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linux/drivers/tty/n_tty.c

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/*
* n_tty.c --- implements the N_TTY line discipline.
*
* This code used to be in tty_io.c, but things are getting hairy
* enough that it made sense to split things off. (The N_TTY
* processing has changed so much that it's hardly recognizable,
* anyway...)
*
* Note that the open routine for N_TTY is guaranteed never to return
* an error. This is because Linux will fall back to setting a line
* to N_TTY if it can not switch to any other line discipline.
*
* Written by Theodore Ts'o, Copyright 1994.
*
* This file also contains code originally written by Linus Torvalds,
* Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
*
* This file may be redistributed under the terms of the GNU General Public
* License.
*
* Reduced memory usage for older ARM systems - Russell King.
*
* 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
* the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
* who actually finally proved there really was a race.
*
* 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
* waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
* Also fixed a bug in BLOCKING mode where n_tty_write returns
* EAGAIN
*/
#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/bitops.h>
#include <linux/audit.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/module.h>
/* number of characters left in xmit buffer before select has we have room */
#define WAKEUP_CHARS 256
/*
* This defines the low- and high-watermarks for throttling and
* unthrottling the TTY driver. These watermarks are used for
* controlling the space in the read buffer.
*/
#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
#define TTY_THRESHOLD_UNTHROTTLE 128
/*
* Special byte codes used in the echo buffer to represent operations
* or special handling of characters. Bytes in the echo buffer that
* are not part of such special blocks are treated as normal character
* codes.
*/
#define ECHO_OP_START 0xff
#define ECHO_OP_MOVE_BACK_COL 0x80
#define ECHO_OP_SET_CANON_COL 0x81
#define ECHO_OP_ERASE_TAB 0x82
static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
unsigned char __user *ptr)
{
tty_audit_add_data(tty, &x, 1);
return put_user(x, ptr);
}
/**
* n_tty_set__room - receive space
* @tty: terminal
*
* Called by the driver to find out how much data it is
* permitted to feed to the line discipline without any being lost
* and thus to manage flow control. Not serialized. Answers for the
* "instant".
*/
static void n_tty_set_room(struct tty_struct *tty)
{
/* tty->read_cnt is not read locked ? */
int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
int old_left;
/*
* If we are doing input canonicalization, and there are no
* pending newlines, let characters through without limit, so
* that erase characters will be handled. Other excess
* characters will be beeped.
*/
if (left <= 0)
left = tty->icanon && !tty->canon_data;
old_left = tty->receive_room;
tty->receive_room = left;
/* Did this open up the receive buffer? We may need to flip */
if (left && !old_left)
schedule_work(&tty->buf.work);
}
static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
{
if (tty->read_cnt < N_TTY_BUF_SIZE) {
tty->read_buf[tty->read_head] = c;
tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
tty->read_cnt++;
}
}
/**
* put_tty_queue - add character to tty
* @c: character
* @tty: tty device
*
* Add a character to the tty read_buf queue. This is done under the
* read_lock to serialize character addition and also to protect us
* against parallel reads or flushes
*/
static void put_tty_queue(unsigned char c, struct tty_struct *tty)
{
unsigned long flags;
/*
* The problem of stomping on the buffers ends here.
* Why didn't anyone see this one coming? --AJK
*/
spin_lock_irqsave(&tty->read_lock, flags);
put_tty_queue_nolock(c, tty);
spin_unlock_irqrestore(&tty->read_lock, flags);
}
/**
* check_unthrottle - allow new receive data
* @tty; tty device
*
* Check whether to call the driver unthrottle functions
*
* Can sleep, may be called under the atomic_read_lock mutex but
* this is not guaranteed.
*/
static void check_unthrottle(struct tty_struct *tty)
{
if (tty->count)
tty_unthrottle(tty);
}
/**
* reset_buffer_flags - reset buffer state
* @tty: terminal to reset
*
* Reset the read buffer counters, clear the flags,
* and make sure the driver is unthrottled. Called
* from n_tty_open() and n_tty_flush_buffer().
