102 lines
3.6 KiB
Text
102 lines
3.6 KiB
Text
# lseek.m4
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# serial 15
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dnl Copyright (C) 2007, 2009-2024 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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dnl This file is offered as-is, without any warranty.
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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* | windows*)
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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:
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dnl In a Cygwin 1.5 environment it succeeds (wrong);
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dnl in a Cygwin 1.7 environment it fails with a wrong errno value;
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dnl in a Cygwin 2.9.0 environment it fails correctly;
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dnl in a Cygwin 3.4.6 environment it succeeds again (wrong).
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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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AS_IF([test $REPLACE_LSEEK = 0],
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[AC_CACHE_CHECK([whether SEEK_DATA works but is incompatible with GNU],
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[gl_cv_func_lseek_works_but_incompatible],
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[AC_PREPROC_IFELSE(
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[AC_LANG_SOURCE(
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dnl Use macOS "9999" to stand for a future fixed macOS version.
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dnl See ../lib/unistd.in.h and <https://bugs.gnu.org/61386>.
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[[#include <unistd.h>
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#if defined __APPLE__ && defined __MACH__ && defined SEEK_DATA
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# ifdef __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__
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# include <AvailabilityMacros.h>
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# endif
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# if 99990000 <= MAC_OS_X_VERSION_MIN_REQUIRED
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# define LSEEK_WORKS_BUT_IS_INCOMPATIBLE_WITH_GNU
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# endif
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#endif
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#ifndef LSEEK_WORKS_BUT_IS_INCOMPATIBLE_WITH_GNU
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#error "No need to work around the bug"
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#endif
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]])],
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[gl_cv_func_lseek_works_but_incompatible=yes],
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[gl_cv_func_lseek_works_but_incompatible=no])])
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if test "$gl_cv_func_lseek_works_but_incompatible" = yes; then
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REPLACE_LSEEK=1
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fi])
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])
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