148 lines
4.2 KiB
C
148 lines
4.2 KiB
C
/*
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* Server-side semaphore management
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*
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* Copyright (C) 1998 Alexandre Julliard
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*/
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "winnt.h"
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#include "handle.h"
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#include "thread.h"
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#include "request.h"
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struct semaphore
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{
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struct object obj; /* object header */
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unsigned int count; /* current count */
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unsigned int max; /* maximum possible count */
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};
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static void semaphore_dump( struct object *obj, int verbose );
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static int semaphore_signaled( struct object *obj, struct thread *thread );
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static int semaphore_satisfied( struct object *obj, struct thread *thread );
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static const struct object_ops semaphore_ops =
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{
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sizeof(struct semaphore), /* size */
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semaphore_dump, /* dump */
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add_queue, /* add_queue */
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remove_queue, /* remove_queue */
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semaphore_signaled, /* signaled */
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semaphore_satisfied, /* satisfied */
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NULL, /* get_poll_events */
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NULL, /* poll_event */
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no_read_fd, /* get_read_fd */
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no_write_fd, /* get_write_fd */
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no_flush, /* flush */
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no_get_file_info, /* get_file_info */
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no_destroy /* destroy */
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};
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static struct semaphore *create_semaphore( const WCHAR *name, size_t len,
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unsigned int initial, unsigned int max )
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{
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struct semaphore *sem;
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if (!max || (initial > max))
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{
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set_error( STATUS_INVALID_PARAMETER );
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return NULL;
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}
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if ((sem = create_named_object( &semaphore_ops, name, len )))
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{
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if (get_error() != STATUS_OBJECT_NAME_COLLISION)
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{
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/* initialize it if it didn't already exist */
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sem->count = initial;
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sem->max = max;
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}
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}
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return sem;
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}
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static unsigned int release_semaphore( int handle, unsigned int count )
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{
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struct semaphore *sem;
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unsigned int prev = 0;
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if ((sem = (struct semaphore *)get_handle_obj( current->process, handle,
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SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
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{
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prev = sem->count;
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if (sem->count + count < sem->count || sem->count + count > sem->max)
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{
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set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
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}
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else if (sem->count)
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{
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/* there cannot be any thread waiting if the count is != 0 */
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assert( !sem->obj.head );
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sem->count += count;
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}
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else
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{
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sem->count = count;
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wake_up( &sem->obj, count );
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}
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release_object( sem );
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}
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return prev;
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}
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static void semaphore_dump( struct object *obj, int verbose )
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{
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struct semaphore *sem = (struct semaphore *)obj;
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assert( obj->ops == &semaphore_ops );
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fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
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dump_object_name( &sem->obj );
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fputc( '\n', stderr );
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}
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static int semaphore_signaled( struct object *obj, struct thread *thread )
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{
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struct semaphore *sem = (struct semaphore *)obj;
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assert( obj->ops == &semaphore_ops );
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return (sem->count > 0);
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}
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static int semaphore_satisfied( struct object *obj, struct thread *thread )
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{
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struct semaphore *sem = (struct semaphore *)obj;
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assert( obj->ops == &semaphore_ops );
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assert( sem->count );
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sem->count--;
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return 0; /* not abandoned */
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}
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/* create a semaphore */
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DECL_HANDLER(create_semaphore)
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{
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size_t len = get_req_strlenW( req, req->name );
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struct semaphore *sem;
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req->handle = -1;
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if ((sem = create_semaphore( req->name, len, req->initial, req->max )))
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{
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req->handle = alloc_handle( current->process, sem, SEMAPHORE_ALL_ACCESS, req->inherit );
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release_object( sem );
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}
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}
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/* open a handle to a semaphore */
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DECL_HANDLER(open_semaphore)
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{
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size_t len = get_req_strlenW( req, req->name );
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req->handle = open_object( req->name, len, &semaphore_ops, req->access, req->inherit );
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}
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/* release a semaphore */
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DECL_HANDLER(release_semaphore)
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{
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req->prev_count = release_semaphore( req->handle, req->count );
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}
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