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55 lines
2.8 KiB
C
55 lines
2.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/runtime/internal.h"
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/**
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* Returns process id.
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*
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* This function does not need to issue a system call. The PID is
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* tracked by a global variable which is updated at fork(). The only
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* exception is when the process is vfork()'d in which case a system
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* call shall be issued. This optimization helps make functions like
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* _rand64() fork-safe, however it could lead to race conditions in
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* programs that mix fork() with threads. In that case, apps should
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* consider using `sys_getpid().ax` instead to force a system call.
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*
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* On Linux, and only Linux, getpid() is guaranteed to equal gettid()
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* for the main thread.
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*
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* @return process id (always successful)
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* @asyncsignalsafe
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* @threadsafe
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* @vforksafe
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*/
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dontasan int getpid(void) {
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int rc;
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if (IsMetal()) {
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rc = 1;
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} else if (!__vforked) {
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rc = __pid;
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} else {
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rc = sys_getpid().ax;
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}
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return rc;
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}
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