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glibc  2.9
Classes | Defines | Functions
dl-deps.c File Reference
#include <atomic.h>
#include <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <libintl.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <dl-dst.h>

Go to the source code of this file.

Classes

struct  openaux_args
struct  list

Defines

#define AUXTAG
#define FILTERTAG
#define expand_dst(l, str, fatal)

Functions

static void openaux (void *a)
static ptrdiff_t internal_function _dl_build_local_scope (struct link_map **list, struct link_map *map)
void internal_function _dl_map_object_deps (struct link_map *map, struct link_map **preloads, unsigned int npreloads, int trace_mode, int open_mode)

Class Documentation

struct openaux_args

Definition at line 47 of file dl-deps.c.

Collaboration diagram for openaux_args:
Class Members
struct link_map * aux
struct link_map * map
const char * name
int open_mode
const char * strtab
int trace_mode
struct list

Definition at line 93 of file dl-deps.c.

Collaboration diagram for list:
Class Members
int done
struct link_map * map
struct list * next
definition * val

Define Documentation

#define AUXTAG
Value:

Definition at line 37 of file dl-deps.c.

#define expand_dst (   l,
  str,
  fatal 
)

Definition at line 102 of file dl-deps.c.

#define FILTERTAG
Value:

Definition at line 41 of file dl-deps.c.


Function Documentation

static ptrdiff_t internal_function _dl_build_local_scope ( struct link_map **  list,
struct link_map map 
) [static]

Definition at line 74 of file dl-deps.c.

{
  struct link_map **p = list;
  struct link_map **q;

  *p++ = map;
  map->l_reserved = 1;
  if (map->l_initfini)
    for (q = map->l_initfini + 1; *q; ++q)
      if (! (*q)->l_reserved)
       p += _dl_build_local_scope (p, *q);
  return p - list;
}

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void internal_function _dl_map_object_deps ( struct link_map map,
struct link_map **  preloads,
unsigned int  npreloads,
int  trace_mode,
int  open_mode 
)

Definition at line 145 of file dl-deps.c.

{
  struct list *known = __alloca (sizeof *known * (1 + npreloads + 1));
  struct list *runp, *tail;
  unsigned int nlist, i;
  /* Object name.  */
  const char *name;
  int errno_saved;
  int errno_reason;
  const char *errstring;
  const char *objname;

  auto inline void preload (struct link_map *map);

  inline void preload (struct link_map *map)
    {
      known[nlist].done = 0;
      known[nlist].map = map;
      known[nlist].next = &known[nlist + 1];

      ++nlist;
      /* We use `l_reserved' as a mark bit to detect objects we have
        already put in the search list and avoid adding duplicate
        elements later in the list.  */
      map->l_reserved = 1;
    }

  /* No loaded object so far.  */
  nlist = 0;

  /* First load MAP itself.  */
  preload (map);

  /* Add the preloaded items after MAP but before any of its dependencies.  */
  for (i = 0; i < npreloads; ++i)
    preload (preloads[i]);

  /* Terminate the lists.  */
  known[nlist - 1].next = NULL;

  /* Pointer to last unique object.  */
  tail = &known[nlist - 1];

  /* Process each element of the search list, loading each of its
     auxiliary objects and immediate dependencies.  Auxiliary objects
     will be added in the list before the object itself and
     dependencies will be appended to the list as we step through it.
     This produces a flat, ordered list that represents a
     breadth-first search of the dependency tree.

     The whole process is complicated by the fact that we better
     should use alloca for the temporary list elements.  But using
     alloca means we cannot use recursive function calls.  */
  errno_saved = errno;
  errno_reason = 0;
  errstring = NULL;
  errno = 0;
  name = NULL;
  for (runp = known; runp; )
    {
      struct link_map *l = runp->map;
      struct link_map **needed = NULL;
      unsigned int nneeded = 0;

      /* Unless otherwise stated, this object is handled.  */
      runp->done = 1;

      /* Allocate a temporary record to contain the references to the
        dependencies of this object.  */
      if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL
         && l != map && l->l_ldnum > 0)
       needed = (struct link_map **) alloca (l->l_ldnum
                                         * sizeof (struct link_map *));

      if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
       {
         const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
         struct openaux_args args;
         struct list *orig;
         const ElfW(Dyn) *d;

         args.strtab = strtab;
         args.map = l;
         args.trace_mode = trace_mode;
         args.open_mode = open_mode;
         orig = runp;

         for (d = l->l_ld; d->d_tag != DT_NULL; ++d)
           if (__builtin_expect (d->d_tag, DT_NEEDED) == DT_NEEDED)
             {
              /* Map in the needed object.  */
              struct link_map *dep;

