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/* Look up a symbol in the loaded objects.

   Copyright (C) 1995,96,97,98,99,2000,2001 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, write to the Free

   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

   02111-1307 USA.  */

#include <alloca.h>

#include <libintl.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <ldsodefs.h>

#include "dl-hash.h"

#include <machine/dl-machine.h>

#include <bits/libc-lock.h>

#include <assert.h>

#define VERSTAG(tag)    (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag))

/* We need this string more than once.  */

static const char undefined_msg[] = "undefined symbol: ";

struct sym_val

  {

    const ElfW(Sym) *s;

    struct link_map *m;

  };

#define make_string(string, rest...) \

  ({                                                                          \

    const char *all[] = { string, ## rest };                                  \

    size_t len, cnt;                                                          \

    char *result, *cp;                                                        \

                                                                              \

    len = 1;                                                                  \

    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)                  \

      len += strlen (all[cnt]);                                               \

                                                                              \

    cp = result = alloca (len);                                               \

    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)                  \

    {                                                                         \

      cp = strcpy (cp, all[cnt]);                                             \

      cp += strlen(all[cnt]);                                                 \

    }                                                                         \

                                                                              \

    result;                                                                   \

  })

/* Statistics function.  */

unsigned long int _dl_num_relocations;

/* We have two different situations when looking up a simple: with or

   without versioning.  gcc is not able to optimize a single function

   definition serving for both purposes so we define two functions.  */

#define VERSIONED       0

#include "do-lookup.h"

#define VERSIONED       1

#include "do-lookup.h"

/* Add extra dependency on MAP to UNDEF_MAP.  */

static int

internal_function

add_dependency (struct link_map *undef_map, struct link_map *map)

{

  struct link_map **list;

  struct link_map *runp;

  unsigned int act;

  unsigned int i;

  int result = 0;

  /* Avoid self-references.  */

  if (undef_map == map)

    return 0;

  /* Make sure nobody can unload the object while we are at it.  */

#ifdef HAVE_DD_LOCK

    __lock_acquire(_dl_load_lock);

#endif

  /* Determine whether UNDEF_MAP already has a reference to MAP.  First

     look in the normal dependencies.  */

  if (undef_map->l_searchlist.r_list != NULL)

    {

      list = undef_map->l_initfini;

      for (i = 0; list[i] != NULL; ++i)

        if (list[i] == map)

          goto out;

    }

  /* No normal dependency.  See whether we already had to add it

     to the special list of dynamic dependencies.  */

  list = undef_map->l_reldeps;

  act = undef_map->l_reldepsact;

  for (i = 0; i < act; ++i)

    if (list[i] == map)

      goto out;

  /* The object is not yet in the dependency list.  Before we add

     it make sure just one more time the object we are about to

     reference is still available.  There is a brief period in

     which the object could have been removed since we found the

     definition.  */

  runp = _dl_loaded;

  while (runp != NULL && runp != map)

    runp = runp->l_next;

  if (runp != NULL)

    {

      /* The object is still available.  Add the reference now.  */

      if (__builtin_expect (act >= undef_map->l_reldepsmax, 0))

        {

          /* Allocate more memory for the dependency list.  Since this

             can never happen during the startup phase we can use

             `realloc'.  */

          void *newp;

          undef_map->l_reldepsmax += 5;

          newp = realloc (undef_map->l_reldeps,

                          undef_map->l_reldepsmax

                          * sizeof (struct link_map *));

          if (__builtin_expect (newp != NULL, 1))

            undef_map->l_reldeps = (struct link_map **) newp;

          else

            /* Correct the addition.  */

            undef_map->l_reldepsmax -= 5;

        }

      /* If we didn't manage to allocate memory for the list this is

         no fatal mistake.  We simply increment the use counter of the

         referenced object and don't record the dependencies.  This

         means this increment can never be reverted and the object

         will never be unloaded.  This is semantically the correct

         behaviour.  */

      if (__builtin_expect (act < undef_map->l_reldepsmax, 1))

        undef_map->l_reldeps[undef_map->l_reldepsact++] = map;

      if (map->l_searchlist.r_list != NULL)

        /* And increment the counter in the referenced object.  */

        ++map->l_opencount;

      else

        /* We have to bump the counts for all dependencies since so far

           this object was only a normal or transitive dependency.

