74 lines
3.5 KiB
C
74 lines
3.5 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/bits/bits.h"
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#include "libc/bits/safemacros.internal.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/errno.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Copies data between file descriptors the slow way.
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*
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* @return -1 on error/interrupt, 0 on eof, or [1..uptobytes] on success
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* @see copy_file_range() for file ↔ file
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* @see sendfile() for seekable → socket
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* @see splice() for fd ↔ pipe
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*/
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ssize_t copyfd(int infd, int64_t *inopt_out_inoffset, int to_fd,
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int64_t *inopt_out_outoffset, size_t uptobytes, uint32_t flags) {
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size_t i;
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int64_t offset;
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ssize_t got, wrote;
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static unsigned char buf[1024 * 64];
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/* unsigned char buf[1024 * 3]; */
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uptobytes = min(sizeof(buf), uptobytes);
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if (inopt_out_inoffset) {
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got = pread(infd, buf, uptobytes, *inopt_out_inoffset);
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} else {
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got = read(infd, buf, uptobytes);
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}
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if (got == -1) return -1;
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offset = inopt_out_outoffset ? *inopt_out_outoffset : -1;
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for (i = 0; i < got; i += wrote) {
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tryagain:
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if (inopt_out_outoffset) {
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wrote = pwrite(to_fd, buf, got - i, offset + i);
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} else {
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wrote = write(to_fd, buf, got - i);
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}
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if (wrote != -1) continue;
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if (errno == EINTR) {
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if (inopt_out_inoffset != NULL) {
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return -1;
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}
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goto tryagain;
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}
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if (errno == EWOULDBLOCK) {
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assert(inopt_out_inoffset != NULL); /* or caller is nuts */
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}
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return -1;
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}
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if (inopt_out_inoffset) *inopt_out_inoffset += got;
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if (inopt_out_outoffset) *inopt_out_outoffset += got;
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return got;
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}
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