elf/dl-error.c

   1 /* Error handling for runtime dynamic linker.
   2    Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <setjmp.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <elf/ldsodefs.h>
  25 #include <bits/libc-tsd.h>
  26
  27 /* This structure communicates state between _dl_catch_error and
  28    _dl_signal_error.  */
  29 struct catch
  30   {
  31     char *errstring;            /* Error detail filled in here.  */
  32     jmp_buf env;                /* longjmp here on error.  */
  33   };
  34
  35 /* Multiple threads at once can use the `_dl_catch_error' function.  The
  36    calls can come from `_dl_map_object_deps', `_dlerror_run', or from
  37    any of the libc functionality which loads dynamic objects (NSS, iconv).
  38    Therefore we have to be prepared to save the state in thread-local
  39    memory.  */
  40
  41 __libc_tsd_define (static, DL_ERROR)
  42 #define tsd_getspecific()       __libc_tsd_get (DL_ERROR)
  43 #define tsd_setspecific(data)   __libc_tsd_set (DL_ERROR, (data))
  44
  45
  46 /* This points to a function which is called when an error is
  47    received.  Unlike the handling of `catch' this function may return.
  48    The arguments will be the `errstring' and `objname'.
  49
  50    Since this functionality is not used in normal programs (only in ld.so)
  51    we do not care about multi-threaded programs here.  We keep this as a
  52    global variable.  */
  53 static receiver_fct receiver;
  54
  55
  56 void
  57 internal_function
  58 _dl_signal_error (int errcode,
  59                   const char *objname,
  60                   const char *errstring)
  61 {
  62   struct catch *lcatch;
  63
  64   if (! errstring)
  65     errstring = "DYNAMIC LINKER BUG!!!";
  66
  67   lcatch = tsd_getspecific ();
  68   if (lcatch != NULL)
  69     {
  70       /* We are inside _dl_catch_error.  Return to it.  We have to
  71          duplicate the error string since it might be allocated on the
  72          stack.  */
  73       size_t objname_len = objname ? strlen (objname) + 2 : 0;
  74       size_t errstring_len = strlen (errstring) + 1;
  75       lcatch->errstring = malloc (objname_len + errstring_len);
  76       if (lcatch->errstring != NULL)
  77         {
  78           if (objname_len > 0)
  79             {
  80               memcpy (lcatch->errstring, objname, objname_len - 2);
  81               memcpy (lcatch->errstring + objname_len - 2, ": ", 2);
  82             }
  83           memcpy (lcatch->errstring + objname_len, errstring, errstring_len);
  84         }
  85       longjmp (lcatch->env, errcode ?: -1);
  86     }
  87   else if (receiver)
  88     {
  89       /* We are inside _dl_receive_error.  Call the user supplied
  90          handler and resume the work.  The receiver will still be
  91          installed.  */
  92       (*receiver) (errcode, objname, errstring);
  93     }
  94   else
  95     {
  96       /* Lossage while resolving the program's own symbols is always fatal.  */
  97       char buffer[1024];
  98       _dl_sysdep_fatal (_dl_argv[0] ?: "<program name unknown>",
  99                         ": error in loading shared libraries: ",
 100                         objname ?: "", objname && *objname ? ": " : "",
 101                         errstring, errcode ? ": " : "",
 102                         (errcode
 103                          ? __strerror_r (errcode, buffer, sizeof buffer)
 104                          : ""), "\n", NULL);
 105     }
 106 }
 107
 108 int
 109 internal_function
 110 _dl_catch_error (char **errstring,
 111                  void (*operate) (void *),
 112                  void *args)
 113 {
 114   int errcode;
 115   struct catch *volatile old;
 116   struct catch c;
 117   /* We need not handle `receiver' since setting a `catch' is handled
 118      before it.  */
 119
 120   /* Some systems (e.g., SPARC) handle constructors to local variables
 121      inefficient.  So we initialize `c' by hand.  */
 122   c.errstring = NULL;
 123
 124   old = tsd_getspecific ();
 125   errcode = setjmp (c.env);
 126   if (errcode == 0)
 127     {
 128       tsd_setspecific (&c);
 129       (*operate) (args);
 130       tsd_setspecific (old);
 131       *errstring = NULL;
 132       return 0;
 133     }
 134
 135   /* We get here only if we longjmp'd out of OPERATE.  */
 136   tsd_setspecific (old);
 137   *errstring = c.errstring;
 138   return errcode == -1 ? 0 : errcode;
 139 }
 140
 141 void
 142 internal_function
 143 _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
 144 {
 145   struct catch *old_catch;
 146   receiver_fct old_receiver;
 147
 148   old_catch = tsd_getspecific ();
 149   old_receiver = receiver;
 150
 151   /* Set the new values.  */
 152   tsd_setspecific (NULL);
 153   receiver = fct;
 154
 155   (*operate) (args);
 156
 157   tsd_setspecific (old_catch);
 158   receiver = old_receiver;
 159 }