*
* Locking: tty_read_lock for read fields.
*/
static void reset_buffer_flags(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_head = tty->read_tail = tty->read_cnt = 0;
spin_unlock_irqrestore(&tty->read_lock, flags);
mutex_lock(&tty->echo_lock);
tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
mutex_unlock(&tty->echo_lock);
tty->canon_head = tty->canon_data = tty->erasing = 0;
memset(&tty->read_flags, 0, sizeof tty->read_flags);
n_tty_set_room(tty);
}
/**
* n_tty_flush_buffer - clean input queue
* @tty: terminal device
*
* Flush the input buffer. Called when the line discipline is
* being closed, when the tty layer wants the buffer flushed (eg
* at hangup) or when the N_TTY line discipline internally has to
* clean the pending queue (for example some signals).
*
* Locking: ctrl_lock, read_lock.
*/
static void n_tty_flush_buffer(struct tty_struct *tty)
{
unsigned long flags;
/* clear everything and unthrottle the driver */
reset_buffer_flags(tty);
if (!tty->link)
return;
spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->link->packet) {
tty->ctrl_status |= TIOCPKT_FLUSHREAD;
wake_up_interruptible(&tty->link->read_wait);
}
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
}
/**
* n_tty_chars_in_buffer - report available bytes
* @tty: tty device
*
* Report the number of characters buffered to be delivered to user
* at this instant in time.
*
* Locking: read_lock
*/
static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
{
unsigned long flags;
ssize_t n = 0;
spin_lock_irqsave(&tty->read_lock, flags);
if (!tty->icanon) {
n = tty->read_cnt;
} else if (tty->canon_data) {
n = (tty->canon_head > tty->read_tail) ?
tty->canon_head - tty->read_tail :
tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
}
spin_unlock_irqrestore(&tty->read_lock, flags);
return n;
}
/**
* is_utf8_continuation - utf8 multibyte check
* @c: byte to check
*
* Returns true if the utf8 character 'c' is a multibyte continuation
* character. We use this to correctly compute the on screen size
* of the character when printing
*/
static inline int is_utf8_continuation(unsigned char c)
{
return (c & 0xc0) == 0x80;
}
/**
* is_continuation - multibyte check
* @c: byte to check
*
* Returns true if the utf8 character 'c' is a multibyte continuation
* character and the terminal is in unicode mode.
*/
static inline int is_continuation(unsigned char c, struct tty_struct *tty)
{
return I_IUTF8(tty) && is_utf8_continuation(c);
}
/**
* do_output_char - output one character
* @c: character (or partial unicode symbol)
* @tty: terminal device
* @space: space available in tty driver write buffer
*
* This is a helper function that handles one output character
* (including special characters like TAB, CR, LF, etc.),
* doing OPOST processing and putting the results in the
* tty driver's write buffer.
*
* Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
* and NLDLY. They simply aren't relevant in the world today.
* If you ever need them, add them here.
*
* Returns the number of bytes of buffer space used or -1 if
* no space left.
*
* Locking: should be called under the output_lock to protect
* the column state and space left in the buffer
*/
static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
{
int spaces;
if (!space)
return -1;
switch (c) {
case '\n':
if (O_ONLRET(tty))
tty->column = 0;
if (O_ONLCR(tty)) {
if (space < 2)
return -1;
tty->canon_column = tty->column = 0;
tty->ops->write(tty, "\r\n", 2);
return 2;
}
tty->canon_column = tty->column;
break;
case '\r':
if (O_ONOCR(tty) && tty->column == 0)
return 0;
if (O_OCRNL(tty)) {
c = '\n';
if (O_ONLRET(tty))
tty->canon_column = tty->column = 0;
break;
}
tty->canon_column = tty->column = 0;
break;
case '\t':
spaces = 8 - (tty->column & 7);
if (O_TABDLY(tty) == XTABS) {
if (space < spaces)
return -1;
tty->column += spaces;
tty->ops->write(tty, " ", spaces);
return spaces;
}
tty->column += spaces;
break;
case '\b':
if (tty->column > 0)
tty->column--;
break;
default:
if (!iscntrl(c)) {
if (O_OLCUC(tty))
c = toupper(c);
if (!is_continuation(c, tty))
tty->column++;
}
break;
}
tty_put_char(tty, c);
return 1;
}
/**
* process_output - output post processor
* @c: character (or partial unicode symbol)
* @tty: terminal device
*
* Output one character with OPOST processing.
