nss/nsswitch.c

   1 /* Copyright (C) 1996-1999,2001,2002,2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <ctype.h>
  21 #include <dlfcn.h>
  22 #include <errno.h>
  23 #include <netdb.h>
  24 #include <bits/libc-lock.h>
  25 #include <search.h>
  26 #include <stdio.h>
  27 #include <stdio_ext.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #include <aliases.h>
  32 #include <grp.h>
  33 #include <netinet/ether.h>
  34 #include <pwd.h>
  35 #include <shadow.h>
  36
  37 #if !defined DO_STATIC_NSS || defined SHARED
  38 # include <gnu/lib-names.h>
  39 #endif
  40
  41 #include "nsswitch.h"
  42 #include "../nscd/nscd_proto.h"
  43
  44 /* Prototypes for the local functions.  */
  45 static name_database *nss_parse_file (const char *fname) internal_function;
  46 static name_database_entry *nss_getline (char *line) internal_function;
  47 static service_user *nss_parse_service_list (const char *line)
  48      internal_function;
  49 static service_library *nss_new_service (name_database *database,
  50                                          const char *name) internal_function;
  51
  52
  53 /* Declare external database variables.  */
  54 #define DEFINE_DATABASE(name)                                                 \
  55   extern service_user *__nss_##name##_database attribute_hidden;              \
  56   weak_extern (__nss_##name##_database)
  57 #include "databases.def"
  58 #undef DEFINE_DATABASE
  59
  60 /* Structure to map database name to variable.  */
  61 static struct
  62 {
  63   const char *name;
  64   service_user **dbp;
  65 } databases[] =
  66 {
  67 #define DEFINE_DATABASE(name)                                                 \
  68   { #name, &__nss_##name##_database },
  69 #include "databases.def"
  70 #undef DEFINE_DATABASE
  71 };
  72
  73
  74 __libc_lock_define_initialized (static, lock)
  75
  76 #if !defined DO_STATIC_NSS || defined SHARED
  77 /* String with revision number of the shared object files.  */
  78 static const char *const __nss_shlib_revision = LIBNSS_FILES_SO + 15;
  79 #endif
  80
  81 /* The root of the whole data base.  */
  82 static name_database *service_table;
  83
  84
  85 /* -1 == database not found
  86     0 == database entry pointer stored */
  87 int
  88 __nss_database_lookup (const char *database, const char *alternate_name,
  89                        const char *defconfig, service_user **ni)
  90 {
  91   /* Prevent multiple threads to change the service table.  */
  92   __libc_lock_lock (lock);
  93
  94   /* Reconsider database variable in case some other thread called
  95      `__nss_configure_lookup' while we waited for the lock.  */
  96   if (*ni != NULL)
  97     {
  98       __libc_lock_unlock (lock);
  99       return 0;
 100     }
 101
 102   /* Are we initialized yet?  */
 103   if (service_table == NULL)
 104     /* Read config file.  */
 105     service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
 106
 107   /* Test whether configuration data is available.  */
 108   if (service_table != NULL)
 109     {
 110       /* Return first `service_user' entry for DATABASE.  */
 111       name_database_entry *entry;
 112
 113       /* XXX Could use some faster mechanism here.  But each database is
 114          only requested once and so this might not be critical.  */
 115       for (entry = service_table->entry; entry != NULL; entry = entry->next)
 116         if (strcmp (database, entry->name) == 0)
 117           *ni = entry->service;
 118
 119       if (*ni == NULL && alternate_name != NULL)
 120         /* We haven't found an entry so far.  Try to find it with the
 121            alternative name.  */
 122         for (entry = service_table->entry; entry != NULL; entry = entry->next)
 123           if (strcmp (alternate_name, entry->name) == 0)
 124             *ni = entry->service;
 125     }
 126
 127   /* No configuration data is available, either because nsswitch.conf
 128      doesn't exist or because it doesn't has a line for this database.
