Line data    Source code

       1             : /* Return size of GNU compressed section.
       2             :    Copyright (C) 2015 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             : 
       5             :    This file is free software; you can redistribute it and/or modify
       6             :    it under the terms of either
       7             : 
       8             :      * the GNU Lesser General Public License as published by the Free
       9             :        Software Foundation; either version 3 of the License, or (at
      10             :        your option) any later version
      11             : 
      12             :    or
      13             : 
      14             :      * the GNU General Public License as published by the Free
      15             :        Software Foundation; either version 2 of the License, or (at
      16             :        your option) any later version
      17             : 
      18             :    or both in parallel, as here.
      19             : 
      20             :    elfutils is distributed in the hope that it will be useful, but
      21             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23             :    General Public License for more details.
      24             : 
      25             :    You should have received copies of the GNU General Public License and
      26             :    the GNU Lesser General Public License along with this program.  If
      27             :    not, see <http://www.gnu.org/licenses/>.  */
      28             : 
      29             : #ifdef HAVE_CONFIG_H
      30             : # include <config.h>
      31             : #endif
      32             : 
      33             : #include "libdwelfP.h"
      34             : #include "libelfP.h"
      35             : 
      36             : ssize_t
      37          36 : dwelf_scn_gnu_compressed_size (Elf_Scn *scn)
      38             : {
      39          36 :   if (scn == NULL)
      40             :     return -1;
      41             : 
      42             :   GElf_Shdr shdr;
      43          36 :   if (gelf_getshdr (scn, &shdr) == NULL)
      44             :     return -1;
      45             : 
      46             :   /* Allocated or no bits sections can never be compressed.  */
      47          36 :   if ((shdr.sh_flags & SHF_ALLOC) != 0
      48          36 :       || shdr.sh_type == SHT_NULL
      49          36 :       || shdr.sh_type == SHT_NOBITS)
      50             :     return -1;
      51             : 
      52          36 :   Elf_Data *d = elf_rawdata (scn, NULL);
      53          36 :   if (d == NULL)
      54             :     return -1;
      55             : 
      56          36 :   if (d->d_size >= 4 + 8
      57          36 :       && memcmp (d->d_buf, "ZLIB", 4) == 0)
      58             :     {
      59             :       /* There is a 12-byte header of "ZLIB" followed by
      60             :          an 8-byte big-endian size.  There is only one type and
      61             :          alignment isn't preserved separately.  */
      62             :       uint64_t size;
      63          36 :       memcpy (&size, d->d_buf + 4, sizeof size);
      64          72 :       size = be64toh (size);
      65             : 
      66             :       /* One more sanity check, size should be bigger than original
      67             :          data size plus some overhead (4 chars ZLIB + 8 bytes size + 6
      68             :          bytes zlib stream overhead + 5 bytes overhead max for one 16K
      69             :          block) and should fit into a size_t.  */
      70          36 :       if (size + 4 + 8 + 6 + 5 < d->d_size || size > SIZE_MAX)
      71             :         return -1;
      72             : 
      73          36 :       return size;
      74             :     }
      75             : 
      76             :   return -1;
      77             : }