glibc/sysdeps/unix/sysv/linux/tst-sysvshm-linux.c

/* Basic tests for Linux SYSV shared memory extensions.
   Copyright (C) 2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <inttypes.h>
#include <limits.h>

#include <support/check.h>
#include <support/temp_file.h>

#define SHM_MODE 0644

/* These are for the temporary file we generate.  */
static char *name;
static int shmid;
static long int pgsz;

static void
remove_shm (void)
{
  /* Enforce message queue removal in case of early test failure.
     Ignore error since the shm may already have being removed.  */
  shmctl (shmid, IPC_RMID, NULL);
}

static void
do_prepare (int argc, char *argv[])
{
  TEST_VERIFY_EXIT (create_temp_file ("tst-sysvshm.", &name) != -1);
}

#define PREPARE do_prepare

struct test_shminfo
{
  __syscall_ulong_t shmall;
  __syscall_ulong_t shmmax;
  __syscall_ulong_t shmmni;
};

/* It tries to obtain some system-wide SysV shared memory information from
   /proc to check against IPC_INFO/SHM_INFO.  The /proc only returns the
   tunables value of SHMALL, SHMMAX, and SHMMNI.  */

static uint64_t
read_proc_file (const char *file)
{
  FILE *f = fopen (file, "r");
  if (f == NULL)
    FAIL_UNSUPPORTED ("/proc is not mounted or %s is not available", file);

  /* Handle 32-bit binaries running on 64-bit kernels.  */
  uint64_t v;
  int r = fscanf (f, "%" SCNu64, &v);
  TEST_VERIFY_EXIT (r == 1);

  fclose (f);
  return v;
}


/* Check if the message queue with IDX (index into the kernel's internal
   array) matches the one with KEY.  The CMD is either SHM_STAT or
   SHM_STAT_ANY.  */

static bool
check_shminfo (int idx, key_t key, int cmd)
{
  struct shmid_ds shminfo;
  int sid = shmctl (idx, cmd, &shminfo);
  /* Ignore unused array slot returned by the kernel or information from
     unknown message queue.  */
  if ((sid == -1 && errno == EINVAL) || sid != shmid)
    return false;

  if (sid == -1)
    FAIL_EXIT1 ("shmctl with %s failed: %m",
		cmd == SHM_STAT ? "SHM_STAT" : "SHM_STAT_ANY");

  TEST_COMPARE (shminfo.shm_perm.__key, key);
  TEST_COMPARE (shminfo.shm_perm.mode, SHM_MODE);
  TEST_COMPARE (shminfo.shm_segsz, pgsz);

  return true;
}

static int
do_test (void)
{
  atexit (remove_shm);

  pgsz = sysconf (_SC_PAGESIZE);
  if (pgsz == -1)
    FAIL_EXIT1 ("sysconf (_SC_PAGESIZE) failed: %m");

  key_t key = ftok (name, 'G');
  if (key == -1)
    FAIL_EXIT1 ("ftok failed: %m");

  shmid = shmget (key, pgsz, IPC_CREAT | IPC_EXCL | SHM_MODE);
  if (shmid == -1)
    FAIL_EXIT1 ("shmget failed: %m");

  struct test_shminfo tipcinfo;
  {
    uint64_t v = read_proc_file ("/proc/sys/kernel/shmmax");
#if LONG_MAX == INT_MAX
    /* Kernel explicit clamp the value for shmmax on compat symbol (32-bit
       binaries running on 64-bit kernels).  */
    if (sizeof (__syscall_ulong_t) == sizeof (unsigned long int)
        && v > INT_MAX)
      v = INT_MAX;
#endif
    tipcinfo.shmmax = v;
  }
  tipcinfo.shmall = read_proc_file ("/proc/sys/kernel/shmall");
  tipcinfo.shmmni = read_proc_file ("/proc/sys/kernel/shmmni");

  int shmidx;

  /* Note: SHM_INFO does not return a shminfo, but rather a 'struct shm_info'.
     It is tricky to verify its values since the syscall returns system wide
     resources consumed by shared memory.  The shmctl implementation handles
     SHM_INFO as IPC_INFO, so the IPC_INFO test should validate SHM_INFO as
     well.  */

  {
    struct shminfo ipcinfo;
    shmidx = shmctl (shmid, IPC_INFO, (struct shmid_ds *) &ipcinfo);
    if (shmidx == -1)
      FAIL_EXIT1 ("shmctl with IPC_INFO failed: %m");

    TEST_COMPARE (ipcinfo.shmall, tipcinfo.shmall);
    TEST_COMPARE (ipcinfo.shmmax, tipcinfo.shmmax);
    TEST_COMPARE (ipcinfo.shmmni, tipcinfo.shmmni);
  }

  /* We check if the created shared memory shows in the global list.  */
  bool found = false;
  for (int i = 0; i <= shmidx; i++)
    {
      /* We can't tell apart if SHM_STAT_ANY is not supported (kernel older
	 than 4.17) or if the index used is invalid.  So it just check if
	 value returned from a valid call matches the created message
	 queue.  */
      check_shminfo (i, key, SHM_STAT_ANY);

      if (check_shminfo (i, key, SHM_STAT))
	{
	  found = true;
	  break;
	}
    }

  if (!found)
    FAIL_EXIT1 ("shmctl with SHM_STAT/SHM_STAT_ANY could not find the "
		"created shared memory");

  if (shmctl (shmid, IPC_RMID, NULL) == -1)
    FAIL_EXIT1 ("shmctl failed");

  return 0;
}

#include <support/test-driver.c>