 129
 130      DEFCONFIG specifies the default service list for this database,
 131      or null to use the most common default.  */
 132   if (*ni == NULL)
 133     *ni = nss_parse_service_list (defconfig
 134                                   ?: "nis [NOTFOUND=return] files");
 135
 136   __libc_lock_unlock (lock);
 137
 138   return 0;
 139 }
 140 libc_hidden_def (__nss_database_lookup)
 141
 142
 143 /* -1 == not found
 144     0 == function found
 145     1 == finished */
 146 int
 147 __nss_lookup (service_user **ni, const char *fct_name, void **fctp)
 148 {
 149   *fctp = __nss_lookup_function (*ni, fct_name);
 150
 151   while (*fctp == NULL
 152          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 153          && (*ni)->next != NULL)
 154     {
 155       *ni = (*ni)->next;
 156
 157       *fctp = __nss_lookup_function (*ni, fct_name);
 158     }
 159
 160   return *fctp != NULL ? 0 : (*ni)->next == NULL ? 1 : -1;
 161 }
 162
 163
 164 /* -1 == not found
 165     0 == adjusted for next function
 166     1 == finished */
 167 int
 168 __nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
 169             int all_values)
 170 {
 171   if (all_values)
 172     {
 173       if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
 174           && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
 175           && nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
 176           && nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
 177         return 1;
 178     }
 179   else
 180     {
 181       /* This is really only for debugging.  */
 182        if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 183          __libc_fatal ("illegal status in __nss_next");
 184
 185        if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
 186          return 1;
 187     }
 188
 189   if ((*ni)->next == NULL)
 190     return -1;
 191
 192   do
 193     {
 194       *ni = (*ni)->next;
 195
 196       *fctp = __nss_lookup_function (*ni, fct_name);
 197     }
 198   while (*fctp == NULL
 199          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 200          && (*ni)->next != NULL);
 201
 202   return *fctp != NULL ? 0 : -1;
 203 }
 204 libc_hidden_def (__nss_next)
 205
 206
 207 int
 208 __nss_configure_lookup (const char *dbname, const char *service_line)
 209 {
 210   service_user *new_db;
 211   size_t cnt;
 212
 213   for (cnt = 0; cnt < sizeof databases; ++cnt)
 214     {
 215       int cmp = strcmp (dbname, databases[cnt].name);
 216       if (cmp == 0)
 217         break;
 218       if (cmp < 0)
 219         {
 220           __set_errno (EINVAL);
 221           return -1;
 222         }
 223     }
 224
 225   if (cnt == sizeof databases)
 226     {
 227       __set_errno (EINVAL);
 228       return -1;
 229     }
 230
 231   /* Test whether it is really used.  */
 232   if (databases[cnt].dbp == NULL)
 233     /* Nothing to do, but we could do.  */
 234     return 0;
 235
 236   /* Try to generate new data.  */
 237   new_db = nss_parse_service_list (service_line);
 238   if (new_db == NULL)
 239     {
 240       /* Illegal service specification.  */
 241       __set_errno (EINVAL);
 242       return -1;
 243     }
 244
 245   /* Prevent multiple threads to change the service table.  */
 246   __libc_lock_lock (lock);
 247
 248   /* Install new rules.  */
 249   *databases[cnt].dbp = new_db;
 250
 251   __libc_lock_unlock (lock);
 252
 253   return 0;
 254 }
 255
 256
 257 /* Comparison function for searching NI->known tree.  */
 258 static int
 259 known_compare (const void *p1, const void *p2)
 260 {
 261   return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
 262                                 *(const char *const *) p2);
 263 }
 264
 265
 266 void *
 267 __nss_lookup_function (service_user *ni, const char *fct_name)
 268 {
 269   void **found, *result;
 270
 271   /* We now modify global data.  Protect it.  */
 272   __libc_lock_lock (lock);
 273
 274   /* Search the tree of functions previously requested.  Data in the
 275      tree are `known_function' structures, whose first member is a
 276      `const char *', the lookup key.  The search returns a pointer to
 277      the tree node structure; the first member of the is a pointer to
 278      our structure (i.e. what will be a `known_function'); since the
 279      first member of that is the lookup key string, &FCT_NAME is close
 280      enough to a pointer to our structure to use as a lookup key that
 281      will be passed to `known_compare' (above).  */
 282
 283   found = __tsearch (&fct_name, (void **) &ni->known, &known_compare);
 284   if (*found != &fct_name)
 285     /* The search found an existing structure in the tree.  */
 286     result = ((known_function *) *found)->fct_ptr;
 287   else
 288     {
 289       /* This name was not known before.  Now we have a node in the tree
 290          (in the proper sorted position for FCT_NAME) that points to
 291          &FCT_NAME instead of any real `known_function' structure.
 292          Allocate a new structure and fill it in.  */
 293
 294       known_function *known = malloc (sizeof *known);
 295       if (! known)
 296         {
 297         remove_from_tree:
 298           /* Oops.  We can't instantiate this node properly.
