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-rw-r--r--m4/lseek.m478
1 files changed, 78 insertions, 0 deletions
diff --git a/m4/lseek.m4 b/m4/lseek.m4
new file mode 100644
index 0000000..0583511
--- /dev/null
+++ b/m4/lseek.m4
@@ -0,0 +1,78 @@
+# lseek.m4 serial 12
+dnl Copyright (C) 2007, 2009-2022 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_LSEEK],
+[
+ AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_REQUIRE([AC_PROG_CC])
+ AC_CHECK_HEADERS_ONCE([unistd.h])
+ AC_CACHE_CHECK([whether lseek detects pipes], [gl_cv_func_lseek_pipe],
+ [case "$host_os" in
+ mingw*)
+ dnl Native Windows.
+ dnl The result of lseek (fd, (off_t)0, SEEK_CUR) or
+ dnl SetFilePointer(handle, 0, NULL, FILE_CURRENT)
+ dnl for a pipe depends on the environment: In a Cygwin 1.5
+ dnl environment it succeeds (wrong); in a Cygwin 1.7 environment
+ dnl it fails with a wrong errno value.
+ gl_cv_func_lseek_pipe=no
+ ;;
+ *)
+ if test $cross_compiling = no; then
+ AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h> /* for off_t */
+#include <stdio.h> /* for SEEK_CUR */
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#else /* on Windows with MSVC */
+# include <io.h>
+#endif
+]GL_MDA_DEFINES],
+[[
+ /* Exit with success only if stdin is seekable. */
+ return lseek (0, (off_t)0, SEEK_CUR) < 0;
+]])],
+ [if test -s conftest$ac_exeext \
+ && ./conftest$ac_exeext < conftest.$ac_ext \
+ && test 1 = "`echo hi \
+ | { ./conftest$ac_exeext; echo $?; cat >/dev/null; }`"; then
+ gl_cv_func_lseek_pipe=yes
+ else
+ gl_cv_func_lseek_pipe=no
+ fi
+ ],
+ [gl_cv_func_lseek_pipe=no])
+ else
+ AC_COMPILE_IFELSE(
+ [AC_LANG_SOURCE([[
+#if defined __BEOS__
+/* BeOS mistakenly return 0 when trying to seek on pipes. */
+ Choke me.
+#endif]])],
+ [gl_cv_func_lseek_pipe=yes], [gl_cv_func_lseek_pipe=no])
+ fi
+ ;;
+ esac
+ ])
+ if test "$gl_cv_func_lseek_pipe" = no; then
+ REPLACE_LSEEK=1
+ AC_DEFINE([LSEEK_PIPE_BROKEN], [1],
+ [Define to 1 if lseek does not detect pipes.])
+ fi
+
+ AC_REQUIRE([gl_SYS_TYPES_H])
+ if test $WINDOWS_64_BIT_OFF_T = 1; then
+ REPLACE_LSEEK=1
+ fi
+
+ dnl macOS SEEK_DATA is incompatible with other platforms.
+ case $host_os in
+ darwin*)
+ REPLACE_LSEEK=1;;
+ esac
+])