elf/dl-error.c

   1 /* Error handling for runtime dynamic linker.
   2    Copyright (C) 1995,96,97,98,99,2000,2001 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 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 <libintl.h>
  21 #include <setjmp.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <ldsodefs.h>
  26 #include <bits/libc-tsd.h>
  27
  28 /* This structure communicates state between _dl_catch_error and
  29    _dl_signal_error.  */
  30 struct catch
  31   {
  32     const char *objname;        /* Object/File name.  */
  33     const char *errstring;      /* Error detail filled in here.  */
  34     jmp_buf env;                /* longjmp here on error.  */
  35   };
  36
  37 /* Multiple threads at once can use the `_dl_catch_error' function.  The
  38    calls can come from `_dl_map_object_deps', `_dlerror_run', or from
  39    any of the libc functionality which loads dynamic objects (NSS, iconv).
  40    Therefore we have to be prepared to save the state in thread-local
  41    memory.  */
  42
  43 __libc_tsd_define (static, DL_ERROR)
  44 #define tsd_getspecific()       __libc_tsd_get (DL_ERROR)
  45 #define tsd_setspecific(data)   __libc_tsd_set (DL_ERROR, (data))
  46
  47
  48 /* This message we return as a last resort.  We define the string in a
  49    variable since we have to avoid freeing it and so have to enable
  50    a pointer comparison.  See below and in dlfcn/dlerror.c.  */
  51 const char _dl_out_of_memory[] = "out of memory";
  52
  53
  54 /* This points to a function which is called when an continuable error is
  55    received.  Unlike the handling of `catch' this function may return.
  56    The arguments will be the `errstring' and `objname'.
  57
  58    Since this functionality is not used in normal programs (only in ld.so)
  59    we do not care about multi-threaded programs here.  We keep this as a
  60    global variable.  */
  61 static receiver_fct receiver;
  62
  63
  64 void
  65 internal_function
  66 _dl_signal_error (int errcode, const char *objname, const char *occation,
  67                   const char *errstring)
  68 {
  69   struct catch *lcatch;
  70
  71   if (! errstring)
  72     errstring = N_("DYNAMIC LINKER BUG!!!");
  73
  74   lcatch = tsd_getspecific ();
  75   if (objname == NULL)
  76     objname = "";
  77   if (lcatch != NULL)
  78     {
  79       /* We are inside _dl_catch_error.  Return to it.  We have to
  80          duplicate the error string since it might be allocated on the
  81          stack.  The object name is always a string constant.  */
  82       size_t len_objname = strlen (objname) + 1;
  83       size_t len_errstring = strlen (errstring) + 1;
  84
  85       lcatch->errstring = (char *) malloc (len_objname + len_errstring);
  86       if (lcatch->errstring != NULL)
  87         /* Make a copy of the object file name and the error string.  */
  88         lcatch->objname = memcpy (__mempcpy ((char *) lcatch->errstring,
  89                                              errstring, len_errstring),
  90                                   objname, len_objname);
  91       else
  92         {
  93           /* This is better than nothing.  */
  94           lcatch->objname = "";
  95           lcatch->errstring = _dl_out_of_memory;
  96         }
  97       longjmp (lcatch->env, errcode ?: -1);
  98     }
  99   else
 100     {
 101       /* Lossage while resolving the program's own symbols is always fatal.  */
 102       char buffer[1024];
 103       _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
 104                         _dl_argv[0] ?: "<program name unknown>",
 105                         occation ?: N_("error while loading shared libraries"),
 106                         objname, *objname ? ": " : "",
 107                         errstring, errcode ? ": " : "",
 108                         (errcode
 109                          ? __strerror_r (errcode, buffer, sizeof buffer)
 110                          : ""));
 111     }
 112 }
 113
 114
 115 void
 116 internal_function
 117 _dl_signal_cerror (int errcode, const char *objname, const char *occation,
 118                    const char *errstring)
 119 {
 120   if (receiver)
 121     {
 122       /* We are inside _dl_receive_error.  Call the user supplied
 123          handler and resume the work.  The receiver will still be
 124          installed.  */
 125       (*receiver) (errcode, objname, errstring);
 126     }
 127   else
 128     _dl_signal_error (errcode, objname, occation, errstring);
 129 }
 130
 131
 132 int
 133 internal_function
 134 _dl_catch_error (const char **objname, const char **errstring,
 135                  void (*operate) (void *), void *args)
 136 {
 137   int errcode;
 138   struct catch *volatile old;
 139   struct catch c;
 140   /* We need not handle `receiver' since setting a `catch' is handled
 141      before it.  */
 142
 143   /* Some systems (e.g., SPARC) handle constructors to local variables
 144      inefficient.  So we initialize `c' by hand.  */
 145   c.errstring = NULL;
 146
 147   old = tsd_getspecific ();
 148   errcode = setjmp (c.env);
 149   if (__builtin_expect (errcode, 0) == 0)
 150     {
 151       tsd_setspecific (&c);
 152       (*operate) (args);
 153       tsd_setspecific (old);
 154       *objname = NULL;
 155       *errstring = NULL;
 156       return 0;
 157     }
 158
 159   /* We get here only if we longjmp'd out of OPERATE.  */
 160   tsd_setspecific (old);
 161   *objname = c.objname;
 162   *errstring = c.errstring;
 163   return errcode == -1 ? 0 : errcode;
 164 }
 165
 166 void
 167 internal_function
 168 _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
 169 {
 170   struct catch *old_catch;
 171   receiver_fct old_receiver;
 172
 173   old_catch = tsd_getspecific ();
 174   old_receiver = receiver;
 175
 176   /* Set the new values.  */
 177   tsd_setspecific (NULL);
 178   receiver = fct;
 179
 180   (*operate) (args);
 181
 182   tsd_setspecific (old_catch);
 183   receiver = old_receiver;
 184 }