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 /* 24 KiB buffer.  */
  51 char buf_rw[24 * 1024];
  52
  53 /* 24 KiB worth of data.  For this test case, we can't allocate a
  54    buffer and then fill it; we want GDB to have to read this data
  55    from the executable; it should NOT find it in the core file.  */
  56
  57 #define C5_16 \
  58   0xc5, 0xc5, 0xc5, 0xc5, \
  59   0xc5, 0xc5, 0xc5, 0xc5, \
  60   0xc5, 0xc5, 0xc5, 0xc5, \
  61   0xc5, 0xc5, 0xc5, 0xc5
  62
  63 #define C5_256 \
  64   C5_16, C5_16, C5_16, C5_16, \
  65   C5_16, C5_16, C5_16, C5_16, \
  66   C5_16, C5_16, C5_16, C5_16, \
  67   C5_16, C5_16, C5_16, C5_16
  68
  69 #define C5_1k \
  70   C5_256, C5_256, C5_256, C5_256
  71
  72 #define C5_24k \
  73   C5_1k, C5_1k, C5_1k, C5_1k, \
  74   C5_1k, C5_1k, C5_1k, C5_1k, \
  75   C5_1k, C5_1k, C5_1k, C5_1k, \
  76   C5_1k, C5_1k, C5_1k, C5_1k, \
  77   C5_1k, C5_1k, C5_1k, C5_1k, \
  78   C5_1k, C5_1k, C5_1k, C5_1k
  79
  80 const char buf_ro[] = { C5_24k };
  81
  82 int
  83 main (int argc, char **argv)
  84 {
  85   int i, bitcount;
  86
  87 #ifdef _SC_PAGESIZE
  88   pagesize = sysconf (_SC_PAGESIZE);
  89 #else
  90   pagesize = 8192;
  91 #endif
  92
  93   /* Verify that pagesize is a power of 2.  */
  94   bitcount = 0;
  95   for (i = 0; i < 4 * sizeof (pagesize); i++)
  96     if (pagesize & (1 << i))
  97       bitcount++;
  98
  99   if (bitcount != 1)
 100     {
 101       fprintf (stderr, "pagesize is not a power of 2.\n");
 102       exit (1);
 103     }
 104
 105   /* Compute an address that should be within buf_ro.  Complain if not.  */
 106   addr = ((unsigned long long) buf_ro + pagesize) & ~(pagesize - 1);
 107
 108   if (addr <= (unsigned long long) buf_ro
 109       || addr >= (unsigned long long) buf_ro + sizeof (buf_ro))
 110     {
 111       fprintf (stderr, "Unable to compute a suitable address within buf_ro.\n");
 112       exit (1);
 113     }
 114
 115   mbuf_ro = mmap ((void *) addr, pagesize, PROT_READ,
 116                MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
 117
 118   if (mbuf_ro == MAP_FAILED)
 119     {
 120       fprintf (stderr, "mmap #1 failed: %s.\n", strerror (errno));
 121       exit (1);
 122     }
 123
 124   /* Write (and fill) the R/W region.  */
 125   for (i = 0; i < sizeof (buf_rw); i++)
 126     buf_rw[i] = 0x6b;
 127
 128   /* Compute an mmap address within buf_rw.  Complain if it's somewhere
 129      else.  */
 130   addr = ((unsigned long long) buf_rw + pagesize) & ~(pagesize - 1);
 131
 132   if (addr <= (unsigned long long) buf_rw
 133       || addr >= (unsigned long long) buf_rw + sizeof (buf_rw))
 134     {
 135       fprintf (stderr, "Unable to compute a suitable address within buf_rw.\n");
 136       exit (1);
 137     }
 138
 139   mbuf_rw = mmap ((void *) addr, pagesize, PROT_READ,
 140                MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
 141
 142   if (mbuf_rw == MAP_FAILED)
 143     {
 144       fprintf (stderr, "mmap #2 failed: %s.\n", strerror (errno));
 145       exit (1);
 146     }
 147
 148   /* With correct ulimit, etc. this should cause a core dump.  */
 149   abort ();
 150 }