elf/dl-minimal.c

   1 /* Minimal replacements for basic facilities used in the dynamic linker.
   2    Copyright (C) 1995,96,97,98,2000,2001,2002 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <limits.h>
  22 #include <string.h>
  23 #include <tls.h>
  24 #include <unistd.h>
  25 #include <sys/mman.h>
  26 #include <sys/param.h>
  27 #include <sys/types.h>
  28 #include <ldsodefs.h>
  29 #include <stdio-common/_itoa.h>
  30
  31 #include <assert.h>
  32
  33 /* Minimal `malloc' allocator for use while loading shared libraries.
  34    No block is ever freed.  */
  35
  36 static void *alloc_ptr, *alloc_end, *alloc_last_block;
  37
  38 /* Declarations of global functions.  */
  39 extern void weak_function free (void *ptr);
  40 extern void * weak_function realloc (void *ptr, size_t n);
  41 extern unsigned long int weak_function __strtoul_internal (const char *nptr,
  42                                                            char **endptr,
  43                                                            int base,
  44                                                            int group);
  45 extern unsigned long int weak_function strtoul (const char *nptr,
  46                                                 char **endptr, int base);
  47
  48
  49 void * weak_function
  50 malloc (size_t n)
  51 {
  52 #ifdef MAP_ANON
  53 #define _dl_zerofd (-1)
  54 #else
  55   extern int _dl_zerofd;
  56
  57   if (_dl_zerofd == -1)
  58     _dl_zerofd = _dl_sysdep_open_zero_fill ();
  59 #define MAP_ANON 0
  60 #endif
  61
  62   if (alloc_end == 0)
  63     {
  64       /* Consume any unused space in the last page of our data segment.  */
  65       extern int _end attribute_hidden;
  66       alloc_ptr = &_end;
  67       alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0)
  68                                  + GL(dl_pagesize) - 1)
  69                                 & ~(GL(dl_pagesize) - 1));
  70     }
  71
  72   /* Make sure the allocation pointer is ideally aligned.  */
  73   alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + sizeof (double) - 1)
  74                             & ~(sizeof (double) - 1));
  75
  76   if (alloc_ptr + n >= alloc_end)
  77     {
  78       /* Insufficient space left; allocate another page.  */
  79       caddr_t page;
  80       size_t nup = (n + GL(dl_pagesize) - 1) & ~(GL(dl_pagesize) - 1);
  81       page = __mmap (0, nup, PROT_READ|PROT_WRITE,
  82                      MAP_ANON|MAP_PRIVATE, _dl_zerofd, 0);
  83       assert (page != MAP_FAILED);
  84       if (page != alloc_end)
  85         alloc_ptr = page;
  86       alloc_end = page + nup;
  87     }
  88
  89   alloc_last_block = (void *) alloc_ptr;
  90   alloc_ptr += n;
  91   return alloc_last_block;
  92 }
  93
  94 /* We use this function occasionally since the real implementation may
  95    be optimized when it can assume the memory it returns already is
  96    set to NUL.  */
  97 void * weak_function
  98 calloc (size_t nmemb, size_t size)
  99 {
 100   size_t total = nmemb * size;
 101   void *result = malloc (total);
 102   return memset (result, '\0', total);
 103 }
 104
 105 /* This will rarely be called.  */
 106 void weak_function
 107 free (void *ptr)
 108 {
 109   /* We can free only the last block allocated.  */
 110   if (ptr == alloc_last_block)
 111     alloc_ptr = alloc_last_block;
 112 }
 113
 114 /* This is only called with the most recent block returned by malloc.  */
 115 void * weak_function
 116 realloc (void *ptr, size_t n)
 117 {
 118   void *new;
 119   if (ptr == NULL)
 120     return malloc (n);
 121   assert (ptr == alloc_last_block);
 122   alloc_ptr = alloc_last_block;
 123   new = malloc (n);
 124   assert (new == ptr);
 125   return new;
 126 }
 127
 128 /* Return alligned memory block.  */
 129 void * weak_function
 130 __libc_memalign (size_t align, size_t n)
 131 {
 132   void *newp = malloc (n + align - 1);
 133
 134   return (void *) roundup ((uintptr_t) newp, align);
 135 }
 136 \f
 137 /* Avoid signal frobnication in setjmp/longjmp.  Keeps things smaller.  */
 138
 139 #include <setjmp.h>
 140
 141 int weak_function
 142 __sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused)))
 143 {
 144   env[0].__mask_was_saved = 0;
 145   return 0;
 146 }
 147
 148 void weak_function
 149 longjmp (jmp_buf env, int val)
 150 {
 151   __longjmp (env[0].__jmpbuf, val);
 152 }
 153 \f
 154 /* Define our own version of the internal function used by strerror.  We
 155    only provide the messages for some common errors.  This avoids pulling
 156    in the whole error list.  */
 157
 158 char * weak_function
 159 __strerror_r (int errnum, char *buf, size_t buflen)
 160 {
 161   char *msg;
 162
 163   switch (errnum)
 164     {
 165     case ENOMEM:
 166       msg = (char *) "Cannot allocate memory";
 167       break;
 168     case EINVAL:
 169       msg = (char *) "Invalid argument";
 170       break;
 171     case ENOENT:
 172       msg = (char *) "No such file or directory";
 173       break;
 174     case EPERM:
 175       msg = (char *) "Operation not permitted";
 176       break;
 177     case EIO:
 178       msg = (char *) "Input/output error";
 179       break;
 180     case EACCES:
 181       msg = (char *) "Permission denied";
 182       break;
 183     default:
 184       /* No need to check buffer size, all calls in the dynamic linker
 185          provide enough space.  */
 186       buf[buflen - 1] = '\0';
 187       msg = _itoa (errnum, buf + buflen - 1, 10, 0);
 188       msg = memcpy (msg - (sizeof ("Error ") - 1), "Error ",
 189                     sizeof ("Error ") - 1);
 190       break;
 191     }
 192
 193   return msg;
 194 }
 195 \f
 196 #ifndef NDEBUG
 197
 198 /* Define (weakly) our own assert failure function which doesn't use stdio.
