/*
* -------------------------------------------------------------
*
* Module: semaphore.c
*
* Purpose:
* Semaphores aren't actually part of the PThreads standard.
* They are defined by the POSIX Standard:
*
* POSIX 1003.1b-1993 (POSIX.1b)
*
* -------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright (C) 1998 Ben Elliston and Ross Johnson
* Copyright (C) 1999,2000,2001 Ross Johnson
*
* Contact Email: rpj@ise.canberra.edu.au
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA
*/
/* ignore warning "unreferenced formal parameter" */
#ifdef _MSC_VER
#pragma warning( disable : 4100 )
#endif
#ifndef _UWIN
# include <process.h>
#endif
#ifndef NEED_FTIME
#include <sys/timeb.h>
#endif
#include "pthread.h"
#include "semaphore.h"
#include "implement.h"
int
sem_init (sem_t * sem, int pshared, unsigned int value)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function initializes an unnamed semaphore. the
* initial value of the semaphore is 'value'
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* pshared
* if zero, this semaphore may only be shared between
* threads in the same process.
* if nonzero, the semaphore can be shared between
* processes
*
* value
* initial value of the semaphore counter
*
* DESCRIPTION
* This function initializes an unnamed semaphore. The
* initial value of the semaphore is set to 'value'.
*
* RESULTS
* 0 successfully created semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSPC a required resource has been exhausted,
* ENOSYS semaphores are not supported,
* EPERM the process lacks appropriate privilege
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s;
if (pshared != 0)
{
/*
* Creating a semaphore that can be shared between
* processes
*/
result = EPERM;
}
else
{
s = (sem_t) calloc (1, sizeof (*s));
if (NULL == s)
{
result = ENOMEM;
}
#ifdef NEED_SEM
else
{
s->value = value;
s->event = CreateEvent (NULL,
FALSE, /* manual reset */
FALSE, /* initial state */
NULL);
if (0 == s->event)
{
result = ENOSPC;
}
else
{
if (value != 0)
{
SetEvent(s->event);
}
InitializeCriticalSection(&s->sem_lock_cs);
}
}
#else /* NEED_SEM */
s->sem = CreateSemaphore (NULL, /* Always NULL */
value, /* Initial value */
0x7FFFFFFFL, /* Maximum value */
NULL); /* Name */
if (0 == s->sem)
{
result = ENOSPC;
}
#endif /* NEED_SEM */
}
if (result != 0)
{
errno = result;
return -1;
}
*sem = s;
return 0;
} /* sem_init */
int
sem_destroy (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function destroys an unnamed semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function destroys an unnamed semaphore.
*
* RESULTS
* 0 successfully destroyed semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EBUSY threads (or processes) are currently
* blocked on 'sem'
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s;
if (sem == NULL || *sem == NULL)
{
result = EINVAL;
}
else
{
s = *sem;
*sem = NULL;
#ifdef NEED_SEM
if (! CloseHandle(s->event))
{
*sem = s;
result = EINVAL;
}
else
{
DeleteCriticalSection(&s->sem_lock_cs);
}
#else /* NEED_SEM */
if (! CloseHandle (s->sem))
{
*sem = s;
result = EINVAL;
}
#endif /* NEED_SEM */
}
if (result != 0)
{
errno = result;
return -1;
}
free(s);
return 0;
} /* sem_destroy */
int
sem_trywait (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function tries to wait on a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function tries to wait on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* this function returns immediately with the error EAGAIN
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EAGAIN the semaphore was already locked,
* EINVAL 'sem' is not a valid semaphore,
* ENOTSUP sem_trywait is not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
#ifdef NEED_SEM
/*
* not yet implemented!
*/
errno = ENOTSUP;
return -1;
#else /* NEED_SEM */
int result = 0;
if (sem == NULL || *sem == NULL)
{
result = EINVAL;
}
else if (WaitForSingleObject ((*sem)->sem, 0) == WAIT_TIMEOUT)
{
result = EAGAIN;
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
#endif /* NEED_SEM */
} /* sem_trywait */
#ifdef NEED_SEM
void
ptw32_decrease_semaphore(sem_t * sem)
{
register sem_t s = *sem;
EnterCriticalSection(&s->sem_lock_cs);
if (s->value != 0)
{
s->value--;
if (s->value != 0)
{
SetEvent(s->event);
}
}
else
{
/* this case should not happen! */
}
LeaveCriticalSection(&s->sem_lock_cs);
}
BOOL
ptw32_increase_semaphore(sem_t * sem, unsigned int n)
{
BOOL result;
register sem_t s = *sem;
EnterCriticalSection(&s->sem_lock_cs);
if (s->value + n > s->value)
{
s->value += n;
SetEvent(s->event);
result = TRUE;
}
else
{
result = FALSE;
}
LeaveCriticalSection(&s->sem_lock_cs);
return result;
}
#endif /* NEED_SEM */
int
sem_wait (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
int result = 0;
if (sem == NULL || *sem == NULL)
{
result = EINVAL;
}
else
{
#ifdef NEED_SEM
result = pthreadCancelableWait ((*sem)->event);
#else /* NEED_SEM */
result = pthreadCancelableWait ((*sem)->sem);
#endif /* NEED_SEM */
}
if (result != 0)
{
errno = result;
return -1;
}
#ifdef NEED_SEM
ptw32_decrease_semaphore(sem);
#endif /* NEED_SEM */
return 0;
} /* sem_wait */
int
sem_timedwait (sem_t * sem, const struct timespec * abstime)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore possibly until
* 'abstime' time.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* abstime
* pointer to an instance of struct timespec
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* If 'abstime' is a NULL pointer then this function will
* block until it can successfully decrease the value or
* until interrupted by a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
* ETIMEDOUT abstime elapsed before success.
