ld/ldindr.c

   1
   2 /* ldindr.c
   3    Handle indirect symbols.
   4
   5    Copyright (C) 1991 Free Software Foundation, Inc.
   6    Written by Steve Chamberlain steve@cygnus.com
   7
   8    This file is part of GLD, the Gnu Linker.
   9
  10    GLD is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2, or (at your option)
  13    any later version.
  14
  15    GLD is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with GLD; see the file COPYING.  If not, write to
  22    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 */
  25
  26 /*
  27    An indirect symbol is where a global symbol in one file say's that
  28    all refs like it should be turned into refs of the symbol pointed
  29    at by the value of the indirect symbol.
  30
  31    BFD supplies symbols to be indirected with the BFD_INDIRECT bit
  32    set. Whenever the linker gets one of these, it calls add_indirect
  33    with the symbol. We look up the symbol which this one dereferneces,
  34    and stop if they are the same. If they are not the same, copy all
  35    the information from the current to the dereffed symbol. Set the
  36    indirect bit in the flag. From now on the ldsym_get stuff will
  37    perform the indirection for us, at no charge.
  38 */
  39
  40
  41
  42 #include "bfd.h"
  43 #include "sysdep.h"
  44 #include "ld.h"
  45 #include "ldsym.h"
  46 #include "ldmain.h"
  47 #include "ldmisc.h"
  48
  49 static asymbol **
  50 move_it (a_list, b_list)
  51      asymbol **a_list;
  52      asymbol **b_list;
  53 {
  54   asymbol **head = a_list;
  55   asymbol **cursor = head;
  56
  57   if (a_list == 0) return b_list;
  58   if (b_list == 0) return a_list;
  59
  60   while (1) {
  61     asymbol *ptr = cursor[0];
  62     asymbol **next = (asymbol **)(ptr->udata);
  63     if (next == 0) {
  64       ptr->udata = (PTR) b_list;
  65       return head;
  66     }
  67     cursor = next;
  68   }
  69 }
  70
  71 #if 0
  72 void
  73 copy_over (ldsym, bfdsym)
  74      ldsym_type *ldsym;
  75      asymbol **bfdsym;
  76 {
  77   while (list && *list)
  78     {
  79       refize(enter_global_ref(list, name));
  80       list = (asymbol **)((*list)->udata);
  81     }
  82 }
  83 #endif
  84
  85 /* This call allows us to change the symbol table so that all future
  86    refs to the symbol are patched to know the alias - but we still
  87    have to fix all the old ones */
  88 void
  89 add_indirect (ptr)
  90      asymbol **ptr;
  91 {
  92   ldsym_type *lgs = ldsym_get((*ptr)->name);
  93   ldsym_type *new = ldsym_get(((asymbol *)((*ptr)->value))->name);
  94
  95   /* If the mapping has already been done, stop now */
  96   if (lgs == new) return;
  97
  98   lgs->flags |= SYM_INDIRECT;
  99
 100   if (lgs->sdefs_chain && lgs->sdefs_chain[0])
 101   {
 102     einfo("indirect symbol already has definition %s\n",   lgs->sdefs_chain[0]);
 103   }
 104   new->scoms_chain = move_it(new->scoms_chain, lgs->scoms_chain);
 105   lgs->scoms_chain = 0;
 106   new->srefs_chain = move_it(new->srefs_chain, lgs->srefs_chain);
 107   lgs->srefs_chain = 0;
 108   new->sdefs_chain = move_it(new->sdefs_chain, lgs->sdefs_chain);
 109   lgs->sdefs_chain = 0;
 110
 111   /* If the result has any commons they should be turned into refs */
 112
 113   if (new->sdefs_chain && new->scoms_chain)
 114   {
 115     refize(new, new->scoms_chain);
 116   }
 117   lgs->sdefs_chain = (asymbol **)new;
 118   lgs->srefs_chain = ptr;
 119 }
 120
 121
 122