sysdeps/unix/sysv/linux/semctl.c

   1 /* Copyright (C) 1995-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
   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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stdarg.h>
  21 #include <sys/sem.h>
  22 #include <ipc_priv.h>
  23
  24 #include <sysdep.h>
  25 #include <string.h>
  26 #include <sys/syscall.h>
  27 #include <shlib-compat.h>
  28
  29 #include <kernel-features.h>
  30
  31 struct __old_semid_ds
  32 {
  33   struct __old_ipc_perm sem_perm;       /* operation permission struct */
  34   __time_t sem_otime;                   /* last semop() time */
  35   __time_t sem_ctime;                   /* last time changed by semctl() */
  36   struct sem *__sembase;                /* ptr to first semaphore in array */
  37   struct sem_queue *__sem_pending;      /* pending operations */
  38   struct sem_queue *__sem_pending_last; /* last pending operation */
  39   struct sem_undo *__undo;              /* ondo requests on this array */
  40   unsigned short int sem_nsems;         /* number of semaphores in set */
  41 };
  42
  43 /* Define a `union semun' suitable for Linux here.  */
  44 union semun
  45 {
  46   int val;                      /* value for SETVAL */
  47   struct semid_ds *buf;         /* buffer for IPC_STAT & IPC_SET */
  48   unsigned short int *array;    /* array for GETALL & SETALL */
  49   struct seminfo *__buf;        /* buffer for IPC_INFO */
  50   struct __old_semid_ds *__old_buf;
  51 };
  52
  53 /* Return identifier for array of NSEMS semaphores associated with
  54    KEY.  */
  55 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
  56 int __old_semctl (int semid, int semnum, int cmd, ...);
  57 #endif
  58 int __new_semctl (int semid, int semnum, int cmd, ...);
  59
  60 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
  61 int
  62 attribute_compat_text_section
  63 __old_semctl (int semid, int semnum, int cmd, ...)
  64 {
  65   union semun arg;
  66   va_list ap;
  67
  68   va_start (ap, cmd);
  69
  70   /* Get the argument only if required.  */
  71   arg.buf = NULL;
  72   switch (cmd)
  73     {
  74     case SETVAL:        /* arg.val */
  75     case GETALL:        /* arg.array */
  76     case SETALL:
  77     case IPC_STAT:      /* arg.buf */
  78     case IPC_SET:
  79     case SEM_STAT:
  80     case IPC_INFO:      /* arg.__buf */
  81     case SEM_INFO:
  82       va_start (ap, cmd);
  83       arg = va_arg (ap, union semun);
  84       va_end (ap);
  85       break;
  86     }
  87
  88   va_end (ap);
  89
  90   return INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd,
  91                          &arg);
  92 }
  93 compat_symbol (libc, __old_semctl, semctl, GLIBC_2_0);
  94 #endif
  95
  96 int
  97 __new_semctl (int semid, int semnum, int cmd, ...)
  98 {
  99   union semun arg;
 100   va_list ap;
 101
 102   va_start (ap, cmd);
 103
 104   /* Get the argument only if required.  */
 105   arg.buf = NULL;
 106   switch (cmd)
 107     {
 108     case SETVAL:        /* arg.val */
 109     case GETALL:        /* arg.array */
 110     case SETALL:
 111     case IPC_STAT:      /* arg.buf */
 112     case IPC_SET:
 113     case SEM_STAT:
 114     case IPC_INFO:      /* arg.__buf */
 115     case SEM_INFO:
 116       va_start (ap, cmd);
 117       arg = va_arg (ap, union semun);
 118       va_end (ap);
 119       break;
 120     }
 121
 122   va_end (ap);
 123
 124 #if __ASSUME_IPC64 > 0
 125   return INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
 126                          &arg);
 127 #else
 128   switch (cmd)
 129     {
 130     case SEM_STAT:
 131     case IPC_STAT:
 132     case IPC_SET:
 133       break;
 134     default:
 135       return INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd,
 136                              &arg);
 137     }
 138
 139   {
 140     int save_errno = errno, result;
 141     struct __old_semid_ds old;
 142     struct semid_ds *buf;
 143
 144     /* Unfortunately there is no way how to find out for sure whether
 145        we should use old or new semctl.  */
 146     result = INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
 147                              &arg);
 148     if (result != -1 || errno != EINVAL)
 149       return result;
 150
 151     __set_errno(save_errno);
 152     buf = arg.buf;
 153     arg.__old_buf = &old;
 154     if (cmd == IPC_SET)
 155       {
 156         old.sem_perm.uid = buf->sem_perm.uid;
 157         old.sem_perm.gid = buf->sem_perm.gid;
 158         old.sem_perm.mode = buf->sem_perm.mode;
 159         if (old.sem_perm.uid != buf->sem_perm.uid ||
 160             old.sem_perm.gid != buf->sem_perm.gid)
 161           {
 162             __set_errno (EINVAL);
 163             return -1;
 164           }
 165       }
 166     result = INLINE_SYSCALL (ipc, 5, IPCOP_semctl, semid, semnum, cmd,
 167                              &arg);
 168     if (result != -1 && cmd != IPC_SET)
 169       {
 170         memset(buf, 0, sizeof(*buf));
 171         buf->sem_perm.__key = old.sem_perm.__key;
 172         buf->sem_perm.uid = old.sem_perm.uid;
 173         buf->sem_perm.gid = old.sem_perm.gid;
 174         buf->sem_perm.cuid = old.sem_perm.cuid;
 175         buf->sem_perm.cgid = old.sem_perm.cgid;
 176         buf->sem_perm.mode = old.sem_perm.mode;
 177         buf->sem_perm.__seq = old.sem_perm.__seq;
 178         buf->sem_otime = old.sem_otime;
 179         buf->sem_ctime = old.sem_ctime;
 180         buf->sem_nsems = old.sem_nsems;
 181       }
 182     return result;
 183   }
 184 #endif
 185 }
 186
 187 versioned_symbol (libc, __new_semctl, semctl, GLIBC_2_2);