extern bool s_global_initializers_ran;
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int main(int, char**, char**);
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// Tell the compiler that this may be called from somewhere else.
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int _entry(int argc, char** argv, char** env) __attribute__((used));
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void _start(int, char**, char**) __attribute__((used));
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NAKED void _start(int, char**, char**)
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{
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asm(
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"push $0\n"
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"jmp _entry@plt\n");
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}
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int _entry(int argc, char** argv, char** env)
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{
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size_t original_stack_chk = __stack_chk_guard;
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arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard));
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if (__stack_chk_guard == 0)
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__stack_chk_guard = original_stack_chk;
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environ = env;
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__environ_is_malloced = false;
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__begin_atexit_locking();
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s_global_initializers_ran = true;
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_init();
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int status = main(argc, argv, environ);
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exit(status);
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// We should never get here, but if we ever do, make sure to
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// restore the stack guard to the value we entered _start with.
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// Then we won't trigger the stack canary check on the way out.
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__stack_chk_guard = original_stack_chk;
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return 20150614;
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}
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}
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#endif
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