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 /* Allocate an aligned memory block.  */
  50 void * weak_function
  51 __libc_memalign (size_t align, size_t n)
  52 {
  53 #ifdef MAP_ANON
  54 #define _dl_zerofd (-1)
  55 #else
  56   extern int _dl_zerofd;
  57
  58   if (_dl_zerofd == -1)
  59     _dl_zerofd = _dl_sysdep_open_zero_fill ();
  60 #define MAP_ANON 0
  61 #endif
  62
  63   if (alloc_end == 0)
  64     {
  65       /* Consume any unused space in the last page of our data segment.  */
  66       extern int _end attribute_hidden;
  67       alloc_ptr = &_end;
  68       alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0)
  69                                  + GL(dl_pagesize) - 1)
  70                                 & ~(GL(dl_pagesize) - 1));
  71     }
  72
  73   /* Make sure the allocation pointer is ideally aligned.  */
  74   alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + align - 1)
  75                             & ~(align - 1));
  76
  77   if (alloc_ptr + n >= alloc_end)
  78     {
  79       /* Insufficient space left; allocate another page.  */
  80       caddr_t page;
  81       size_t nup = (n + GL(dl_pagesize) - 1) & ~(GL(dl_pagesize) - 1);
  82       page = __mmap (0, nup, PROT_READ|PROT_WRITE,
  83                      MAP_ANON|MAP_PRIVATE, _dl_zerofd, 0);
  84       assert (page != MAP_FAILED);
  85       if (page != alloc_end)
  86         alloc_ptr = page;
  87       alloc_end = page + nup;
  88     }
  89
  90   alloc_last_block = (void *) alloc_ptr;
  91   alloc_ptr += n;
  92   return alloc_last_block;
  93 }
  94
  95 void * weak_function
  96 malloc (size_t n)
  97 {
  98   return __libc_memalign (sizeof (double), n);
  99 }
 100
 101 /* We use this function occasionally since the real implementation may
 102    be optimized when it can assume the memory it returns already is
 103    set to NUL.  */
 104 void * weak_function
 105 calloc (size_t nmemb, size_t size)
 106 {
 107   size_t total = nmemb * size;
 108   void *result = malloc (total);
 109   return memset (result, '\0', total);
 110 }
 111
 112 /* This will rarely be called.  */
 113 void weak_function
 114 free (void *ptr)
 115 {
 116   /* We can free only the last block allocated.  */
 117   if (ptr == alloc_last_block)
 118     alloc_ptr = alloc_last_block;
 119 }
 120
 121 /* This is only called with the most recent block returned by malloc.  */
 122 void * weak_function
 123 realloc (void *ptr, size_t n)
 124 {
 125   void *new;
 126   if (ptr == NULL)
 127     return malloc (n);
 128   assert (ptr == alloc_last_block);
 129   alloc_ptr = alloc_last_block;
 130   new = malloc (n);
 131   assert (new == ptr);
 132   return new;
 133 }
 134 \f
 135 /* Avoid signal frobnication in setjmp/longjmp.  Keeps things smaller.  */
 136
 137 #include <setjmp.h>
 138
 139 int weak_function
 140 __sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused)))
 141 {
 142   env[0].__mask_was_saved = 0;
 143   return 0;
 144 }
 145
 146 void weak_function
 147 longjmp (jmp_buf env, int val)
 148 {
 149   __longjmp (env[0].__jmpbuf, val);
 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
 352 /* The '_itoa_lower_digits' variable in libc.so is able to handle bases
 353    up to 36.  We don't need this here.  */
 354 const char INTUSE(_itoa_lower_digits)[16] attribute_hidden
 355   = "0123456789abcdef";
 356
 357
 358
 359 #undef errno
 360 /* The 'errno' in ld.so is not exported.  */
 361 #if USE_TLS && HAVE___THREAD
 362 extern __thread int errno attribute_hidden;
 363 #else
 364 extern int errno attribute_hidden;
 365
 366 int *
 367 __errno_location (void)
 368 {
 369   return &errno;
 370 }
 371 #endif