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/*-
* Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
* All rights reserved.
*
* Portions of this software were developed under sponsorship from Snow
* B.V., the Netherlands.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/tty_inq.c 223575 2011-06-26 18:26:20Z ed $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/tty.h>
#include <sys/uio.h>
#include <vm/uma.h>
/*
* TTY input queue buffering.
*
* Unlike the output queue, the input queue has more features that are
* needed to properly implement various features offered by the TTY
* interface:
*
* - Data can be removed from the tail of the queue, which is used to
* implement backspace.
* - Once in a while, input has to be `canonicalized'. When ICANON is
* turned on, this will be done after a CR has been inserted.
* Otherwise, it should be done after any character has been inserted.
* - The input queue can store one bit per byte, called the quoting bit.
* This bit is used by TTYDISC to make backspace work on quoted
* characters.
*
* In most cases, there is probably less input than output, so unlike
* the outq, we'll stick to 128 byte blocks here.
*/
static int ttyinq_flush_secure = 1;
SYSCTL_INT(_kern, OID_AUTO, tty_inq_flush_secure, CTLFLAG_RW,
&ttyinq_flush_secure, 0, "Zero buffers while flushing");
#define TTYINQ_QUOTESIZE (TTYINQ_DATASIZE / BMSIZE)
#define BMSIZE 32
#define GETBIT(tib,boff) \
((tib)->tib_quotes[(boff) / BMSIZE] & (1 << ((boff) % BMSIZE)))
#define SETBIT(tib,boff) \
((tib)->tib_quotes[(boff) / BMSIZE] |= (1 << ((boff) % BMSIZE)))
#define CLRBIT(tib,boff) \
((tib)->tib_quotes[(boff) / BMSIZE] &= ~(1 << ((boff) % BMSIZE)))
struct ttyinq_block {
struct ttyinq_block *tib_prev;
struct ttyinq_block *tib_next;
uint32_t tib_quotes[TTYINQ_QUOTESIZE];
char tib_data[TTYINQ_DATASIZE];
};
static uma_zone_t ttyinq_zone;
#define TTYINQ_INSERT_TAIL(ti, tib) do { \
if (ti->ti_end == 0) { \
tib->tib_prev = NULL; \
tib->tib_next = ti->ti_firstblock; \
ti->ti_firstblock = tib; \
} else { \
tib->tib_prev = ti->ti_lastblock; \
tib->tib_next = ti->ti_lastblock->tib_next; \
ti->ti_lastblock->tib_next = tib; \
} \
if (tib->tib_next != NULL) \
tib->tib_next->tib_prev = tib; \
ti->ti_nblocks++; \
} while (0)
#define TTYINQ_REMOVE_HEAD(ti) do { \
ti->ti_firstblock = ti->ti_firstblock->tib_next; \
if (ti->ti_firstblock != NULL) \
ti->ti_firstblock->tib_prev = NULL; \
ti->ti_nblocks--; \
} while (0)
#define TTYINQ_RECYCLE(ti, tib) do { \
if (ti->ti_quota <= ti->ti_nblocks) \
uma_zfree(ttyinq_zone, tib); \
else \
TTYINQ_INSERT_TAIL(ti, tib); \
} while (0)
void
ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size)
{
struct ttyinq_block *tib;
ti->ti_quota = howmany(size, TTYINQ_DATASIZE);
while (ti->ti_quota > ti->ti_nblocks) {
/*
* List is getting bigger.
* Add new blocks to the tail of the list.
*
* We must unlock the TTY temporarily, because we need
* to allocate memory. This won't be a problem, because
* in the worst case, another thread ends up here, which
* may cause us to allocate too many blocks, but this
* will be caught by the loop below.
