| 1 | # lseek.m4 serial 11
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| 2 | dnl Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | AC_DEFUN([gl_FUNC_LSEEK],
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| 8 | [
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| 9 | AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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| 10 |
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| 11 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 12 | AC_REQUIRE([AC_PROG_CC])
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| 13 | AC_CHECK_HEADERS_ONCE([unistd.h])
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| 14 | AC_CACHE_CHECK([whether lseek detects pipes], [gl_cv_func_lseek_pipe],
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| 15 | [case "$host_os" in
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| 16 | mingw*)
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| 17 | dnl Native Windows.
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| 18 | dnl The result of lseek (fd, (off_t)0, SEEK_CUR) or
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| 19 | dnl SetFilePointer(handle, 0, NULL, FILE_CURRENT)
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| 20 | dnl for a pipe depends on the environment: In a Cygwin 1.5
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| 21 | dnl environment it succeeds (wrong); in a Cygwin 1.7 environment
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| 22 | dnl it fails with a wrong errno value.
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| 23 | gl_cv_func_lseek_pipe=no
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| 24 | ;;
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| 25 | *)
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| 26 | if test $cross_compiling = no; then
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| 27 | AC_LINK_IFELSE([AC_LANG_PROGRAM([[
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| 28 | #include <sys/types.h> /* for off_t */
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| 29 | #include <stdio.h> /* for SEEK_CUR */
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| 30 | #if HAVE_UNISTD_H
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| 31 | # include <unistd.h>
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| 32 | #else /* on Windows with MSVC */
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| 33 | # include <io.h>
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| 34 | #endif
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| 35 | ]GL_MDA_DEFINES],
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| 36 | [[
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| 37 | /* Exit with success only if stdin is seekable. */
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| 38 | return lseek (0, (off_t)0, SEEK_CUR) < 0;
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| 39 | ]])],
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| 40 | [if test -s conftest$ac_exeext \
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| 41 | && ./conftest$ac_exeext < conftest.$ac_ext \
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| 42 | && test 1 = "`echo hi \
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| 43 | | { ./conftest$ac_exeext; echo $?; cat >/dev/null; }`"; then
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| 44 | gl_cv_func_lseek_pipe=yes
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| 45 | else
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| 46 | gl_cv_func_lseek_pipe=no
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| 47 | fi
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| 48 | ],
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| 49 | [gl_cv_func_lseek_pipe=no])
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| 50 | else
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| 51 | AC_COMPILE_IFELSE(
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| 52 | [AC_LANG_SOURCE([[
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| 53 | #if defined __BEOS__
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| 54 | /* BeOS mistakenly return 0 when trying to seek on pipes. */
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| 55 | Choke me.
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| 56 | #endif]])],
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| 57 | [gl_cv_func_lseek_pipe=yes], [gl_cv_func_lseek_pipe=no])
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| 58 | fi
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| 59 | ;;
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| 60 | esac
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| 61 | ])
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| 62 | if test $gl_cv_func_lseek_pipe = no; then
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| 63 | REPLACE_LSEEK=1
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| 64 | AC_DEFINE([LSEEK_PIPE_BROKEN], [1],
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| 65 | [Define to 1 if lseek does not detect pipes.])
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| 66 | fi
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| 67 |
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| 68 | AC_REQUIRE([gl_SYS_TYPES_H])
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| 69 | if test $WINDOWS_64_BIT_OFF_T = 1; then
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| 70 | REPLACE_LSEEK=1
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| 71 | fi
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| 72 | ])
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