elf/dl-minimal.c

   1 /* Minimal replacements for basic facilities used in the dynamic linker.
   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 <sys/types.h>
  21 #include <sys/mman.h>
  22 #include <unistd.h>
  23 #include <assert.h>
  24 #include <string.h>
  25 #include <link.h>
  26 #include "../stdio-common/_itoa.h"
  27
  28 /* Minimal `malloc' allocator for use while loading shared libraries.
  29    Only small blocks are allocated, and none are ever freed.  */
  30
  31 static void *alloc_ptr, *alloc_end, *alloc_last_block;
  32
  33 void * weak_function
  34 malloc (size_t n)
  35 {
  36 #ifdef MAP_ANON
  37 #define _dl_zerofd (-1)
  38 #else
  39   extern int _dl_zerofd;
  40
  41   if (_dl_zerofd == -1)
  42     _dl_zerofd = _dl_sysdep_open_zero_fill ();
  43 #define MAP_ANON 0
  44 #endif
  45
  46   if (_dl_pagesize == 0)
  47     _dl_pagesize = __getpagesize ();
  48
  49   if (alloc_end == 0)
  50     {
  51       /* Consume any unused space in the last page of our data segment.  */
  52       extern int _end;
  53       alloc_ptr = &_end;
  54       alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0) + _dl_pagesize - 1)
  55                                 & ~(_dl_pagesize - 1));
  56     }
  57
  58   /* Make sure the allocation pointer is ideally aligned.  */
  59   alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + sizeof (double) - 1)
  60                             & ~(sizeof (double) - 1));
  61
  62   if (alloc_ptr + n >= alloc_end)
  63     {
  64       /* Insufficient space left; allocate another page.  */
  65       caddr_t page;
  66       assert (n <= _dl_pagesize);
  67       page = __mmap (0, _dl_pagesize, PROT_READ|PROT_WRITE,
  68                      MAP_ANON|MAP_PRIVATE, _dl_zerofd, 0);
  69       assert (page != (caddr_t) -1);
  70       if (page != alloc_end)
  71         alloc_ptr = page;
  72       alloc_end = page + _dl_pagesize;
  73     }
  74
  75   alloc_last_block = (void *) alloc_ptr;
  76   alloc_ptr += n;
  77   return alloc_last_block;
  78 }
  79
  80 /* We use this function occasionally since the real implementation may
  81    be optimized when it can assume the memory it returns already is
  82    set to NUL.  */
  83 void * weak_function
  84 calloc (size_t nmemb, size_t size)
  85 {
  86   size_t total = nmemb * size;
  87   void *result = malloc (total);
  88   return memset (result, '\0', total);
  89 }
  90
  91 /* This will rarely be called.  */
  92 void weak_function
  93 free (void *ptr)
  94 {
  95   /* We can free only the last block allocated.  */
  96   if (ptr == alloc_last_block)
  97     alloc_ptr = alloc_last_block;
  98 }
  99
 100 /* This is only called with the most recent block returned by malloc.  */
 101 void * weak_function
 102 realloc (void *ptr, size_t n)
 103 {
 104   void *new;
 105   assert (ptr == alloc_last_block);
 106   alloc_ptr = alloc_last_block;
 107   new = malloc (n);
 108   assert (new == ptr);
 109   return new;
 110 }
 111 \f
 112 /* Avoid signal frobnication in setjmp/longjmp.  Keeps things smaller.  */
 113
 114 #include <setjmp.h>
 115
 116 int weak_function
 117 __sigjmp_save (sigjmp_buf env, int savemask)
 118 { env[0].__mask_was_saved = savemask; return 0; }
 119
 120 void weak_function
 121 longjmp (jmp_buf env, int val) { __longjmp (env[0].__jmpbuf, val); }
 122 \f
 123 /* Define our own stub for the localization function used by strerror.
 124    English-only in the dynamic linker keeps it smaller.  */
 125
 126 char * weak_function
 127 __dcgettext (const char *domainname, const char *msgid, int category)
 128 {
 129   assert (domainname == _libc_intl_domainname);
 130   return (char *) msgid;
 131 }
 132 weak_alias (__dcgettext, dcgettext)
 133 \f
 134 #ifndef NDEBUG
 135
 136 /* Define (weakly) our own assert failure function which doesn't use stdio.
 137    If we are linked into the user program (-ldl), the normal __assert_fail
 138    defn can override this one.  */
 139
 140 void weak_function
 141 __assert_fail (const char *assertion,
 142                const char *file, unsigned int line, const char *function)
 143 {
 144   char buf[64];
 145   buf[sizeof buf - 1] = '\0';
 146   _dl_sysdep_fatal ("BUG IN DYNAMIC LINKER ld.so: ",
 147                     file, ": ", _itoa (line, buf + sizeof buf - 1, 10, 0),
 148                     ": ", function ?: "", function ? ": " : "",
 149                     "Assertion `", assertion, "' failed!\n",
 150                     NULL);
 151
 152 }
 153
 154 void weak_function
 155 __assert_perror_fail (int errnum,
 156                       const char *file, unsigned int line,
 157                       const char *function)
 158 {
 159   char buf[64];
 160   buf[sizeof buf - 1] = '\0';
 161   _dl_sysdep_fatal ("BUG IN DYNAMIC LINKER ld.so: ",
 162                     file, ": ", _itoa (line, buf + sizeof buf - 1, 10, 0),
 163                     ": ", function ?: "", function ? ": " : "",
 164                     "Unexpected error: ", strerror (errnum), "\n", NULL);
 165
 166 }
 167
 168 #endif