1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
/* forktest.c: FORK SAFETY TEST
 *
 * $Id: //info.ravenbrook.com/project/mps/branch/2018-06-13/fork/code/tagtest.c#1 $
 * Copyright (c) 2018 Ravenbrook Limited.  See end of file for license.
 *
 * .overview: This test case is a regression test for job004062. It
 * checks that the MPS correctly runs in the child process after a
 * fork() on FreeBSD, Linux or macOS.
 *
 * .format: This test case uses a trivial object format in which each
 * object contains a single reference.
 */

#include <stdio.h>
#include <sys/wait.h>
#include <unistd.h>

#include "mps.h"
#include "mpsavm.h"
#include "mpscamc.h"
#include "testlib.h"

enum {
  TYPE_REF,
  TYPE_FWD,
  TYPE_PAD
};

typedef struct obj_s {
  unsigned type;                /* One of the TYPE_ enums */
  union {
    struct obj_s *ref;          /* TYPE_REF */
    mps_addr_t fwd;             /* TYPE_FWD */
    size_t pad;                 /* TYPE_PAD */
  } u;
} obj_s, *obj_t;

static void obj_fwd(mps_addr_t old, mps_addr_t new)
{
  obj_t obj = old;
  obj->type = TYPE_FWD;
  obj->u.fwd = new;
}

static mps_addr_t obj_isfwd(mps_addr_t addr)
{
  obj_t obj = addr;
  if (obj->type == TYPE_FWD) {
    return obj->u.fwd;
  } else {
    return NULL;
  }
}

static void obj_pad(mps_addr_t addr, size_t size)
{
  obj_t obj = addr;
  obj->type = TYPE_PAD;
  obj->u.pad = size;
}

static mps_addr_t obj_skip(mps_addr_t addr)
{
  obj_t obj = addr;
  size_t size;
  if (obj->type == TYPE_PAD) {
    size = obj->u.pad;
  } else {
    size = sizeof(obj_s);
  }
  return (char *)addr + size;
}

static mps_res_t obj_scan(mps_ss_t ss, mps_addr_t base, mps_addr_t limit)
{
  MPS_SCAN_BEGIN(ss) {
    while (base < limit) {
      obj_t obj = base;
      if (obj->type == TYPE_REF) {
        mps_addr_t p = obj->u.ref;
        mps_res_t res = MPS_FIX12(ss, &p);
        if (res != MPS_RES_OK) {
          return res;
        }
        obj->u.ref = p;
      }
      base = obj_skip(base);
    }
  } MPS_SCAN_END(ss);
  return MPS_RES_OK;
}

int main(int argc, char *argv[])
{
  void *marker = &marker;
  int pid;
  mps_arena_t arena;
  mps_fmt_t obj_fmt;
  mps_pool_t pool;
  mps_thr_t thread;
  mps_root_t stack_root;
  mps_ap_t obj_ap;
  size_t i;
  obj_t obj, first;

  testlib_init(argc, argv);

  /* Set the pause time to be very small so that the incremental
     collector (when it runs) will have to leave a read barrier in
     place for us to hit. */
  MPS_ARGS_BEGIN(args) {
    MPS_ARGS_ADD(args, MPS_KEY_PAUSE_TIME, 0.0);
    die(mps_arena_create_k(&arena, mps_arena_class_vm(), args),
        "mps_arena_create");
  } MPS_ARGS_END(args);
  mps_arena_park(arena);

  die(mps_thread_reg(&thread, arena), "Couldn't register thread");
  die(mps_root_create_thread(&stack_root, arena, thread, marker),
      "Couldn't create thread root");

  MPS_ARGS_BEGIN(args) {
    MPS_ARGS_ADD(args, MPS_KEY_FMT_ALIGN, sizeof(obj_s));
    MPS_ARGS_ADD(args, MPS_KEY_FMT_SCAN, obj_scan);
    MPS_ARGS_ADD(args, MPS_KEY_FMT_SKIP, obj_skip);
    MPS_ARGS_ADD(args, MPS_KEY_FMT_FWD, obj_fwd);
    MPS_ARGS_ADD(args, MPS_KEY_FMT_ISFWD, obj_isfwd);
    MPS_ARGS_ADD(args, MPS_KEY_FMT_PAD, obj_pad);
    die(mps_fmt_create_k(&obj_fmt, arena, args), "Couldn't create obj format");
  } MPS_ARGS_END(args);

  MPS_ARGS_BEGIN(args) {
    MPS_ARGS_ADD(args, MPS_KEY_FORMAT, obj_fmt);
    die(mps_pool_create_k(&pool, arena, mps_class_amc(), args),
        "Couldn't create pool");
  } MPS_ARGS_END(args);

  die(mps_ap_create_k(&obj_ap, pool, mps_args_none),
      "Couldn't create obj allocation point");

  /* Create a linked list of objects. */
  first = NULL;
  for (i = 0; i < 100000; ++i) {
    size_t size = sizeof(obj_s);
    mps_addr_t addr;
    do {
      die(mps_reserve(&addr, obj_ap, size), "Couldn't allocate.");
      obj = addr;
      obj->type = TYPE_REF;
      obj->u.ref = NULL;
    } while (!mps_commit(obj_ap, addr, size));
    obj->u.ref = first;
    first = obj;
  }

  pid = fork();
  cdie(pid >= 0, "fork failed");

  /* Allow a collection to start, which will cause a read barrier to
     be applied to any segment containing live objects that was
     scanned. */
  mps_arena_release(arena);

  /* Read all the objects, so that if there is read barrier in place
     we will hit it. */
  for (obj = first; obj != NULL; obj = obj->u.ref) {
    Insist(obj->type == TYPE_REF);
  }

  mps_arena_park(arena);

  if (pid != 0) {
    /* Parent: wait for child and check that its exit status is zero. */
    int stat;
    cdie(pid == waitpid(pid, &stat, 0), "waitpid failed");
    cdie(WIFEXITED(stat), "child did not exit normally");
    cdie(WEXITSTATUS(stat) == 0, "child exited with nonzero status");
    printf("%s: Conclusion: Failed to find any defects.\n", argv[0]);
  }

  mps_ap_destroy(obj_ap);
  mps_pool_destroy(pool);
  mps_fmt_destroy(obj_fmt);
  mps_root_destroy(stack_root);
  mps_thread_dereg(thread);
  mps_arena_destroy(arena);

  return 0;
}


/* C. COPYRIGHT AND LICENSE
 *
 * Copyright (c) 2018 Ravenbrook Limited <http://www.ravenbrook.com/>.
 * All rights reserved.  This is an open source license.  Contact
 * Ravenbrook for commercial licensing options.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * 3. Redistributions in any form must be accompanied by information on how
 * to obtain complete source code for this software and any accompanying
 * software that uses this software.  The source code must either be
 * included in the distribution or be available for no more than the cost
 * of distribution plus a nominal fee, and must be freely redistributable
 * under reasonable conditions.  For an executable file, complete source
 * code means the source code for all modules it contains. It does not
 * include source code for modules or files that typically accompany the
 * major components of the operating system on which the executable file
 * runs.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */