diff options
| -rw-r--r-- | hurd/io.defs | 36 |
1 files changed, 16 insertions, 20 deletions
diff --git a/hurd/io.defs b/hurd/io.defs index 617cf9d9..01f87a87 100644 --- a/hurd/io.defs +++ b/hurd/io.defs @@ -1,5 +1,5 @@ /* Definitions for generic IO interface - Copyright (C) 1991, 1993 Free Software Foundation + Copyright (C) 1991, 1993, 1994 Free Software Foundation This file is part of the GNU Hurd. @@ -179,31 +179,27 @@ routine io_server_version ( /* Definitions for mapped io */ -/* Return object mapping the data underlying this memory object. If - the read-data and the write-data are the same (as for files) - memobjxx will be set and both memobjrd and memobjwt will be - MACH_PORT_NULL. If the read-object and the write-object are - distinct (as for TCP streams) memobjxx is MACH_PORT_NULL and the - either or both of memobjrd and memobjwr will be set. If memobjxx - is returned, the the memory object will be readable, and writable - iff the object is O_RDWR or O_WRONLY. If memobjxx is not returned, - memobjrd will be returned if the object is O_RDWR or O_RDONLY, and - will not be writable; memobjwr will be returned if the object is - O_RDWR or O_WRONLY, and will be readable and writable. Some - objects do not provide mapping; they will set none of the ports and - return an error. Such objects can still be accessed by io_read and - io_write. */ +/* Return objects mapping the data underlying this memory object. If + the object can be read then memobjrd will be provided; if the + object can be written then memobjwr will be provided. For objects + where read data and write data are the same, these objects will be + equal, otherwise they will be disjoint. Servers are permitted to + implement io_map but not io_map_cntl. Some objects do not provide + mapping; they will set none of the ports and return an error. Such + objects can still be accessed by io_read and io_write. */ routine io_map ( io_object: io_t; out memobjrd: mach_port_send_t; out memobjwt: mach_port_send_t); /* This call can only be made once per request port. If it returns - POSIX_EBUSY, then the user should duplicate the port (using - io_duplicate) and try again. This maps the shared page data - structures corresponding to the data maps in io_map. The format - and meaning of the shared page is described in shared.h and the - calls below. */ + EBUSY, then the user should duplicate the port (using io_duplicate) + and try again. This maps the shared page data structures + corresponding to the data maps in io_map. The format and meaning + of the shared page is described in shared.h and the calls below. + This call may be unimplemented by some servers; they will return + EOPNOTSUPP. + */ routine io_map_cntl ( io_object: io_t; out memobj: memory_object_t); |