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https://github.com/jart/cosmopolitan.git
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ccbae7799e
This change also found a few POSIX compliance bugs with errnos. Another bug was discovered where, on Windows, pread() and pwrite() could modify the file position in cases where ReadFile() returned an error e.g. when seeking past the end of file. We also have more tests!
54 lines
2.8 KiB
C
54 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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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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