           Now it might be closed with _dl_close() directly.  */

        for (list = map->l_initfini; *list != NULL; ++list)

          ++(*list)->l_opencount;

      /* Display information if we are debugging.  */

      if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))

        _dl_debug_printf ("\

\nfile=%s;  needed by %s (relocation dependency)\n\n",

                          map->l_name[0] ? map->l_name : _dl_argv[0],

                          undef_map->l_name[0]

                          ? undef_map->l_name : _dl_argv[0]);

    }

  else

    /* Whoa, that was bad luck.  We have to search again.  */

    result = -1;

 out:

  /* Release the lock.  */

#ifdef HAVE_DD_LOCK

    __lock_release(_dl_load_lock);

#endif

  return result;

}

static int

internal_function

_dl_do_lookup (const char *undef_name, unsigned long int hash,

               const ElfW(Sym) *ref, struct sym_val *result,

               struct r_scope_elem *scope, size_t i,

               struct link_map *skip, int type_class);

static int

internal_function

_dl_do_lookup_versioned (const char *undef_name, unsigned long int hash,

                         const ElfW(Sym) *ref, struct sym_val *result,

                         struct r_scope_elem *scope, size_t i,

                         const struct r_found_version *const version,

                         struct link_map *skip, int type_class);

/* Search loaded objects' symbol tables for a definition of the symbol

   UNDEF_NAME.  */

lookup_t

internal_function

_dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,

                   const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[],

                   int type_class, int explicit)

{

  unsigned long int hash = _dl_elf_hash (undef_name);

  struct sym_val current_value = { NULL, NULL };

  struct r_scope_elem **scope;

  int protected;

  ++_dl_num_relocations;

  /* Search the relevant loaded objects for a definition.  */

  for (scope = symbol_scope; *scope; ++scope)

    if (do_lookup (undef_name, hash, *ref, &current_value, *scope, 0, NULL,

                   type_class))

      {

        /* We have to check whether this would bind UNDEF_MAP to an object

           in the global scope which was dynamically loaded.  In this case

           we have to prevent the latter from being unloaded unless the

           UNDEF_MAP object is also unloaded.  */

        if (__builtin_expect (current_value.m->l_type == lt_loaded, 0)

            /* Don't do this for explicit lookups as opposed to implicit

               runtime lookups.  */

            && ! explicit

            /* Add UNDEF_MAP to the dependencies.  */

            && add_dependency (undef_map, current_value.m) < 0)

          /* Something went wrong.  Perhaps the object we tried to reference

             was just removed.  Try finding another definition.  */

          return _dl_lookup_symbol (undef_name, undef_map, ref, symbol_scope,

                                    type_class, 0);

        break;

      }

  if (__builtin_expect (current_value.s == NULL, 0))

    {

      const char *reference_name = undef_map ? undef_map->l_name : NULL;

      if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)

        /* We could find no value for a strong reference.  */

        /* XXX We cannot translate the messages.  */

        _dl_signal_cerror (0, (reference_name && reference_name[0]

                               ? reference_name

                               : (_dl_argv[0] ?: "<main program>")),

                           N_("relocation error"),

                           make_string (undefined_msg, undef_name));

      *ref = NULL;

      return 0;

    }

  protected = *ref && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED;

  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_BINDINGS, 0))

    {

      const char *reference_name = undef_map ? undef_map->l_name : NULL;

      _dl_debug_printf ("binding file %s to %s: %s symbol `%s'\n",

                        (reference_name && reference_name[0]

                         ? reference_name : (_dl_argv[0] ?: "<main program>")),

                        current_value.m->l_name[0]

                        ? current_value.m->l_name : _dl_argv[0],

                        protected ? "protected" : "normal", undef_name);

    }

  if (__builtin_expect (protected == 0, 1))

    {

      *ref = current_value.s;

      return LOOKUP_VALUE (current_value.m);

