elf/dl-minimal.c

   1 /* Minimal replacements for basic facilities used in the dynamic linker.
   2    Copyright (C) 1995-1998,2000-2002,2004,2005,2006
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <limits.h>
  23 #include <string.h>
  24 #include <tls.h>
  25 #include <unistd.h>
  26 #include <sys/mman.h>
  27 #include <sys/param.h>
  28 #include <sys/types.h>
  29 #include <ldsodefs.h>
  30 #include <stdio-common/_itoa.h>
  31
  32 #include <assert.h>
  33
  34 /* Minimal `malloc' allocator for use while loading shared libraries.
  35    No block is ever freed.  */
  36
  37 static void *alloc_ptr, *alloc_end, *alloc_last_block;
  38
  39 /* Declarations of global functions.  */
  40 extern void weak_function free (void *ptr);
  41 extern void * weak_function realloc (void *ptr, size_t n);
  42 extern unsigned long int weak_function __strtoul_internal (const char *nptr,
  43                                                            char **endptr,
  44                                                            int base,
  45                                                            int group);
  46 extern unsigned long int weak_function strtoul (const char *nptr,
  47                                                 char **endptr, int base);
  48
  49
  50 /* Allocate an aligned memory block.  */
  51 void * weak_function
  52 __libc_memalign (size_t align, size_t n)
  53 {
  54 #ifdef MAP_ANON
  55 #define _dl_zerofd (-1)
  56 #else
  57   extern int _dl_zerofd;
  58
  59   if (_dl_zerofd == -1)
  60     _dl_zerofd = _dl_sysdep_open_zero_fill ();
  61 #define MAP_ANON 0
  62 #endif
  63
  64   if (alloc_end == 0)
  65     {
  66       /* Consume any unused space in the last page of our data segment.  */
  67       extern int _end attribute_hidden;
  68       alloc_ptr = &_end;
  69       alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0)
  70                                  + GLRO(dl_pagesize) - 1)
  71                                 & ~(GLRO(dl_pagesize) - 1));
  72     }
  73
  74   /* Make sure the allocation pointer is ideally aligned.  */
  75   alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + align - 1)
  76                             & ~(align - 1));
  77
  78   if (alloc_ptr + n >= alloc_end)
  79     {
  80       /* Insufficient space left; allocate another page.  */
  81       caddr_t page;
  82       size_t nup = (n + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1);
  83       page = __mmap (0, nup, PROT_READ|PROT_WRITE,
  84                      MAP_ANON|MAP_PRIVATE, _dl_zerofd, 0);
  85       assert (page != MAP_FAILED);
  86       if (page != alloc_end)
  87         alloc_ptr = page;
  88       alloc_end = page + nup;
  89     }
  90
  91   alloc_last_block = (void *) alloc_ptr;
  92   alloc_ptr += n;
  93   return alloc_last_block;
  94 }
  95
  96 void * weak_function
  97 malloc (size_t n)
  98 {
  99   return __libc_memalign (sizeof (double), n);
 100 }
 101
 102 /* We use this function occasionally since the real implementation may
 103    be optimized when it can assume the memory it returns already is
 104    set to NUL.  */
 105 void * weak_function
 106 calloc (size_t nmemb, size_t size)
 107 {
 108   /* New memory from the trivial malloc above is always already cleared.
 109      (We make sure that's true in the rare occasion it might not be,
 110      by clearing memory in free, below.)  */
 111   return malloc (nmemb * size);
 112 }
 113
 114 /* This will rarely be called.  */
 115 void weak_function
 116 free (void *ptr)
 117 {
 118   /* We can free only the last block allocated.  */
 119   if (ptr == alloc_last_block)
 120     {
 121       /* Since this is rare, we clear the freed block here
 122          so that calloc can presume malloc returns cleared memory.  */
 123       memset (alloc_last_block, '\0', alloc_ptr - alloc_last_block);
 124       alloc_ptr = alloc_last_block;
 125     }
 126 }
 127
 128 /* This is only called with the most recent block returned by malloc.  */
 129 void * weak_function
 130 realloc (void *ptr, size_t n)
 131 {
 132   if (ptr == NULL)
 133     return malloc (n);
 134   assert (ptr == alloc_last_block);
 135   size_t old_size = alloc_ptr - alloc_last_block;
 136   alloc_ptr = alloc_last_block;
 137   void *new = malloc (n);
 138   return new != ptr ? memcpy (new, ptr, old_size) : new;
 139 }
 140 \f
 141 /* Avoid signal frobnication in setjmp/longjmp.  Keeps things smaller.  */
 142
 143 #include <setjmp.h>
 144
 145 int weak_function
 146 __sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused)))
 147 {
 148   env[0].__mask_was_saved = 0;
 149   return 0;
 150 }
 151 \f
 152 /* Define our own version of the internal function used by strerror.  We
 153    only provide the messages for some common errors.  This avoids pulling
 154    in the whole error list.  */
 155
 156 char * weak_function
 157 __strerror_r (int errnum, char *buf, size_t buflen)
 158 {
 159   char *msg;
 160
 161   switch (errnum)
 162     {
 163     case ENOMEM:
 164       msg = (char *) "Cannot allocate memory";
 165       break;
 166     case EINVAL:
 167       msg = (char *) "Invalid argument";
 168       break;
 169     case ENOENT:
 170       msg = (char *) "No such file or directory";
 171       break;
 172     case EPERM:
 173       msg = (char *) "Operation not permitted";
 174       break;
 175     case EIO:
 176       msg = (char *) "Input/output error";
 177       break;
 178     case EACCES:
 179       msg = (char *) "Permission denied";
 180       break;
 181     default:
 182       /* No need to check buffer size, all calls in the dynamic linker
 183          provide enough space.  */
 184       buf[buflen - 1] = '\0';
 185       msg = _itoa (errnum, buf + buflen - 1, 10, 0);
 186       msg = memcpy (msg - (sizeof ("Error ") - 1), "Error ",
 187                     sizeof ("Error ") - 1);
 188       break;
 189     }
 190
 191   return msg;
 192 }
 193 \f
 194 #ifndef NDEBUG
 195
 196 /* Define (weakly) our own assert failure function which doesn't use stdio.
