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

   1 /* Basic tests for Linux SYSV shared memory extensions.
   2    Copyright (C) 2020-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/ipc.h>
  20 #include <sys/shm.h>
  21 #include <errno.h>
  22 #include <stdlib.h>
  23 #include <stdbool.h>
  24 #include <stdio.h>
  25 #include <unistd.h>
  26 #include <inttypes.h>
  27 #include <limits.h>
  28
  29 #include <support/check.h>
  30 #include <support/temp_file.h>
  31
  32 #define SHM_MODE 0644
  33
  34 /* These are for the temporary file we generate.  */
  35 static char *name;
  36 static int shmid;
  37 static long int pgsz;
  38
  39 static void
  40 remove_shm (void)
  41 {
  42   /* Enforce message queue removal in case of early test failure.
  43      Ignore error since the shm may already have being removed.  */
  44   shmctl (shmid, IPC_RMID, NULL);
  45 }
  46
  47 static void
  48 do_prepare (int argc, char *argv[])
  49 {
  50   TEST_VERIFY_EXIT (create_temp_file ("tst-sysvshm.", &name) != -1);
  51 }
  52
  53 #define PREPARE do_prepare
  54
  55 struct test_shminfo
  56 {
  57   __syscall_ulong_t shmall;
  58   __syscall_ulong_t shmmax;
  59   __syscall_ulong_t shmmni;
  60 };
  61
  62 /* It tries to obtain some system-wide SysV shared memory information from
  63    /proc to check against IPC_INFO/SHM_INFO.  The /proc only returns the
  64    tunables value of SHMALL, SHMMAX, and SHMMNI.  */
  65
  66 static uint64_t
  67 read_proc_file (const char *file)
  68 {
  69   FILE *f = fopen (file, "r");
  70   if (f == NULL)
  71     FAIL_UNSUPPORTED ("/proc is not mounted or %s is not available", file);
  72
  73   /* Handle 32-bit binaries running on 64-bit kernels.  */
  74   uint64_t v;
  75   int r = fscanf (f, "%" SCNu64, &v);
  76   TEST_VERIFY_EXIT (r == 1);
  77
  78   fclose (f);
  79   return v;
  80 }
  81
  82
  83 /* Check if the message queue with IDX (index into the kernel's internal
  84    array) matches the one with KEY.  The CMD is either SHM_STAT or
  85    SHM_STAT_ANY.  */
  86
  87 static bool
  88 check_shminfo (int idx, key_t key, int cmd)
  89 {
  90   struct shmid_ds shminfo;
  91   int sid = shmctl (idx, cmd, &shminfo);
  92   /* Ignore unused array slot returned by the kernel or information from
  93      unknown message queue.  */
  94   if ((sid == -1 && errno == EINVAL) || sid != shmid)
  95     return false;
  96
  97   if (sid == -1)
  98     FAIL_EXIT1 ("shmctl with %s failed: %m",
  99                 cmd == SHM_STAT ? "SHM_STAT" : "SHM_STAT_ANY");
 100
 101   TEST_COMPARE (shminfo.shm_perm.__key, key);
 102   TEST_COMPARE (shminfo.shm_perm.mode, SHM_MODE);
 103   TEST_COMPARE (shminfo.shm_segsz, pgsz);
 104
 105   return true;
 106 }
 107
 108 static int
 109 do_test (void)
 110 {
 111   atexit (remove_shm);
 112
 113   pgsz = sysconf (_SC_PAGESIZE);
 114   if (pgsz == -1)
 115     FAIL_EXIT1 ("sysconf (_SC_PAGESIZE) failed: %m");
 116
 117   key_t key = ftok (name, 'G');
 118   if (key == -1)
 119     FAIL_EXIT1 ("ftok failed: %m");
 120
 121   shmid = shmget (key, pgsz, IPC_CREAT | IPC_EXCL | SHM_MODE);
 122   if (shmid == -1)
 123     FAIL_EXIT1 ("shmget failed: %m");
 124
 125   /* It does not check shmmax because kernel clamp its value to INT_MAX for:
 126
 127      1. Compat symbols with IPC_64, i.e, 32-bit binaries running on 64-bit
 128         kernels.
 129
 130      2. Default symbol without IPC_64 (defined as IPC_OLD within Linux) and
 131         glibc always use IPC_64 for 32-bit ABIs (to support 64-bit time_t).
 132         It means that 32-bit binaries running on 32-bit kernels will not see
 133         shmmax being clamped.
 134
 135      And finding out whether the compat symbol is used would require checking
 136      the underlying kernel against the current ABI.  The shmall and shmmni
 137      already provided enough coverage.  */
 138
 139   struct test_shminfo tipcinfo;
 140   tipcinfo.shmall = read_proc_file ("/proc/sys/kernel/shmall");
 141   tipcinfo.shmmni = read_proc_file ("/proc/sys/kernel/shmmni");
 142
 143   int shmidx;
 144
 145   /* Note: SHM_INFO does not return a shminfo, but rather a 'struct shm_info'.
 146      It is tricky to verify its values since the syscall returns system wide
 147      resources consumed by shared memory.  The shmctl implementation handles
 148      SHM_INFO as IPC_INFO, so the IPC_INFO test should validate SHM_INFO as
 149      well.  */
 150
 151   {
 152     struct shminfo ipcinfo;
 153     shmidx = shmctl (shmid, IPC_INFO, (struct shmid_ds *) &ipcinfo);
 154     if (shmidx == -1)
 155       FAIL_EXIT1 ("shmctl with IPC_INFO failed: %m");
 156
 157     TEST_COMPARE (ipcinfo.shmall, tipcinfo.shmall);
 158     TEST_COMPARE (ipcinfo.shmmni, tipcinfo.shmmni);
 159   }
 160
 161   /* We check if the created shared memory shows in the global list.  */
 162   bool found = false;
 163   for (int i = 0; i <= shmidx; i++)
 164     {
 165       /* We can't tell apart if SHM_STAT_ANY is not supported (kernel older
 166          than 4.17) or if the index used is invalid.  So it just check if
 167          value returned from a valid call matches the created message
 168          queue.  */
 169       check_shminfo (i, key, SHM_STAT_ANY);
 170
 171       if (check_shminfo (i, key, SHM_STAT))
 172         {
 173           found = true;
 174           break;
 175         }
 176     }
 177
 178   if (!found)
 179     FAIL_EXIT1 ("shmctl with SHM_STAT/SHM_STAT_ANY could not find the "
 180                 "created shared memory");
 181
 182   if (shmctl (shmid, IPC_RMID, NULL) == -1)
 183     FAIL_EXIT1 ("shmctl failed");
 184
 185   return 0;
 186 }
 187
 188 #include <support/test-driver.c>