    }

  else

    {

      /* It is very tricky. We need to figure out what value to

         return for the protected symbol */

      struct sym_val protected_value = { NULL, NULL };

      for (scope = symbol_scope; *scope; ++scope)

        if (_dl_do_lookup (undef_name, hash, *ref, &protected_value, *scope,

                           0, NULL, ELF_RTYPE_CLASS_PLT))

          break;

      if (protected_value.s == NULL || protected_value.m == undef_map)

        {

          *ref = current_value.s;

          return LOOKUP_VALUE (current_value.m);

        }

      return LOOKUP_VALUE (undef_map);

    }

}

/* This function is nearly the same as `_dl_lookup_symbol' but it

   skips in the first list all objects until SKIP_MAP is found.  I.e.,

   it only considers objects which were loaded after the described

   object.  If there are more search lists the object described by

   SKIP_MAP is only skipped.  */

lookup_t

internal_function

_dl_lookup_symbol_skip (const char *undef_name,

                        struct link_map *undef_map, const ElfW(Sym) **ref,

                        struct r_scope_elem *symbol_scope[],

                        struct link_map *skip_map)

{

  const char *reference_name = undef_map ? undef_map->l_name : NULL;

  const unsigned long int hash = _dl_elf_hash (undef_name);

  struct sym_val current_value = { NULL, NULL };

  struct r_scope_elem **scope;

  size_t i;

  int protected;

  ++_dl_num_relocations;

  /* Search the relevant loaded objects for a definition.  */

  scope = symbol_scope;

  for (i = 0; (*scope)->r_list[i] != skip_map; ++i)

    assert (i < (*scope)->r_nlist);

  if (! _dl_do_lookup (undef_name, hash, *ref, &current_value, *scope, i,

                       skip_map, 0))

    while (*++scope)

      if (_dl_do_lookup (undef_name, hash, *ref, &current_value, *scope, 0,

                         skip_map, 0))

        break;

  if (__builtin_expect (current_value.s == NULL, 0))

    {

      *ref = NULL;

      return 0;

    }

  protected = *ref && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED;

  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_BINDINGS, 0))

    _dl_debug_printf ("binding file %s to %s: %s symbol `%s'\n",

                       (reference_name && reference_name[0]

                        ? reference_name : (_dl_argv[0] ?: "<main program>")),

                       current_value.m->l_name[0]

                       ? current_value.m->l_name : _dl_argv[0],

                       protected ? "protected" : "normal", undef_name);

  if (__builtin_expect (protected == 0, 1))

    {

      *ref = current_value.s;

      return LOOKUP_VALUE (current_value.m);

    }

  else

    {

      /* It is very tricky.  We need to figure out what value to

         return for the protected symbol.  */

      struct sym_val protected_value = { NULL, NULL };

      if (i >= (*scope)->r_nlist

          || !_dl_do_lookup (undef_name, hash, *ref, &protected_value, *scope,

                             i, skip_map, ELF_RTYPE_CLASS_PLT))

        while (*++scope)

          if (_dl_do_lookup (undef_name, hash, *ref, &protected_value, *scope,

                             0, skip_map, ELF_RTYPE_CLASS_PLT))

            break;

      if (protected_value.s == NULL || protected_value.m == undef_map)

        {

          *ref = current_value.s;

          return LOOKUP_VALUE (current_value.m);

        }

      return LOOKUP_VALUE (undef_map);

    }

}

/* This function works like _dl_lookup_symbol but it takes an

   additional arguement with the version number of the requested

   symbol.