              /* Recognize DSTs.  */
              name = expand_dst (l, strtab + d->d_un.d_val, 0);
              /* Store the tag in the argument structure.  */
              args.name = name;

              bool malloced;
              int err = _dl_catch_error (&objname, &errstring, &malloced,
                                      openaux, &args);
              if (__builtin_expect (errstring != NULL, 0))
                {
                  char *new_errstring = strdupa (errstring);
                  objname = strdupa (objname);
                  if (malloced)
                    free ((char *) errstring);
                  errstring = new_errstring;

                  if (err)
                    errno_reason = err;
                  else
                    errno_reason = -1;
                  goto out;
                }
              else
                dep = args.aux;

              if (! dep->l_reserved)
                {
                  /* Allocate new entry.  */
                  struct list *newp;

                  newp = alloca (sizeof (struct list));

                  /* Append DEP to the list.  */
                  newp->map = dep;
                  newp->done = 0;
                  newp->next = NULL;
                  tail->next = newp;
                  tail = newp;
                  ++nlist;
                  /* Set the mark bit that says it's already in the list.  */
                  dep->l_reserved = 1;
                }

              /* Remember this dependency.  */
              if (needed != NULL)
                needed[nneeded++] = dep;
             }
           else if (d->d_tag == DT_AUXILIARY || d->d_tag == DT_FILTER)
             {
              struct list *newp;

              /* Recognize DSTs.  */
              name = expand_dst (l, strtab + d->d_un.d_val,
                               d->d_tag == DT_AUXILIARY);
              /* Store the tag in the argument structure.  */
              args.name = name;

              if (d->d_tag == DT_AUXILIARY)
                {
                  /* Say that we are about to load an auxiliary library.  */
                  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS,
                                     0))
                    _dl_debug_printf ("load auxiliary object=%s"
                                   " requested by file=%s\n",
                                   name,
                                   l->l_name[0]
                                   ? l->l_name : rtld_progname);

                  /* We must be prepared that the addressed shared
                     object is not available.  */
                  bool malloced;
                  (void) _dl_catch_error (&objname, &errstring, &malloced,
                                       openaux, &args);
                  if (__builtin_expect (errstring != NULL, 0))
                    {
                     /* We are not interested in the error message.  */
                     assert (errstring != NULL);
                     if (malloced)
                       free ((char *) errstring);

                     /* Simply ignore this error and continue the work.  */
                     continue;
                    }
                }
              else
                {
                  /* Say that we are about to load an auxiliary library.  */
                  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS,
                                     0))
                    _dl_debug_printf ("load filtered object=%s"
                                   " requested by file=%s\n",
                                   name,
                                   l->l_name[0]
                                   ? l->l_name : rtld_progname);

                  /* For filter objects the dependency must be available.  */
                  bool malloced;
                  int err = _dl_catch_error (&objname, &errstring, &malloced,
                                          openaux, &args);
                  if (__builtin_expect (errstring != NULL, 0))
                    {
                     char *new_errstring = strdupa (errstring);
                     objname = strdupa (objname);
                     if (malloced)
                       free ((char *) errstring);
                     errstring = new_errstring;

                     if (err)
                       errno_reason = err;
                     else
                       errno_reason = -1;
                     goto out;
                    }
                }

              /* The auxiliary object is actually available.
                 Incorporate the map in all the lists.  */

              /* Allocate new entry.  This always has to be done.  */
              newp = alloca (sizeof (struct list));

              /* We want to insert the new map before the current one,
                 but we have no back links.  So we copy the contents of
                 the current entry over.  Note that ORIG and NEWP now
                 have switched their meanings.  */
              memcpy (newp, orig, sizeof (*newp));

              /* Initialize new entry.  */
              orig->done = 0;
              orig->map = args.aux;

              /* Remember this dependency.  */
              if (needed != NULL)
                needed[nneeded++] = args.aux;

              /* We must handle two situations here: the map is new,
                 so we must add it in all three lists.  If the map
                 is already known, we have two further possibilities:
                 - if the object is before the current map in the
                 search list, we do nothing.  It is already found
                 early
                 - if the object is after the current one, we must
                 move it just before the current map to make sure
                 the symbols are found early enough
              */
              if (args.aux->l_reserved)
                {
                  /* The object is already somewhere in the list.
                     Locate it first.  */
                  struct list *late;

                  /* This object is already in the search list we
                     are building.  Don't add a duplicate pointer.
                     Just added by _dl_map_object.  */
                  for (late = newp; late->next != NULL; late = late->next)
                    if (late->next->map == args.aux)
                     break;

                  if (late->next != NULL)
                    {
                     /* The object is somewhere behind the current
                        position in the search path.  We have to
                        move it to this earlier position.  */
                     orig->next = newp;

                     /* Now remove the later entry from the list
                        and adjust the tail pointer.  */
                     if (tail == late->next)
                       tail = late;
                     late->next = late->next->next;

