elf/dl-misc.c

   1 /* Miscellaneous support functions for dynamic linker
   2    Copyright (C) 1997-2016 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <fcntl.h>
  21 #include <ldsodefs.h>
  22 #include <limits.h>
  23 #include <link.h>
  24 #include <stdarg.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <stdint.h>
  29 #include <sys/mman.h>
  30 #include <sys/param.h>
  31 #include <sys/stat.h>
  32 #include <sys/uio.h>
  33 #include <sysdep.h>
  34 #include <_itoa.h>
  35 #include <dl-writev.h>
  36
  37
  38 /* Read the whole contents of FILE into new mmap'd space with given
  39    protections.  *SIZEP gets the size of the file.  On error MAP_FAILED
  40    is returned.  */
  41
  42 void *
  43 internal_function
  44 _dl_sysdep_read_whole_file (const char *file, size_t *sizep, int prot)
  45 {
  46   void *result = MAP_FAILED;
  47   struct stat64 st;
  48   int flags = O_RDONLY;
  49 #ifdef O_CLOEXEC
  50   flags |= O_CLOEXEC;
  51 #endif
  52   int fd = __open (file, flags);
  53   if (fd >= 0)
  54     {
  55       if (__fxstat64 (_STAT_VER, fd, &st) >= 0)
  56         {
  57           *sizep = st.st_size;
  58
  59           /* No need to map the file if it is empty.  */
  60           if (*sizep != 0)
  61             /* Map a copy of the file contents.  */
  62             result = __mmap (NULL, *sizep, prot,
  63 #ifdef MAP_COPY
  64                              MAP_COPY
  65 #else
  66                              MAP_PRIVATE
  67 #endif
  68 #ifdef MAP_FILE
  69                              | MAP_FILE
  70 #endif
  71                              , fd, 0);
  72         }
  73       __close (fd);
  74     }
  75   return result;
  76 }
  77
  78
  79 /* Bare-bones printf implementation.  This function only knows about
  80    the formats and flags needed and can handle only up to 64 stripes in
  81    the output.  */
  82 static void
  83 _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
  84 {
  85 # define NIOVMAX 64
  86   struct iovec iov[NIOVMAX];
  87   int niov = 0;
  88   pid_t pid = 0;
  89   char pidbuf[12];
  90
  91   while (*fmt != '\0')
  92     {
  93       const char *startp = fmt;
  94
  95       if (tag_p > 0)
  96         {
  97           /* Generate the tag line once.  It consists of the PID and a
  98              colon followed by a tab.  */
  99           if (pid == 0)
 100             {
 101               char *p;
 102               pid = __getpid ();
 103               assert (pid >= 0 && sizeof (pid_t) <= 4);
 104               p = _itoa (pid, &pidbuf[10], 10, 0);
 105               while (p > pidbuf)
 106                 *--p = ' ';
 107               pidbuf[10] = ':';
 108               pidbuf[11] = '\t';
 109             }
 110
 111           /* Append to the output.  */
 112           assert (niov < NIOVMAX);
 113           iov[niov].iov_len = 12;
 114           iov[niov++].iov_base = pidbuf;
 115
 116           /* No more tags until we see the next newline.  */
 117           tag_p = -1;
 118         }
 119
 120       /* Skip everything except % and \n (if tags are needed).  */
 121       while (*fmt != '\0' && *fmt != '%' && (! tag_p || *fmt != '\n'))
 122         ++fmt;
 123
 124       /* Append constant string.  */
 125       assert (niov < NIOVMAX);
 126       if ((iov[niov].iov_len = fmt - startp) != 0)
 127         iov[niov++].iov_base = (char *) startp;
 128
 129       if (*fmt == '%')
 130         {
 131           /* It is a format specifier.  */
 132           char fill = ' ';
 133           int width = -1;
 134           int prec = -1;
 135 #if LONG_MAX != INT_MAX
 136           int long_mod = 0;
 137 #endif
 138
 139           /* Recognize zero-digit fill flag.  */
 140           if (*++fmt == '0')
 141             {
 142               fill = '0';
 143               ++fmt;
 144             }
 145
 146           /* See whether with comes from a parameter.  Note that no other
 147              way to specify the width is implemented.  */
 148           if (*fmt == '*')
 149             {
 150               width = va_arg (arg, int);
 151               ++fmt;
 152             }
 153
 154           /* Handle precision.  */
 155           if (*fmt == '.' && fmt[1] == '*')
 156             {
 157               prec = va_arg (arg, int);
 158               fmt += 2;
 159             }
 160
 161           /* Recognize the l modifier.  It is only important on some
 162              platforms where long and int have a different size.  We
 163              can use the same code for size_t.  */
 164           if (*fmt == 'l' || *fmt == 'Z')
 165             {
 166 #if LONG_MAX != INT_MAX
 167               long_mod = 1;
 168 #endif
 169               ++fmt;
 170             }
 171
 172           switch (*fmt)
 173             {
 174               /* Integer formatting.  */
 175             case 'u':
 176             case 'x':
 177               {
 178                 /* We have to make a difference if long and int have a
 179                    different size.  */
 180 #if LONG_MAX != INT_MAX
 181                 unsigned long int num = (long_mod
 182                                          ? va_arg (arg, unsigned long int)
 183                                          : va_arg (arg, unsigned int));
 184 #else
