sysdeps/generic/dl-sysdep.c

   1 /* Operating system support for run-time dynamic linker.  Generic Unix version.
   2    Copyright (C) 1995, 1996, 1997 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 not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <elf.h>
  21 #include <entry.h>
  22 #include <sys/types.h>
  23 #include <sys/stat.h>
  24 #include <sys/mman.h>
  25 #include <fcntl.h>
  26 #include <link.h>
  27 #include <unistd.h>
  28 #include <stdio-common/_itoa.h>
  29
  30 #include <dl-machine.h>
  31
  32 extern int _dl_argc;
  33 extern char **_dl_argv;
  34 extern char **_environ;
  35 extern size_t _dl_pagesize;
  36 extern const char *_dl_platform;
  37 extern unsigned long _dl_hwcap;
  38 extern size_t _dl_platformlen;
  39 extern void _end;
  40 extern void ENTRY_POINT (void);
  41
  42 ElfW(Addr) _dl_base_addr;
  43 int __libc_enable_secure;
  44 int __libc_multiple_libcs;      /* Defining this here avoids the inclusion
  45                                    of init-first.  */
  46 static ElfW(auxv_t) *_dl_auxv;
  47
  48
  49 #ifndef DL_FIND_ARG_COMPONENTS
  50 #define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp)  \
  51   do {                                                          \
  52     void **_tmp;                                                \
  53     (argc) = *(long *) cookie;                                  \
  54     (argv) = (char **) cookie + 1;                              \
  55     (envp) = (argv) + (argc) + 1;                               \
  56     for (_tmp = (void **) (envp); *_tmp; ++_tmp)                \
  57       continue;                                                 \
  58     (auxp) = (void *) ++_tmp;                                   \
  59   } while (0)
  60 #endif
  61
  62
  63 ElfW(Addr)
  64 _dl_sysdep_start (void **start_argptr,
  65                   void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
  66                                    ElfW(Addr) *user_entry))
  67 {
  68   const ElfW(Phdr) *phdr = NULL;
  69   ElfW(Word) phnum = 0;
  70   ElfW(Addr) user_entry;
  71   ElfW(auxv_t) *av;
  72   uid_t uid = 0;
  73   uid_t euid = 0;
  74   gid_t gid = 0;
  75   gid_t egid = 0;
  76   unsigned int seen;
  77
  78   DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ, _dl_auxv);
  79
  80   user_entry = (ElfW(Addr)) &ENTRY_POINT;
  81   _dl_platform = NULL; /* Default to nothing known about the platform.  */
  82
  83   seen = 0;
  84 #define M(type) (1 << (type))
  85
  86   for (av = _dl_auxv; av->a_type != AT_NULL; seen |= M ((++av)->a_type))
  87     switch (av->a_type)
  88       {
  89       case AT_PHDR:
  90         phdr = av->a_un.a_ptr;
  91         break;
  92       case AT_PHNUM:
  93         phnum = av->a_un.a_val;
  94         break;
  95       case AT_PAGESZ:
  96         _dl_pagesize = av->a_un.a_val;
  97         break;
  98       case AT_ENTRY:
  99         user_entry = av->a_un.a_val;
 100         break;
 101       case AT_BASE:
 102         _dl_base_addr = av->a_un.a_val;
 103         break;
 104       case AT_UID:
 105         uid = av->a_un.a_val;
 106         break;
 107       case AT_GID:
 108         gid = av->a_un.a_val;
 109         break;
 110       case AT_EUID:
 111         euid = av->a_un.a_val;
 112         break;
 113       case AT_EGID:
 114         egid = av->a_un.a_val;
 115         break;
 116       case AT_PLATFORM:
 117         _dl_platform = av->a_un.a_ptr;
 118         break;
 119       case AT_HWCAP:
 120         _dl_hwcap = av->a_un.a_val;
 121         break;
 122       }
 123
 124   /* Linux doesn't provide us with any of these values on the stack
 125      when the dynamic linker is run directly as a program.  */
 126
 127 #define SEE(UID, uid) if ((seen & M (AT_##UID)) == 0) uid = __get##uid ()
 128   SEE (UID, uid);
 129   SEE (GID, gid);
 130   SEE (EUID, euid);
 131   SEE (EGID, egid);
 132
 133   __libc_enable_secure = uid != euid || gid != egid;
 134
 135   if (_dl_pagesize == 0)
 136     _dl_pagesize = __getpagesize ();