                     /* We must move the object earlier in the chain.  */
                     if (args.aux->l_prev != NULL)
                       args.aux->l_prev->l_next = args.aux->l_next;
                     if (args.aux->l_next != NULL)
                       args.aux->l_next->l_prev = args.aux->l_prev;

                     args.aux->l_prev = newp->map->l_prev;
                     newp->map->l_prev = args.aux;
                     if (args.aux->l_prev != NULL)
                       args.aux->l_prev->l_next = args.aux;
                     args.aux->l_next = newp->map;
                    }
                  else
                    {
                     /* The object must be somewhere earlier in the
                        list.  Undo to the current list element what
                        we did above.  */
                     memcpy (orig, newp, sizeof (*newp));
                     continue;
                    }
                }
              else
                {
                  /* This is easy.  We just add the symbol right here.  */
                  orig->next = newp;
                  ++nlist;
                  /* Set the mark bit that says it's already in the list.  */
                  args.aux->l_reserved = 1;

                  /* The only problem is that in the double linked
                     list of all objects we don't have this new
                     object at the correct place.  Correct this here.  */
                  if (args.aux->l_prev)
                    args.aux->l_prev->l_next = args.aux->l_next;
                  if (args.aux->l_next)
                    args.aux->l_next->l_prev = args.aux->l_prev;

                  args.aux->l_prev = newp->map->l_prev;
                  newp->map->l_prev = args.aux;
                  if (args.aux->l_prev != NULL)
                    args.aux->l_prev->l_next = args.aux;
                  args.aux->l_next = newp->map;
                }

              /* Move the tail pointer if necessary.  */
              if (orig == tail)
                tail = newp;

              /* Move on the insert point.  */
              orig = newp;
             }
       }

      /* Terminate the list of dependencies and store the array address.  */
      if (needed != NULL)
       {
         needed[nneeded++] = NULL;

         struct link_map **l_initfini = (struct link_map **)
           malloc ((2 * nneeded + 1) * sizeof needed[0]);
         if (l_initfini == NULL)
           _dl_signal_error (ENOMEM, map->l_name, NULL,
                           N_("cannot allocate dependency list"));
         l_initfini[0] = l;
         memcpy (&l_initfini[1], needed, nneeded * sizeof needed[0]);
         memcpy (&l_initfini[nneeded + 1], l_initfini,
                nneeded * sizeof needed[0]);
         atomic_write_barrier ();
         l->l_initfini = l_initfini;
       }

      /* If we have no auxiliary objects just go on to the next map.  */
      if (runp->done)
       do
         runp = runp->next;
       while (runp != NULL && runp->done);
    }

 out:
  if (errno == 0 && errno_saved != 0)
    __set_errno (errno_saved);

  struct link_map **old_l_initfini = NULL;
  if (map->l_initfini != NULL && map->l_type == lt_loaded)
    {
      /* This object was previously loaded as a dependency and we have
        a separate l_initfini list.  We don't need it anymore.  */
      assert (map->l_searchlist.r_list == NULL);
      old_l_initfini = map->l_initfini;
    }

  /* Store the search list we built in the object.  It will be used for
     searches in the scope of this object.  */
  struct link_map **l_initfini =
    (struct link_map **) malloc ((2 * nlist + 1)
                             * sizeof (struct link_map *));
  if (l_initfini == NULL)
    _dl_signal_error (ENOMEM, map->l_name, NULL,
                    N_("cannot allocate symbol search list"));


  map->l_searchlist.r_list = &l_initfini[nlist + 1];
  map->l_searchlist.r_nlist = nlist;

  for (nlist = 0, runp = known; runp; runp = runp->next)
    {
      if (__builtin_expect (trace_mode, 0) && runp->map->l_faked)
       /* This can happen when we trace the loading.  */
       --map->l_searchlist.r_nlist;
      else
       map->l_searchlist.r_list[nlist++] = runp->map;

      /* Now clear all the mark bits we set in the objects on the search list
        to avoid duplicates, so the next call starts fresh.  */
      runp->map->l_reserved = 0;
    }

  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK, 0) != 0
      && map == GL(dl_ns)[LM_ID_BASE]._ns_loaded)
    {
      /* If we are to compute conflicts, we have to build local scope
        for each library, not just the ultimate loader.  */
      for (i = 0; i < nlist; ++i)
       {
         struct link_map *l = map->l_searchlist.r_list[i];
         unsigned int j, cnt;

