elf/dl-misc.c

   1 /* Miscellaneous support functions for dynamic linker
   2    Copyright (C) 1997-2017 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 fd = __open (file, O_RDONLY | O_CLOEXEC);
  49   if (fd >= 0)
  50     {
  51       if (__fxstat64 (_STAT_VER, fd, &st) >= 0)
  52         {
  53           *sizep = st.st_size;
  54
  55           /* No need to map the file if it is empty.  */
  56           if (*sizep != 0)
  57             /* Map a copy of the file contents.  */
  58             result = __mmap (NULL, *sizep, prot,
  59 #ifdef MAP_COPY
  60                              MAP_COPY
  61 #else
  62                              MAP_PRIVATE
  63 #endif
  64 #ifdef MAP_FILE
  65                              | MAP_FILE
  66 #endif
  67                              , fd, 0);
  68         }
  69       __close (fd);
  70     }
  71   return result;
  72 }
  73
  74
  75 /* Bare-bones printf implementation.  This function only knows about
  76    the formats and flags needed and can handle only up to 64 stripes in
  77    the output.  */
  78 static void
  79 _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
  80 {
  81 # define NIOVMAX 64
  82   struct iovec iov[NIOVMAX];
  83   int niov = 0;
  84   pid_t pid = 0;
  85   char pidbuf[12];
  86
  87   while (*fmt != '\0')
  88     {
  89       const char *startp = fmt;
  90
  91       if (tag_p > 0)
  92         {
  93           /* Generate the tag line once.  It consists of the PID and a
  94              colon followed by a tab.  */
  95           if (pid == 0)
  96             {
  97               char *p;
  98               pid = __getpid ();
  99               assert (pid >= 0 && sizeof (pid_t) <= 4);
 100               p = _itoa (pid, &pidbuf[10], 10, 0);
 101               while (p > pidbuf)
 102                 *--p = ' ';
 103               pidbuf[10] = ':';
 104               pidbuf[11] = '\t';
 105             }
 106
 107           /* Append to the output.  */
 108           assert (niov < NIOVMAX);
 109           iov[niov].iov_len = 12;
 110           iov[niov++].iov_base = pidbuf;
 111
 112           /* No more tags until we see the next newline.  */
 113           tag_p = -1;
 114         }
 115
 116       /* Skip everything except % and \n (if tags are needed).  */
 117       while (*fmt != '\0' && *fmt != '%' && (! tag_p || *fmt != '\n'))
 118         ++fmt;
 119
 120       /* Append constant string.  */
 121       assert (niov < NIOVMAX);
 122       if ((iov[niov].iov_len = fmt - startp) != 0)
 123         iov[niov++].iov_base = (char *) startp;
 124
 125       if (*fmt == '%')
 126         {
 127           /* It is a format specifier.  */
 128           char fill = ' ';
 129           int width = -1;
 130           int prec = -1;
 131 #if LONG_MAX != INT_MAX
 132           int long_mod = 0;
 133 #endif
 134
 135           /* Recognize zero-digit fill flag.  */
 136           if (*++fmt == '0')
 137             {
 138               fill = '0';
 139               ++fmt;
 140             }
 141
 142           /* See whether with comes from a parameter.  Note that no other
 143              way to specify the width is implemented.  */
 144           if (*fmt == '*')
 145             {
 146               width = va_arg (arg, int);
 147               ++fmt;
 148             }
 149
 150           /* Handle precision.  */
 151           if (*fmt == '.' && fmt[1] == '*')
 152             {
 153               prec = va_arg (arg, int);
 154               fmt += 2;
 155             }
 156
 157           /* Recognize the l modifier.  It is only important on some
 158              platforms where long and int have a different size.  We
 159              can use the same code for size_t.  */
 160           if (*fmt == 'l' || *fmt == 'Z')
 161             {
 162 #if LONG_MAX != INT_MAX
 163               long_mod = 1;
 164 #endif
 165               ++fmt;
 166             }
 167
 168           switch (*fmt)
 169             {
 170               /* Integer formatting.  */
 171             case 'u':
 172             case 'x':
 173               {
 174                 /* We have to make a difference if long and int have a
 175                    different size.  */
 176 #if LONG_MAX != INT_MAX
 177                 unsigned long int num = (long_mod
 178                                          ? va_arg (arg, unsigned long int)
 179                                          : va_arg (arg, unsigned int));
 180 #else
 181                 unsigned long int num = va_arg (arg, unsigned int);
 182 #endif
 183                 /* We use alloca() to allocate the buffer with the most
 184                    pessimistic guess for the size.  Using alloca() allows
 185                    having more than one integer formatting in a call.  */
 186                 char *buf = (char *) alloca (3 * sizeof (unsigned long int));
