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