* Returns -1 when the output device is full and the character
* must be retried.
*
* Locking: output_lock to protect column state and space left
* (also, this is called from n_tty_write under the
* tty layer write lock)
*/
static int process_output(unsigned char c, struct tty_struct *tty)
{
int space, retval;
mutex_lock(&tty->output_lock);
space = tty_write_room(tty);
retval = do_output_char(c, tty, space);
mutex_unlock(&tty->output_lock);
if (retval < 0)
return -1;
else
return 0;
}
/**
* process_output_block - block post processor
* @tty: terminal device
* @buf: character buffer
* @nr: number of bytes to output
*
* Output a block of characters with OPOST processing.
* Returns the number of characters output.
*
* This path is used to speed up block console writes, among other
* things when processing blocks of output data. It handles only
* the simple cases normally found and helps to generate blocks of
* symbols for the console driver and thus improve performance.
*
* Locking: output_lock to protect column state and space left
* (also, this is called from n_tty_write under the
* tty layer write lock)
*/
static ssize_t process_output_block(struct tty_struct *tty,
const unsigned char *buf, unsigned int nr)
{
int space;
int i;
const unsigned char *cp;
mutex_lock(&tty->output_lock);
space = tty_write_room(tty);
if (!space) {
mutex_unlock(&tty->output_lock);
return 0;
}
if (nr > space)
nr = space;
for (i = 0, cp = buf; i < nr; i++, cp++) {
unsigned char c = *cp;
switch (c) {
case '\n':
if (O_ONLRET(tty))
tty->column = 0;
if (O_ONLCR(tty))
goto break_out;
tty->canon_column = tty->column;
break;
case '\r':
if (O_ONOCR(tty) && tty->column == 0)
goto break_out;
if (O_OCRNL(tty))
goto break_out;
tty->canon_column = tty->column = 0;
break;
case '\t':
goto break_out;
case '\b':
if (tty->column > 0)
tty->column--;
break;
default:
if (!iscntrl(c)) {
if (O_OLCUC(tty))
goto break_out;
if (!is_continuation(c, tty))
tty->column++;
}
break;
}
}
break_out:
i = tty->ops->write(tty, buf, i);
mutex_unlock(&tty->output_lock);
return i;
}
/**
* process_echoes - write pending echo characters
* @tty: terminal device
*
* Write previously buffered echo (and other ldisc-generated)
* characters to the tty.
*
* Characters generated by the ldisc (including echoes) need to
* be buffered because the driver's write buffer can fill during
* heavy program output. Echoing straight to the driver will
* often fail under these conditions, causing lost characters and
* resulting mismatches of ldisc state information.
*
* Since the ldisc state must represent the characters actually sent
* to the driver at the time of the write, operations like certain
* changes in column state are also saved in the buffer and executed
* here.
*
* A circular fifo buffer is used so that the most recent characters
* are prioritized. Also, when control characters are echoed with a
* prefixed "^", the pair is treated atomically and thus not separated.
