Home | History | Annotate | Download | only in libdw
      1 /* Find CU for given offset.
      2    Copyright (C) 2003, 2004, 2005, 2007 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 static int
     61 findcu_cb (const void *arg1, const void *arg2)
     62 {
     63   struct Dwarf_CU *cu1 = (struct Dwarf_CU *) arg1;
     64   struct Dwarf_CU *cu2 = (struct Dwarf_CU *) arg2;
     65 
     66   /* Find out which of the two arguments is the search value.  It has
     67      end offset 0.  */
     68   if (cu1->end == 0)
     69     {
     70       if (cu1->start < cu2->start)
     71 	return -1;
     72       if (cu1->start >= cu2->end)
     73 	return 1;
     74     }
     75   else
     76     {
     77       if (cu2->start < cu1->start)
     78 	return 1;
     79       if (cu2->start >= cu1->end)
     80 	return -1;
     81     }
     82 
     83   return 0;
     84 }
     85 
     86 
     87 struct Dwarf_CU *
     88 __libdw_findcu (dbg, start)
     89      Dwarf *dbg;
     90      Dwarf_Off start;
     91 {
     92   /* Maybe we already know that CU.  */
     93   struct Dwarf_CU fake = { .start = start, .end = 0 };
     94   struct Dwarf_CU **found = tfind (&fake, &dbg->cu_tree, findcu_cb);
     95   if (found != NULL)
     96     return *found;
     97 
     98   if (start < dbg->next_cu_offset)
     99     {
    100     invalid:
    101       __libdw_seterrno (DWARF_E_INVALID_DWARF);
    102       return NULL;
    103     }
    104 
    105   /* No.  Then read more CUs.  */
    106   while (1)
    107     {
    108       Dwarf_Off oldoff = dbg->next_cu_offset;
    109       uint8_t address_size;
    110       uint8_t offset_size;
    111       Dwarf_Off abbrev_offset;
    112 
    113       if (INTUSE(dwarf_nextcu) (dbg, oldoff, &dbg->next_cu_offset, NULL,
    114 				&abbrev_offset, &address_size, &offset_size)
    115 	  != 0)
    116 	/* No more entries.  */
    117 	return NULL;
    118 
    119       /* XXX We need the version number but dwarf_nextcu swallows it.  */
    120       const char *bytes = (dbg->sectiondata[IDX_debug_info]->d_buf + oldoff
    121 			   + (2 * offset_size - 4));
    122       uint16_t version = read_2ubyte_unaligned (dbg, bytes);
    123 
    124       /* We only know how to handle the DWARF version 2 and 3 formats.  */
    125       if (unlikely (version != 2) && unlikely (version != 3))
    126 	goto invalid;
    127 
    128       /* Create an entry for this CU.  */
    129       struct Dwarf_CU *newp = libdw_typed_alloc (dbg, struct Dwarf_CU);
    130 
    131       newp->dbg = dbg;
    132       newp->start = oldoff;
    133       newp->end = dbg->next_cu_offset;
    134       newp->address_size = address_size;
    135       newp->offset_size = offset_size;
    136       newp->version = version;
    137       Dwarf_Abbrev_Hash_init (&newp->abbrev_hash, 41);
    138       newp->orig_abbrev_offset = newp->last_abbrev_offset = abbrev_offset;
    139       newp->lines = NULL;
    140       newp->locs = NULL;
    141 
    142       /* Add the new entry to the search tree.  */
    143       if (tsearch (newp, &dbg->cu_tree, findcu_cb) == NULL)
    144 	{
    145 	  /* Something went wrong.  Unfo the operation.  */
    146 	  dbg->next_cu_offset = oldoff;
    147 	  __libdw_seterrno (DWARF_E_NOMEM);
    148 	  return NULL;
    149 	}
    150 
    151       /* Is this the one we are looking for?  */
    152       if (start < dbg->next_cu_offset)
    153 	// XXX Match exact offset.
    154 	return newp;
    155     }
    156   /* NOTREACHED */
    157 }
    158