         /* The local scope has been already computed.  */
         if (l == map
             || (l->l_local_scope[0]
                && l->l_local_scope[0]->r_nlist) != 0)
           continue;

         if (l->l_info[AUXTAG] || l->l_info[FILTERTAG])
           {
             /* As current DT_AUXILIARY/DT_FILTER implementation needs to be
               rewritten, no need to bother with prelinking the old
               implementation.  */
             _dl_signal_error (EINVAL, l->l_name, NULL, N_("\
Filters not supported with LD_TRACE_PRELINKING"));
           }

         cnt = _dl_build_local_scope (l_initfini, l);
         assert (cnt <= nlist);
         for (j = 0; j < cnt; j++)
           l_initfini[j]->l_reserved = 0;

         l->l_local_scope[0] =
           (struct r_scope_elem *) malloc (sizeof (struct r_scope_elem)
                                       + (cnt
                                          * sizeof (struct link_map *)));
         if (l->l_local_scope[0] == NULL)
           _dl_signal_error (ENOMEM, map->l_name, NULL,
                           N_("cannot allocate symbol search list"));
         l->l_local_scope[0]->r_nlist = cnt;
         l->l_local_scope[0]->r_list =
           (struct link_map **) (l->l_local_scope[0] + 1);
         memcpy (l->l_local_scope[0]->r_list, l_initfini,
                cnt * sizeof (struct link_map *));
       }
    }

  /* Maybe we can remove some relocation dependencies now.  */
  assert (map->l_searchlist.r_list[0] == map);
  struct link_map_reldeps *l_reldeps = NULL;
  if (map->l_reldeps != NULL)
    {
      for (i = 1; i < nlist; ++i)
       map->l_searchlist.r_list[i]->l_reserved = 1;

      struct link_map **list = &map->l_reldeps->list[0];
      for (i = 0; i < map->l_reldeps->act; ++i)
       if (list[i]->l_reserved)
         {
           /* Need to allocate new array of relocation dependencies.  */
           struct link_map_reldeps *l_reldeps;
           l_reldeps = malloc (sizeof (*l_reldeps)
                            + map->l_reldepsmax
                              * sizeof (struct link_map *));
           if (l_reldeps == NULL)
             /* Bad luck, keep the reldeps duplicated between
               map->l_reldeps->list and map->l_initfini lists.  */
             ;
           else
             {
              unsigned int j = i;
              memcpy (&l_reldeps->list[0], &list[0],
                     i * sizeof (struct link_map *));
              for (i = i + 1; i < map->l_reldeps->act; ++i)
                if (!list[i]->l_reserved)
                  l_reldeps->list[j++] = list[i];
              l_reldeps->act = j;
             }
         }

      for (i = 1; i < nlist; ++i)
       map->l_searchlist.r_list[i]->l_reserved = 0;
    }

  /* Now determine the order in which the initialization has to happen.  */
  memcpy (l_initfini, map->l_searchlist.r_list,
         nlist * sizeof (struct link_map *));
  /* We can skip looking for the binary itself which is at the front
     of the search list.  Look through the list backward so that circular
     dependencies are not changing the order.  */
  for (i = 1; i < nlist; ++i)
    {
      struct link_map *l = map->l_searchlist.r_list[i];
      unsigned int j;
      unsigned int k;

      /* Find the place in the initfini list where the map is currently
        located.  */
      for (j = 1; l_initfini[j] != l; ++j)
       ;

      /* Find all object for which the current one is a dependency and
        move the found object (if necessary) in front.  */
      for (k = j + 1; k < nlist; ++k)
       {
         struct link_map **runp;

         runp = l_initfini[k]->l_initfini;
         if (runp != NULL)
           {
             while (*runp != NULL)
              if (__builtin_expect (*runp++ == l, 0))
                {
                  struct link_map *here = l_initfini[k];

                  /* Move it now.  */
                  memmove (&l_initfini[j] + 1, &l_initfini[j],
                          (k - j) * sizeof (struct link_map *));
                  l_initfini[j] = here;

                  /* Don't insert further matches before the last
                     entry moved to the front.  */
                  ++j;

                  break;
                }
           }
       }
    }
  /* Terminate the list of dependencies.  */
  l_initfini[nlist] = NULL;
  atomic_write_barrier ();
  map->l_initfini = l_initfini;
  if (l_reldeps != NULL)
    {
      atomic_write_barrier ();
      void *old_l_reldeps = map->l_reldeps;
      map->l_reldeps = l_reldeps;
      _dl_scope_free (old_l_reldeps);
    }
  if (old_l_initfini != NULL)
    _dl_scope_free (old_l_initfini);

  if (errno_reason)
    _dl_signal_error (errno_reason == -1 ? 0 : errno_reason, objname,
                    NULL, errstring);

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static void openaux ( void *  a) [static]

Definition at line 61 of file dl-deps.c.

{
  struct openaux_args *args = (struct openaux_args *) a;

  args->aux = _dl_map_object (args->map, args->name, 0,
                           (args->map->l_type == lt_executable
                            ? lt_library : args->map->l_type),
                           args->trace_mode, args->open_mode,
                           args->map->l_ns);
}

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