semaphore.c

 
#include <winpr/config.h>
#include <winpr/debug.h>
#include <winpr/synch.h>
 
#include "synch.h"
 
#ifdef WINPR_HAVE_UNISTD_H
#include <unistd.h>
#endif
 
#ifndef _WIN32
 
#include <errno.h>
#include <fcntl.h>
#include "../handle/handle.h"
#include "../log.h"
#define TAG WINPR_TAG("synch.semaphore")
 
static BOOL SemaphoreCloseHandle(HANDLE handle);
 
static BOOL SemaphoreIsHandled(HANDLE handle)
{
  return WINPR_HANDLE_IS_HANDLED(handle, HANDLE_TYPE_SEMAPHORE, FALSE);
}
 
static int SemaphoreGetFd(HANDLE handle)
{
  WINPR_SEMAPHORE* sem = (WINPR_SEMAPHORE*)handle;
 
  if (!SemaphoreIsHandled(handle))
    return -1;
 
  return sem->pipe_fd[0];
}
 
static DWORD SemaphoreCleanupHandle(HANDLE handle)
{
  WINPR_SEMAPHORE* sem = (WINPR_SEMAPHORE*)handle;
 
  if (!SemaphoreIsHandled(handle))
    return WAIT_FAILED;
 
  uint8_t val = 0;
  const SSIZE_T length = read(sem->pipe_fd[0], &val, sizeof(val));
 
  if (length != 1)
  {
    char ebuffer[256] = WINPR_C_ARRAY_INIT;
    WLog_ERR(TAG, "semaphore read() failure [%d] %s", errno,
             winpr_strerror(errno, ebuffer, sizeof(ebuffer)));
    return WAIT_FAILED;
  }
 
  return WAIT_OBJECT_0;
}
 
BOOL SemaphoreCloseHandle(HANDLE handle)
{
  WINPR_SEMAPHORE* semaphore = (WINPR_SEMAPHORE*)handle;
 
  if (!SemaphoreIsHandled(handle))
    return FALSE;
 
#ifdef WINPR_PIPE_SEMAPHORE
 
  if (semaphore->pipe_fd[0] != -1)
  {
    close(semaphore->pipe_fd[0]);
    semaphore->pipe_fd[0] = -1;
 
    if (semaphore->pipe_fd[1] != -1)
    {
      close(semaphore->pipe_fd[1]);
      semaphore->pipe_fd[1] = -1;
    }
  }
 
#else
#if defined __APPLE__
  semaphore_destroy(mach_task_self(), *((winpr_sem_t*)semaphore->sem));
#else
  sem_destroy((winpr_sem_t*)semaphore->sem);
#endif
#endif
  return TRUE;
}
 
static HANDLE_OPS ops = { SemaphoreIsHandled,
                        SemaphoreCloseHandle,
                        SemaphoreGetFd,
                        SemaphoreCleanupHandle,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr,
                        nullptr };
 
HANDLE CreateSemaphoreW(WINPR_ATTR_UNUSED LPSECURITY_ATTRIBUTES lpSemaphoreAttributes,
                        LONG lInitialCount, WINPR_ATTR_UNUSED LONG lMaximumCount,
                        WINPR_ATTR_UNUSED LPCWSTR lpName)
{
  HANDLE handle = nullptr;
  WINPR_SEMAPHORE* semaphore = nullptr;
  semaphore = (WINPR_SEMAPHORE*)calloc(1, sizeof(WINPR_SEMAPHORE));
 
  if (!semaphore)
    return nullptr;
 
  semaphore->pipe_fd[0] = -1;
  semaphore->pipe_fd[1] = -1;
  semaphore->sem = (winpr_sem_t*)nullptr;
  semaphore->common.ops = &ops;
#ifdef WINPR_PIPE_SEMAPHORE
 
#ifdef WINPR_HAVE_PIPE2
  if (pipe2(semaphore->pipe_fd, O_CLOEXEC) < 0)
#else
  if (pipe(semaphore->pipe_fd) < 0)
#endif
  {
    WLog_ERR(TAG, "failed to create semaphore");
    free(semaphore);
    return nullptr;
  }
 
