glibc/sysdeps/unix/sysv/linux/semctl.c

/* Copyright (C) 1995-2025 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/sem.h>
#include <stdarg.h>
#include <ipc_priv.h>
#include <sysdep.h>
#include <shlib-compat.h>
#include <linux/posix_types.h>             /* For __kernel_mode_t.  */

/* The struct used to issue the syscall.  For architectures that assume
   64-bit time as default (!__ASSUME_TIME64_SYSCALLS) the syscall will
   split the resulting 64-bit sem_{o,c}time in two fields (sem_{o,c}time
   and __sem_{o,c}time_high).  */
union semun
{
  int val;			/* value for SETVAL */
  struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */
  unsigned short int *array;	/* array for GETALL & SETALL */
  struct seminfo *__buf;	/* buffer for IPC_INFO */
};

#if __IPC_TIME64 == 0
# define semun64 semun
typedef union semun semctl_arg_t;
#else
# include <struct_kernel_semid64_ds.h>

union ksemun64
{
  int val;
  struct kernel_semid64_ds *buf;
  unsigned short int *array;
  struct seminfo *__buf;
};

# if __TIMESIZE == 64
#  define semun64 semun
# else
/* The struct used when __semctl64 is called.  */
union semun64
{
  int val;
  struct __semid64_ds *buf;
  unsigned short int *array;
  struct seminfo *__buf;
};
# endif

static void
semid64_to_ksemid64 (const struct __semid64_ds *semid64,
		     struct kernel_semid64_ds *ksemid)
{
  ksemid->sem_perm       = semid64->sem_perm;
  ksemid->sem_otime      = semid64->sem_otime;
  ksemid->sem_otime_high = semid64->sem_otime >> 32;
  ksemid->sem_ctime      = semid64->sem_ctime;
  ksemid->sem_ctime_high = semid64->sem_ctime >> 32;
  ksemid->sem_nsems      = semid64->sem_nsems;
}

static void
ksemid64_to_semid64 (const struct kernel_semid64_ds *ksemid,
		     struct __semid64_ds *semid64)
{
  semid64->sem_perm  = ksemid->sem_perm;
  semid64->sem_otime = ksemid->sem_otime
		       | ((__time64_t) ksemid->sem_otime_high << 32);
  semid64->sem_ctime = ksemid->sem_ctime
		       | ((__time64_t) ksemid->sem_ctime_high << 32);
  semid64->sem_nsems = ksemid->sem_nsems;
}

static union ksemun64
semun64_to_ksemun64 (int cmd, union semun64 semun64,
		     struct kernel_semid64_ds *buf)
{
  union ksemun64 r = { 0 };
  switch (cmd)
    {
    case SETVAL:
      r.val = semun64.val;
      break;
    case GETALL:
    case SETALL:
      r.array = semun64.array;
      break;
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_STAT:
    case IPC_SET:
      r.buf = buf;
      semid64_to_ksemid64 (semun64.buf, r.buf);
      break;
    case IPC_INFO:
    case SEM_INFO:
      r.__buf = semun64.__buf;
      break;
    }
  return r;
}

typedef union ksemun64 semctl_arg_t;
#endif

static int
semctl_syscall (int semid, int semnum, int cmd, semctl_arg_t arg)
{
#ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
  return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd | __IPC_64,
			      arg.array);
#else
  return INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
			      SEMCTL_ARG_ADDRESS (arg));
#endif
}

/* POSIX states ipc_perm mode should have type of mode_t.  */
_Static_assert (sizeof ((struct semid_ds){0}.sem_perm.mode)
		== sizeof (mode_t),
		"sizeof (msqid_ds.msg_perm.mode) != sizeof (mode_t)");

int
__semctl64 (int semid, int semnum, int cmd, ...)
{
  union semun64 arg64 = { 0 };
  va_list ap;

  /* Some applications pass the __IPC_64 flag in cmd, to invoke
     previously unsupported commands back when there was no EINVAL
     error checking in glibc.  Mask the flag for the switch statements
     below.  semctl_syscall adds back the __IPC_64 flag for the actual
     system call.  */
  cmd &= ~__IPC_64;

  /* Get the argument only if required.  */
  switch (cmd)
    {
    case SETVAL:        /* arg.val */
    case GETALL:        /* arg.array */
    case SETALL:
    case IPC_STAT:      /* arg.buf */
    case IPC_SET:
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_INFO:      /* arg.__buf */
    case SEM_INFO:
      va_start (ap, cmd);
      arg64 = va_arg (ap, union semun64);
      va_end (ap);
      break;
    case IPC_RMID:      /* arg ignored.  */
    case GETNCNT:
    case GETPID:
    case GETVAL:
    case GETZCNT:
      break;
    default:
      __set_errno (EINVAL);
      return -1;
    }

#if __IPC_TIME64
  struct kernel_semid64_ds ksemid;
  union ksemun64 ksemun = semun64_to_ksemun64 (cmd, arg64, &ksemid);
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
  if (cmd == IPC_SET)
    ksemid.sem_perm.mode *= 0x10000U;
# endif
  union ksemun64 arg = ksemun;
#else
  union semun arg = arg64;
#endif

  int ret = semctl_syscall (semid, semnum, cmd, arg);
  if (ret < 0)
    return ret;

  switch (cmd)
    {
    case IPC_STAT:
    case SEM_STAT:
    case SEM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
      arg.buf->sem_perm.mode >>= 16;
#else
      /* Old Linux kernel versions might not clear the mode padding.  */
      if (sizeof ((struct semid_ds){0}.sem_perm.mode)
	  != sizeof (__kernel_mode_t))
	arg.buf->sem_perm.mode &= 0xFFFF;
#endif