*/
tty_unlock(tp);
tib = uma_zalloc(ttyinq_zone, M_WAITOK);
tty_lock(tp);
TTYINQ_INSERT_TAIL(ti, tib);
}
}
void
ttyinq_free(struct ttyinq *ti)
{
struct ttyinq_block *tib;
ttyinq_flush(ti);
ti->ti_quota = 0;
while ((tib = ti->ti_firstblock) != NULL) {
TTYINQ_REMOVE_HEAD(ti);
uma_zfree(ttyinq_zone, tib);
}
MPASS(ti->ti_nblocks == 0);
}
int
ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
size_t rlen, size_t flen)
{
MPASS(rlen <= uio->uio_resid);
while (rlen > 0) {
int error;
struct ttyinq_block *tib;
size_t cbegin, cend, clen;
/* See if there still is data. */
if (ti->ti_begin == ti->ti_linestart)
return (0);
tib = ti->ti_firstblock;
if (tib == NULL)
return (0);
/*
* The end address should be the lowest of these three:
* - The write pointer
* - The blocksize - we can't read beyond the block
* - The end address if we could perform the full read
*/
cbegin = ti->ti_begin;
cend = MIN(MIN(ti->ti_linestart, ti->ti_begin + rlen),
TTYINQ_DATASIZE);
clen = cend - cbegin;
MPASS(clen >= flen);
rlen -= clen;
/*
* We can prevent buffering in some cases:
* - We need to read the block until the end.
* - We don't need to read the block until the end, but
* there is no data beyond it, which allows us to move
* the write pointer to a new block.
*/
if (cend == TTYINQ_DATASIZE || cend == ti->ti_end) {
/*
* Fast path: zero copy. Remove the first block,
* so we can unlock the TTY temporarily.
*/
TTYINQ_REMOVE_HEAD(ti);
ti->ti_begin = 0;
/*
* Because we remove the first block, we must
* fix up the block offsets.
*/
#define CORRECT_BLOCK(t) do { \
if (t <= TTYINQ_DATASIZE) \
t = 0; \
else \
t -= TTYINQ_DATASIZE; \
} while (0)
CORRECT_BLOCK(ti->ti_linestart);
CORRECT_BLOCK(ti->ti_reprint);
CORRECT_BLOCK(ti->ti_end);
#undef CORRECT_BLOCK
/*
* Temporary unlock and copy the data to
* userspace. We may need to flush trailing
* bytes, like EOF characters.
*/
tty_unlock(tp);
error = uiomove(tib->tib_data + cbegin,
clen - flen, uio);
tty_lock(tp);
/* Block can now be readded to the list. */
TTYINQ_RECYCLE(ti, tib);
} else {
char ob[TTYINQ_DATASIZE - 1];
/*
* Slow path: store data in a temporary buffer.
*/
memcpy(ob, tib->tib_data + cbegin, clen - flen);
ti->ti_begin += clen;
MPASS(ti->ti_begin < TTYINQ_DATASIZE);
/* Temporary unlock and copy the data to userspace. */
tty_unlock(tp);
error = uiomove(ob, clen - flen, uio);
tty_lock(tp);
}
if (error != 0)
return (error);
if (tty_gone(tp))
return (ENXIO);
}
return (0);
}
static __inline void
ttyinq_set_quotes(struct ttyinq_block *tib, size_t offset,
size_t length, int value)
{
if (value) {
/* Set the bits. */
for (; length > 0; length--, offset++)
SETBIT(tib, offset);
} else {
/* Unset the bits. */
for (; length > 0; length--, offset++)
CLRBIT(tib, offset);
}
}
size_t
ttyinq_write(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
{
const char *cbuf = buf;
struct ttyinq_block *tib;
unsigned int boff;
size_t l;
while (nbytes > 0) {
boff = ti->ti_end % TTYINQ_DATASIZE;
if (ti->ti_end == 0) {
/* First time we're being used or drained. */
MPASS(ti->ti_begin == 0);
tib = ti->ti_firstblock;
if (tib == NULL) {
/* Queue has no blocks. */
break;
}
ti->ti_lastblock = tib;
} else if (boff == 0) {
/* We reached the end of this block on last write. */
tib = ti->ti_lastblock->tib_next;
if (tib == NULL) {
/* We've reached the watermark. */
break;
}
ti->ti_lastblock = tib;
} else {
tib = ti->ti_lastblock;
}
/* Don't copy more than was requested. */
l = MIN(nbytes, TTYINQ_DATASIZE - boff);
MPASS(l > 0);
memcpy(tib->tib_data + boff, cbuf, l);
/* Set the quoting bits for the proper region. */
ttyinq_set_quotes(tib, boff, l, quote);