 185                 unsigned long int num = va_arg (arg, unsigned int);
 186 #endif
 187                 /* We use alloca() to allocate the buffer with the most
 188                    pessimistic guess for the size.  Using alloca() allows
 189                    having more than one integer formatting in a call.  */
 190                 char *buf = (char *) alloca (3 * sizeof (unsigned long int));
 191                 char *endp = &buf[3 * sizeof (unsigned long int)];
 192                 char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0);
 193
 194                 /* Pad to the width the user specified.  */
 195                 if (width != -1)
 196                   while (endp - cp < width)
 197                     *--cp = fill;
 198
 199                 iov[niov].iov_base = cp;
 200                 iov[niov].iov_len = endp - cp;
 201                 ++niov;
 202               }
 203               break;
 204
 205             case 's':
 206               /* Get the string argument.  */
 207               iov[niov].iov_base = va_arg (arg, char *);
 208               iov[niov].iov_len = strlen (iov[niov].iov_base);
 209               if (prec != -1)
 210                 iov[niov].iov_len = MIN ((size_t) prec, iov[niov].iov_len);
 211               ++niov;
 212               break;
 213
 214             case '%':
 215               iov[niov].iov_base = (void *) fmt;
 216               iov[niov].iov_len = 1;
 217               ++niov;
 218               break;
 219
 220             default:
 221               assert (! "invalid format specifier");
 222             }
 223           ++fmt;
 224         }
 225       else if (*fmt == '\n')
 226         {
 227           /* See whether we have to print a single newline character.  */
 228           if (fmt == startp)
 229             {
 230               iov[niov].iov_base = (char *) startp;
 231               iov[niov++].iov_len = 1;
 232             }
 233           else
 234             /* No, just add it to the rest of the string.  */
 235             ++iov[niov - 1].iov_len;
 236
 237           /* Next line, print a tag again.  */
 238           tag_p = 1;
 239           ++fmt;
 240         }
 241     }
 242
 243   /* Finally write the result.  */
 244   _dl_writev (fd, iov, niov);
 245 }
 246
 247
 248 /* Write to debug file.  */
 249 void
 250 _dl_debug_printf (const char *fmt, ...)
 251 {
 252   va_list arg;
 253
 254   va_start (arg, fmt);
 255   _dl_debug_vdprintf (GLRO(dl_debug_fd), 1, fmt, arg);
 256   va_end (arg);
 257 }
 258
 259
 260 /* Write to debug file but don't start with a tag.  */
 261 void
 262 _dl_debug_printf_c (const char *fmt, ...)
 263 {
 264   va_list arg;
 265
 266   va_start (arg, fmt);
 267   _dl_debug_vdprintf (GLRO(dl_debug_fd), -1, fmt, arg);
 268   va_end (arg);
 269 }
 270
 271
 272 /* Write the given file descriptor.  */
 273 void
 274 _dl_dprintf (int fd, const char *fmt, ...)
 275 {
 276   va_list arg;
 277
 278   va_start (arg, fmt);
 279   _dl_debug_vdprintf (fd, 0, fmt, arg);
 280   va_end (arg);
 281 }
 282
 283
 284 /* Test whether given NAME matches any of the names of the given object.  */
 285 int
 286 internal_function
 287 _dl_name_match_p (const char *name, const struct link_map *map)
 288 {
 289   if (strcmp (name, map->l_name) == 0)
 290     return 1;
 291
 292   struct libname_list *runp = map->l_libname;
 293
 294   while (runp != NULL)
 295     if (strcmp (name, runp->name) == 0)
 296       return 1;
 297     else
 298       runp = runp->next;
 299
 300   return 0;
 301 }
 302
 303
 304 unsigned long int
 305 internal_function
 306 _dl_higher_prime_number (unsigned long int n)
 307 {
 308   /* These are primes that are near, but slightly smaller than, a
 309      power of two.  */
 310   static const uint32_t primes[] = {
 311     UINT32_C (7),
 312     UINT32_C (13),
 313     UINT32_C (31),
 314     UINT32_C (61),
 315     UINT32_C (127),
 316     UINT32_C (251),
 317     UINT32_C (509),
 318     UINT32_C (1021),
 319     UINT32_C (2039),
 320     UINT32_C (4093),
 321     UINT32_C (8191),
 322     UINT32_C (16381),
 323     UINT32_C (32749),
 324     UINT32_C (65521),
 325     UINT32_C (131071),
 326     UINT32_C (262139),
 327     UINT32_C (524287),
 328     UINT32_C (1048573),
 329     UINT32_C (2097143),
 330     UINT32_C (4194301),
 331     UINT32_C (8388593),
 332     UINT32_C (16777213),
 333     UINT32_C (33554393),
 334     UINT32_C (67108859),
 335     UINT32_C (134217689),
 336     UINT32_C (268435399),
 337     UINT32_C (536870909),
 338     UINT32_C (1073741789),
 339     UINT32_C (2147483647),
 340                                        /* 4294967291L */
 341     UINT32_C (2147483647) + UINT32_C (2147483644)
 342   };
 343
 344   const uint32_t *low = &primes[0];
 345   const uint32_t *high = &primes[sizeof (primes) / sizeof (primes[0])];
 346
 347   while (low != high)
 348     {
 349       const uint32_t *mid = low + (high - low) / 2;
 350       if (n > *mid)
 351        low = mid + 1;
 352       else
 353        high = mid;
 354     }
 355
 356 #if 0
 357   /* If we've run out of primes, abort.  */
 358   if (n > *low)
 359     {
 360       fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
 361       abort ();
 362     }
 363 #endif
 364
 365   return *low;
 366 }