elf/dl-error.c

   1 /* Error handling for runtime dynamic linker.
   2    Copyright (C) 1995-2002,2004,2005 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
  27 /* This structure communicates state between _dl_catch_error and
  28    _dl_signal_error.  */
  29 struct catch
  30   {
  31     const char *objname;        /* Object/File name.  */
  32     const char *errstring;      /* Error detail filled in here.  */
  33     jmp_buf env;                /* longjmp here on error.  */
  34   };
  35
  36 /* Multiple threads at once can use the `_dl_catch_error' function.  The
  37    calls can come from `_dl_map_object_deps', `_dlerror_run', or from
  38    any of the libc functionality which loads dynamic objects (NSS, iconv).
  39    Therefore we have to be prepared to save the state in thread-local
  40    memory.  The _dl_error_catch_tsd function pointer is reset by the thread
  41    library so that it returns the address of a thread-local variable.  */
  42
  43
  44 /* This message we return as a last resort.  We define the string in a
  45    variable since we have to avoid freeing it and so have to enable
  46    a pointer comparison.  See below and in dlfcn/dlerror.c.  */
  47 const char _dl_out_of_memory[] = "out of memory";
  48 rtld_hidden_data_def (_dl_out_of_memory)
  49
  50
  51 /* This points to a function which is called when an continuable error is
  52    received.  Unlike the handling of `catch' this function may return.
  53    The arguments will be the `errstring' and `objname'.
  54
  55    Since this functionality is not used in normal programs (only in ld.so)
  56    we do not care about multi-threaded programs here.  We keep this as a
  57    global variable.  */
  58 static receiver_fct receiver;
  59
  60 #ifdef _LIBC_REENTRANT
  61 # define CATCH_HOOK     (*(struct catch **) (*GL(dl_error_catch_tsd)) ())
  62 #else
  63 static struct catch *catch_hook;
  64 # define CATCH_HOOK     catch_hook
  65 #endif
  66
  67 void
  68 internal_function
  69 _dl_signal_error (int errcode, const char *objname, const char *occation,
  70                   const char *errstring)
  71 {
  72   struct catch *lcatch;
  73
  74   if (! errstring)
  75     errstring = N_("DYNAMIC LINKER BUG!!!");
  76
  77   lcatch = CATCH_HOOK;
  78   if (objname == NULL)
  79     objname = "";
  80   if (lcatch != NULL)
  81     {
  82       /* We are inside _dl_catch_error.  Return to it.  We have to
  83          duplicate the error string since it might be allocated on the
  84          stack.  The object name is always a string constant.  */
  85       size_t len_objname = strlen (objname) + 1;
  86       size_t len_errstring = strlen (errstring) + 1;
  87
  88       lcatch->errstring = (char *) malloc (len_objname + len_errstring);
  89       if (lcatch->errstring != NULL)
  90         /* Make a copy of the object file name and the error string.  */
  91         lcatch->objname = memcpy (__mempcpy ((char *) lcatch->errstring,
  92                                              errstring, len_errstring),
  93                                   objname, len_objname);
  94       else
  95         {
  96           /* This is better than nothing.  */
  97           lcatch->objname = "";
  98           lcatch->errstring = _dl_out_of_memory;
  99         }
 100       longjmp (lcatch->env, errcode ?: -1);
 101     }
 102   else
 103     {
 104       /* Lossage while resolving the program's own symbols is always fatal.  */
 105       char buffer[1024];
 106       _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
 107                         rtld_progname ?: "<program name unknown>",
 108                         occation ?: N_("error while loading shared libraries"),
 109                         objname, *objname ? ": " : "",
 110                         errstring, errcode ? ": " : "",
 111                         (errcode
 112                          ? __strerror_r (errcode, buffer, sizeof buffer)
 113                          : ""));
 114     }
 115 }
 116
 117
 118 void
 119 internal_function
 120 _dl_signal_cerror (int errcode, const char *objname, const char *occation,
 121                    const char *errstring)
 122 {
 123   if (__builtin_expect (GLRO(dl_debug_mask)
 124                         & ~(DL_DEBUG_STATISTICS|DL_DEBUG_PRELINK), 0))
 125     _dl_debug_printf ("%s: error: %s: %s (%s)\n", objname, occation,
 126                       errstring, receiver ? "continued" : "fatal");
 127
 128   if (receiver)
 129     {
 130       /* We are inside _dl_receive_error.  Call the user supplied
 131          handler and resume the work.  The receiver will still be
 132          installed.  */
 133       (*receiver) (errcode, objname, errstring);
 134     }
 135   else
 136     _dl_signal_error (errcode, objname, occation, errstring);
 137 }
 138
 139
 140 int
 141 internal_function
 142 _dl_catch_error (const char **objname, const char **errstring,
 143                  void (*operate) (void *), void *args)
 144 {
 145   int errcode;
 146   struct catch *volatile old;
 147   struct catch c;
 148   /* We need not handle `receiver' since setting a `catch' is handled
 149      before it.  */
 150
 151   /* Some systems (e.g., SPARC) handle constructors to local variables
 152      inefficient.  So we initialize `c' by hand.  */
 153   c.errstring = NULL;
 154
 155   struct catch **const catchp = &CATCH_HOOK;
 156   old = *catchp;
 157   errcode = setjmp (c.env);
 158   if (__builtin_expect (errcode, 0) == 0)
 159     {
 160       *catchp = &c;
 161       (*operate) (args);
 162       *catchp = old;
 163       *objname = NULL;
 164       *errstring = NULL;
 165       return 0;
 166     }
 167
 168   /* We get here only if we longjmp'd out of OPERATE.  */
 169   *catchp = old;
 170   *objname = c.objname;
 171   *errstring = c.errstring;
 172   return errcode == -1 ? 0 : errcode;
 173 }
 174
 175
 176 void
 177 internal_function
 178 _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
 179 {
 180   struct catch **const catchp = &CATCH_HOOK;
 181   struct catch *old_catch;
 182   receiver_fct old_receiver;
 183
 184   old_catch = *catchp;
 185   old_receiver = receiver;
 186
 187   /* Set the new values.  */
 188   *catchp = NULL;
 189   receiver = fct;
 190
 191   (*operate) (args);
 192
 193   *catchp = old_catch;
 194   receiver = old_receiver;
 195 }