etc/getenv64.sh

   1 #!/bin/sh
   2 #
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 2 of the License, or
   6 # (at your option) any later version.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU Library General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program; if not, write to the Free Software
  15 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  16 #
  17 # Copyright (c) 2006 Guillaume Chazarain <guichaz@gmail.com>
  18 #
  19 # History:
  20 #  20061027: Initial release
  21 #  20110314: Compile with -fPIC
  22
  23 if [ "$#" -eq 0 ]; then
  24     echo "Usage: $0 COMMAND [ARGS...]" >&2
  25     exit 1
  26 fi
  27
  28 TEMPDIR=$(mktemp -d)
  29 [ -z "$TEMPDIR" ] && exit 1
  30 trap "rm -fr $TEMPDIR" EXIT
  31
  32 cat > "$TEMPDIR/getenv.c" <<'EOF' || exit 1
  33 #include <stdlib.h>
  34 #include <stdio.h>
  35 #include <dlfcn.h>
  36
  37 char *getenv (const char *name)
  38 {
  39         static char *(*real_getenv)(const char *name) = NULL;
  40         char *ret;
  41
  42         if (real_getenv == NULL) {
  43                 void *handle = dlopen("/lib64/libc.so.6", RTLD_LAZY);
  44                 if (handle == NULL) {
  45                         fprintf(stderr, "dlopen: %s\n", dlerror());
  46                         exit(1);
  47                 }
  48
  49                 real_getenv = dlsym(handle, "getenv");
  50                 if (real_getenv == NULL) {
  51                         fprintf(stderr, "dlsym: %s\n", dlerror());
  52                         exit(1);
  53                 }
  54         }
  55
  56         ret = real_getenv(name);
  57         if (ret == NULL)
  58                 printf("getenv(\"%s\") = NULL\n", name);
  59         else
  60                 printf("getenv(\"%s\") = \"%s\"\n", name, ret);
  61
  62         return ret;
  63 }
  64 EOF
  65
  66 gcc -fPIC -O0 -ldl -shared "$TEMPDIR/getenv.c" -o "$TEMPDIR/libgetenv.so" || exit 1
  67 LD_PRELOAD="$TEMPDIR/libgetenv.so:$LD_PRELOAD" "$@"