*
* ------------------------------------------------------
*/
{
int result = 0;
#ifdef NEED_FTIME
struct timespec currSysTime;
#else /* NEED_FTIME */
struct _timeb currSysTime;
#endif /* NEED_FTIME */
const DWORD NANOSEC_PER_MILLISEC = 1000000;
const DWORD MILLISEC_PER_SEC = 1000;
DWORD milliseconds;
if (sem == NULL)
{
result = EINVAL;
}
else
{
if (abstime == NULL)
{
milliseconds = INFINITE;
}
else
{
/*
* Calculate timeout as milliseconds from current system time.
*/
/* get current system time */
#ifdef NEED_FTIME
{
FILETIME ft;
SYSTEMTIME st;
GetSystemTime(&st);
SystemTimeToFileTime(&st, &ft);
/*
* GetSystemTimeAsFileTime(&ft); would be faster,
* but it does not exist on WinCE
*/
filetime_to_timespec(&ft, &currSysTime);
}
/*
* subtract current system time from abstime
*/
milliseconds = (abstime->tv_sec - currSysTime.tv_sec) * MILLISEC_PER_SEC;
milliseconds += ((abstime->tv_nsec - currSysTime.tv_nsec) + (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC;
#else /* NEED_FTIME */
_ftime(&currSysTime);
/*
* subtract current system time from abstime
*/
milliseconds = (abstime->tv_sec - currSysTime.time) * MILLISEC_PER_SEC;
milliseconds += ((abstime->tv_nsec + (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC) -
currSysTime.millitm;
#endif /* NEED_FTIME */
if (((int) milliseconds) < 0)
milliseconds = 0;
}
#ifdef NEED_SEM
result = (pthreadCancelableTimedWait ((*sem)->event, milliseconds));
#else /* NEED_SEM */
result = (pthreadCancelableTimedWait ((*sem)->sem, milliseconds));
#endif
}
if (result != 0)
{
errno = result;
return -1;
}
#ifdef NEED_SEM
ptw32_decrease_semaphore(sem);
#endif /* NEED_SEM */
return 0;
} /* sem_timedwait */
int
sem_post (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function posts a wakeup to a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function posts a wakeup to a semaphore. If there
* are waiting threads (or processes), one is awakened;
* otherwise, the semaphore value is incremented by one.
*
* RESULTS
* 0 successfully posted semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
*
* ------------------------------------------------------
*/
{
int result = 0;
if (sem == NULL || *sem == NULL)
{
result = EINVAL;
}
#ifdef NEED_SEM
else if (! ptw32_increase_semaphore (sem, 1))
#else /* NEED_SEM */
else if (! ReleaseSemaphore ((*sem)->sem, 1, 0))
#endif /* NEED_SEM */
{
result = EINVAL;
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
} /* sem_post */
int
sem_post_multiple (sem_t * sem, int count )
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function posts multiple wakeups to a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* count
* counter, must be greater than zero.
*
* DESCRIPTION
* This function posts multiple wakeups to a semaphore. If there
* are waiting threads (or processes), n <= count are awakened;
* the semaphore value is incremented by count - n.
*
* RESULTS
* 0 successfully posted semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore
* or count is less than or equal to zero.
*
* ------------------------------------------------------
*/
{
int result = 0;
if (sem == NULL || *sem == NULL || count <= 0)
{
result = EINVAL;
}
#ifdef NEED_SEM
else if (! ptw32_increase_semaphore (sem, count))
#else /* NEED_SEM */
else if (! ReleaseSemaphore ((*sem)->sem, count, 0))
#endif /* NEED_SEM */
{
result = EINVAL;
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
} /* sem_post_multiple */
int
sem_open (const char * name, int oflag, mode_t mode, unsigned int value)
{
errno = ENOSYS;
return -1;
} /* sem_open */
int
sem_close (sem_t * sem)
{
errno = ENOSYS;
return -1;
} /* sem_close */
int
sem_unlink (const char * name)
{
errno = ENOSYS;
return -1;
} /* sem_unlink */
int
sem_getvalue (sem_t * sem, int * sval)
{
errno = ENOSYS;
return -1;
} /* sem_getvalue */