 187                 char *endp = &buf[3 * sizeof (unsigned long int)];
 188                 char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0);
 189
 190                 /* Pad to the width the user specified.  */
 191                 if (width != -1)
 192                   while (endp - cp < width)
 193                     *--cp = fill;
 194
 195                 iov[niov].iov_base = cp;
 196                 iov[niov].iov_len = endp - cp;
 197                 ++niov;
 198               }
 199               break;
 200
 201             case 's':
 202               /* Get the string argument.  */
 203               iov[niov].iov_base = va_arg (arg, char *);
 204               iov[niov].iov_len = strlen (iov[niov].iov_base);
 205               if (prec != -1)
 206                 iov[niov].iov_len = MIN ((size_t) prec, iov[niov].iov_len);
 207               ++niov;
 208               break;
 209
 210             case '%':
 211               iov[niov].iov_base = (void *) fmt;
 212               iov[niov].iov_len = 1;
 213               ++niov;
 214               break;
 215
 216             default:
 217               assert (! "invalid format specifier");
 218             }
 219           ++fmt;
 220         }
 221       else if (*fmt == '\n')
 222         {
 223           /* See whether we have to print a single newline character.  */
 224           if (fmt == startp)
 225             {
 226               iov[niov].iov_base = (char *) startp;
 227               iov[niov++].iov_len = 1;
 228             }
 229           else
 230             /* No, just add it to the rest of the string.  */
 231             ++iov[niov - 1].iov_len;
 232
 233           /* Next line, print a tag again.  */
 234           tag_p = 1;
 235           ++fmt;
 236         }
 237     }
 238
 239   /* Finally write the result.  */
 240   _dl_writev (fd, iov, niov);
 241 }
 242
 243
 244 /* Write to debug file.  */
 245 void
 246 _dl_debug_printf (const char *fmt, ...)
 247 {
 248   va_list arg;
 249
 250   va_start (arg, fmt);
 251   _dl_debug_vdprintf (GLRO(dl_debug_fd), 1, fmt, arg);
 252   va_end (arg);
 253 }
 254
 255
 256 /* Write to debug file but don't start with a tag.  */
 257 void
 258 _dl_debug_printf_c (const char *fmt, ...)
 259 {
 260   va_list arg;
 261
 262   va_start (arg, fmt);
 263   _dl_debug_vdprintf (GLRO(dl_debug_fd), -1, fmt, arg);
 264   va_end (arg);
 265 }
 266
 267
 268 /* Write the given file descriptor.  */
 269 void
 270 _dl_dprintf (int fd, const char *fmt, ...)
 271 {
 272   va_list arg;
 273
 274   va_start (arg, fmt);
 275   _dl_debug_vdprintf (fd, 0, fmt, arg);
 276   va_end (arg);
 277 }
 278
 279
 280 /* Test whether given NAME matches any of the names of the given object.  */
 281 int
 282 internal_function
 283 _dl_name_match_p (const char *name, const struct link_map *map)
 284 {
 285   if (strcmp (name, map->l_name) == 0)
 286     return 1;
 287
 288   struct libname_list *runp = map->l_libname;
 289
 290   while (runp != NULL)
 291     if (strcmp (name, runp->name) == 0)
 292       return 1;
 293     else
 294       runp = runp->next;
 295
 296   return 0;
 297 }
 298
 299
 300 unsigned long int
 301 internal_function
 302 _dl_higher_prime_number (unsigned long int n)
 303 {
 304   /* These are primes that are near, but slightly smaller than, a
 305      power of two.  */
 306   static const uint32_t primes[] = {
 307     UINT32_C (7),
 308     UINT32_C (13),
 309     UINT32_C (31),
 310     UINT32_C (61),
 311     UINT32_C (127),
 312     UINT32_C (251),
 313     UINT32_C (509),
 314     UINT32_C (1021),
 315     UINT32_C (2039),
 316     UINT32_C (4093),
 317     UINT32_C (8191),
 318     UINT32_C (16381),
 319     UINT32_C (32749),
 320     UINT32_C (65521),
 321     UINT32_C (131071),
 322     UINT32_C (262139),
 323     UINT32_C (524287),
 324     UINT32_C (1048573),
 325     UINT32_C (2097143),
 326     UINT32_C (4194301),
 327     UINT32_C (8388593),
 328     UINT32_C (16777213),
 329     UINT32_C (33554393),
 330     UINT32_C (67108859),
 331     UINT32_C (134217689),
 332     UINT32_C (268435399),
 333     UINT32_C (536870909),
 334     UINT32_C (1073741789),
 335     UINT32_C (2147483647),
 336                                        /* 4294967291L */
 337     UINT32_C (2147483647) + UINT32_C (2147483644)
 338   };
 339
 340   const uint32_t *low = &primes[0];
 341   const uint32_t *high = &primes[sizeof (primes) / sizeof (primes[0])];
 342
 343   while (low != high)
 344     {
 345       const uint32_t *mid = low + (high - low) / 2;
 346       if (n > *mid)
 347        low = mid + 1;
 348       else
 349        high = mid;
 350     }
 351
 352 #if 0
 353   /* If we've run out of primes, abort.  */
 354   if (n > *low)
 355     {
 356       fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
 357       abort ();
 358     }
 359 #endif
 360
 361   return *low;
 362 }