1 files changed, 43 insertions, 0 deletions

diff --git a/gl/m4/getprogname.m4 b/gl/m4/getprogname.m4
new file mode 100644
index 00000000..65917d6a
--- /dev/null
+++ b/gl/m4/getprogname.m4
@@ -0,0 +1,43 @@
+# getprogname.m4 - check for getprogname or replacements for it
+
+# Copyright (C) 2016-2021 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# serial 4
+
+AC_DEFUN([gl_FUNC_GETPROGNAME],
+[
+  AC_CHECK_FUNCS_ONCE([getprogname getexecname])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  ac_found=0
+  AC_CHECK_DECLS([program_invocation_name], [ac_found=1], [],
+    [#include <errno.h>])
+  AC_CHECK_DECLS([program_invocation_short_name], [ac_found=1], [],
+    [#include <errno.h>])
+  AC_CHECK_DECLS([__argv], [ac_found=1], [], [#include <stdlib.h>])
+
+  # Incur the cost of this test only if none of the above worked.
+  if test $ac_found = 0; then
+    # On OpenBSD 5.1, using the global __progname variable appears to be
+    # the only way to implement getprogname.
+    AC_CACHE_CHECK([whether __progname is defined in default libraries],
+      [gl_cv_var___progname],
+      [
+        gl_cv_var___progname=
+        AC_LINK_IFELSE(
+          [AC_LANG_PROGRAM(
+            [[extern char *__progname;]],
+            [[return *__progname;]]
+          )],
+          [gl_cv_var___progname=yes]
+        )
+      ]
+    )
+    if test "$gl_cv_var___progname" = yes; then
+      AC_DEFINE([HAVE_VAR___PROGNAME], 1,
+        [Define if you have a global __progname variable])
+    fi
+  fi
+])