Rename FD to "handle" #62
Description
The current design has a hidden table of implementation-defined objects that are indexed by the integer "file descriptors" exposed through the API.
These "file descriptors" could be more generally called handles, and the table of implementation-defined objects generalized to include other kinds of objects: processes, threads, mutexes, clocks, etc.
This would allow, for example, WASI APIs that work with process objects without exposing a global process ID namespace, and without adding a separate "process descriptor" table that maps indices to process objects.
The impact on the current API would be pretty minimal:
typedef struct __wasi_fdstat_t
{
__wasi_filetype_t fs_filetype;
__wasi_fdflags_t fs_flags;
- // __wasi_rights_t fs_rights_base;
- // __wasi_rights_t fs_rights_inheriting;
} __wasi_fdstat_t;
-typedef int32_t __wasi_fd_t;
-__wasi_errno_t __wasi_fd_close(__wasi_fd_t fd);
-__wasi_errno_t __wasi_fd_renumber(__wasi_fd_t from,
- __wasi_fd_t to);
-__wasi_errno_t __wasi_fd_fdstat_set_rights(__wasi_fd_t fd,
- __wasi_rights_t base,
- __wasi_rights_t inheriting);
-__wasi_errno_t __wasi_fd_prestat_get(__wasi_fd_t fd,
- __wasi_prestat_t* out_prestat);
+typedef intptr_t __wasi_handle_t;
+typedef uint32_t __wasi_object_kind_t;
+#define __WASI_OBJECT_KIND_FD (UINT32_C(0))
+__wasi_errno_t __wasi_handle_close(__wasi_wasi_handle_t handle);
+__wasi_errno_t __wasi_handle_renumber(__wasi_handle_t from,
+ __wasi_handle_t to);
+__wasi_errno_t __wasi_handle_set_rights(__wasi_handle_t handle,
+ __wasi_rights_t base,
+ __wasi_rights_t inheriting);
+__wasi_errno_t __wasi_handle_get_rights(__wasi_handle_t handle,
+ __wasi_rights_t* out_base,
+ __wasi_rights_t* out_inheriting);
+__wasi_errno_t __wasi_handle_get_object_kind(__wasi_handle_t handle,
+ __wasi_object_kind_t* out_kind);
+__wasi_errno_t __wasi_handle_prestat_get(__wasi_handle_t handle,
+ __wasi_prestat_t* out_prestat);And everywhere the API currently takes a __wasi_fd_t would be changed to take a __wasi_handle_t. EBADF could be aliased as EBADHANDLE, and returned when using an invalid handle. ENOTCAPABLE could returned when using an API function with a handle that references the wrong kind of object (as presumably the handle will not have the capabilities corresponding to the API function), or a distinct error code could be added.
This would apply the same if the integer handles are replaced by anyref:
typedef anyref __wasi_handle_t