ld.elf_so: Add stub library to access non-POSIX rtld api

JIRA: RTOS-664

ld.elf_so/Makefile

@@ -54,3 +54,8 @@ LANGUAGE_EXTENSIONS += %.S
 include $(binary.mk)
 
 LANGUAGE_EXTENSIONS := $(LANGUAGE_EXTENSIONS_OLD)
+
+
+rtld: ld.elf_so librtld_stubs
+rtld-install: ld.elf_so-install librtld_stubs-install
+rtld-clean: ld.elf_so-clean librtld_stubs-clean

ld.elf_so/stubs/Makefile

@@ -0,0 +1,12 @@
+#
+# Makefile for Phoenix-RTOS librtld_stubs
+#
+# Copyright 2024 Phoenix Systems
+#
+
+# Make library with stubs of non POSIX functions.
+# This is required as this linker doesn't allow to add itself to NEEDED libs.
+# To resolve a symbol from linker in dynamic binary a weak symbol is required.
+NAME := librtld_stubs
+LOCAL_SRCS := librtld_stubs.c
+include $(shared-lib.mk)

ld.elf_so/stubs/librtld_stubs.c

@@ -0,0 +1,62 @@
+/*
+ * Phoenix-RTOS
+ *
+ * librtld_stubs
+ *
+ * Copyright 2024 Phoenix Systems
+ * Author: Hubert Badocha
+ *
+ * This file is part of Phoenix-RTOS.
+ *
+ * %LICENSE%
+ */
+
+#include <stdlib.h>
+
+#include "../include/NetBSD/dlfcn.h"
+#include "../include/NetBSD/link_elf.h"
+
+
+void *___dlauxinfo(void)
+{
+	abort();
+}
+
+
+int __dlctl(void *a, int b, void *c)
+{
+	abort();
+}
+
+
+int __dlinfo(void *a, int b, void *c)
+{
+	abort();
+}
+
+
+void *__dlvsym(void * restrict a, const char * restrict b, const char * restrict c)
+{
+	abort();
+}
+
+
+void ____dl_cxa_refcount(void *a, ssize_t b)
+{
+	abort();
+}
+
+
+int __dl_iterate_phdr(int (*a)(struct dl_phdr_info *, size_t, void *), void *b)
+{
+	abort();
+}
+
+
+extern void *_dlauxinfo(void) __attribute__((__pure__, weak, alias("___dlauxinfo")));
+
+extern int	dlctl(void *, int, void *) __attribute__((weak, alias("__dlctl")));
+extern int	dlinfo(void *, int, void *) __attribute__((weak, alias("__dlinfo")));
+extern void *dlvsym(void * restrict, const char * restrict, const char * restrict) __attribute__((weak, alias("__dlvsym")));
+extern void __dl_cxa_refcount(void *, ssize_t) __attribute__((weak, alias("____dl_cxa_refcount")));
+extern int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), void *) __attribute__((weak, alias("__dl_iterate_phdr")));