   XXX We'll see whether we need this separate function.  */

lookup_t

internal_function

_dl_lookup_versioned_symbol (const char *undef_name,

                             struct link_map *undef_map, const ElfW(Sym) **ref,

                             struct r_scope_elem *symbol_scope[],

                             const struct r_found_version *version,

                             int type_class, int explicit)

{

  unsigned long int hash = _dl_elf_hash (undef_name);

  struct sym_val current_value = { NULL, NULL };

  struct r_scope_elem **scope;

  int protected;

  ++_dl_num_relocations;

  /* Search the relevant loaded objects for a definition.  */

  for (scope = symbol_scope; *scope; ++scope)

    {

      int res = do_lookup_versioned (undef_name, hash, *ref, &current_value,

                                     *scope, 0, version, NULL, type_class);

      if (res > 0)

        {

          /* We have to check whether this would bind UNDEF_MAP to an object

             in the global scope which was dynamically loaded.  In this case

             we have to prevent the latter from being unloaded unless the

             UNDEF_MAP object is also unloaded.  */

          if (__builtin_expect (current_value.m->l_type == lt_loaded, 0)

              /* Don't do this for explicit lookups as opposed to implicit

                 runtime lookups.  */

              && ! explicit

              /* Add UNDEF_MAP to the dependencies.  */

              && add_dependency (undef_map, current_value.m) < 0)

            /* Something went wrong.  Perhaps the object we tried to reference

               was just removed.  Try finding another definition.  */

            return _dl_lookup_versioned_symbol (undef_name, undef_map, ref,

                                                symbol_scope, version,

                                                type_class, 0);

          break;

        }

      if (__builtin_expect (res, 0) < 0)

        {

          /* Oh, oh.  The file named in the relocation entry does not

             contain the needed symbol.  */

          const char *reference_name = undef_map ? undef_map->l_name : NULL;

          /* XXX We cannot translate the message.  */

          _dl_signal_cerror (0, (reference_name && reference_name[0]

                                 ? reference_name

                                 : (_dl_argv[0] ?: "<main program>")),

                             N_("relocation error"),

                             make_string ("symbol ", undef_name, ", version ",

                                          version->name,

                                          " not defined in file ",

                                          version->filename,

                                          " with link time reference",

                                          res == -2

                                          ? " (no version symbols)" : ""));

          *ref = NULL;

          return 0;

        }

    }

  if (__builtin_expect (current_value.s == NULL, 0))

    {

      if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)

        {

          /* We could find no value for a strong reference.  */

          const char *reference_name = undef_map ? undef_map->l_name : NULL;

          /* XXX We cannot translate the message.  */

          _dl_signal_cerror (0, (reference_name && reference_name[0]

                                 ? reference_name

                                 : (_dl_argv[0] ?: "<main program>")), NULL,

                             make_string (undefined_msg, undef_name,

                                          ", version ",

                                          version->name ?: NULL));

        }

      *ref = NULL;

      return 0;

    }

  protected = *ref && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED;

  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_BINDINGS, 0))

    {

      const char *reference_name = undef_map ? undef_map->l_name : NULL;

      _dl_debug_printf ("binding file %s to %s: %s symbol `%s' [%s]\n",

                        (reference_name && reference_name[0]

                         ? reference_name : (_dl_argv[0] ?: "<main program>")),

                        current_value.m->l_name[0]

                        ? current_value.m->l_name : _dl_argv[0],

                        protected ? "protected" : "normal",

                        undef_name, version->name);

    }

  if (__builtin_expect (protected == 0, 1))

    {

      *ref = current_value.s;

      return LOOKUP_VALUE (current_value.m);

    }

  else

    {

      /* It is very tricky. We need to figure out what value to

         return for the protected symbol */

      struct sym_val protected_value = { NULL, NULL };

      for (scope = symbol_scope; *scope; ++scope)

        if (_dl_do_lookup_versioned (undef_name, hash, *ref, &protected_value,

                                     *scope, 0, version, NULL,

                                     ELF_RTYPE_CLASS_PLT))

          break;

      if (protected_value.s == NULL || protected_value.m == undef_map)

        {

          *ref = current_value.s;

          return LOOKUP_VALUE (current_value.m);

        }

      return LOOKUP_VALUE (undef_map);

    }

}

/* Similar to _dl_lookup_symbol_skip but takes an additional argument

   with the version we are looking for.  */

lookup_t

internal_function

_dl_lookup_versioned_symbol_skip (const char *undef_name,

                                  struct link_map *undef_map,

                                  const ElfW(Sym) **ref,

                                  struct r_scope_elem *symbol_scope[],

                                  const struct r_found_version *version,

                                  struct link_map *skip_map)