*
* Locking: output_lock to protect column state and space left,
* echo_lock to protect the echo buffer
*/
static void process_echoes(struct tty_struct *tty)
{
int space, nr;
unsigned char c;
unsigned char *cp, *buf_end;
if (!tty->echo_cnt)
return;
mutex_lock(&tty->output_lock);
mutex_lock(&tty->echo_lock);
space = tty_write_room(tty);
buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
cp = tty->echo_buf + tty->echo_pos;
nr = tty->echo_cnt;
while (nr > 0) {
c = *cp;
if (c == ECHO_OP_START) {
unsigned char op;
unsigned char *opp;
int no_space_left = 0;
/*
* If the buffer byte is the start of a multi-byte
* operation, get the next byte, which is either the
* op code or a control character value.
*/
opp = cp + 1;
if (opp == buf_end)
opp -= N_TTY_BUF_SIZE;
op = *opp;
switch (op) {
unsigned int num_chars, num_bs;
case ECHO_OP_ERASE_TAB:
if (++opp == buf_end)
opp -= N_TTY_BUF_SIZE;
num_chars = *opp;
/*
* Determine how many columns to go back
* in order to erase the tab.
* This depends on the number of columns
* used by other characters within the tab
* area. If this (modulo 8) count is from
* the start of input rather than from a
* previous tab, we offset by canon column.
* Otherwise, tab spacing is normal.
*/
if (!(num_chars & 0x80))
num_chars += tty->canon_column;
num_bs = 8 - (num_chars & 7);
if (num_bs > space) {
no_space_left = 1;
break;
}
space -= num_bs;
while (num_bs--) {
tty_put_char(tty, '\b');
if (tty->column > 0)
tty->column--;
}
cp += 3;
nr -= 3;
break;
case ECHO_OP_SET_CANON_COL:
tty->canon_column = tty->column;
cp += 2;
nr -= 2;
break;
case ECHO_OP_MOVE_BACK_COL:
if (tty->column > 0)
tty->column--;
cp += 2;
nr -= 2;
break;
case ECHO_OP_START:
/* This is an escaped echo op start code */
if (!space) {
no_space_left = 1;
break;
}
tty_put_char(tty, ECHO_OP_START);
tty->column++;
space--;
cp += 2;
nr -= 2;
break;
default:
/*
* If the op is not a special byte code,
* it is a ctrl char tagged to be echoed
* as "^X" (where X is the letter
* representing the control char).
* Note that we must ensure there is
* enough space for the whole ctrl pair.
*
*/
if (space < 2) {
no_space_left = 1;
break;
}
tty_put_char(tty, '^');
tty_put_char(tty, op ^ 0100);
tty->column += 2;
space -= 2;
cp += 2;
nr -= 2;
}
if (no_space_left)
break;
} else {
if (O_OPOST(tty) &&
!(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
int retval = do_output_char(c, tty, space);
if (retval < 0)
break;
space -= retval;
} else {
if (!space)
break;
tty_put_char(tty, c);
space -= 1;
}
cp += 1;
nr -= 1;
}
/* When end of circular buffer reached, wrap around */
if (cp >= buf_end)
cp -= N_TTY_BUF_SIZE;
}
if (nr == 0) {
tty->echo_pos = 0;
tty->echo_cnt = 0;
tty->echo_overrun = 0;
} else {
int num_processed = tty->echo_cnt - nr;
tty->echo_pos += num_processed;
tty->echo_pos &= N_TTY_BUF_SIZE - 1;
tty->echo_cnt = nr;
if (num_processed > 0)
tty->echo_overrun = 0;
}
mutex_unlock(&tty->echo_lock);
mutex_unlock(&tty->output_lock);
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}
/**
* add_echo_byte - add a byte to the echo buffer
* @c: unicode byte to echo
* @tty: terminal device
*
* Add a character or operation byte to the echo buffer.
*
* Should be called under the echo lock to protect the echo buffer.