 299              Remove it from the tree.  */
 300           __tdelete (&fct_name, (void **) &ni->known, &known_compare);
 301           result = NULL;
 302         }
 303       else
 304         {
 305           /* Point the tree node at this new structure.  */
 306           *found = known;
 307           known->fct_name = fct_name;
 308
 309           if (ni->library == NULL)
 310             {
 311               /* This service has not yet been used.  Fetch the service
 312                  library for it, creating a new one if need be.  If there
 313                  is no service table from the file, this static variable
 314                  holds the head of the service_library list made from the
 315                  default configuration.  */
 316               static name_database default_table;
 317               ni->library = nss_new_service (service_table ?: &default_table,
 318                                              ni->name);
 319               if (ni->library == NULL)
 320                 {
 321                   /* This only happens when out of memory.  */
 322                   free (known);
 323                   goto remove_from_tree;
 324                 }
 325             }
 326
 327 #if !defined DO_STATIC_NSS || defined SHARED
 328           if (ni->library->lib_handle == NULL)
 329             {
 330               /* Load the shared library.  */
 331               size_t shlen = (7 + strlen (ni->library->name) + 3
 332                               + strlen (__nss_shlib_revision) + 1);
 333               int saved_errno = errno;
 334               char shlib_name[shlen];
 335
 336               /* Construct shared object name.  */
 337               __stpcpy (__stpcpy (__stpcpy (__stpcpy (shlib_name,
 338                                                       "libnss_"),
 339                                             ni->library->name),
 340                                   ".so"),
 341                         __nss_shlib_revision);
 342
 343               ni->library->lib_handle = __libc_dlopen (shlib_name);
 344               if (ni->library->lib_handle == NULL)
 345                 {
 346                   /* Failed to load the library.  */
 347                   ni->library->lib_handle = (void *) -1l;
 348                   __set_errno (saved_errno);
 349                 }
 350             }
 351
 352           if (ni->library->lib_handle == (void *) -1l)
 353             /* Library not found => function not found.  */
 354             result = NULL;
 355           else
 356             {
 357               /* Get the desired function.  */
 358               size_t namlen = (5 + strlen (ni->library->name) + 1
 359                                + strlen (fct_name) + 1);
 360               char name[namlen];
 361
 362               /* Construct the function name.  */
 363               __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
 364                                             ni->library->name),
 365                                   "_"),
 366                         fct_name);
 367
 368               /* Look up the symbol.  */
 369               result = __libc_dlsym (ni->library->lib_handle, name);
 370             }
 371 #else
 372           /* We can't get function address dynamically in static linking. */
 373           {
 374 # define DEFINE_ENT(h,nm)                                                     \
 375             { #h"_get"#nm"ent_r", _nss_##h##_get##nm##ent_r },                \
 376             { #h"_end"#nm"ent", _nss_##h##_end##nm##ent },                    \
 377             { #h"_set"#nm"ent", _nss_##h##_set##nm##ent },
 378 # define DEFINE_GET(h,nm)                                                     \
 379             { #h"_get"#nm"_r", _nss_##h##_get##nm##_r },
 380 # define DEFINE_GETBY(h,nm,ky)                                                \
 381             { #h"_get"#nm"by"#ky"_r", _nss_##h##_get##nm##by##ky##_r },
 382             static struct fct_tbl { const char *fname; void *fp; } *tp, tbl[] =
 383               {
 384 # include "function.def"
 385                 { NULL, NULL }
 386               };
 387             size_t namlen = (5 + strlen (ni->library->name) + 1
 388                              + strlen (fct_name) + 1);
 389             char name[namlen];
 390
 391             /* Construct the function name.  */
 392             __stpcpy (__stpcpy (__stpcpy (name, ni->library->name),
 393                                 "_"),
 394                       fct_name);
 395
 396             result = NULL;
 397             for (tp = &tbl[0]; tp->fname; tp++)
 398               if (strcmp (tp->fname, name) == 0)
 399                 {
 400                   result = tp->fp;
 401                   break;
 402                 }
 403           }
 404 #endif
 405
 406           /* Remember function pointer for later calls.  Even if null, we
 407              record it so a second try needn't search the library again.  */
 408           known->fct_ptr = result;
 409         }
 410     }
 411
 412   /* Remove the lock.  */
 413   __libc_lock_unlock (lock);
 414
 415   return result;
 416 }
 417
 418
 419 static name_database *
 420 internal_function
