dl-object.c

用于嵌入式Linux系统的标准C的库函数

/* Storage management for the chain of loaded shared 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 <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <ldsodefs.h>

#include <assert.h>


/* Allocate a `struct link_map' for a new object being loaded,
   and enter it into the _dl_loaded list.  */

struct link_map *
internal_function
_dl_new_object (char *realname, const char *libname, int type,
		struct link_map *loader)
{
  struct link_map *l;
  int idx;
  size_t libname_len = strlen (libname) + 1;
  struct link_map *new;
  struct libname_list *newname;

  new = (struct link_map *) calloc (sizeof (*new) + sizeof (*newname)
				    + libname_len, 1);
  if (new == NULL)
    return NULL;

  new->l_libname = newname = (struct libname_list *) (new + 1);
  newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  /* newname->next = NULL;	We use calloc therefore not necessary.  */
  newname->dont_free = 1;

  new->l_name = realname;
  new->l_type = type;
  new->l_loader = loader;
  /* new->l_global = 0;	We use calloc therefore not necessary.  */

  /* Use the 'l_scope_mem' array by default for the the 'l_scope'
     information.  If we need more entries we will allocate a large
     array dynamically.  */
  new->l_scope = new->l_scope_mem;
  new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);

  /* Counter for the scopes we have to handle.  */
  idx = 0;

  if (_dl_loaded != NULL)
    {
      l = _dl_loaded;
      while (l->l_next != NULL)
	l = l->l_next;
      new->l_prev = l;
      /* new->l_next = NULL;	Would be necessary but we use calloc.  */
      l->l_next = new;

      /* Add the global scope.  */
      new->l_scope[idx++] = &_dl_loaded->l_searchlist;
    }
  else
    _dl_loaded = new;
  ++_dl_nloaded;

  /* If we have no loader the new object acts as it.  */
  if (loader == NULL)
    loader = new;
  else
    /* Determine the local scope.  */
    while (loader->l_loader != NULL)
      loader = loader->l_loader;

  /* Insert the scope if it isn't the global scope we already added.  */
  if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
    new->l_scope[idx] = &loader->l_searchlist;

  new->l_local_scope[0] = &new->l_searchlist;

  /* Don't try to find the origin for the main map which has the name "".  */
  if (realname[0] != '\0')
    {
      size_t realname_len = strlen (realname) + 1;
      char *origin;
      char *cp;

      if (realname[0] == '/')
	{
	  /* It is an absolute path.  Use it.  But we have to make a
	     copy since we strip out the trailing slash.  */
	  cp = origin = (char *) malloc (realname_len);
	  if (origin == NULL)
	    {
	      origin = (char *) -1;
	      goto out;
	    }
	}
      else
	{
	  size_t len = realname_len;
	  char *result = NULL;

	  /* Get the current directory name.  */
	  origin = NULL;
	  do
	    {
	      len += 128;
	      origin = (char *) realloc (origin, len);
	    }
	  while (origin != NULL
		 && (result = getcwd (origin, len - realname_len)) == NULL
		 && errno == ERANGE);

	  if (result == NULL)
	    {
	      /* We were not able to determine the current directory.
	         Note that free(origin) is OK if origin == NULL.  */
	      free (origin);
	      origin = (char *) -1;
	      goto out;
	    }

	  /* Find the end of the path and see whether we have to add
	     a slash.  */
	  cp = memchr (origin, '\0', strlen(origin));
	  if (cp[-1] != '/')
	    *cp++ = '/';
	}

      /* Add the real file name.  */
      memcpy (cp, realname, realname_len);

      /* Now remove the filename and the slash.  Leave the slash if it
	 the name is something like "/foo".  */
      cp = strrchr (origin, '/');
      if (cp == origin)
	origin[1] = '\0';
      else
	*cp = '\0';

    out:
      new->l_origin = origin;
    }

  return new;
}