elf/dl-libc.c

   1 /* Handle loading and unloading shared objects for internal libc purposes.
   2    Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Zack Weinberg <zack@rabi.columbia.edu>, 1999.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <ldsodefs.h>
  24
  25 /* The purpose of this file is to provide wrappers around the dynamic
  26    linker error mechanism (similar to dlopen() et al in libdl) which
  27    are usable from within libc.  Generally we want to throw away the
  28    string that dlerror() would return and just pass back a null pointer
  29    for errors.  This also lets the rest of libc not know about the error
  30    handling mechanism.
  31
  32    Much of this code came from gconv_dl.c with slight modifications. */
  33
  34 static int
  35 internal_function
  36 dlerror_run (void (*operate) (void *), void *args)
  37 {
  38   const char *objname;
  39   const char *last_errstring = NULL;
  40   int result;
  41
  42   (void) _dl_catch_error (&objname, &last_errstring, operate, args);
  43
  44   result = last_errstring != NULL;
  45   if (result && last_errstring != _dl_out_of_memory)
  46     free ((char *) last_errstring);
  47
  48   return result;
  49 }
  50
  51 /* These functions are called by dlerror_run... */
  52
  53 struct do_dlopen_args
  54 {
  55   /* Argument to do_dlopen.  */
  56   const char *name;
  57   /* Opening mode.  */
  58   int mode;
  59
  60   /* Return from do_dlopen.  */
  61   struct link_map *map;
  62 };
  63
  64 struct do_dlsym_args
  65 {
  66   /* Arguments to do_dlsym.  */
  67   struct link_map *map;
  68   const char *name;
  69
  70   /* Return values of do_dlsym.  */
  71   lookup_t loadbase;
  72   const ElfW(Sym) *ref;
  73 };
  74
  75 static void
  76 do_dlopen (void *ptr)
  77 {
  78   struct do_dlopen_args *args = (struct do_dlopen_args *) ptr;
  79   /* Open and relocate the shared object.  */
  80   args->map = _dl_open (args->name, args->mode, NULL);
  81 }
  82
  83 static void
  84 do_dlsym (void *ptr)
  85 {
  86   struct do_dlsym_args *args = (struct do_dlsym_args *) ptr;
  87   args->ref = NULL;
  88   args->loadbase = _dl_lookup_symbol (args->name, args->map, &args->ref,
  89                                       args->map->l_local_scope, 0,
  90                                       DL_LOOKUP_RETURN_NEWEST);
  91 }
  92
  93 static void
  94 do_dlclose (void *ptr)
  95 {
  96   _dl_close ((struct link_map *) ptr);
  97 }
  98
  99 /* ... and these functions call dlerror_run. */
 100
 101 void *
 102 __libc_dlopen_mode (const char *name, int mode)
 103 {
 104   struct do_dlopen_args args;
 105   args.name = name;
 106   args.mode = mode;
 107
 108   return (dlerror_run (do_dlopen, &args) ? NULL : (void *) args.map);
 109 }
 110
 111 void *
 112 __libc_dlsym (void *map, const char *name)
 113 {
 114   struct do_dlsym_args args;
 115   args.map = map;
 116   args.name = name;
 117
 118   return (dlerror_run (do_dlsym, &args) ? NULL
 119           : (void *) (DL_SYMBOL_ADDRESS (args.loadbase, args.ref)));
 120 }
 121
 122 int
 123 __libc_dlclose (void *map)
 124 {
 125   return dlerror_run (do_dlclose, map);
 126 }
 127
 128
 129 libc_freeres_fn (free_mem)
 130 {
 131   struct link_map *l;
 132   struct r_search_path_elem *d;
 133
 134   /* Remove all search directories.  */
 135   d = GL(dl_all_dirs);
 136   while (d != GL(dl_init_all_dirs))
 137     {
 138       struct r_search_path_elem *old = d;
 139       d = d->next;
 140       free (old);
 141     }
 142
 143   /* Remove all additional names added to the objects.  */
 144   for (l = GL(dl_loaded); l != NULL; l = l->l_next)
 145     {
 146       struct libname_list *lnp = l->l_libname->next;
 147
 148       l->l_libname->next = NULL;
 149
 150       while (lnp != NULL)
 151         {
 152           struct libname_list *old = lnp;
 153           lnp = lnp->next;
 154           if (! old->dont_free)
 155             free (old);
 156         }
 157     }
 158 }