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      1 /* Find CU for given offset.
      2    Copyright (C) 2003-2010 Red Hat, Inc.
      3    This file is part of Red Hat elfutils.
      4    Written by Ulrich Drepper <drepper (at) redhat.com>, 2003.
      5 
      6    Red Hat elfutils is free software; you can redistribute it and/or modify
      7    it under the terms of the GNU General Public License as published by the
      8    Free Software Foundation; version 2 of the License.
      9 
     10    Red Hat elfutils is distributed in the hope that it will be useful, but
     11    WITHOUT ANY WARRANTY; without even the implied warranty of
     12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13    General Public License for more details.
     14 
     15    You should have received a copy of the GNU General Public License along
     16    with Red Hat elfutils; if not, write to the Free Software Foundation,
     17    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
     18 
     19    In addition, as a special exception, Red Hat, Inc. gives You the
     20    additional right to link the code of Red Hat elfutils with code licensed
     21    under any Open Source Initiative certified open source license
     22    (http://www.opensource.org/licenses/index.php) which requires the
     23    distribution of source code with any binary distribution and to
     24    distribute linked combinations of the two.  Non-GPL Code permitted under
     25    this exception must only link to the code of Red Hat elfutils through
     26    those well defined interfaces identified in the file named EXCEPTION
     27    found in the source code files (the "Approved Interfaces").  The files
     28    of Non-GPL Code may instantiate templates or use macros or inline
     29    functions from the Approved Interfaces without causing the resulting
     30    work to be covered by the GNU General Public License.  Only Red Hat,
     31    Inc. may make changes or additions to the list of Approved Interfaces.
     32    Red Hat's grant of this exception is conditioned upon your not adding
     33    any new exceptions.  If you wish to add a new Approved Interface or
     34    exception, please contact Red Hat.  You must obey the GNU General Public
     35    License in all respects for all of the Red Hat elfutils code and other
     36    code used in conjunction with Red Hat elfutils except the Non-GPL Code
     37    covered by this exception.  If you modify this file, you may extend this
     38    exception to your version of the file, but you are not obligated to do
     39    so.  If you do not wish to provide this exception without modification,
     40    you must delete this exception statement from your version and license
     41    this file solely under the GPL without exception.
     42 
     43    Red Hat elfutils is an included package of the Open Invention Network.
     44    An included package of the Open Invention Network is a package for which
     45    Open Invention Network licensees cross-license their patents.  No patent
     46    license is granted, either expressly or impliedly, by designation as an
     47    included package.  Should you wish to participate in the Open Invention
     48    Network licensing program, please visit www.openinventionnetwork.com
     49    <http://www.openinventionnetwork.com>.  */
     50 
     51 #ifdef HAVE_CONFIG_H
     52 # include <config.h>
     53 #endif
     54 
     55 #include <assert.h>
     56 #include <search.h>
     57 #include "libdwP.h"
     58 
     59 
     60 struct Dwarf_CU *
     61 internal_function
     62 __libdw_intern_next_unit (dbg, debug_types)
     63      Dwarf *dbg;
     64      bool debug_types;
     65 {
     66   Dwarf_Off *const offsetp
     67     = debug_types ? &dbg->next_tu_offset : &dbg->next_cu_offset;
     68 
     69   Dwarf_Off oldoff = *offsetp;
     70   uint16_t version;
     71   uint8_t address_size;
     72   uint8_t offset_size;
     73   Dwarf_Off abbrev_offset;
     74   uint64_t type_sig8 = 0;
     75   Dwarf_Off type_offset = 0;
     76 
     77   if (INTUSE(dwarf_next_unit) (dbg, oldoff, offsetp, NULL,
     78 			       &version, &abbrev_offset,
     79 			       &address_size, &offset_size,
     80 			       debug_types ? &type_sig8 : NULL,
     81 			       debug_types ? &type_offset : NULL) != 0)
     82     /* No more entries.  */
     83     return NULL;
     84 
     85   /* We only know how to handle the DWARF version 2 through 4 formats.  */
     86   if (unlikely (version < 2) || unlikely (version > 4))
     87     {
     88       __libdw_seterrno (DWARF_E_INVALID_DWARF);
     89       return NULL;
     90     }
     91 
     92   /* Create an entry for this CU.  */
     93   struct Dwarf_CU *newp = libdw_typed_alloc (dbg, struct Dwarf_CU);
     94 
     95   newp->dbg = dbg;
     96   newp->start = oldoff;
     97   newp->end = *offsetp;
     98   newp->address_size = address_size;
     99   newp->offset_size = offset_size;
    100   newp->version = version;
    101   newp->type_sig8 = type_sig8;
    102   newp->type_offset = type_offset;
    103   Dwarf_Abbrev_Hash_init (&newp->abbrev_hash, 41);
    104   newp->orig_abbrev_offset = newp->last_abbrev_offset = abbrev_offset;
    105   newp->lines = NULL;
    106   newp->locs = NULL;
    107 
    108   return newp;
    109 }
    110 
    111 
    112 static int
    113 findcu_cb (const void *arg1, const void *arg2)
    114 {
    115   struct Dwarf_CU *cu1 = (struct Dwarf_CU *) arg1;
    116   struct Dwarf_CU *cu2 = (struct Dwarf_CU *) arg2;
    117 
    118   /* Find out which of the two arguments is the search value.  It has
    119      end offset 0.  */
    120   if (cu1->end == 0)
    121     {
    122       if (cu1->start < cu2->start)
    123 	return -1;
    124       if (cu1->start >= cu2->end)
    125 	return 1;
    126     }
    127   else
    128     {
    129       if (cu2->start < cu1->start)
    130 	return 1;
    131       if (cu2->start >= cu1->end)
    132 	return -1;
    133     }
    134 
    135   return 0;
    136 }
    137 
    138 struct Dwarf_CU *
    139 __libdw_findcu (dbg, start, debug_types)
    140      Dwarf *dbg;
    141      Dwarf_Off start;
    142      bool debug_types;
    143 {
    144   void **tree = debug_types ? &dbg->tu_tree : &dbg->cu_tree;
    145   Dwarf_Off *next_offset
    146     = debug_types ? &dbg->next_tu_offset : &dbg->next_cu_offset;
    147 
    148   /* Maybe we already know that CU.  */
    149   struct Dwarf_CU fake = { .start = start, .end = 0 };
    150   struct Dwarf_CU **found = tfind (&fake, tree, findcu_cb);
    151   if (found != NULL)
    152     return *found;
    153 
    154   if (start < *next_offset)
    155     {
    156       __libdw_seterrno (DWARF_E_INVALID_DWARF);
    157       return NULL;
    158     }
    159 
    160   /* No.  Then read more CUs.  */
    161   while (1)
    162     {
    163       Dwarf_Off oldoff = *next_offset;
    164       struct Dwarf_CU *newp = __libdw_intern_next_unit (dbg, debug_types);
    165       if (newp == NULL)
    166 	return NULL;
    167 
    168       /* Add the new entry to the search tree.  */
    169       if (tsearch (newp, tree, findcu_cb) == NULL)
    170 	{
    171 	  /* Something went wrong.  Undo the operation.  */
    172 	  *next_offset = oldoff;
    173 	  __libdw_seterrno (DWARF_E_NOMEM);
    174 	  return NULL;
    175 	}
    176 
    177       /* Is this the one we are looking for?  */
    178       if (start < *next_offset)
    179 	// XXX Match exact offset.
    180 	return newp;
    181     }
    182   /* NOTREACHED */
    183 }
    184