 137
 138 #ifdef DL_SYSDEP_INIT
 139   DL_SYSDEP_INIT;
 140 #endif
 141
 142 #ifdef DL_PLATFORM_INIT
 143   DL_PLATFORM_INIT;
 144 #endif
 145
 146   /* Determine the length of the platform name.  */
 147   if (_dl_platform != NULL)
 148     _dl_platformlen = strlen (_dl_platform);
 149
 150   if (__sbrk (0) == &_end)
 151     /* The dynamic linker was run as a program, and so the initial break
 152        starts just after our bss, at &_end.  The malloc in dl-minimal.c
 153        will consume the rest of this page, so tell the kernel to move the
 154        break up that far.  When the user program examines its break, it
 155        will see this new value and not clobber our data.  */
 156     __sbrk (_dl_pagesize - ((&_end - (void *) 0) & (_dl_pagesize - 1)));
 157
 158   (*dl_main) (phdr, phnum, &user_entry);
 159   return user_entry;
 160 }
 161
 162 void
 163 _dl_sysdep_start_cleanup (void)
 164 {
 165 }
 166
 167 void
 168 _dl_show_auxv (void)
 169 {
 170   char buf[64];
 171   ElfW(auxv_t) *av;
 172
 173   /* Terminate string.  */
 174   buf[63] = '\0';
 175
 176   for (av = _dl_auxv; av->a_type != AT_NULL; ++av)
 177     switch (av->a_type)
 178       {
 179       case AT_PHDR:
 180         _dl_sysdep_message ("AT_PHDR:     0x",
 181                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 182                                         16, 0),
 183                             "\n", NULL);
 184         break;
 185       case AT_PHNUM:
 186         _dl_sysdep_message ("AT_PHNUM:    ",
 187                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 188                                         10, 0),
 189                             "\n", NULL);
 190         break;
 191       case AT_PAGESZ:
 192         _dl_sysdep_message ("AT_PAGESZ:   ",
 193                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 194                                         10, 0),
 195                             "\n", NULL);
 196         break;
 197       case AT_ENTRY:
 198         _dl_sysdep_message ("AT_ENTRY:    0x",
 199                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 200                                         16, 0),
 201                             "\n", NULL);
 202         break;
 203       case AT_BASE:
 204         _dl_sysdep_message ("AT_BASE:    0x",
 205                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 206                                         16, 0),
 207                             "\n", NULL);
 208         break;
 209       case AT_UID:
 210         _dl_sysdep_message ("AT_UID:      ",
 211                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 212                                         10, 0),
 213                             "\n", NULL);
 214         break;
 215       case AT_GID:
 216         _dl_sysdep_message ("AT_GID:      ",
 217                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 218                                         10, 0),
 219                             "\n", NULL);
 220         break;
 221       case AT_EUID:
 222         _dl_sysdep_message ("AT_EUID:     ",
 223                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 224                                         10, 0),
 225                             "\n", NULL);
 226         break;
 227       case AT_EGID:
 228         _dl_sysdep_message ("AT_EGID:     ",
 229                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 230                                         10, 0),
 231                             "\n", NULL);
 232         break;
 233       case AT_PLATFORM:
 234         _dl_sysdep_message ("AT_PLATFORM: ", av->a_un.a_ptr, NULL);
 235         break;
 236       case AT_HWCAP:
 237         _dl_sysdep_message ("AT_HWCAP:    ",
 238                             _itoa_word (av->a_un.a_val, buf + sizeof buf - 1,
 239                                         16, 0),
 240                             "\n", NULL);
 241         break;
 242       }
 243 }