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 <stdbool.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <ldsodefs.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     bool malloced;              /* Nonzero if the string is malloced
  35                                    by the libc malloc.  */
  36     jmp_buf env;                /* longjmp here on error.  */
  37   };
  38
  39 /* Multiple threads at once can use the `_dl_catch_error' function.  The
  40    calls can come from `_dl_map_object_deps', `_dlerror_run', or from
  41    any of the libc functionality which loads dynamic objects (NSS, iconv).
  42    Therefore we have to be prepared to save the state in thread-local
  43    memory.  The _dl_error_catch_tsd function pointer is reset by the thread
  44    library so that it returns the address of a thread-local variable.  */
  45
  46
  47 /* This message we return as a last resort.  We define the string in a
  48    variable since we have to avoid freeing it and so have to enable
  49    a pointer comparison.  See below and in dlfcn/dlerror.c.  */
  50 static const char _dl_out_of_memory[] = "out of memory";
  51
  52
  53 /* This points to a function which is called when an continuable error is
  54    received.  Unlike the handling of `catch' this function may return.
  55    The arguments will be the `errstring' and `objname'.
  56
  57    Since this functionality is not used in normal programs (only in ld.so)
  58    we do not care about multi-threaded programs here.  We keep this as a
  59    global variable.  */
  60 static receiver_fct receiver;
  61
  62 #ifdef _LIBC_REENTRANT
  63 # define CATCH_HOOK     (*(struct catch **) (*GL(dl_error_catch_tsd)) ())
  64 #else
  65 static struct catch *catch_hook;
  66 # define CATCH_HOOK     catch_hook
  67 #endif
  68
  69 void
  70 internal_function
  71 _dl_signal_error (int errcode, const char *objname, const char *occation,
  72                   const char *errstring)
  73 {
  74   struct catch *lcatch;
  75
  76   if (! errstring)
  77     errstring = N_("DYNAMIC LINKER BUG!!!");
  78
  79   lcatch = CATCH_HOOK;
  80   if (objname == NULL)
  81     objname = "";
  82   if (lcatch != NULL)
  83     {
  84       /* We are inside _dl_catch_error.  Return to it.  We have to
  85          duplicate the error string since it might be allocated on the
  86          stack.  The object name is always a string constant.  */
  87       size_t len_objname = strlen (objname) + 1;
  88       size_t len_errstring = strlen (errstring) + 1;
  89
  90       lcatch->errstring = (char *) malloc (len_objname + len_errstring);
  91       if (lcatch->errstring != NULL)
  92         {
  93           /* Make a copy of the object file name and the error string.  */
  94           lcatch->objname = memcpy (__mempcpy ((char *) lcatch->errstring,
  95                                                errstring, len_errstring),
  96                                     objname, len_objname);
  97
  98           /* If the main executable is relocated it means the libc's malloc
  99              is used.  */
 100 #ifdef SHARED
 101           lcatch->malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL
 102                               && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated
 103                                   != 0));
 104 #else
 105           lcatch->malloced = true;
 106 #endif
 107         }
 108       else
 109         {
 110           /* This is better than nothing.  */
 111           lcatch->objname = "";
 112           lcatch->errstring = _dl_out_of_memory;
 113           lcatch->malloced = false;
 114         }
 115       /* We do not restore the signal mask because none was saved.  */
 116       __longjmp (lcatch->env[0].__jmpbuf, errcode ?: -1);
 117     }
 118   else
 119     {
 120       /* Lossage while resolving the program's own symbols is always fatal.  */
 121       char buffer[1024];
 122       _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
 123                         rtld_progname ?: "<program name unknown>",
 124                         occation ?: N_("error while loading shared libraries"),
 125                         objname, *objname ? ": " : "",
 126                         errstring, errcode ? ": " : "",
 127                         (errcode
 128                          ? __strerror_r (errcode, buffer, sizeof buffer)
 129                          : ""));
 130     }
 131 }
 132
 133
 134 void
 135 internal_function
 136 _dl_signal_cerror (int errcode, const char *objname, const char *occation,
 137                    const char *errstring)
 138 {
 139   if (__builtin_expect (GLRO(dl_debug_mask)
 140                         & ~(DL_DEBUG_STATISTICS|DL_DEBUG_PRELINK), 0))
 141     _dl_debug_printf ("%s: error: %s: %s (%s)\n", objname, occation,
 142                       errstring, receiver ? "continued" : "fatal");
 143
 144   if (receiver)
 145     {
 146       /* We are inside _dl_receive_error.  Call the user supplied
 147          handler and resume the work.  The receiver will still be
 148          installed.  */
 149       (*receiver) (errcode, objname, errstring);
 150     }
 151   else
 152     _dl_signal_error (errcode, objname, occation, errstring);
 153 }
 154
 155
 156 int
 157 internal_function
 158 _dl_catch_error (const char **objname, const char **errstring,
 159                  bool *mallocedp, void (*operate) (void *), void *args)
 160 {
 161   int errcode;
 162   struct catch *volatile old;
 163   struct catch c;
 164   /* We need not handle `receiver' since setting a `catch' is handled
 165      before it.  */
 166
 167   /* Some systems (e.g., SPARC) handle constructors to local variables
 168      inefficient.  So we initialize `c' by hand.  */
 169   c.errstring = NULL;
 170
 171   struct catch **const catchp = &CATCH_HOOK;
 172   old = *catchp;
 173   /* Do not save the signal mask.  */
 174   errcode = __sigsetjmp (c.env, 0);
 175   if (__builtin_expect (errcode, 0) == 0)
 176     {
 177       *catchp = &c;
 178       (*operate) (args);
 179       *catchp = old;
 180       *objname = NULL;
 181       *errstring = NULL;
 182       *mallocedp = false;
 183       return 0;
 184     }
 185
 186   /* We get here only if we longjmp'd out of OPERATE.  */
 187   *catchp = old;
 188   *objname = c.objname;
 189   *errstring = c.errstring;
 190   *mallocedp = c.malloced;
 191   return errcode == -1 ? 0 : errcode;
 192 }
 193
 194
 195 void
 196 internal_function
 197 _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
 198 {
 199   struct catch **const catchp = &CATCH_HOOK;
 200   struct catch *old_catch;
 201   receiver_fct old_receiver;
 202
 203   old_catch = *catchp;
 204   old_receiver = receiver;
 205
 206   /* Set the new values.  */
 207   *catchp = NULL;
 208   receiver = fct;
 209
 210   (*operate) (args);
 211
 212   *catchp = old_catch;
 213   receiver = old_receiver;
 214 }