Lines Matching +full:write +full:- +full:only

1 .\" Copyright (C) Caldera International Inc. 2001-2002.  All rights reserved.
37 .EH 'PSD:3-%''The UNIX I/O System'
38 .OH 'The UNIX I/O System''PSD:3-%'
61 in the paper ``The UNIX Time-sharing System.''
79 which work, or can work, with addressible 512-byte blocks.
84 blocks can be written only at the end of the tape.
91 Character-type devices have a much
102 in the low-order 8 bits and the major device number
103 in the next-higher 8 bits;
134 which is stored in the system's per-process
145 .I write,
147 An entry contains only
152 which is a per-system data base.
160 This table is per-system because the same instance
173 There is also a 32-bit file offset
175 or write will take place.
180 which contains a copy of the file's i-node.
205 table not only because it is open,
208 is a special file containing a currently-mounted
214 corresponding i-node as stored on the disk;
220 and the device and i-number
224 the 3-byte, compressed format used on the disk to full
237 the data-terminal-ready lead of a modem, etc.).
241 routine is called only when the last
243 that is, when the i-node table entry
249 implement an exclusive-use device which cannot
255 .I write
267 of the I/O target area, the byte-count for the transfer,
270 a character-type special file, the appropriate read
271 or write routine is called; it is responsible
279 to a physical block number; a block-type
286 read or write the appropriate device.
295 open, close, read, write, and special-function
304 on non-exclusive devices that require no setup)
311 .I write
312 on read-only devices)
327 non-zero only if the device is to be written upon.
331 routine is called only when the file
338 the second is a flag which is non-zero
344 .I write
347 The per-user variable
369 .I write
393 Write routines which want to transfer
409 (which is 0) in the write case.
412 the count is not too large and is non-zero.
424 .I write,
427 is guaranteed to be non-zero.
440 .I write;
445 The ``special-functions'' routine
475 Finally, each device should have appropriate interrupt-time
477 When an interrupt occurs, it is turned into a C-compatible call
479 The interrupt-catching mechanism makes
480 the low-order four bits of the ``new PS'' word in the
494 between their ``top half'' (read/write)
496 For relatively low data-rate devices, the best mechanism
522 which returns either the (non-negative) character
527 and in the standard system there are only some 600
530 especially write routines, must take
534 to device handlers is the sleep-wakeup mechanism.
541 at that time, the process is marked ready-to-run
555 by the sleeper and the waker-up.
566 a higher numerical value indicates a less-favored
595 (for example, a device going on-line, which does not
610 If a device needs to know about real-time intervals,
623 to provide real-time delays after function characters
624 like new-line and tab in typewriter output,
632 and that only a bounded number of timeouts
636 is called at clock-interrupt time, so it should
640 The Block-device Interface
651 keeping in-core copies of blocks that are being
658 which maintain a doubly-linked list
663 which generally maintain a doubly-linked list of blocks
698 block only if it is already in core (whether it is
716 routine is used to implement read-ahead.
731 There are three subtly-different write routines,
738 waits for the write to be done,
757 it is used, for example, when updating i-nodes.
762 write is really required.
764 is used when there is doubt that the write is
769 .I write
773 .I write
774 will be given soon which will re-use the same block.
810 which indicates read or write.
827 if it is non-zero.
834 whereby a more detailed error-reporting
891 write has been finished, usually at interrupt time.
927 Instead of separate read and write routines,
933 a read/write flag, the core address,
952 is capable, under error-free operation,
954 the device's word-count register should be placed
990 except for the buffer-chain pointers.
998 in the simplest case it may be maintained as a first-in
999 first-out list.
1027 It may be called only in the non-interrupt
1032 Raw Block-device I/O
1039 The method involves setting up a character-type special file
1044 .I write
1046 non-shared buffer header with the appropriate information
1053 A special-function routine might come in handy, especially for
1070 and a read-write flag