minix/servers/vfs/file.h
Thomas Veerman aba392e630 Clean up and fix multiple bugs in select:
- Remove redundant code.
 - Always wait for the initial reply from an asynchronous select request,
   even if the select has been satisfied on another file descriptor or
   was canceled due to a serious error.
 - Restart asynchronous selects if upon reply from the driver turns out
   that there are deferred operations (and do not forget we're still
   interested in the results of the deferred operations).
 - Do not hang a non-blocking select when another blocking select on
   the same filp is still blocking.
 - Split blocking operations in read, write, and exceptions (i.e.,
   blocking on read does not imply the write will block as well).
 - Some loops would iterate over OPEN_MAX file descriptors instead of
   the "highest" file descriptor.
 - Use proper internal error return values.
 - A secondary reply from a synchronous driver is essentially the same
   as from an asynchronous driver (the only difference being how the 
   answer is received). Merge.
 - Return proper error code after a driver failure.
 - Auto-detect whether a driver is synchronous or asynchronous.
 - Remove some code duplication.
 - Clean up code (coding style, add missing comments, put all select
   related code together).
2011-04-13 13:25:34 +00:00

45 lines
1.6 KiB
C

#ifndef __VFS_FILE_H__
#define __VFS_FILE_H__
/* This is the filp table. It is an intermediary between file descriptors and
* inodes. A slot is free if filp_count == 0.
*/
EXTERN struct filp {
mode_t filp_mode; /* RW bits, telling how file is opened */
int filp_flags; /* flags from open and fcntl */
int filp_state; /* state for crash recovery */
int filp_count; /* how many file descriptors share this slot?*/
struct vnode *filp_vno; /* vnode belonging to this file */
u64_t filp_pos; /* file position */
/* the following fields are for select() and are owned by the generic
* select() code (i.e., fd-type-specific select() code can't touch these).
*/
int filp_selectors; /* select()ing processes blocking on this fd */
int filp_select_ops; /* interested in these SEL_* operations */
int filp_select_flags; /* Select flags for the filp */
/* following are for fd-type-specific select() */
int filp_pipe_select_ops;
} filp[NR_FILPS];
#define FILP_CLOSED 0 /* filp_mode: associated device closed */
#define FS_NORMAL 0 /* file descriptor can be used normally */
#define FS_NEEDS_REOPEN 1 /* file descriptor needs to be re-opened */
#define FSF_UPDATE 001 /* The driver should be informed about new
* state.
*/
#define FSF_BUSY 002 /* Select operation sent to driver but no
* reply yet.
*/
#define FSF_RD_BLOCK 010 /* Read request is blocking, the driver should
* keep state.
*/
#define FSF_WR_BLOCK 020 /* Write request is blocking */
#define FSF_ERR_BLOCK 040 /* Exception request is blocking */
#define FSF_BLOCKED 070
#endif