Here's the code for using named and unnamed semaphores in Mingw-w64. The
only function I have not tested (but looks OK now) is _sem_timedwait().
Code is included in libtubo release 5.0.12 (http://xffm.org/libtubo.html)
with GPLV3, so if it is of any use, feel free to use it. I've prepared
Mingw-w64 7z package at download site too.
// Copyright 2000-2013(C) Edscott Wilson Garcia under GNU GPLv3
#ifdef DEBUG_TRACE
# define TRACE(...) \
{ \
fprintf(stderr, "TRACE:");\
fprintf(stderr, __VA_ARGS__); \
fflush(stderr);\
}
#else
# define TRACE(...) { (void)0; }
#endif
// Semaphore wrappers
#ifdef HAVE_WINDOWS_H
#include <stdarg.h>
#include <sys/types.h>
# define _sem_t HANDLE
#ifndef SEM_FAILED
#define SEM_FAILED ((_sem_t *)(-1))
#endif
#ifndef SEM_VALUE_MAX
#define SEM_VALUE_MAX 1024
#endif
static
_sem_t *_sem_open(const char *name, int oflag, ...){
va_list var_args;
int mode;
unsigned int value;
TRACE("--> _sem_open(%s)\n", name);
_sem_t *sem = (_sem_t *)malloc(sizeof(_sem_t));
if (!sem) {
fprintf(stderr, "*** Tubo: malloc(%d): %s\n",
sizeof(_sem_t),strerror(errno));
return (_sem_t *)SEM_FAILED;
}
HANDLE handle;
if (oflag & O_CREAT) {
va_start(var_args, oflag);
mode = va_arg(var_args, int);
value = va_arg(var_args, unsigned int);
va_end(var_args);
handle = CreateSemaphore(NULL, (LONG) value, (LONG) SEM_VALUE_MAX,
name);
} else {
handle = OpenSemaphore( SEMAPHORE_ALL_ACCESS, FALSE, name);
}
if (handle == NULL){
TRACE("--> %s semaphore %s failed.\n", (oflag &
O_CREAT)?"Create":"Open", name);
errno = EINVAL;
free(sem);
return (_sem_t *)SEM_FAILED;
}
TRACE ("--> %s semaphore %s (%d) OK!\n", (oflag &
O_CREAT)?"Create":"Open", name,
(intptr_t)handle);
*sem = handle;
return sem;
}
static
int _sem_init(_sem_t *sem, int pshared, unsigned int value){
HANDLE handle = CreateSemaphore(NULL, (LONG) value, (LONG)
SEM_VALUE_MAX, NULL);
if (handle == NULL) {
fprintf(stderr, "*** Tubo: Error in CreateSemaphore: %d\n",
GetLastError());
return -1;
}
TRACE("--> _sem_open(unnamed) got %d initialized to %d\n",
(intptr_t)handle, value);
SetHandleInformation(handle, HANDLE_FLAG_PROTECT_FROM_CLOSE,
HANDLE_FLAG_PROTECT_FROM_CLOSE);
*sem = handle;
return 0;
}
static
int _sem_close(_sem_t *sem){
TRACE("closing semaphore %d\n", *sem);
if (!sem || sem == SEM_FAILED) {
errno = EBADF;
return -1;
}
DWORD dwFlags;
GetHandleInformation(*sem, &dwFlags);
int unnamed = 0;
if (dwFlags & HANDLE_FLAG_PROTECT_FROM_CLOSE) {
unnamed = 1;
SetHandleInformation(*sem, HANDLE_FLAG_PROTECT_FROM_CLOSE, 0);
}
BOOL result = CloseHandle(*sem);
if (!result){
errno = EINVAL;
return -1;
}
// If it is a named semaphore, we must free allocated memory.
if (!unnamed) {
TRACE("Free sem %d now\n", *sem);
free(sem);
} else TRACE("Will not free sem %d (unnamed)\n", *sem);
return 0;
}
static
int _sem_unlink(const char *name){
// Big Fat Warning:
// Windows does this when all processes close the semaphore.
