server: Add support for opening a new file handle from a mapping object.

server/file.c

@@ -141,6 +141,31 @@ struct file *create_file_for_fd( int fd, unsigned int access, unsigned int shari
     return file;
 }
 
+/* create a file by duplicating an fd object */
+struct file *create_file_for_fd_obj( struct fd *fd, unsigned int access, unsigned int sharing )
+{
+    struct file *file;
+    struct stat st;
+
+    if (fstat( get_unix_fd(fd), &st ) == -1)
+    {
+        file_set_error();
+        return NULL;
+    }
+
+    if ((file = alloc_object( &file_ops )))
+    {
+        file->mode = st.st_mode;
+        file->access = default_fd_map_access( &file->obj, access );
+        if (!(file->fd = dup_fd_object( fd, access, sharing, FILE_SYNCHRONOUS_IO_NONALERT )))
+        {
+            release_object( file );
+            return NULL;
+        }
+    }
+    return file;
+}
+
 static struct object *create_file_obj( struct fd *fd, unsigned int access, mode_t mode )
 {
     struct file *file = alloc_object( &file_ops );

server/file.h

@@ -116,11 +116,20 @@ extern struct file *get_file_obj( struct process *process, obj_handle_t handle,
 extern int get_file_unix_fd( struct file *file );
 extern int is_same_file( struct file *file1, struct file *file2 );
 extern struct file *create_file_for_fd( int fd, unsigned int access, unsigned int sharing );
+extern struct file *create_file_for_fd_obj( struct fd *fd, unsigned int access, unsigned int sharing );
 extern struct file *grab_file_unless_removable( struct file *file );
 extern void file_set_error(void);
 extern struct security_descriptor *mode_to_sd( mode_t mode, const SID *user, const SID *group );
 extern mode_t sd_to_mode( const struct security_descriptor *sd, const SID *owner );
 
+/* file mapping functions */
+
+extern struct mapping *get_mapping_obj( struct process *process, obj_handle_t handle,
+                                        unsigned int access );
+extern obj_handle_t open_mapping_file( struct process *process, struct mapping *mapping,
+                                       unsigned int access, unsigned int sharing );
+extern int get_page_size(void);
+
 /* change notification functions */
 
 extern void do_change_notify( int unix_fd );

server/mapping.c

@@ -565,6 +565,24 @@ static struct object *create_mapping( struct directory *root, const struct unico
     return NULL;
 }
 
+struct mapping *get_mapping_obj( struct process *process, obj_handle_t handle, unsigned int access )
+{
+    return (struct mapping *)get_handle_obj( process, handle, access, &mapping_ops );
+}
+
+/* open a new file handle to the file backing the mapping */
+obj_handle_t open_mapping_file( struct process *process, struct mapping *mapping,
+                                unsigned int access, unsigned int sharing )
+{
+    obj_handle_t handle;
+    struct file *file = create_file_for_fd_obj( mapping->fd, access, sharing );
+
+    if (!file) return 0;
+    handle = alloc_handle( process, file, access, 0 );
+    release_object( file );
+    return handle;
+}
+
 static void mapping_dump( struct object *obj, int verbose )
 {
     struct mapping *mapping = (struct mapping *)obj;
@@ -682,8 +700,7 @@ DECL_HANDLER(get_mapping_info)
     struct mapping *mapping;
     struct fd *fd;
 
-    if ((mapping = (struct mapping *)get_handle_obj( current->process, req->handle,
-                                                     req->access, &mapping_ops )))
+    if ((mapping = get_mapping_obj( current->process, req->handle, req->access )))
     {
         reply->size        = mapping->size;
         reply->protect     = mapping->protect;
@@ -713,7 +730,7 @@ DECL_HANDLER(get_mapping_committed_range)
 {
     struct mapping *mapping;
 
-    if ((mapping = (struct mapping *)get_handle_obj( current->process, req->handle, 0, &mapping_ops )))
+    if ((mapping = get_mapping_obj( current->process, req->handle, 0 )))
     {
         if (!(req->offset & page_mask) && req->offset < mapping->size)
             reply->committed = find_committed_range( mapping, req->offset, &reply->size );
@@ -729,7 +746,7 @@ DECL_HANDLER(add_mapping_committed_range)
 {
     struct mapping *mapping;
 
-    if ((mapping = (struct mapping *)get_handle_obj( current->process, req->handle, 0, &mapping_ops )))
+    if ((mapping = get_mapping_obj( current->process, req->handle, 0 )))
     {
         if (!(req->size & page_mask) &&
             !(req->offset & page_mask) &&

server/object.h

@@ -180,10 +180,6 @@ extern void generate_debug_event( struct thread *thread, int code, const void *a
 extern void generate_startup_debug_events( struct process *process, client_ptr_t entry );
 extern void debug_exit_thread( struct thread *thread );
 
-/* mapping functions */
-
-extern int get_page_size(void);
-
 /* registry functions */
 
 extern unsigned int get_prefix_cpu_mask(void);