elf/dl-dst.h

   1 /* Handling of dynamic sring tokens.
   2    Copyright (C) 1999-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include "trusted-dirs.h"
  20
  21 #ifdef SHARED
  22 # define IS_RTLD(l) (l) == &GL(dl_rtld_map)
  23 #else
  24 # define IS_RTLD(l) 0
  25 #endif
  26 /* Guess from the number of DSTs the length of the result string.  */
  27 #define DL_DST_REQUIRED(l, name, len, cnt) \
  28   ({                                                                          \
  29     size_t __len = (len);                                                     \
  30     size_t __cnt = (cnt);                                                     \
  31                                                                               \
  32     if (__cnt > 0)                                                            \
  33       {                                                                       \
  34         size_t dst_len;                                                       \
  35         /* Now we make a guess how many extra characters on top of the        \
  36            length of S we need to represent the result.  We know that         \
  37            we have CNT replacements.  Each at most can use                    \
  38              MAX (MAX (strlen (ORIGIN), strlen (_dl_platform)),               \
  39                   strlen (DL_DST_LIB))                                        \
  40            minus 4 (which is the length of "$LIB").                           \
  41                                                                               \
  42            First get the origin string if it is not available yet.            \
  43            This can only happen for the map of the executable or, when        \
  44            auditing, in ld.so.  */                                            \
  45         if ((l)->l_origin == NULL)                                            \
  46           {                                                                   \
  47             assert ((l)->l_name[0] == '\0' || IS_RTLD (l));                   \
  48             (l)->l_origin = _dl_get_origin ();                                \
  49             dst_len = ((l)->l_origin && (l)->l_origin != (char *) -1          \
  50                           ? strlen ((l)->l_origin) : 0);                      \
  51           }                                                                   \
  52         else                                                                  \
  53           dst_len = (l)->l_origin == (char *) -1                              \
  54             ? 0 : strlen ((l)->l_origin);                                     \
  55         dst_len = MAX (MAX (dst_len, GLRO(dl_platformlen)),                   \
  56                        strlen (DL_DST_LIB));                                  \
  57         if (dst_len > 4)                                                      \
  58           __len += __cnt * (dst_len - 4);                                     \
  59       }                                                                       \
  60                                                                               \
  61     __len; })