libdl: Add object file dependencies to track references

Tracking references lets us manage when an object file can be
unloaded. If an object file has references to it, it cannot be
unloaded.

Modules that depend on each other cannot be unloaded.

Updates #3605

1 files changed, 46 insertions, 8 deletions

diff --git a/cpukit/libdl/rtl-shell.c b/cpukit/libdl/rtl-shell.c
index 5c144977a0..f3471d8d8e 100644
--- a/cpukit/libdl/rtl-shell.c
+++ b/cpukit/libdl/rtl-shell.c
@@ -117,13 +117,14 @@ rtems_rtl_shell_status (rtems_rtl_data* rtl, int argc, char *argv[])
  */
 typedef struct
 {
-  rtems_rtl_data* rtl;        /**< The RTL data. */
-  int             indent;     /**< Spaces to indent. */
-  bool            oname;      /**< Print object names. */
-  bool            names;      /**< Print details of all names. */
-  bool            memory_map; /**< Print the memory map. */
-  bool            symbols;    /**< Print the global symbols. */
-  bool            base;       /**< Include the base object file. */
+  rtems_rtl_data* rtl;          /**< The RTL data. */
+  int             indent;       /**< Spaces to indent. */
+  bool            oname;        /**< Print object names. */
+  bool            names;        /**< Print details of all names. */
+  bool            memory_map;   /**< Print the memory map. */
+  bool            symbols;      /**< Print the global symbols. */
+  bool            dependencies; /**< Print any dependencies. */
+  bool            base;         /**< Include the base object file. */
 } rtems_rtl_obj_print;
 
 /**
@@ -169,6 +170,29 @@ rtems_rtl_symbols_arg (int argc, char *argv[])
 }
 
 /**
+ * Dependenncies printer.
+ */
+typedef struct
+{
+  bool   first;   /**< Is this the first line printed. */
+  size_t indent;  /**< The indent. */
+} rtems_rtl_dep_data;
+
+static bool
+rtems_rtl_dependencies (rtems_rtl_obj* obj,
+                        rtems_rtl_obj* dependent,
+                        void*          data)
+{
+  rtems_rtl_dep_data* dd = (rtems_rtl_dep_data*) data;
+  if (!dd->first)
+    printf ("\n%-*c: ", dd->indent, ' ');
+  else
+    dd->first = false;
+  printf ("%s", dependent->oname);
+  return false;
+}
+
+/**
  * Object printer.
  */
 static bool
@@ -214,7 +238,9 @@ rtems_rtl_obj_printer (rtems_rtl_obj_print* print, rtems_rtl_obj* obj)
     printf ("%-*cbss base      : %p (%zi)\n", print->indent, ' ',
             obj->bss_base, obj->bss_size);
   }
-  printf ("%-*cunresolved    : %" PRIu32 "\n", print->indent, ' ', obj->unresolved);
+  printf ("%-*cunresolved    : %zu\n", print->indent, ' ', obj->unresolved);
+  printf ("%-*cusers         : %zu\n", print->indent, ' ', obj->users);
+  printf ("%-*creferences    : %zu\n", print->indent, ' ', obj->refs);
   printf ("%-*csymbols       : %zi\n", print->indent, ' ', obj->global_syms);
   printf ("%-*csymbol memory : %zi\n", print->indent, ' ', obj->global_size);
   if (print->symbols)
@@ -231,6 +257,16 @@ rtems_rtl_obj_printer (rtems_rtl_obj_print* print, rtems_rtl_obj* obj)
       printf ("%-*c%-*s = %p\n", print->indent + 2, ' ',
               max_len, obj->global_table[s].name, obj->global_table[s].value);
   }
+  if (print->dependencies)
+  {
+    rtems_rtl_dep_data dd = {
+      .first = true,
+      .indent = strlen ("dependencies :") + print->indent
+    };
+    printf ("%-*cdependencies  : ", print->indent, ' ');
+    rtems_rtl_obj_iterate_dependents (obj, rtems_rtl_dependencies, &dd);
+    printf ("\n");
+  }
   printf ("\n");
   return true;
 }
@@ -269,6 +305,7 @@ rtems_rtl_shell_list (rtems_rtl_data* rtl, int argc, char *argv[])
   print.names = true;
   print.memory_map = true;
   print.symbols = rtems_rtl_symbols_arg (argc, argv);
+  print.dependencies = true;
   print.base = false;
   rtems_rtl_chain_iterate (&rtl->objects,
                            rtems_rtl_obj_print_iterator,
@@ -286,6 +323,7 @@ rtems_rtl_shell_sym (rtems_rtl_data* rtl, int argc, char *argv[])
   print.names = false;
   print.memory_map = false;
   print.symbols = true;
+  print.dependencies = false;
   print.base = rtems_rtl_base_arg (argc, argv);
   rtems_rtl_chain_iterate (&rtl->objects,
                            rtems_rtl_obj_print_iterator,