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-rw-r--r--elf/dl-lookup.c129
1 files changed, 129 insertions, 0 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
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index 0000000000..b4600b1970
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+++ b/elf/dl-lookup.c
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+/* Look up a symbol in the loaded objects.
+Copyright (C) 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <stddef.h>
+#include <libelf.h>
+#include <link.h>
+
+/* Search loaded objects' symbol tables for a definition of 
+   the symbol UNDEF_NAME.  Don't use a PLT defn in UNDEF_MAP, since
+   that is the object making the reference.  */
+
+Elf32_Addr
+_dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
+		   struct link_map *symbol_scope)
+{
+  unsigned long int hash = elf_hash (undef_name);
+  struct link_map *map;
+  struct
+    {
+      Elf32_Addr a;
+      const Elf32_Sym *s;
+    } weak_value = { 0, NULL };
+
+  /* Search the relevant loaded objects for a definition.  */
+  for (map = symbol_scope; map; map = map->l_next)
+    {
+      const Elf32_Sym *symtab;
+      const char *strtab;
+      Elf32_Word symidx;
+
+      symtab = ((void *) map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
+      strtab = ((void *) map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
+
+      /* Search the appropriate hash bucket in this object's symbol table
+	 for a definition for the same symbol name.  */
+      for (symidx = map->l_buckets[hash % map->l_nbuckets];
+	   symidx != STN_UNDEF;
+	   symidx = map->l_chain[symidx])
+	{
+	  const Elf32_Sym *sym = &symtab[symidx];
+
+	  if (sym->st_value == 0)
+	    continue;
+
+	  switch (ELF32_ST_TYPE (sym->st_info))
+	    {
+	    case STT_NOTYPE:
+	    case STT_FUNC:
+	    case STT_OBJECT:
+	      break;
+	    default:
+	      /* Not a code/data definition.  */
+	      continue;
+	    }
+
+	  if (sym == *ref)
+	    /* This is the same symbol we are looking for the value for.
+	       If it is a PLT entry, it will have a value of its own;
+	       but that is not what we are looking for.  */
+	    continue;
+
+	  if (strcmp (strtab + sym->st_name, undef_name))
+	    /* Not the symbol we are looking for.  */
+	    continue;
+
+	  switch (ELF32_ST_BIND (sym->st_info))
+	    {
+	    case STB_GLOBAL:
+	      /* Global definition.  Just what we need.  */
+	      *ref = sym;
+	      return map->l_addr;
+	    case STB_WEAK:
+	      /* Weak definition.  Use this value if we don't find another.  */
+	      if (weak_value.a == 0)
+		{
+		  weak_value.s = sym;
+		  weak_value.a = map->l_addr;
+		}
+	      break;
+	    default:
+	      /* Local symbols are ignored.  */
+	      break;
+	    }
+	}
+    }
+
+  if (weak_value.s == NULL)
+    {
+      const char msg[] = "undefined symbol: ";
+      char buf[sizeof msg + strlen (undef_name)];
+      memcpy (buf, msg, sizeof msg - 1);
+      memcpy (&buf[sizeof msg - 1], undef_name, sizeof buf - sizeof msg);
+      _dl_signal_error (0, msg);
+    }
+
+  *ref = weak_value.s;
+  return weak_value.a;
+}
+
+
+/* Cache the location of MAP's hash table.  */
+
+void
+_dl_setup_hash (struct link_map *map)
+{
+  Elf32_Word *hash = (void *) map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr;
+  Elf32_Word nchain;
+  map->l_nbuckets = *hash++;
+  nchain = *hash++;
+  map->l_buckets = hash;
+  hash += map->l_nbuckets;
+  map->l_chain = hash;
+}