gdb/testsuite/gdb.base/bigcore.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2004, 2007 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18    Please email any bugs, comments, and/or additions to this file to:
  19    bug-gdb@prep.ai.mit.edu  */
  20
  21 /* Get 64-bit stuff if on a GNU system.  */
  22 #define _GNU_SOURCE
  23
  24 #include <sys/types.h>
  25 #include <sys/time.h>
  26 #include <sys/resource.h>
  27 #include <sys/stat.h>
  28 #include <fcntl.h>
  29
  30 #include <stdlib.h>
  31 #include <unistd.h>
  32
  33 /* This test was written for >2GB core files on 32-bit systems.  On
  34    current 64-bit systems, generating a >4EB (2 ** 63) core file is
  35    not practical, and getting as close as we can takes a lot of
  36    useless CPU time.  So limit ourselves to a bit bigger than
  37    32-bit, which is still a useful test.  */
  38 #define RLIMIT_CAP (1ULL << 34)
  39
  40 /* Print routines:
  41
  42    The following are so that printf et.al. can be avoided.  Those
  43    might try to use malloc() and that, for this code, would be a
  44    disaster.  */
  45
  46 #define printf do not use
  47
  48 const char digit[] = "0123456789abcdefghijklmnopqrstuvwxyz";
  49
  50 static void
  51 print_char (char c)
  52 {
  53   write (1, &c, sizeof (c));
  54 }
  55
  56 static void
  57 print_unsigned (unsigned long long u)
  58 {
  59   if (u >= 10)
  60     print_unsigned (u / 10);
  61   print_char (digit[u % 10]);
  62 }
  63
  64 static void
  65 print_hex (unsigned long long u)
  66 {
  67   if (u >= 16)
  68     print_hex (u / 16);
  69   print_char (digit[u % 16]);
  70 }
  71
  72 static void
  73 print_string (const char *s)
  74 {
  75   for (; (*s) != '\0'; s++)
  76     print_char ((*s));
  77 }
  78
  79 static void
  80 print_address (const void *a)
  81 {
  82   print_string ("0x");
  83   print_hex ((unsigned long) a);
  84 }
  85
  86 static void
  87 print_byte_count (unsigned long long u)
  88 {
  89   print_unsigned (u);
  90   print_string (" (");
  91   print_string ("0x");
  92   print_hex (u);
  93   print_string (") bytes");
  94 }
  95
  96 /* Print the current values of RESOURCE.  */
  97
  98 static void
  99 print_rlimit (int resource)
 100 {
 101   struct rlimit rl;
 102   getrlimit (resource, &rl);
 103   print_string ("cur=0x");
 104   print_hex (rl.rlim_cur);
 105   print_string (" max=0x");
 106   print_hex (rl.rlim_max);
 107 }
 108
 109 static void
 110 maximize_rlimit (int resource, const char *prefix)
 111 {
 112   struct rlimit rl;
 113   print_string ("  ");
 114   print_string (prefix);
 115   print_string (": ");
 116   print_rlimit (resource);
 117   getrlimit (resource, &rl);
 118   rl.rlim_cur = rl.rlim_max;
 119   if (sizeof (rl.rlim_cur) >= sizeof (RLIMIT_CAP))
 120     rl.rlim_cur = (rlim_t) RLIMIT_CAP;
 121   setrlimit (resource, &rl);
 122   print_string (" -> ");
 123   print_rlimit (resource);
 124   print_string ("\n");
 125 }
 126
 127 /* Maintain a doublely linked list.  */
 128 struct list
 129 {
 130   struct list *next;
 131   struct list *prev;
 132   size_t size;
 133 };
 134
 135 /* Put the "heap" in the DATA section.  That way it is more likely
 136    that the variable will occur early in the core file (an address
 137    before the heap) and hence more likely that GDB will at least get
 138    its value right.