cbuf += l;
nbytes -= l;
ti->ti_end += l;
}
return (cbuf - (const char *)buf);
}
int
ttyinq_write_nofrag(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
{
size_t ret;
if (ttyinq_bytesleft(ti) < nbytes)
return (-1);
/* We should always be able to write it back. */
ret = ttyinq_write(ti, buf, nbytes, quote);
MPASS(ret == nbytes);
return (0);
}
void
ttyinq_canonicalize(struct ttyinq *ti)
{
ti->ti_linestart = ti->ti_reprint = ti->ti_end;
ti->ti_startblock = ti->ti_reprintblock = ti->ti_lastblock;
}
size_t
ttyinq_findchar(struct ttyinq *ti, const char *breakc, size_t maxlen,
char *lastc)
{
struct ttyinq_block *tib = ti->ti_firstblock;
unsigned int boff = ti->ti_begin;
unsigned int bend = MIN(MIN(TTYINQ_DATASIZE, ti->ti_linestart),
ti->ti_begin + maxlen);
MPASS(maxlen > 0);
if (tib == NULL)
return (0);
while (boff < bend) {
if (index(breakc, tib->tib_data[boff]) && !GETBIT(tib, boff)) {
*lastc = tib->tib_data[boff];
return (boff - ti->ti_begin + 1);
}
boff++;
}
/* Not found - just process the entire block. */
return (bend - ti->ti_begin);
}
void
ttyinq_flush(struct ttyinq *ti)
{
struct ttyinq_block *tib;
ti->ti_begin = 0;
ti->ti_linestart = 0;
ti->ti_reprint = 0;
ti->ti_end = 0;
/* Zero all data in the input queue to get rid of passwords. */
if (ttyinq_flush_secure) {
for (tib = ti->ti_firstblock; tib != NULL; tib = tib->tib_next)
bzero(&tib->tib_data, sizeof tib->tib_data);
}
}
int
ttyinq_peekchar(struct ttyinq *ti, char *c, int *quote)
{
unsigned int boff;
struct ttyinq_block *tib = ti->ti_lastblock;
if (ti->ti_linestart == ti->ti_end)
return (-1);
MPASS(ti->ti_end > 0);
boff = (ti->ti_end - 1) % TTYINQ_DATASIZE;
*c = tib->tib_data[boff];
*quote = GETBIT(tib, boff);
return (0);
}
void
ttyinq_unputchar(struct ttyinq *ti)
{
MPASS(ti->ti_linestart < ti->ti_end);
if (--ti->ti_end % TTYINQ_DATASIZE == 0) {
/* Roll back to the previous block. */
ti->ti_lastblock = ti->ti_lastblock->tib_prev;
/*
* This can only fail if we are unputchar()'ing the
* first character in the queue.
*/
MPASS((ti->ti_lastblock == NULL) == (ti->ti_end == 0));
}
}
void
ttyinq_reprintpos_set(struct ttyinq *ti)
{
ti->ti_reprint = ti->ti_end;
ti->ti_reprintblock = ti->ti_lastblock;
}
void
ttyinq_reprintpos_reset(struct ttyinq *ti)
{
ti->ti_reprint = ti->ti_linestart;
ti->ti_reprintblock = ti->ti_startblock;
}
static void
ttyinq_line_iterate(struct ttyinq *ti,
ttyinq_line_iterator_t *iterator, void *data,
unsigned int offset, struct ttyinq_block *tib)
{
unsigned int boff;
/* Use the proper block when we're at the queue head. */
if (offset == 0)
tib = ti->ti_firstblock;
/* Iterate all characters and call the iterator function. */
for (; offset < ti->ti_end; offset++) {
boff = offset % TTYINQ_DATASIZE;
MPASS(tib != NULL);
/* Call back the iterator function. */
iterator(data, tib->tib_data[boff], GETBIT(tib, boff));
/* Last byte iterated - go to the next block. */
if (boff == TTYINQ_DATASIZE - 1)
tib = tib->tib_next;
MPASS(tib != NULL);
}
}
void
ttyinq_line_iterate_from_linestart(struct ttyinq *ti,
ttyinq_line_iterator_t *iterator, void *data)
{
ttyinq_line_iterate(ti, iterator, data,
ti->ti_linestart, ti->ti_startblock);
}
void
ttyinq_line_iterate_from_reprintpos(struct ttyinq *ti,
ttyinq_line_iterator_t *iterator, void *data)
{
ttyinq_line_iterate(ti, iterator, data,
ti->ti_reprint, ti->ti_reprintblock);
}
static void
ttyinq_startup(void *dummy)
{
ttyinq_zone = uma_zcreate("ttyinq", sizeof(struct ttyinq_block),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
}
SYSINIT(ttyinq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyinq_startup, NULL);