return 0;
}
static
int _sem_post(_sem_t *sem){
TRACE("Releasing semaphore %d\n", *sem);
BOOL result = ReleaseSemaphore( *sem, 1, NULL);
if (!result) return -1;
return 0;
}
static
int _sem_timeout(_sem_t *sem, long timeout){
TRACE("Wait on semaphore %d\n", *sem);
DWORD result = WaitForSingleObject(*sem, timeout);
switch (result){
case WAIT_OBJECT_0:
TRACE("Wait OK on semaphore %d\n", *sem);
return 0;
case WAIT_TIMEOUT:
TRACE("Wait timed out on semaphore %d\n", *sem);
return -1;
case WAIT_FAILED:
TRACE("Wait failed on semaphore %d\n", *sem);
return -1;
}
}
static
int _sem_timedwait(_sem_t *sem, const struct timespec *abs_timeout){
struct timeval tv;
if (gettimeofday(&tv, NULL) < 0) return -1;
time_t seconds = abs_timeout->tv_sec - tv.tv_sec;
long milliseconds = seconds * 1000;
long microseconds = (abs_timeout->tv_nsec / 1000) - tv.tv_usec;
milliseconds += (microseconds/1000);
return tubo_sem_timeout(sem, milliseconds);
}
#define _sem_wait(X) _sem_timeout(X, INFINITE)
#define _sem_trywait(X) _sem_timeout(X, 0L)
#else
# define _sem_t sem_t
# define _sem_open(...) sem_open(__VA_ARGS__)
# define _sem_close(X) sem_close(X)
# define _sem_unlink(X) sem_unlink(X)
# define _sem_post(X) sem_post(X)
# define _sem_wait(X) sem_wait(X)
# define _sem_init(X,Y,Z) sem_init(X,Y,Z)
# define _sem_trywait(X) sem_trywait(X)
# define _sem_timedwait(X) sem_timedwait(X)
#endif
2013/11/11 Edscott Wilson <edscott.wilson.gar...@gmail.com>
>
>
>
> 2013/11/9 dw <limegreenso...@yahoo.com>
>
>> handle = CreateSemaphore(NULL, (LONG) value, (LONG) 1024, name);
>>
>>
>> Why 1024? Is this the same as SEM_VALUE_MAX?
>>
>
> Probably not the same. I'm now changing it to SEM_VALUE_MAX.
>
>
>>
>> if (handle == NULL){
>> LPTSTR buffer;
>> errno = EINVAL;
>> return (_sem_t *)SEM_FAILED;
>> }
>>
>>
>> What's the "buffer" for?
>>
>
>
> Missed that on cleanup. It was there for debugging purposes but now is
> useless.
>
>
>>
>>
>> static int _sem_timedwait(_sem_t *sem, const struct timespec
>> *abs_timeout){
>> long milliseconds = abs_timeout->tv_sec * 1000;
>> milliseconds += (abs_timeout->tv_nsec/1000000);
>> tubo_sem_timeout(sem, milliseconds);
>> }
>>
>>
>> This doesn't appear to match the man
>> page<http://man7.org/linux/man-pages/man3/sem_wait.3.html>I read: "If the
>> timeout has already expired by the time of the call"
>> implies that an absolute time is being specified, not a duration. While I
>> think your definition is more useful, this may result in unexpected
>> behavior for others.
>>
>
> Right. An absolute time is better to keep things consistent. As soon as I
> put in the code to support unnamed semaphores, I'll post the corrected code
> to the list.
>
> Thanks for your comments!
>
>
>
>
> ------------------------------------------------------------------------------------
> Dr. Edscott Wilson Garcia
> Applied Mathematics and Computing
> Mexican Petroleum Institute
>
--
------------------------------------------------------------------------------------
Dr. Edscott Wilson Garcia
Applied Mathematics and Computing
Mexican Petroleum Institute
------------------------------------------------------------------------------
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