 139
 140    To simplify the list append logic, start the heap out with one
 141    entry (that lives in the BSS section).  */
 142
 143 static struct list dummy;
 144 static struct list heap = { &dummy, &dummy };
 145
 146 static unsigned long bytes_allocated;
 147
 148 #ifdef O_LARGEFILE
 149 #define large_off_t off64_t
 150 #define large_lseek lseek64
 151 #else
 152 #define large_off_t off_t
 153 #define O_LARGEFILE 0
 154 #define large_lseek lseek
 155 #endif
 156
 157 int
 158 main ()
 159 {
 160   size_t max_chunk_size;
 161   large_off_t max_core_size;
 162
 163   /* Try to expand all the resource limits beyond the point of sanity
 164      - we're after the biggest possible core file.  */
 165
 166   print_string ("Maximize resource limits ...\n");
 167 #ifdef RLIMIT_CORE
 168   maximize_rlimit (RLIMIT_CORE, "core");
 169 #endif
 170 #ifdef RLIMIT_DATA
 171   maximize_rlimit (RLIMIT_DATA, "data");
 172 #endif
 173 #ifdef RLIMIT_STACK
 174   maximize_rlimit (RLIMIT_STACK, "stack");
 175 #endif
 176 #ifdef RLIMIT_AS
 177   maximize_rlimit (RLIMIT_AS, "stack");
 178 #endif
 179
 180   print_string ("Maximize allocation limits ...\n");
 181
 182   /* Compute the largest possible corefile size.  No point in trying
 183      to create a corefile larger than the largest file supported by
 184      the file system.  What about 64-bit lseek64?  */
 185   {
 186     int fd;
 187     large_off_t tmp;
 188     unlink ("bigcore.corefile");
 189     fd = open ("bigcore.corefile", O_RDWR | O_CREAT | O_TRUNC | O_LARGEFILE,
 190                0666);
 191     for (tmp = 1; tmp > 0; tmp <<= 1)
 192       {
 193         if (large_lseek (fd, tmp, SEEK_SET) > 0)
 194           max_core_size = tmp;
 195       }
 196     close (fd);
 197   }
 198
 199   /* Compute an initial chunk size.  The math is dodgy but it works
 200      for the moment.  Perhaphs there's a constant around somewhere.
 201      Limit this to max_core_size bytes - no point in trying to
 202      allocate more than can be written to the corefile.  */
 203   {
 204     size_t tmp;
 205     for (tmp = 1; tmp > 0 && tmp < max_core_size; tmp <<= 1)
 206       max_chunk_size = tmp;
 207   }
 208
 209   print_string ("  core: ");
 210   print_byte_count (max_core_size);
 211   print_string ("\n");
 212   print_string ("  chunk: ");
 213   print_byte_count (max_chunk_size);
 214   print_string ("\n");
 215   print_string ("  large? ");
 216   if (O_LARGEFILE)
 217     print_string ("yes\n");
 218   else
 219     print_string ("no\n");
 220
 221   /* Allocate as much memory as possible creating a linked list of
 222      each section.  The linking ensures that some, but not all, the
 223      memory is allocated.  NB: Some kernels handle this efficiently -
 224      only allocating and writing out referenced pages leaving holes in
 225      the file for unmodified pages - while others handle this poorly -
 226      writing out all pages including those that weren't modified.  */
 227
 228   print_string ("Alocating the entire heap ...\n");
 229   {
 230     size_t chunk_size;
 231     unsigned long chunks_allocated = 0;
 232     /* Create a linked list of memory chunks.  Start with
 233        MAX_CHUNK_SIZE blocks of memory and then try allocating smaller
 234        and smaller amounts until all (well at least most) memory has
 235        been allocated.  */
 236     for (chunk_size = max_chunk_size;
 237          chunk_size >= sizeof (struct list);
 238          chunk_size >>= 1)
 239       {
 240         unsigned long count = 0;
 241         print_string ("  ");
 242         print_byte_count (chunk_size);
 243         print_string (" ... ");
 244         while (bytes_allocated + (1 + count) * chunk_size
 245                < max_core_size)
 246           {
 247             struct list *chunk = malloc (chunk_size);
 248             if (chunk == NULL)
 249               break;
 250             chunk->size = chunk_size;
 251             /* Link it in.  */
 252             chunk->next = NULL;
 253             chunk->prev = heap.prev;
 254             heap.prev->next = chunk;
 255             heap.prev = chunk;
 256             count++;
 257           }
 258         print_unsigned (count);
 259         print_string (" chunks\n");
 260         chunks_allocated += count;
 261         bytes_allocated += chunk_size * count;
 262       }
 263     print_string ("Total of ");
 264     print_byte_count (bytes_allocated);
 265     print_string (" bytes ");
 266     print_unsigned (chunks_allocated);
 267     print_string (" chunks\n");
 268   }
 269
 270   /* Push everything out to disk.  */
 271
 272   print_string ("Dump core ....\n");
 273   *(char*)0 = 0;
 274 }