text: /*
   * Server-side semaphore management
   *
   * Copyright (C) 1998 Alexandre Julliard
   *
   * This 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.
   *
   * 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
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
   */
  
  #include "config.h"
  #include "wine/port.h"
  
  #include <assert.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <stdarg.h>
  
  #include "ntstatus.h"
  #define WIN32_NO_STATUS
  #include "windef.h"
  #include "winternl.h"
  
  #include "handle.h"
  #include "thread.h"
  #include "request.h"
  #include "security.h"
  
  static const WCHAR semaphore_name[] = {'S','e','m','a','p','h','o','r','e'};
  
  struct type_descr semaphore_type =
  {
      { semaphore_name, sizeof(semaphore_name) },   /* name */
      SEMAPHORE_ALL_ACCESS,                         /* valid_access */
      {                                             /* mapping */
          STANDARD_RIGHTS_READ | SEMAPHORE_QUERY_STATE,
          STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE,
          STANDARD_RIGHTS_EXECUTE | SYNCHRONIZE,
          SEMAPHORE_ALL_ACCESS
      },
  };
  
  struct semaphore
  {
      struct object  obj;    /* object header */
      unsigned int   count;  /* current count */
      unsigned int   max;    /* maximum possible count */
  };
  
  static void semaphore_dump( struct object *obj, int verbose );
  static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry );
  static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry );
  static int semaphore_signal( struct object *obj, unsigned int access );
  
  static const struct object_ops semaphore_ops =
  {
      sizeof(struct semaphore),      /* size */
      &semaphore_type,               /* type */
      semaphore_dump,                /* dump */
      add_queue,                     /* add_queue */
      remove_queue,                  /* remove_queue */
      semaphore_signaled,            /* signaled */
      NULL,                          /* get_esync_fd */
      NULL,                          /* get_fsync_idx */
      semaphore_satisfied,           /* satisfied */
      semaphore_signal,              /* signal */
      no_get_fd,                     /* get_fd */
      default_map_access,            /* map_access */
      default_get_sd,                /* get_sd */
      default_set_sd,                /* set_sd */
      default_get_full_name,         /* get_full_name */
      no_lookup_name,                /* lookup_name */
      directory_link_name,           /* link_name */
      default_unlink_name,           /* unlink_name */
      no_open_file,                  /* open_file */
      no_kernel_obj_list,            /* get_kernel_obj_list */
      no_close_handle,               /* close_handle */
      no_destroy                     /* destroy */
  };
  
  
  static struct semaphore *create_semaphore( struct object *root, const struct unicode_str *name,
                                             unsigned int attr, unsigned int initial, unsigned int max,
                                             const struct security_descriptor *sd )
  {
      struct semaphore *sem;
  
      if (!max || (initial > max))
      {
          set_error( STATUS_INVALID_PARAMETER );
          return NULL;
      }
      if ((sem = create_named_object( root, &semaphore_ops, name, attr, sd )))
      {
          if (get_error() != STATUS_OBJECT_NAME_EXISTS)
          {
              /* initialize it if it didn't already exist */
              sem->count = initial;
              sem->max   = max;
          }
      }
      return sem;
  }
  
  static int release_semaphore( struct semaphore *sem, unsigned int count,
                                unsigned int *prev )
  {
      if (prev) *prev = sem->count;
      if (sem->count + count < sem->count || sem->count + count > sem->max)
      {
          set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
          return 0;
      }
      else if (sem->count)
      {
          /* there cannot be any thread to wake up if the count is != 0 */
          sem->count += count;
      }
      else
      {
          sem->count = count;
          wake_up( &sem->obj, count );
      }
      return 1;
  }
  
  static void semaphore_dump( struct object *obj, int verbose )
  {
      struct semaphore *sem = (struct semaphore *)obj;
      assert( obj->ops == &semaphore_ops );
      fprintf( stderr, "Semaphore count=%d max=%d\n", sem->count, sem->max );
  }
  
  static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry )
  {
      struct semaphore *sem = (struct semaphore *)obj;
      assert( obj->ops == &semaphore_ops );
      return (sem->count > 0);
  }
  
  static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry )
  {
      struct semaphore *sem = (struct semaphore *)obj;
      assert( obj->ops == &semaphore_ops );
      assert( sem->count );
      sem->count--;
  }
  
  static int semaphore_signal( struct object *obj, unsigned int access )
  {
      struct semaphore *sem = (struct semaphore *)obj;
      assert( obj->ops == &semaphore_ops );
  
      if (!(access & SEMAPHORE_MODIFY_STATE))
      {
          set_error( STATUS_ACCESS_DENIED );
          return 0;
      }
      return release_semaphore( sem, 1, NULL );
  }
  
  /* create a semaphore */
  DECL_HANDLER(create_semaphore)
  {
      struct semaphore *sem;
      struct unicode_str name;
      struct object *root;
      const struct security_descriptor *sd;
      const struct object_attributes *objattr = get_req_object_attributes( &sd, &name, &root );
  
      if (!objattr) return;
  
      if ((sem = create_semaphore( root, &name, objattr->attributes, req->initial, req->max, sd )))
      {
          if (get_error() == STATUS_OBJECT_NAME_EXISTS)
              reply->handle = alloc_handle( current->process, sem, req->access, objattr->attributes );
          else
              reply->handle = alloc_handle_no_access_check( current->process, sem,
                                                            req->access, objattr->attributes );
          release_object( sem );
      }
  
      if (root) release_object( root );
  }
  
  /* open a handle to a semaphore */
  DECL_HANDLER(open_semaphore)
  {
      struct unicode_str name = get_req_unicode_str();
  
      reply->handle = open_object( current->process, req->rootdir, req->access,
                                   &semaphore_ops, &name, req->attributes );
  }
  
  /* release a semaphore */
  DECL_HANDLER(release_semaphore)
  {
      struct semaphore *sem;
  
      if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
                                                     SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
      {
          release_semaphore( sem, req->count, &reply->prev_count );
          release_object( sem );
      }
  }
  
  /* query details about the semaphore */
  DECL_HANDLER(query_semaphore)
  {
      struct semaphore *sem;
  
      if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
                                                     SEMAPHORE_QUERY_STATE, &semaphore_ops )))
      {
          reply->current = sem->count;
          reply->max = sem->max;
          release_object( sem );
      }
  }
  