*/
static void add_echo_byte(unsigned char c, struct tty_struct *tty)
{
int new_byte_pos;
if (tty->echo_cnt == N_TTY_BUF_SIZE) {
/* Circular buffer is already at capacity */
new_byte_pos = tty->echo_pos;
/*
* Since the buffer start position needs to be advanced,
* be sure to step by a whole operation byte group.
*/
if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
if (tty->echo_buf[(tty->echo_pos + 1) &
(N_TTY_BUF_SIZE - 1)] ==
ECHO_OP_ERASE_TAB) {
tty->echo_pos += 3;
tty->echo_cnt -= 2;
} else {
tty->echo_pos += 2;
tty->echo_cnt -= 1;
}
} else {
tty->echo_pos++;
}
tty->echo_pos &= N_TTY_BUF_SIZE - 1;
tty->echo_overrun = 1;
} else {
new_byte_pos = tty->echo_pos + tty->echo_cnt;
new_byte_pos &= N_TTY_BUF_SIZE - 1;
tty->echo_cnt++;
}
tty->echo_buf[new_byte_pos] = c;
}
/**
* echo_move_back_col - add operation to move back a column
* @tty: terminal device
*
* Add an operation to the echo buffer to move back one column.
*
* Locking: echo_lock to protect the echo buffer
*/
static void echo_move_back_col(struct tty_struct *tty)
{
mutex_lock(&tty->echo_lock);
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
mutex_unlock(&tty->echo_lock);
}
/**
* echo_set_canon_col - add operation to set the canon column
* @tty: terminal device
*
* Add an operation to the echo buffer to set the canon column
* to the current column.
*
* Locking: echo_lock to protect the echo buffer
*/
static void echo_set_canon_col(struct tty_struct *tty)
{
mutex_lock(&tty->echo_lock);
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
mutex_unlock(&tty->echo_lock);
}
/**
* echo_erase_tab - add operation to erase a tab
* @num_chars: number of character columns already used
* @after_tab: true if num_chars starts after a previous tab
* @tty: terminal device
*
* Add an operation to the echo buffer to erase a tab.
*
* Called by the eraser function, which knows how many character
* columns have been used since either a previous tab or the start
* of input. This information will be used later, along with
* canon column (if applicable), to go back the correct number
* of columns.
*
* Locking: echo_lock to protect the echo buffer
*/
static void echo_erase_tab(unsigned int num_chars, int after_tab,
struct tty_struct *tty)
{
mutex_lock(&tty->echo_lock);
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(ECHO_OP_ERASE_TAB, tty);
/* We only need to know this modulo 8 (tab spacing) */
num_chars &= 7;
/* Set the high bit as a flag if num_chars is after a previous tab */
if (after_tab)
num_chars |= 0x80;
add_echo_byte(num_chars, tty);
mutex_unlock(&tty->echo_lock);
}
/**
* echo_char_raw - echo a character raw
* @c: unicode byte to echo
* @tty: terminal device
*
* Echo user input back onto the screen. This must be called only when
* L_ECHO(tty) is true. Called from the driver receive_buf path.
*
* This variant does not treat control characters specially.
*
* Locking: echo_lock to protect the echo buffer
*/
static void echo_char_raw(unsigned char c, struct tty_struct *tty)
{
mutex_lock(&tty->echo_lock);
if (c == ECHO_OP_START) {
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(ECHO_OP_START, tty);
} else {
add_echo_byte(c, tty);
}
mutex_unlock(&tty->echo_lock);
}
/**
* echo_char - echo a character
* @c: unicode byte to echo
* @tty: terminal device
*
* Echo user input back onto the screen. This must be called only when
* L_ECHO(tty) is true. Called from the driver receive_buf path.
*
* This variant tags control characters to be echoed as "^X"
* (where X is the letter representing the control char).