{

  const char *reference_name = undef_map ? undef_map->l_name : NULL;

  const unsigned long int hash = _dl_elf_hash (undef_name);

  struct sym_val current_value = { NULL, NULL };

  struct r_scope_elem **scope;

  size_t i;

  int protected;

  ++_dl_num_relocations;

  /* Search the relevant loaded objects for a definition.  */

  scope = symbol_scope;

  for (i = 0; (*scope)->r_list[i] != skip_map; ++i)

    assert (i < (*scope)->r_nlist);

  if (! _dl_do_lookup_versioned (undef_name, hash, *ref, &current_value,

                                 *scope, i, version, skip_map, 0))

    while (*++scope)

      if (_dl_do_lookup_versioned (undef_name, hash, *ref, &current_value,

                                   *scope, 0, version, skip_map, 0))

        break;

  if (__builtin_expect (current_value.s == NULL, 0))

    {

      if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)

        {

          /* We could find no value for a strong reference.  */

          const size_t len = strlen (undef_name);

          char buf[sizeof undefined_msg + len];

          char *tmp;

          tmp = memcpy (buf, undefined_msg, sizeof undefined_msg - 1);

          tmp += (sizeof undefined_msg - 1);

          memcpy (tmp, undef_name, len + 1);

          /* XXX We cannot translate the messages.  */

          _dl_signal_cerror (0, (reference_name && reference_name[0]

                                 ? reference_name

                                 : (_dl_argv[0] ?: "<main program>")),

                             NULL, buf);

        }

      *ref = NULL;

      return 0;

    }

  protected = *ref && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED;

  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_BINDINGS, 0))

    _dl_debug_printf ("binding file %s to %s: %s symbol `%s' [%s]\n",

                      (reference_name && reference_name[0]

                       ? reference_name : (_dl_argv[0] ?: "<main program>")),

                      current_value.m->l_name[0]

                      ? current_value.m->l_name : _dl_argv[0],

                      protected ? "protected" : "normal",

                      undef_name, version->name);

  if (__builtin_expect (protected == 0, 1))

    {

      *ref = current_value.s;

      return LOOKUP_VALUE (current_value.m);

    }

  else

    {

      /* It is very tricky. We need to figure out what value to

         return for the protected symbol */

      struct sym_val protected_value = { NULL, NULL };

      if (i >= (*scope)->r_nlist

          || !_dl_do_lookup_versioned (undef_name, hash, *ref,

                                       &protected_value, *scope, i, version,

                                       skip_map, ELF_RTYPE_CLASS_PLT))

        while (*++scope)

          if (_dl_do_lookup_versioned (undef_name, hash, *ref,

                                       &protected_value, *scope, 0, version,

                                       skip_map, ELF_RTYPE_CLASS_PLT))

            break;

      if (protected_value.s == NULL || protected_value.m == undef_map)

        {

          *ref = current_value.s;

          return LOOKUP_VALUE (current_value.m);

        }

      return LOOKUP_VALUE (undef_map);

    }

}

/* Cache the location of MAP's hash table.  */

void

internal_function

_dl_setup_hash (struct link_map *map)

{

  Elf_Symndx *hash;

  Elf_Symndx nchain;

  if (!map->l_info[DT_HASH])

    return;

  hash = (void *)(map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr);

  map->l_nbuckets = *hash++;

  nchain = *hash++;

  map->l_buckets = hash;

  hash += map->l_nbuckets;

  map->l_chain = hash;

}

/* These are here so that we only inline do_lookup{,_versioned} in the common

   case, not everywhere.  */

static int

internal_function

_dl_do_lookup (const char *undef_name, unsigned long int hash,

               const ElfW(Sym) *ref, struct sym_val *result,

               struct r_scope_elem *scope, size_t i,

               struct link_map *skip, int type_class)

{

  return do_lookup (undef_name, hash, ref, result, scope, i, skip,

                    type_class);

}

static int

internal_function

_dl_do_lookup_versioned (const char *undef_name, unsigned long int hash,