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      1 /* Find an ELF file for a module from its build ID.
      2    Copyright (C) 2007, 2008 Red Hat, Inc.
      3    This file is part of Red Hat elfutils.
      4 
      5    Red Hat elfutils is free software; you can redistribute it and/or modify
      6    it under the terms of the GNU General Public License as published by the
      7    Free Software Foundation; version 2 of the License.
      8 
      9    Red Hat elfutils is distributed in the hope that it will be useful, but
     10    WITHOUT ANY WARRANTY; without even the implied warranty of
     11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     12    General Public License for more details.
     13 
     14    You should have received a copy of the GNU General Public License along
     15    with Red Hat elfutils; if not, write to the Free Software Foundation,
     16    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
     17 
     18    In addition, as a special exception, Red Hat, Inc. gives You the
     19    additional right to link the code of Red Hat elfutils with code licensed
     20    under any Open Source Initiative certified open source license
     21    (http://www.opensource.org/licenses/index.php) which requires the
     22    distribution of source code with any binary distribution and to
     23    distribute linked combinations of the two.  Non-GPL Code permitted under
     24    this exception must only link to the code of Red Hat elfutils through
     25    those well defined interfaces identified in the file named EXCEPTION
     26    found in the source code files (the "Approved Interfaces").  The files
     27    of Non-GPL Code may instantiate templates or use macros or inline
     28    functions from the Approved Interfaces without causing the resulting
     29    work to be covered by the GNU General Public License.  Only Red Hat,
     30    Inc. may make changes or additions to the list of Approved Interfaces.
     31    Red Hat's grant of this exception is conditioned upon your not adding
     32    any new exceptions.  If you wish to add a new Approved Interface or
     33    exception, please contact Red Hat.  You must obey the GNU General Public
     34    License in all respects for all of the Red Hat elfutils code and other
     35    code used in conjunction with Red Hat elfutils except the Non-GPL Code
     36    covered by this exception.  If you modify this file, you may extend this
     37    exception to your version of the file, but you are not obligated to do
     38    so.  If you do not wish to provide this exception without modification,
     39    you must delete this exception statement from your version and license
     40    this file solely under the GPL without exception.
     41 
     42    Red Hat elfutils is an included package of the Open Invention Network.
     43    An included package of the Open Invention Network is a package for which
     44    Open Invention Network licensees cross-license their patents.  No patent
     45    license is granted, either expressly or impliedly, by designation as an
     46    included package.  Should you wish to participate in the Open Invention
     47    Network licensing program, please visit www.openinventionnetwork.com
     48    <http://www.openinventionnetwork.com>.  */
     49 
     50 #include "libdwflP.h"
     51 #include <inttypes.h>
     52 #include <fcntl.h>
     53 #include <unistd.h>
     54 
     55 int
     56 internal_function
     57 __libdwfl_open_by_build_id (Dwfl_Module *mod, bool debug, char **file_name)
     58 {
     59   /* If *FILE_NAME was primed into the module, leave it there
     60      as the fallback when we have nothing to offer.  */
     61   errno = 0;
     62   if (mod->build_id_len <= 0)
     63     return -1;
     64 
     65   const size_t id_len = mod->build_id_len;
     66   const uint8_t *id = mod->build_id_bits;
     67 
     68   /* Search debuginfo_path directories' .build-id/ subdirectories.  */
     69 
     70   char id_name[sizeof "/.build-id/" + 1 + id_len * 2 + sizeof ".debug" - 1];
     71   strcpy (id_name, "/.build-id/");
     72   int n = snprintf (&id_name[sizeof "/.build-id/" - 1],
     73 		    4, "%02" PRIx8 "/", (uint8_t) id[0]);
     74   assert (n == 3);
     75   for (size_t i = 1; i < id_len; ++i)
     76     {
     77       n = snprintf (&id_name[sizeof "/.build-id/" - 1 + 3 + (i - 1) * 2],
     78 		    3, "%02" PRIx8, (uint8_t) id[i]);
     79       assert (n == 2);
     80     }
     81   if (debug)
     82     strcpy (&id_name[sizeof "/.build-id/" - 1 + 3 + (id_len - 1) * 2],
     83 	    ".debug");
     84 
     85   const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
     86 
     87 /* ANDROID_CHANGE_BEGIN */
     88 #if defined(__BIONIC__) || defined(__APPLE__)
     89   char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
     90 			?: DEFAULT_DEBUGINFO_PATH);
     91 #else
     92   char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
     93 			?: DEFAULT_DEBUGINFO_PATH);
     94 #endif
     95 /* ANDROID_CHANGE_END */
     96 
     97   int fd = -1;
     98   char *dir;
     99   while (fd < 0 && (dir = strsep (&path, ":")) != NULL)
    100     {
    101       if (dir[0] == '+' || dir[0] == '-')
    102 	++dir;
    103 
    104       /* Only absolute directory names are useful to us.  */
    105       if (dir[0] != '/')
    106 	continue;
    107 
    108       size_t dirlen = strlen (dir);
    109       char *name = malloc (dirlen + sizeof id_name);
    110       if (unlikely (name == NULL))
    111 	break;
    112       memcpy (mempcpy (name, dir, dirlen), id_name, sizeof id_name);
    113       fd = TEMP_FAILURE_RETRY (open64 (name, O_RDONLY));
    114       if (fd >= 0)
    115 	{
    116 	  if (*file_name != NULL)
    117 	    free (*file_name);
    118 	  *file_name = canonicalize_file_name (name);
    119 	  if (*file_name == NULL)
    120 	    {
    121 	      *file_name = name;
    122 	      name = NULL;
    123 	    }
    124 	}
    125       free (name);
    126     }
    127 
    128 /* ANDROID_CHANGE_BEGIN */
    129 #ifdef __BIONIC__
    130   free(path);
    131 #endif
    132 /* ANDROID_CHANGE_END */
    133 
    134   /* If we simply found nothing, clear errno.  If we had some other error
    135      with the file, report that.  Possibly this should treat other errors
    136      like ENOENT too.  But ignoring all errors could mask some that should
    137      be reported.  */
    138   if (fd < 0 && errno == ENOENT)
    139     errno = 0;
    140 
    141   return fd;
    142 }
    143 
    144 int
    145 dwfl_build_id_find_elf (Dwfl_Module *mod,
    146 			void **userdata __attribute__ ((unused)),
    147 			const char *modname __attribute__ ((unused)),
    148 			Dwarf_Addr base __attribute__ ((unused)),
    149 			char **file_name, Elf **elfp)
    150 {
    151   *elfp = NULL;
    152   int fd = __libdwfl_open_by_build_id (mod, false, file_name);
    153   if (fd >= 0)
    154     {
    155       *elfp = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL);
    156       if (__libdwfl_find_build_id (mod, false, *elfp) == 2)
    157 	/* This is a backdoor signal to short-circuit the ID refresh.  */
    158 	mod->main.valid = true;
    159       else
    160 	{
    161 	  /* This file does not contain the ID it should!  */
    162 	  elf_end (*elfp);
    163 	  *elfp = NULL;
    164 	  close (fd);
    165 	  fd = -1;
    166 	  free (*file_name);
    167 	  *file_name = NULL;
    168 	}
    169     }
    170   return fd;
    171 }
    172 INTDEF (dwfl_build_id_find_elf)
    173