*
* Locking: echo_lock to protect the echo buffer
*/
static void echo_char(unsigned char c, struct tty_struct *tty)
{
mutex_lock(&tty->echo_lock);
if (c == ECHO_OP_START) {
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(ECHO_OP_START, tty);
} else {
if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
add_echo_byte(ECHO_OP_START, tty);
add_echo_byte(c, tty);
}
mutex_unlock(&tty->echo_lock);
}
/**
* finish_erasing - complete erase
* @tty: tty doing the erase
*/
static inline void finish_erasing(struct tty_struct *tty)
{
if (tty->erasing) {
echo_char_raw('/', tty);
tty->erasing = 0;
}
}
/**
* eraser - handle erase function
* @c: character input
* @tty: terminal device
*
* Perform erase and necessary output when an erase character is
* present in the stream from the driver layer. Handles the complexities
* of UTF-8 multibyte symbols.
*
* Locking: read_lock for tty buffers
*/
static void eraser(unsigned char c, struct tty_struct *tty)
{
enum { ERASE, WERASE, KILL } kill_type;
int head, seen_alnums, cnt;
unsigned long flags;
/* FIXME: locking needed ? */
if (tty->read_head == tty->canon_head) {
/* process_output('\a', tty); */ /* what do you think? */
return;
}
if (c == ERASE_CHAR(tty))
kill_type = ERASE;
else if (c == WERASE_CHAR(tty))
kill_type = WERASE;
else {
if (!L_ECHO(tty)) {
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_cnt -= ((tty->read_head - tty->canon_head) &
(N_TTY_BUF_SIZE - 1));
tty->read_head = tty->canon_head;
spin_unlock_irqrestore(&tty->read_lock, flags);
return;
}
if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_cnt -= ((tty->read_head - tty->canon_head) &
(N_TTY_BUF_SIZE - 1));
tty->read_head = tty->canon_head;
spin_unlock_irqrestore(&tty->read_lock, flags);
finish_erasing(tty);
echo_char(KILL_CHAR(tty), tty);
/* Add a newline if ECHOK is on and ECHOKE is off. */
if (L_ECHOK(tty))
echo_char_raw('\n', tty);
return;
}
kill_type = KILL;
}
seen_alnums = 0;
/* FIXME: Locking ?? */
while (tty->read_head != tty->canon_head) {
head = tty->read_head;
/* erase a single possibly multibyte character */
do {
head = (head - 1) & (N_TTY_BUF_SIZE-1);
c = tty->read_buf[head];
} while (is_continuation(c, tty) && head != tty->canon_head);
/* do not partially erase */
if (is_continuation(c, tty))
break;
if (kill_type == WERASE) {
/* Equivalent to BSD's ALTWERASE. */
if (isalnum(c) || c == '_')
seen_alnums++;
else if (seen_alnums)
break;
}
cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_head = head;
tty->read_cnt -= cnt;
spin_unlock_irqrestore(&tty->read_lock, flags);
if (L_ECHO(tty)) {
if (L_ECHOPRT(tty)) {
if (!tty->erasing) {
echo_char_raw('\\', tty);
tty->erasing = 1;
}
/* if cnt > 1, output a multi-byte character */
echo_char(c, tty);
while (--cnt > 0) {
head = (head+1) & (N_TTY_BUF_SIZE-1);
echo_char_raw(tty->read_buf[head], tty);
echo_move_back_col(tty);
}
} else if (kill_type == ERASE && !L_ECHOE(tty)) {
echo_char(ERASE_CHAR(tty), tty);
} else if (c == '\t') {
unsigned int num_chars = 0;
int after_tab = 0;
unsigned long tail = tty->read_head;
/*
* Count the columns used for characters
* since the start of input or after a
* previous tab.
* This info is used to go back the correct
* number of columns.
