Add gnulib modules to replace missing libc functionality

This enables us to build a fully featured elfutils package on systems
with reduced C libraries, such as windows. All the modules are built
into libgnu.a, which is then linked into all binaries if
--enable-gnulib is given on the configure line.

Change-Id: I743fd22172bc85d9f10dcc3dad8eb921f462b554
Reviewed-by: Christian Kandeler <[email protected]>

1 files changed, 62 insertions, 0 deletions

diff --git a/m4/vsnprintf.m4 b/m4/vsnprintf.m4
new file mode 100644
index 00000000..9c37bca9
--- /dev/null
+++ b/m4/vsnprintf.m4
@@ -0,0 +1,62 @@
+# vsnprintf.m4 serial 7
+dnl Copyright (C) 2002-2004, 2007-2017 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.
+
+dnl Libintl 0.17 will replace vsnprintf only if it does not support %1$s,
+dnl but defers to any gnulib vsnprintf replacements.  Therefore, gnulib
+dnl must guarantee that the decision for replacing vsnprintf is a superset
+dnl of the reasons checked by libintl.
+AC_DEFUN([gl_FUNC_VSNPRINTF],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  gl_cv_func_vsnprintf_usable=no
+  AC_CHECK_FUNCS([vsnprintf])
+  if test $ac_cv_func_vsnprintf = yes; then
+    gl_SNPRINTF_SIZE1
+    case "$gl_cv_func_snprintf_size1" in
+      *yes)
+        gl_SNPRINTF_RETVAL_C99
+        case "$gl_cv_func_snprintf_retval_c99" in
+          *yes)
+            gl_PRINTF_POSITIONS
+            case "$gl_cv_func_printf_positions" in
+              *yes)
+                gl_cv_func_vsnprintf_usable=yes
+                ;;
+            esac
+            ;;
+        esac
+        ;;
+    esac
+  fi
+  if test $gl_cv_func_vsnprintf_usable = no; then
+    gl_REPLACE_VSNPRINTF
+  fi
+  AC_CHECK_DECLS_ONCE([vsnprintf])
+  if test $ac_cv_have_decl_vsnprintf = no; then
+    HAVE_DECL_VSNPRINTF=0
+  fi
+])
+
+AC_DEFUN([gl_REPLACE_VSNPRINTF],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_LIBOBJ([vsnprintf])
+  if test $ac_cv_func_vsnprintf = yes; then
+    REPLACE_VSNPRINTF=1
+  else
+    AC_CHECK_DECLS_ONCE([vsnprintf])
+    if test $ac_cv_have_decl_vsnprintf = yes; then
+      dnl If the function is declared but does not appear to exist, it may be
+      dnl defined as an inline function. In order to avoid a conflict, we have
+      dnl to define rpl_vsnprintf, not vsnprintf.
+      REPLACE_VSNPRINTF=1
+    fi
+  fi
+  gl_PREREQ_VSNPRINTF
+])
+
+# Prerequisites of lib/vsnprintf.c.
+AC_DEFUN([gl_PREREQ_VSNPRINTF], [:])