68 lines
2.2 KiB
C
68 lines
2.2 KiB
C
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/* Stub for copy_file_range
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Copyright 2019-2022 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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#if defined __linux__ && HAVE_COPY_FILE_RANGE
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# include <sys/utsname.h>
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#endif
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ssize_t
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copy_file_range (int infd, off_t *pinoff,
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int outfd, off_t *poutoff,
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size_t length, unsigned int flags)
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{
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#undef copy_file_range
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#if defined __linux__ && HAVE_COPY_FILE_RANGE
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/* The implementation of copy_file_range (which first appeared in
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Linux kernel release 4.5) had many issues before release 5.3
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<https://lwn.net/Articles/789527/>, so fail with ENOSYS for Linux
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kernels 5.2 and earlier.
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This workaround, and the configure-time check for Linux, can be
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removed when such kernels (released March 2016 through September
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2019) are no longer a consideration. As of January 2021, the
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furthest-future planned kernel EOL is December 2024 for kernel
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release 4.19. */
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static signed char ok;
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if (! ok)
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{
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struct utsname name;
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uname (&name);
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char *p = name.release;
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ok = ((p[1] != '.' || '5' < p[0]
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|| (p[0] == '5' && (p[3] != '.' || '2' < p[2])))
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? 1 : -1);
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}
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if (0 < ok)
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return copy_file_range (infd, pinoff, outfd, poutoff, length, flags);
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#endif
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/* There is little need to emulate copy_file_range with read+write,
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since programs that use copy_file_range must fall back on
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read+write anyway. */
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errno = ENOSYS;
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return -1;
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}
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