#if __IPC_TIME64
      ksemid64_to_semid64 (arg.buf, arg64.buf);
#endif
    }

  return ret;
}
#if __TIMESIZE != 64
libc_hidden_def (__semctl64)


/* The 64-bit time_t semid_ds version might have a different layout and
   internal field alignment.  */

static void
semid_to_semid64 (struct __semid64_ds *ds64, const struct semid_ds *ds)
{
  ds64->sem_perm  = ds->sem_perm;
  ds64->sem_otime = ds->sem_otime
		    | ((__time64_t) ds->__sem_otime_high << 32);
  ds64->sem_ctime = ds->sem_ctime
		    | ((__time64_t) ds->__sem_ctime_high << 32);
  ds64->sem_nsems = ds->sem_nsems;
}

static void
semid64_to_semid (struct semid_ds *ds, const struct __semid64_ds *ds64)
{
  ds->sem_perm         = ds64->sem_perm;
  ds->sem_otime        = ds64->sem_otime;
  ds->__sem_otime_high = 0;
  ds->sem_ctime        = ds64->sem_ctime;
  ds->__sem_ctime_high = 0;
  ds->sem_nsems        = ds64->sem_nsems;
}

static union semun64
semun_to_semun64 (int cmd, union semun semun, struct __semid64_ds *semid64)
{
  union semun64 r = { 0 };
  switch (cmd)
    {
    case SETVAL:
      r.val = semun.val;
      break;
    case GETALL:
    case SETALL:
      r.array = semun.array;
      break;
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_STAT:
    case IPC_SET:
      r.buf = semid64;
      semid_to_semid64 (r.buf, semun.buf);
      break;
    case IPC_INFO:
    case SEM_INFO:
      r.__buf = semun.__buf;
      break;
    }
  return r;
}

int
__semctl (int semid, int semnum, int cmd, ...)
{
  union semun arg = { 0 };

  va_list ap;

  /* Get the argument only if required.  */
  switch (cmd)
    {
    case SETVAL:        /* arg.val */
    case GETALL:        /* arg.array */
    case SETALL:
    case IPC_STAT:      /* arg.buf */
    case IPC_SET:
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_INFO:      /* arg.__buf */
    case SEM_INFO:
      va_start (ap, cmd);
      arg = va_arg (ap, union semun);
      va_end (ap);
      break;
    /* __semctl64 handles non-supported commands.  */
    }

  struct __semid64_ds semid64;
  union semun64 arg64 = semun_to_semun64 (cmd, arg, &semid64);

  int ret = __semctl64 (semid, semnum, cmd, arg64);
  if (ret < 0)
    return ret;

  switch (cmd)
    {
    case IPC_STAT:
    case SEM_STAT:
    case SEM_STAT_ANY:
      semid64_to_semid (arg.buf, arg64.buf);
    }

  return ret;
}
#endif

#ifndef DEFAULT_VERSION
# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
#  define DEFAULT_VERSION GLIBC_2_2
# else
#  define DEFAULT_VERSION GLIBC_2_31
# endif
#endif
versioned_symbol (libc, __semctl, semctl, DEFAULT_VERSION);

#if defined __ASSUME_SYSVIPC_BROKEN_MODE_T \
    && SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_31)
int
attribute_compat_text_section
__semctl_mode16 (int semid, int semnum, int cmd, ...)
{
  semctl_arg_t arg = { 0 };
  va_list ap;

  /* Get the argument only if required.  */
  switch (cmd)
    {
    case SETVAL:        /* arg.val */
    case GETALL:        /* arg.array */
    case SETALL:
    case IPC_STAT:      /* arg.buf */
    case IPC_SET:
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_INFO:      /* arg.__buf */
    case SEM_INFO:
      va_start (ap, cmd);
      arg = va_arg (ap, semctl_arg_t);
      va_end (ap);
      break;
    }

  return semctl_syscall (semid, semnum, cmd, arg);
}
compat_symbol (libc, __semctl_mode16, semctl, GLIBC_2_2);
#endif

#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
/* Since semctl use a variadic argument for semid_ds there is not need to
   define and tie the compatibility symbol to the old 'union semun'
   definition.  */
int
attribute_compat_text_section
__old_semctl (int semid, int semnum, int cmd, ...)
{
  union semun arg = { 0 };
  va_list ap;

  /* Get the argument only if required.  */
  switch (cmd)
    {
    case SETVAL:        /* arg.val */
    case GETALL:        /* arg.array */
    case SETALL:
    case IPC_STAT:      /* arg.buf */
    case IPC_SET:
    case SEM_STAT:
    case SEM_STAT_ANY:
    case IPC_INFO:      /* arg.__buf */
    case SEM_INFO:
      va_start (ap, cmd);
      arg = va_arg (ap, union semun);
      va_end (ap);
      break;
    }

#if defined __ASSUME_DIRECT_SYSVIPC_SYSCALLS \
    && !defined __ASSUME_SYSVIPC_DEFAULT_IPC_64
 /* For architectures that have wire-up semctl but also have __IPC_64 to a
    value different than default (0x0) it means the compat symbol used the
    __NR_ipc syscall.  */
  return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd, arg.array);
# else
  return INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd,
			      SEMCTL_ARG_ADDRESS (arg));
# endif
}
compat_symbol (libc, __old_semctl, semctl, GLIBC_2_0);
#endif