*/
while (tail != tty->canon_head) {
tail = (tail-1) & (N_TTY_BUF_SIZE-1);
c = tty->read_buf[tail];
if (c == '\t') {
after_tab = 1;
break;
} else if (iscntrl(c)) {
if (L_ECHOCTL(tty))
num_chars += 2;
} else if (!is_continuation(c, tty)) {
num_chars++;
}
}
echo_erase_tab(num_chars, after_tab, tty);
} else {
if (iscntrl(c) && L_ECHOCTL(tty)) {
echo_char_raw('\b', tty);
echo_char_raw(' ', tty);
echo_char_raw('\b', tty);
}
if (!iscntrl(c) || L_ECHOCTL(tty)) {
echo_char_raw('\b', tty);
echo_char_raw(' ', tty);
echo_char_raw('\b', tty);
}
}
}
if (kill_type == ERASE)
break;
}
if (tty->read_head == tty->canon_head && L_ECHO(tty))
finish_erasing(tty);
}
/**
* isig - handle the ISIG optio
* @sig: signal
* @tty: terminal
* @flush: force flush
*
* Called when a signal is being sent due to terminal input. This
* may caus terminal flushing to take place according to the termios
* settings and character used. Called from the driver receive_buf
* path so serialized.
*
* Locking: ctrl_lock, read_lock (both via flush buffer)
*/
static inline void isig(int sig, struct tty_struct *tty, int flush)
{
if (tty->pgrp)
kill_pgrp(tty->pgrp, sig, 1);
if (flush || !L_NOFLSH(tty)) {
n_tty_flush_buffer(tty);
tty_driver_flush_buffer(tty);
}
}
/**
* n_tty_receive_break - handle break
* @tty: terminal
*
* An RS232 break event has been hit in the incoming bitstream. This
* can cause a variety of events depending upon the termios settings.
*
* Called from the receive_buf path so single threaded.
*/
static inline void n_tty_receive_break(struct tty_struct *tty)
{
if (I_IGNBRK(tty))
return;
if (I_BRKINT(tty)) {
isig(SIGINT, tty, 1);
return;
}
if (I_PARMRK(tty)) {
put_tty_queue('\377', tty);
put_tty_queue('\0', tty);
}
put_tty_queue('\0', tty);
wake_up_interruptible(&tty->read_wait);
}
/**
* n_tty_receive_overrun - handle overrun reporting
* @tty: terminal
*
* Data arrived faster than we could process it. While the tty
* driver has flagged this the bits that were missed are gone
* forever.
*
* Called from the receive_buf path so single threaded. Does not
* need locking as num_overrun and overrun_time are function
* private.
*/
static inline void n_tty_receive_overrun(struct tty_struct *tty)
{
char buf[64];
tty->num_overrun++;
if (time_before(tty->overrun_time, jiffies - HZ) ||
time_after(tty->overrun_time, jiffies)) {
printk(KERN_WARNING "%s: %d input overrun(s)\n",
tty_name(tty, buf),
tty->num_overrun);
tty->overrun_time = jiffies;
tty->num_overrun = 0;
}
}
/**
* n_tty_receive_parity_error - error notifier
* @tty: terminal device
* @c: character
*
* Process a parity error and queue the right data to indicate
* the error case if necessary. Locking as per n_tty_receive_buf.
*/
static inline void n_tty_receive_parity_error(struct tty_struct *tty,
unsigned char c)
{
if (I_IGNPAR(tty))
return;
if (I_PARMRK(tty)) {
put_tty_queue('\377', tty);
put_tty_queue('\0', tty);
put_tty_queue(c, tty);
} else if (I_INPCK(tty))
put_tty_queue('\0', tty);
else
put_tty_queue(c, tty);
wake_up_interruptible(&tty->read_wait);
}
/**
* n_tty_receive_char - perform processing
* @tty: terminal device
* @c: character
*
* Process an individual character of input received from the driver.
* This is serialized with respect to itself by the rules for the
* driver above.