 421 nss_parse_file (const char *fname)
 422 {
 423   FILE *fp;
 424   name_database *result;
 425   name_database_entry *last;
 426   char *line;
 427   size_t len;
 428
 429   /* Open the configuration file.  */
 430   fp = fopen (fname, "r");
 431   if (fp == NULL)
 432     return NULL;
 433
 434   /* No threads use this stream.  */
 435   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 436
 437   result = (name_database *) malloc (sizeof (name_database));
 438   if (result == NULL)
 439     return NULL;
 440
 441   result->entry = NULL;
 442   result->library = NULL;
 443   last = NULL;
 444   line = NULL;
 445   len = 0;
 446   do
 447     {
 448       name_database_entry *this;
 449       ssize_t n;
 450
 451       n = __getline (&line, &len, fp);
 452       if (n < 0)
 453         break;
 454       if (line[n - 1] == '\n')
 455         line[n - 1] = '\0';
 456
 457       /* Because the file format does not know any form of quoting we
 458          can search forward for the next '#' character and if found
 459          make it terminating the line.  */
 460       *__strchrnul (line, '#') = '\0';
 461
 462       /* If the line is blank it is ignored.  */
 463       if (line[0] == '\0')
 464         continue;
 465
 466       /* Each line completely specifies the actions for a database.  */
 467       this = nss_getline (line);
 468       if (this != NULL)
 469         {
 470           if (last != NULL)
 471             last->next = this;
 472           else
 473             result->entry = this;
 474
 475           last = this;
 476         }
 477     }
 478   while (!feof_unlocked (fp));
 479
 480   /* Free the buffer.  */
 481   free (line);
 482   /* Close configuration file.  */
 483   fclose (fp);
 484
 485   return result;
 486 }
 487
 488
 489 /* Read the source names:
 490         `( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
 491    */
 492 static service_user *
 493 internal_function
 494 nss_parse_service_list (const char *line)
 495 {
 496   service_user *result = NULL, **nextp = &result;
 497
 498   while (1)
 499     {
 500       service_user *new_service;
 501       const char *name;
 502
 503       while (isspace (line[0]))
 504         ++line;
 505       if (line[0] == '\0')
 506         /* No source specified.  */
 507         return result;
 508
 509       /* Read <source> identifier.  */
 510       name = line;
 511       while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
 512         ++line;
 513       if (name == line)
 514         return result;
 515
 516
 517       new_service = (service_user *) malloc (sizeof (service_user)
 518                                              + (line - name + 1));
 519       if (new_service == NULL)
 520         return result;
 521
 522       *((char *) __mempcpy (new_service->name, name, line - name)) = '\0';
 523
 524       /* Set default actions.  */
 525       new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
 526       new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
 527       new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
 528       new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
 529       new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
 530       new_service->library = NULL;
 531       new_service->known = NULL;
 532       new_service->next = NULL;
 533
 534       while (isspace (line[0]))
 535         ++line;
 536
 537       if (line[0] == '[')
 538         {
 539           /* Read criterions.  */
 540           do
 541             ++line;
 542           while (line[0] != '\0' && isspace (line[0]));
 543
 544           do
 545             {
 546               int not;
 547               enum nss_status status;
 548               lookup_actions action;
 549
 550               /* Grok ! before name to mean all statii but that one.  */
 551               not = line[0] == '!';
 552               if (not)
 553                 ++line;
 554
 555               /* Read status name.  */
 556               name = line;
 557               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 558                      && line[0] != ']')
 559                 ++line;
 560
 561               /* Compare with known statii.  */
 562               if (line - name == 7)
 563                 {
 564                   if (__strncasecmp (name, "SUCCESS", 7) == 0)
 565                     status = NSS_STATUS_SUCCESS;
 566                   else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
 567                     status = NSS_STATUS_UNAVAIL;
 568                   else
 569                     return result;
 570                 }
 571               else if (line - name == 8)
 572                 {
 573                   if (__strncasecmp (name, "NOTFOUND", 8) == 0)
 574                     status = NSS_STATUS_NOTFOUND;
 575                   else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
 576                     status = NSS_STATUS_TRYAGAIN;
 577                   else
 578                     return result;
 579                 }
 580               else
 581                 return result;
 582
 583               while (isspace (line[0]))
 584                 ++line;
 585               if (line[0] != '=')
