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https://github.com/morgan9e/systemd
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27 lines
1.3 KiB
C
27 lines
1.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <sys/types.h>
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#include "macro.h"
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#include "rm-rf.h"
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/* These functions implement various potentially slow operations that are executed asynchronously. They are
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* carefully written to not use pthreads, but use fork() or clone() (without CLONE_VM) so that the child does
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* not share any memory with the parent process, and thus cannot possibly interfere with the malloc()
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* synchronization locks.
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*
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* Background: glibc only synchronizes malloc() locks when doing fork(), but not when doing clone()
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* (regardless if through glibc's own wrapper or ours). This means if another thread in the parent has the
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* malloc() lock taken while a thread is cloning, the mutex will remain locked in the child (but the other
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* thread won't exist there), with no chance to ever be unlocked again. This will result in deadlocks. Hence
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* one has to make the choice: either never use threads in the parent, or never do memory allocation in the
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* child, or never use clone()/clone3() and stick to fork() only. Because we need clone()/clone3() we opted
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* for avoiding threads. */
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int asynchronous_sync(pid_t *ret_pid);
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int asynchronous_close(int fd);
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int asynchronous_rm_rf(const char *p, RemoveFlags flags);
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DEFINE_TRIVIAL_CLEANUP_FUNC(int, asynchronous_close);
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