#ifndef WINPR_HAVE_PIPE2
  if (!winpr_set_cloexec(semaphore->pipe_fd[0], TRUE) ||
      !winpr_set_cloexec(semaphore->pipe_fd[1], TRUE))
  {
    WLog_ERR(TAG, "failed to set close-on-exec on semaphore pipe");
    close(semaphore->pipe_fd[0]);
    close(semaphore->pipe_fd[1]);
    free(semaphore);
    return nullptr;
  }
#endif
 
  while (lInitialCount > 0)
  {
    if (write(semaphore->pipe_fd[1], "-", 1) != 1)
    {
      close(semaphore->pipe_fd[0]);
      close(semaphore->pipe_fd[1]);
      free(semaphore);
      return nullptr;
    }
 
    lInitialCount--;
  }
 
#else
  semaphore->sem = (winpr_sem_t*)malloc(sizeof(winpr_sem_t));
 
  if (!semaphore->sem)
  {
    WLog_ERR(TAG, "failed to allocate semaphore memory");
    free(semaphore);
    return nullptr;
  }
 
#if defined __APPLE__
 
  if (semaphore_create(mach_task_self(), semaphore->sem, SYNC_POLICY_FIFO, lMaximumCount) !=
      KERN_SUCCESS)
#else
  if (sem_init(semaphore->sem, 0, lMaximumCount) == -1)
#endif
  {
    WLog_ERR(TAG, "failed to create semaphore");
    free(semaphore->sem);
    free(semaphore);
    return nullptr;
  }
 
#endif
  WINPR_HANDLE_SET_TYPE_AND_MODE(semaphore, HANDLE_TYPE_SEMAPHORE, WINPR_FD_READ);
  handle = (HANDLE)semaphore;
  return handle;
}
 
HANDLE CreateSemaphoreA(LPSECURITY_ATTRIBUTES lpSemaphoreAttributes, LONG lInitialCount,
                        LONG lMaximumCount, WINPR_ATTR_UNUSED LPCSTR lpName)
{
  return CreateSemaphoreW(lpSemaphoreAttributes, lInitialCount, lMaximumCount, nullptr);
}
 
HANDLE OpenSemaphoreW(WINPR_ATTR_UNUSED DWORD dwDesiredAccess,
                      WINPR_ATTR_UNUSED BOOL bInheritHandle, WINPR_ATTR_UNUSED LPCWSTR lpName)
{
  WLog_ERR(TAG, "not implemented");
  return nullptr;
}
 
HANDLE OpenSemaphoreA(WINPR_ATTR_UNUSED DWORD dwDesiredAccess,
                      WINPR_ATTR_UNUSED BOOL bInheritHandle, WINPR_ATTR_UNUSED LPCSTR lpName)
{
  WLog_ERR(TAG, "not implemented");
  return nullptr;
}
 
BOOL ReleaseSemaphore(HANDLE hSemaphore, LONG lReleaseCount,
                      WINPR_ATTR_UNUSED LPLONG lpPreviousCount)
{
  ULONG Type = 0;
  WINPR_HANDLE* Object = nullptr;
  WINPR_SEMAPHORE* semaphore = nullptr;
 
  if (!winpr_Handle_GetInfo(hSemaphore, &Type, &Object))
    return FALSE;
 
  if (Type == HANDLE_TYPE_SEMAPHORE)
  {
    semaphore = (WINPR_SEMAPHORE*)Object;
#ifdef WINPR_PIPE_SEMAPHORE
 
    if (semaphore->pipe_fd[0] != -1)
    {
      while (lReleaseCount > 0)
      {
        if (write(semaphore->pipe_fd[1], "-", 1) != 1)
          return FALSE;
 
        lReleaseCount--;
      }
    }
 
#else
 
    while (lReleaseCount > 0)
    {
#if defined __APPLE__
      semaphore_signal(*((winpr_sem_t*)semaphore->sem));
#else
      sem_post((winpr_sem_t*)semaphore->sem);
#endif
    }
 
#endif
    return TRUE;
  }
 
  WLog_ERR(TAG, "called on a handle that is not a semaphore");
  return FALSE;
}
 
#endif