126 lines
3.2 KiB
C
126 lines
3.2 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 "winerror.h"
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#include "winnt.h"
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#include "server/thread.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 void semaphore_destroy( struct object *obj );
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static const struct object_ops semaphore_ops =
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{
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semaphore_dump,
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add_queue,
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remove_queue,
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semaphore_signaled,
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semaphore_satisfied,
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no_read_fd,
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no_write_fd,
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no_flush,
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no_get_file_info,
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semaphore_destroy
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};
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struct object *create_semaphore( const char *name, 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( ERROR_INVALID_PARAMETER );
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return NULL;
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}
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if (!(sem = (struct semaphore *)create_named_object( name, &semaphore_ops, sizeof(*sem) )))
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return NULL;
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if (GET_ERROR() != ERROR_ALREADY_EXISTS)
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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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return &sem->obj;
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}
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int open_semaphore( unsigned int access, int inherit, const char *name )
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{
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return open_object( name, &semaphore_ops, access, inherit );
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}
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int release_semaphore( int handle, unsigned int count, unsigned int *prev_count )
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{
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struct semaphore *sem;
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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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return 0;
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*prev_count = 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( ERROR_TOO_MANY_POSTS );
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return 0;
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}
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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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return 1;
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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 name='%s'\n",
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sem->count, sem->max, get_object_name( &sem->obj ) );
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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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static void semaphore_destroy( struct object *obj )
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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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free( sem );
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}
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