78 lines
2.4 KiB
Text
78 lines
2.4 KiB
Text
# lseek.m4 serial 12
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dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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AC_DEFUN([gl_FUNC_LSEEK],
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[
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AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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AC_REQUIRE([AC_CANONICAL_HOST])
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AC_REQUIRE([AC_PROG_CC])
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AC_CHECK_HEADERS_ONCE([unistd.h])
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AC_CACHE_CHECK([whether lseek detects pipes], [gl_cv_func_lseek_pipe],
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[case "$host_os" in
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mingw*)
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dnl Native Windows.
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dnl The result of lseek (fd, (off_t)0, SEEK_CUR) or
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dnl SetFilePointer(handle, 0, NULL, FILE_CURRENT)
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dnl for a pipe depends on the environment: In a Cygwin 1.5
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dnl environment it succeeds (wrong); in a Cygwin 1.7 environment
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dnl it fails with a wrong errno value.
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gl_cv_func_lseek_pipe=no
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;;
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*)
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if test $cross_compiling = no; then
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AC_LINK_IFELSE([AC_LANG_PROGRAM([[
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#include <sys/types.h> /* for off_t */
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#include <stdio.h> /* for SEEK_CUR */
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#else /* on Windows with MSVC */
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# include <io.h>
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#endif
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]GL_MDA_DEFINES],
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[[
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/* Exit with success only if stdin is seekable. */
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return lseek (0, (off_t)0, SEEK_CUR) < 0;
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]])],
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[if test -s conftest$ac_exeext \
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&& ./conftest$ac_exeext < conftest.$ac_ext \
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&& test 1 = "`echo hi \
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| { ./conftest$ac_exeext; echo $?; cat >/dev/null; }`"; then
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gl_cv_func_lseek_pipe=yes
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else
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gl_cv_func_lseek_pipe=no
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fi
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],
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[gl_cv_func_lseek_pipe=no])
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else
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AC_COMPILE_IFELSE(
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[AC_LANG_SOURCE([[
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#if defined __BEOS__
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/* BeOS mistakenly return 0 when trying to seek on pipes. */
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Choke me.
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#endif]])],
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[gl_cv_func_lseek_pipe=yes], [gl_cv_func_lseek_pipe=no])
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fi
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;;
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esac
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])
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if test "$gl_cv_func_lseek_pipe" = no; then
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REPLACE_LSEEK=1
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AC_DEFINE([LSEEK_PIPE_BROKEN], [1],
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[Define to 1 if lseek does not detect pipes.])
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fi
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AC_REQUIRE([gl_SYS_TYPES_H])
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if test $WINDOWS_64_BIT_OFF_T = 1; then
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REPLACE_LSEEK=1
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fi
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dnl macOS SEEK_DATA is incompatible with other platforms.
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case $host_os in
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darwin*)
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REPLACE_LSEEK=1;;
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esac
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])
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