 197    If we are linked into the user program (-ldl), the normal __assert_fail
 198    defn can override this one.  */
 199
 200 void weak_function
 201 __assert_fail (const char *assertion,
 202                const char *file, unsigned int line, const char *function)
 203 {
 204   _dl_fatal_printf ("\
 205 Inconsistency detected by ld.so: %s: %u: %s%sAssertion `%s' failed!\n",
 206                     file, line, function ?: "", function ? ": " : "",
 207                     assertion);
 208
 209 }
 210 rtld_hidden_weak(__assert_fail)
 211
 212 void weak_function
 213 __assert_perror_fail (int errnum,
 214                       const char *file, unsigned int line,
 215                       const char *function)
 216 {
 217   char errbuf[400];
 218   _dl_fatal_printf ("\
 219 Inconsistency detected by ld.so: %s: %u: %s%sUnexpected error: %s.\n",
 220                     file, line, function ?: "", function ? ": " : "",
 221                     __strerror_r (errnum, errbuf, sizeof errbuf));
 222
 223 }
 224 rtld_hidden_weak (__assert_perror_fail)
 225 #endif
 226
 227 unsigned long int weak_function
 228 __strtoul_internal (const char *nptr, char **endptr, int base, int group)
 229 {
 230   unsigned long int result = 0;
 231   long int sign = 1;
 232
 233   while (*nptr == ' ' || *nptr == '\t')
 234     ++nptr;
 235
 236   if (*nptr == '-')
 237     {
 238       sign = -1;
 239       ++nptr;
 240     }
 241   else if (*nptr == '+')
 242     ++nptr;
 243
 244   if (*nptr < '0' || *nptr > '9')
 245     {
 246       if (endptr != NULL)
 247         *endptr = (char *) nptr;
 248       return 0UL;
 249     }
 250
 251   assert (base == 0);
 252   base = 10;
 253   if (*nptr == '0')
 254     {
 255       if (nptr[1] == 'x' || nptr[1] == 'X')
 256         {
 257           base = 16;
 258           nptr += 2;
 259         }
 260       else
 261         base = 8;
 262     }
 263
 264   while (*nptr >= '0' && *nptr <= '9')
 265     {
 266       unsigned long int digval = *nptr - '0';
 267       if (result > LONG_MAX / 10
 268           || (result == ULONG_MAX / 10 && digval > ULONG_MAX % 10))
 269         {
 270           errno = ERANGE;
 271           if (endptr != NULL)
 272             *endptr = (char *) nptr;
 273           return ULONG_MAX;
 274         }
 275       result *= base;
 276       result += digval;
 277       ++nptr;
 278     }
 279
 280   if (endptr != NULL)
 281     *endptr = (char *) nptr;
 282   return result * sign;
 283 }
 284
 285
 286 /* We always use _itoa instead of _itoa_word in ld.so since the former
 287    also has to be present and it is never about speed when these
 288    functions are used.  */
 289 char *
 290 _itoa (value, buflim, base, upper_case)
 291      unsigned long long int value;
 292      char *buflim;
 293      unsigned int base;
 294      int upper_case;
 295 {
 296   extern const char INTUSE(_itoa_lower_digits)[] attribute_hidden;
 297
 298   assert (! upper_case);
 299
 300   do
 301     *--buflim = INTUSE(_itoa_lower_digits)[value % base];
 302   while ((value /= base) != 0);
 303
 304   return buflim;
 305 }
 306
 307
 308 /* The following is not a complete strsep implementation.  It cannot
 309    handle empty delimiter strings.  But this isn't necessary for the
 310    execution of ld.so.  */
 311 #undef strsep
 312 #undef __strsep
 313 char *
 314 __strsep (char **stringp, const char *delim)
 315 {
 316   char *begin;
 317
 318   assert (delim[0] != '\0');
 319
 320   begin = *stringp;
 321   if (begin != NULL)
 322     {
 323       char *end = begin;
 324
 325       while (*end != '\0' || (end = NULL))
 326         {
 327           const char *dp = delim;
 328
 329           do
 330             if (*dp == *end)
 331               break;
 332           while (*++dp != '\0');
 333
 334           if (*dp != '\0')
 335             {
 336               *end++ = '\0';
 337               break;
 338             }
 339
 340           ++end;
 341         }
 342
 343       *stringp = end;
 344     }
 345
 346   return begin;
 347 }
 348 weak_alias (__strsep, strsep)
 349 strong_alias (__strsep, __strsep_g)
 350
 351 void
 352 __attribute__ ((noreturn))
 353 __chk_fail (void)
 354 {
 355   _exit (127);
 356 }
 357 rtld_hidden_def (__chk_fail)
 358
 359 /* The '_itoa_lower_digits' variable in libc.so is able to handle bases
 360    up to 36.  We don't need this here.  */
 361 const char INTUSE(_itoa_lower_digits)[16] attribute_hidden
 362   = "0123456789abcdef";