mirror of
https://github.com/jart/cosmopolitan.git
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76 lines
3 KiB
C
76 lines
3 KiB
C
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/*-*- 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/calls.h"
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#include "libc/errno.h"
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#include "libc/mem/mem.h"
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#define CHUNK 32768
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/**
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* Copies data between fds the old fashioned way.
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*
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* @return bytes successfully exchanged
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*/
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ssize_t _copyfd(int infd, int outfd, size_t n) {
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int e;
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char *buf;
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ssize_t rc;
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size_t i, j, got, sent;
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rc = 0;
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if (n) {
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if ((buf = malloc(CHUNK))) {
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for (e = errno, i = 0; i < n; i += j) {
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rc = read(infd, buf, CHUNK);
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if (rc == -1) {
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// eintr may interrupt the read operation
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if (i && errno == EINTR) {
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// suppress error if partially completed
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errno = e;
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rc = i;
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}
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break;
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}
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got = rc;
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if (!got) {
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rc = i;
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break;
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}
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// write operation must complete
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for (j = 0; j < got; j += sent) {
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rc = write(outfd, buf + j, got - j);
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if (rc != -1) {
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sent = rc;
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} else if (errno == EINTR) {
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// write operation must be uninterruptible
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errno = e;
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sent = 0;
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} else {
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break;
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}
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}
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if (rc == -1) break;
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}
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free(buf);
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} else {
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rc = -1;
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}
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}
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return rc;
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}
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