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# copy-file-range.m4
dnl Copyright 2019-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST])
dnl Persuade glibc <unistd.h> to declare copy_file_range.
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
dnl Use AC_LINK_IFELSE, rather than AC_CHECK_FUNCS or a variant,
dnl since we don't want AC_CHECK_FUNCS's checks for glibc stubs.
dnl Programs that use copy_file_range must fall back on read+write
dnl anyway, and there's little point to substituting the Gnulib stub
dnl for a glibc stub.
AC_CACHE_CHECK([for copy_file_range], [gl_cv_func_copy_file_range],
[AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
]],
[[ssize_t (*func) (int, off_t *, int, off_t *, size_t, unsigned)
= copy_file_range;
return func (0, 0, 0, 0, 0, 0) & 127;
]])
],
[gl_cv_func_copy_file_range=yes],
[gl_cv_func_copy_file_range=no])
])
if test "$gl_cv_func_copy_file_range" != yes; then
HAVE_COPY_FILE_RANGE=0
else
AC_DEFINE([HAVE_COPY_FILE_RANGE], 1,
[Define to 1 if the function copy_file_range exists.])
case $host_os in
linux*)
AC_CACHE_CHECK([whether copy_file_range is known to work],
[gl_cv_copy_file_range_known_to_work],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[#include <linux/version.h>
]],
[[#if LINUX_VERSION_CODE < KERNEL_VERSION (5, 3, 0)
#error "copy_file_range is buggy"
#endif
]])],
[gl_cv_copy_file_range_known_to_work=yes],
[gl_cv_copy_file_range_known_to_work=no])])
if test "$gl_cv_copy_file_range_known_to_work" = no; then
REPLACE_COPY_FILE_RANGE=1
fi;;
esac
fi
])
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