mirror of
https://github.com/jart/cosmopolitan.git
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c995838e5c
- Clean up sigaction() code - Add a port scanner example - Introduce a ParseCidr() API - Clean up our futex abstraction code - Fix a harmless integer overflow in ParseIp() - Use kernel semaphores on NetBSD to make threads much faster
56 lines
2.9 KiB
C
56 lines
2.9 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 2022 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/struct/timeval.h"
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#include "libc/limits.h"
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/**
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* Reduces `ts` from 1e-6 to 1e-3 granularity w/ ceil rounding.
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*
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* This function returns the absolute number of milliseconds in a
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* timeval. Ceiling rounding is used. For example, if `ts` is one
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* nanosecond, then one millisecond will be returned. Ceil rounding is
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* needed by many interfaces, e.g. setitimer(), because the zero
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* timestamp has a valial meaning.
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*
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* This function also detects overflow in which case `INT64_MAX` or
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* `INT64_MIN` may be returned. The `errno` variable isn't changed.
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*
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* @return 64-bit scalar milliseconds since epoch
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*/
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int64_t timeval_tomillis(struct timeval ts) {
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int64_t ms;
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// reduce precision from micros to millis
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if (ts.tv_usec <= 999000) {
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ts.tv_usec = (ts.tv_usec + 999) / 1000;
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} else {
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ts.tv_usec = 0;
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if (ts.tv_sec < INT64_MAX) {
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ts.tv_sec += 1;
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}
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}
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// convert to scalar result
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if (!__builtin_mul_overflow(ts.tv_sec, 1000ul, &ms) &&
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!__builtin_add_overflow(ms, ts.tv_usec, &ms)) {
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return ms;
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} else if (ts.tv_sec < 0) {
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return INT64_MIN;
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} else {
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return INT64_MAX;
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}
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}
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