 199    If we are linked into the user program (-ldl), the normal __assert_fail
 200    defn can override this one.  */
 201
 202 void weak_function
 203 __assert_fail (const char *assertion,
 204                const char *file, unsigned int line, const char *function)
 205 {
 206   _dl_fatal_printf ("\
 207 Inconsistency detected by ld.so: %s: %u: %s%sAssertion `%s' failed!\n",
 208                     file, line, function ?: "", function ? ": " : "",
 209                     assertion);
 210
 211 }
 212 INTDEF(__assert_fail)
 213
 214 void weak_function
 215 __assert_perror_fail (int errnum,
 216                       const char *file, unsigned int line,
 217                       const char *function)
 218 {
 219   char errbuf[64];
 220   _dl_fatal_printf ("\
 221 Inconsistency detected by ld.so: %s: %u: %s%sUnexpected error: %s\n",
 222                     file, line, function ?: "", function ? ": " : "",
 223                     __strerror_r (errnum, errbuf, sizeof (errbuf)));
 224 }
 225
 226 #endif
 227
 228 unsigned long int weak_function
 229 __strtoul_internal (const char *nptr, char **endptr, int base, int group)
 230 {
 231   unsigned long int result = 0;
 232   long int sign = 1;
 233
 234   while (*nptr == ' ' || *nptr == '\t')
 235     ++nptr;
 236
 237   if (*nptr == '-')
 238     {
 239       sign = -1;
 240       ++nptr;
 241     }
 242   else if (*nptr == '+')
 243     ++nptr;
 244
 245   if (*nptr < '0' || *nptr > '9')
 246     {
 247       if (endptr != NULL)
 248         *endptr = (char *) nptr;
 249       return 0UL;
 250     }
 251
 252   assert (base == 0);
 253   base = 10;
 254   if (*nptr == '0')
 255     {
 256       if (nptr[1] == 'x' || nptr[1] == 'X')
 257         {
 258           base = 16;
 259           nptr += 2;
 260         }
 261       else
 262         base = 8;
 263     }
 264
 265   while (*nptr >= '0' && *nptr <= '9')
 266     {
 267       unsigned long int digval = *nptr - '0';
 268       if (result > LONG_MAX / 10
 269           || (result == ULONG_MAX / 10 && digval > ULONG_MAX % 10))
 270         {
 271           errno = ERANGE;
 272           if (endptr != NULL)
 273             *endptr = (char *) nptr;
 274           return ULONG_MAX;
 275         }
 276       result *= base;
 277       result += digval;
 278       ++nptr;
 279     }
 280
 281   if (endptr != NULL)
 282     *endptr = (char *) nptr;
 283   return result * sign;
 284 }
 285
 286
 287 /* We always use _itoa instead of _itoa_word in ld.so since the former
 288    also has to be present and it is never about speed when these
 289    functions are used.  */
 290 char *
 291 _itoa (value, buflim, base, upper_case)
 292      unsigned long long int value;
 293      char *buflim;
 294      unsigned int base;
 295      int upper_case;
 296 {
 297   extern const char INTUSE(_itoa_lower_digits)[] attribute_hidden;
 298
 299   assert (! upper_case);
 300
 301   do
 302     *--buflim = INTUSE(_itoa_lower_digits)[value % base];
 303   while ((value /= base) != 0);
 304
 305   return buflim;
 306 }
 307
 308
 309 /* The following is not a complete strsep implementation.  It cannot
 310    handle empty delimiter strings.  But this isn't necessary for the
 311    execution of ld.so.  */
 312 #undef strsep
 313 #undef __strsep
 314 char *
 315 __strsep (char **stringp, const char *delim)
 316 {
 317   char *begin;
 318
 319   assert (delim[0] != '\0');
 320
 321   begin = *stringp;
 322   if (begin != NULL)
 323     {
 324       char *end = begin;
 325
 326       while (*end != '\0' || (end = NULL))
 327         {
 328           const char *dp = delim;
 329
 330           do
 331             if (*dp == *end)
 332               break;
 333           while (*++dp != '\0');
 334
 335           if (*dp != '\0')
 336             {
 337               *end++ = '\0';
 338               break;
 339             }
 340
 341           ++end;
 342         }
 343
 344       *stringp = end;
 345     }
 346
 347   return begin;
 348 }
 349 weak_alias (__strsep, strsep)
 350 strong_alias (__strsep, __strsep_g)
 351
 352
 353 /* The '_itoa_lower_digits' variable in libc.so is able to handle bases
 354    up to 36.  We don't need this here.  */
 355 const char INTUSE(_itoa_lower_digits)[16] attribute_hidden
 356   = "0123456789abcdef";
 357
 358
 359
 360 #undef errno
 361 /* The 'errno' in ld.so is not exported.  */
 362 #if USE_TLS && HAVE___THREAD
 363 extern __thread int errno attribute_hidden;
 364 #else
 365 extern int errno attribute_hidden;
 366
 367 int *
 368 __errno_location (void)
 369 {
 370   return &errno;
 371 }
 372 #endif