1 files changed, 77 insertions, 0 deletions
diff --git a/m4/fseeko.m4 b/m4/fseeko.m4
new file mode 100644
index 0000000..05ee06b
--- /dev/null
+++ b/m4/fseeko.m4
@@ -0,0 +1,77 @@
+# fseeko.m4 serial 20
+dnl Copyright (C) 2007-2023 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_FSEEKO],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([gl_STDIN_LARGE_OFFSET])
+  AC_REQUIRE([gl_SYS_TYPES_H])
+  AC_REQUIRE([AC_PROG_CC])
+
+  dnl Persuade glibc <stdio.h> to declare fseeko().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CACHE_CHECK([for fseeko], [gl_cv_func_fseeko],
+    [
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>
+]], [[fseeko (stdin, 0, 0);]])],
+        [gl_cv_func_fseeko=yes], [gl_cv_func_fseeko=no])
+    ])
+
+  AC_CHECK_DECLS_ONCE([fseeko])
+  if test $ac_cv_have_decl_fseeko = no; then
+    HAVE_DECL_FSEEKO=0
+  fi
+
+  if test $gl_cv_func_fseeko = no; then
+    HAVE_FSEEKO=0
+  else
+    if test $WINDOWS_64_BIT_OFF_T = 1; then
+      REPLACE_FSEEKO=1
+    fi
+    if test $gl_cv_var_stdin_large_offset = no; then
+      REPLACE_FSEEKO=1
+    fi
+    m4_ifdef([gl_FUNC_FFLUSH_STDIN], [
+      gl_FUNC_FFLUSH_STDIN
+      case "$gl_cv_func_fflush_stdin" in
+        *yes) ;;
+        *) REPLACE_FSEEKO=1 ;;
+      esac
+    ])
+  fi
+])
+
+dnl Code shared by fseeko and ftello.  Determine if large files are supported,
+dnl but stdin does not start as a large file by default.
+AC_DEFUN([gl_STDIN_LARGE_OFFSET],
+  [
+    AC_CACHE_CHECK([whether stdin defaults to large file offsets],
+      [gl_cv_var_stdin_large_offset],
+      [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]],
+[[#if defined __SL64 && defined __SCLE /* cygwin */
+  /* Cygwin 1.5.24 and earlier fail to put stdin in 64-bit mode, making
+     fseeko/ftello needlessly fail.  This bug was fixed in 1.5.25, and
+     it is easier to do a version check than building a runtime test.  */
+# include <cygwin/version.h>
+# if CYGWIN_VERSION_DLL_COMBINED < CYGWIN_VERSION_DLL_MAKE_COMBINED (1005, 25)
+  choke me
+# endif
+#endif]])],
+        [gl_cv_var_stdin_large_offset=yes],
+        [gl_cv_var_stdin_large_offset=no])])
+])
+
+# Prerequisites of lib/fseeko.c.
+AC_DEFUN([gl_PREREQ_FSEEKO],
+[
+  dnl Native Windows has the function _fseeki64. mingw hides it in some
+  dnl circumstances, but mingw64 makes it usable again.
+  AC_CHECK_FUNCS([_fseeki64])
+  if test $ac_cv_func__fseeki64 = yes; then
+    AC_CHECK_DECLS([_fseeki64])
+  fi
+])