 586                 return result;
 587               do
 588                 ++line;
 589               while (isspace (line[0]));
 590
 591               name = line;
 592               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 593                      && line[0] != ']')
 594                 ++line;
 595
 596               if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
 597                 action = NSS_ACTION_RETURN;
 598               else if (line - name == 8
 599                        && __strncasecmp (name, "CONTINUE", 8) == 0)
 600                 action = NSS_ACTION_CONTINUE;
 601               else
 602                 return result;
 603
 604               if (not)
 605                 {
 606                   /* Save the current action setting for this status,
 607                      set them all to the given action, and reset this one.  */
 608                   const lookup_actions save = new_service->actions[2 + status];
 609                   new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
 610                   new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
 611                   new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
 612                   new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
 613                   new_service->actions[2 + status] = save;
 614                 }
 615               else
 616                 new_service->actions[2 + status] = action;
 617
 618               /* Skip white spaces.  */
 619               while (isspace (line[0]))
 620                 ++line;
 621             }
 622           while (line[0] != ']');
 623
 624           /* Skip the ']'.  */
 625           ++line;
 626         }
 627
 628       *nextp = new_service;
 629       nextp = &new_service->next;
 630     }
 631 }
 632
 633 static name_database_entry *
 634 internal_function
 635 nss_getline (char *line)
 636 {
 637   const char *name;
 638   name_database_entry *result;
 639   size_t len;
 640
 641   /* Ignore leading white spaces.  ATTENTION: this is different from
 642      what is implemented in Solaris.  The Solaris man page says a line
 643      beginning with a white space character is ignored.  We regard
 644      this as just another misfeature in Solaris.  */
 645   while (isspace (line[0]))
 646     ++line;
 647
 648   /* Recognize `<database> ":"'.  */
 649   name = line;
 650   while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
 651     ++line;
 652   if (line[0] == '\0' || name == line)
 653     /* Syntax error.  */
 654     return NULL;
 655   *line++ = '\0';
 656
 657   len = strlen (name) + 1;
 658
 659   result = (name_database_entry *) malloc (sizeof (name_database_entry) + len);
 660   if (result == NULL)
 661     return NULL;
 662
 663   /* Save the database name.  */
 664   memcpy (result->name, name, len);
 665
 666   /* Parse the list of services.  */
 667   result->service = nss_parse_service_list (line);
 668
 669   result->next = NULL;
 670   return result;
 671 }
 672
 673
 674 static service_library *
 675 internal_function
 676 nss_new_service (name_database *database, const char *name)
 677 {
 678   service_library **currentp = &database->library;
 679
 680   while (*currentp != NULL)
 681     {
 682       if (strcmp ((*currentp)->name, name) == 0)
 683         return *currentp;
 684       currentp = &(*currentp)->next;
 685     }
 686
 687   /* We have to add the new service.  */
 688   *currentp = (service_library *) malloc (sizeof (service_library));
 689   if (*currentp == NULL)
 690     return NULL;
 691
 692   (*currentp)->name = name;
 693   (*currentp)->lib_handle = NULL;
 694   (*currentp)->next = NULL;
 695
 696   return *currentp;
 697 }
 698
 699
 700 /* Called by nscd and nscd alone.  */
 701 void
 702 __nss_disable_nscd (void)
 703 {
 704   /* Disable all uses of NSCD.  */
 705   __nss_not_use_nscd_passwd = -1;
 706   __nss_not_use_nscd_group = -1;
 707   __nss_not_use_nscd_hosts = -1;
 708 }
 709
 710
 711 /* Free all resources if necessary.  */
 712 libc_freeres_fn (free_mem)
 713 {
 714   name_database *top = service_table;
 715   name_database_entry *entry;
 716   service_library *library;
 717
 718   if (top == NULL)
 719     /* Maybe we have not read the nsswitch.conf file.  */
 720     return;
 721
 722   /* Don't disturb ongoing other threads (if there are any).  */
 723   service_table = NULL;
 724
 725   entry = top->entry;
 726   while (entry != NULL)
 727     {
 728       name_database_entry *olde = entry;
 729       service_user *service = entry->service;
 730
 731       while (service != NULL)
 732         {
 733           service_user *olds = service;
 734
 735           if (service->known != NULL)
 736             __tdestroy (service->known, free);
 737
 738           service = service->next;
 739           free (olds);
 740         }
 741
 742       entry = entry->next;
 743       free (olde);
 744     }
 745
 746   library = top->library;
 747   while (library != NULL)
 748     {
 749       service_library *oldl = library;
 750
 751       __libc_dlclose (library->lib_handle);
 752
 753       library = library->next;
 754       free (oldl);
 755     }
 756
 757   free (top);
 758 }