sysdeps/generic/dl-sysdep.c

   1 /* Operating system support for run-time dynamic linker.  Generic Unix version.
   2 Copyright (C) 1995, 96 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <elf.h>
  21 #include <sys/types.h>
  22 #include <fcntl.h>
  23 #include <link.h>
  24 #include <unistd.h>
  25 #include <stdarg.h>
  26 #include <string.h>
  27
  28
  29 extern int _dl_argc;
  30 extern char **_dl_argv;
  31 extern char **_environ;
  32 extern void _start (void);
  33 extern int _dl_secure;
  34
  35 ElfW(Addr)
  36 _dl_sysdep_start (void **start_argptr,
  37                   void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
  38                                    ElfW(Addr) *user_entry))
  39 {
  40   const ElfW(Phdr) *phdr;
  41   ElfW(Word) phnum;
  42   ElfW(Addr) user_entry;
  43   ElfW(auxv_t) *av;
  44   uid_t uid, euid;
  45   gid_t gid, egid;
  46   unsigned int seen;
  47
  48   user_entry = (ElfW(Addr)) &_start;
  49   _dl_argc = *(long *) start_argptr;
  50   _dl_argv = (char **) start_argptr + 1;
  51   _environ = &_dl_argv[_dl_argc + 1];
  52   start_argptr = (void **) _environ;
  53   while (*start_argptr)
  54     ++start_argptr;
  55
  56   seen = 0;
  57 #define M(type) (1 << (type))
  58
  59   for (av = (void *) ++start_argptr;
  60        av->a_type != AT_NULL;
  61        seen |= M ((++av)->a_type))
  62     switch (av->a_type)
  63       {
  64       case AT_PHDR:
  65         phdr = av->a_un.a_ptr;
  66         break;
  67       case AT_PHNUM:
  68         phnum = av->a_un.a_val;
  69         break;
  70       case AT_ENTRY:
  71         user_entry = av->a_un.a_val;
  72         break;
  73       case AT_UID:
  74         uid = av->a_un.a_val;
  75         break;
  76       case AT_GID:
  77         gid = av->a_un.a_val;
  78         break;
  79       case AT_EUID:
  80         euid = av->a_un.a_val;
  81         break;
  82       case AT_EGID:
  83         egid = av->a_un.a_val;
  84         break;
  85       }
  86
  87   /* Linux doesn't provide us with any of these values on the stack
  88      when the dynamic linker is run directly as a program.  */
  89
  90 #define SEE(UID, uid) if ((seen & M (AT_##UID)) == 0) uid = __get##uid ()
  91   SEE (UID, uid);
  92   SEE (GID, gid);
  93   SEE (EUID, euid);
  94   SEE (EGID, egid);
  95
  96
  97   _dl_secure = uid != euid || gid != egid;
  98
  99 #ifdef DL_SYSDEP_INIT
 100   DL_SYSDEP_INIT;
 101 #endif
 102
 103   (*dl_main) (phdr, phnum, &user_entry);
 104   return user_entry;
 105 }
 106
 107 void
 108 _dl_sysdep_start_cleanup (void)
 109 {
 110 }
 111
 112 int
 113 _dl_sysdep_open_zero_fill (void)
 114 {
 115   return __open ("/dev/zero", O_RDONLY);
 116 }
 117
 118 void
 119 _dl_sysdep_fatal (const char *msg, ...)
 120 {
 121   va_list ap;
 122
 123   va_start (ap, msg);
 124   do
 125     {
 126       size_t len = strlen (msg);
 127       __write (STDERR_FILENO, msg, len);
 128       msg = va_arg (ap, const char *);
 129     } while (msg);
 130   va_end (ap);
 131
 132   _exit (127);
 133 }
 134
 135
 136 void
 137 _dl_sysdep_message (const char *msg, ...)
 138 {
 139   va_list ap;
 140
 141   va_start (ap, msg);
 142   do
 143     {
 144       size_t len = strlen (msg);
 145       __write (STDOUT_FILENO, msg, len);
 146       msg = va_arg (ap, const char *);
 147     } while (msg);
 148   va_end (ap);
 149 }