gdb/testsuite/gdb.base/coremaker2.c

   1 /* Copyright 1992-2020 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   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 /*  This test has two large memory areas buf_rw and buf_ro.
  19
  20     buf_rw is written to by the program while buf_ro is initialized at
  21     compile / load time.  Thus, when a core file is created, buf_rw's
  22     memory should reside in the core file, but buf_ro probably won't be.
  23     Instead, the contents of buf_ro are available from the executable.
  24
  25     Now, for the wrinkle:  We create a one page read-only mapping over
  26     both of these areas.  This will create a one page "hole" of all
  27     zeros in each area.
  28
  29     Will GDB be able to correctly read memory from each of the four
  30     (or six, if you count the regions on the other side of each hole)
  31     memory regions?  */
  32
  33 #include <stdio.h>
  34 #include <sys/types.h>
  35 #include <fcntl.h>
  36 #include <sys/mman.h>
  37 #include <signal.h>
  38 #include <stdlib.h>
  39 #include <unistd.h>
  40 #include <string.h>
  41 #include <errno.h>
  42
  43 /* These are globals so that we can find them easily when debugging
  44    the core file.  */
  45 long pagesize;
  46 unsigned long long addr;
  47 char *mbuf_ro;
  48 char *mbuf_rw;
  49
  50 /* 256 KiB buffer.  */
  51 char buf_rw[256 * 1024];
  52
  53 #define C5_16 \
  54   0xc5, 0xc5, 0xc5, 0xc5, \
  55   0xc5, 0xc5, 0xc5, 0xc5, \
  56   0xc5, 0xc5, 0xc5, 0xc5, \
  57   0xc5, 0xc5, 0xc5, 0xc5
  58
  59 #define C5_256 \
  60   C5_16, C5_16, C5_16, C5_16, \
  61   C5_16, C5_16, C5_16, C5_16, \
  62   C5_16, C5_16, C5_16, C5_16, \
  63   C5_16, C5_16, C5_16, C5_16
  64
  65 #define C5_1k \
  66   C5_256, C5_256, C5_256, C5_256
  67
  68 #define C5_8k \
  69   C5_1k, C5_1k, C5_1k, C5_1k, \
  70   C5_1k, C5_1k, C5_1k, C5_1k
  71
  72 #define C5_64k \
  73   C5_8k, C5_8k, C5_8k, C5_8k, \
  74   C5_8k, C5_8k, C5_8k, C5_8k
  75
  76 #define C5_256k \
  77   C5_64k, C5_64k, C5_64k, C5_64k
  78
  79 /* 256 KiB worth of data.  For this test case, we can't allocate a
  80    buffer and then fill it; we want GDB to have to read this data
  81    from the executable; it should NOT find it in the core file.  */
  82
  83 const char buf_ro[] = { C5_256k };
  84
  85 int
  86 main (int argc, char **argv)
  87 {
  88   int i, bitcount;
  89
  90 #ifdef _SC_PAGESIZE
  91   pagesize = sysconf (_SC_PAGESIZE);
  92 #else
  93   pagesize = 8192;
  94 #endif
  95
  96   /* Verify that pagesize is a power of 2.  */
  97   bitcount = 0;
  98   for (i = 0; i < 4 * sizeof (pagesize); i++)
  99     if (pagesize & (1 << i))
 100       bitcount++;
 101
 102   if (bitcount != 1)
 103     {
 104       fprintf (stderr, "pagesize is not a power of 2.\n");
 105       exit (1);
 106     }
 107
 108   /* Compute an address that should be within buf_ro.  Complain if not.  */
 109   addr = ((unsigned long long) buf_ro + pagesize) & ~(pagesize - 1);
 110
 111   if (addr <= (unsigned long long) buf_ro
 112       || addr >= (unsigned long long) buf_ro + sizeof (buf_ro))
 113     {
 114       fprintf (stderr, "Unable to compute a suitable address within buf_ro.\n");
 115       exit (1);
 116     }
 117
 118   mbuf_ro = mmap ((void *) addr, pagesize, PROT_READ,
 119                MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
 120
 121   if (mbuf_ro == MAP_FAILED)
 122     {
 123       fprintf (stderr, "mmap #1 failed: %s.\n", strerror (errno));
 124       exit (1);
 125     }
 126
 127   /* Write (and fill) the R/W region.  */
 128   for (i = 0; i < sizeof (buf_rw); i++)
 129     buf_rw[i] = 0x6b;
 130
 131   /* Compute an mmap address within buf_rw.  Complain if it's somewhere
 132      else.  */
 133   addr = ((unsigned long long) buf_rw + pagesize) & ~(pagesize - 1);
 134
 135   if (addr <= (unsigned long long) buf_rw
 136       || addr >= (unsigned long long) buf_rw + sizeof (buf_rw))
 137     {
 138       fprintf (stderr, "Unable to compute a suitable address within buf_rw.\n");
 139       exit (1);
 140     }
 141
 142   mbuf_rw = mmap ((void *) addr, pagesize, PROT_READ,
 143                MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
 144
 145   if (mbuf_rw == MAP_FAILED)
 146     {
 147       fprintf (stderr, "mmap #2 failed: %s.\n", strerror (errno));
 148       exit (1);
 149     }
 150
 151   /* With correct ulimit, etc. this should cause a core dump.  */
 152   abort ();
 153 }