*/
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
{
unsigned long flags;
int parmrk;
if (tty->raw) {
put_tty_queue(c, tty);
return;
}
if (I_ISTRIP(tty))
c &= 0x7f;
if (I_IUCLC(tty) && L_IEXTEN(tty))
c = tolower(c);
if (L_EXTPROC(tty)) {
put_tty_queue(c, tty);
return;
}
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
start_tty(tty);
process_echoes(tty);
}
if (tty->closing) {
if (I_IXON(tty)) {
if (c == START_CHAR(tty)) {
start_tty(tty);
process_echoes(tty);
} else if (c == STOP_CHAR(tty))
stop_tty(tty);
}
return;
}
/*
* If the previous character was LNEXT, or we know that this
* character is not one of the characters that we'll have to
* handle specially, do shortcut processing to speed things
* up.
*/
if (!test_bit(c, tty->process_char_map) || tty->lnext) {
tty->lnext = 0;
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
/* beep if no space */
if (L_ECHO(tty))
process_output('\a', tty);
return;
}
if (L_ECHO(tty)) {
finish_erasing(tty);
/* Record the column of first canon char. */
if (tty->canon_head == tty->read_head)
echo_set_canon_col(tty);
echo_char(c, tty);
process_echoes(tty);
}
if (parmrk)
put_tty_queue(c, tty);
put_tty_queue(c, tty);
return;
}
if (I_IXON(tty)) {
if (c == START_CHAR(tty)) {
start_tty(tty);
process_echoes(tty);
return;
}
if (c == STOP_CHAR(tty)) {
stop_tty(tty);
return;
}
}
if (L_ISIG(tty)) {
int signal;
signal = SIGINT;
if (c == INTR_CHAR(tty))
goto send_signal;
signal = SIGQUIT;
if (c == QUIT_CHAR(tty))
goto send_signal;
signal = SIGTSTP;
if (c == SUSP_CHAR(tty)) {
send_signal:
/*
* Note that we do not use isig() here because we want
* the order to be:
* 1) flush, 2) echo, 3) signal
*/
if (!L_NOFLSH(tty)) {
n_tty_flush_buffer(tty);
tty_driver_flush_buffer(tty);
}
if (I_IXON(tty))
start_tty(tty);
if (L_ECHO(tty)) {
echo_char(c, tty);
process_echoes(tty);
}
if (tty->pgrp)
kill_pgrp(tty->pgrp, signal, 1);
return;
}
}
if (c == '\r') {
if (I_IGNCR(tty))
return;
if (I_ICRNL(tty))
c = '\n';
} else if (c == '\n' && I_INLCR(tty))
c = '\r';
if (tty->icanon) {
if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
(c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
eraser(c, tty);
process_echoes(tty);
return;
}
if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
tty->lnext = 1;
if (L_ECHO(tty)) {
finish_erasing(tty);
if (L_ECHOCTL(tty)) {
echo_char_raw('^', tty);
echo_char_raw('\b', tty);
process_echoes(tty);
}
}
return;
}
if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
L_IEXTEN(tty)) {
unsigned long tail = tty->canon_head;
finish_erasing(tty);
echo_char(c, tty);
echo_char_raw('\n', tty);
while (tail != tty->read_head) {
echo_char(tty->read_buf[tail], tty);
tail = (tail+1) & (N_TTY_BUF_SIZE-1);
}
process_echoes(tty);
return;
}
if (c == '\n') {
if (tty->read_cnt >= N_TTY_BUF_SIZE) {
if (L_ECHO(tty))
process_output('\a', tty);
return;
}
if (L_ECHO(tty) || L_ECHONL(tty)) {
echo_char_raw('\n', tty);
process_echoes(tty);
}
goto handle_newline;
}
if (c == EOF_CHAR(tty)) {
if (tty->read_cnt >= N_TTY_BUF_SIZE)
return;
if (tty->canon_head != tty->read_head)
set_bit(TTY_PUSH, &tty->flags);
c = __DISABLED_CHAR;
goto handle_newline;
}
if ((c == EOL_CHAR(tty)) ||
(c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
? 1 : 0;
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
if (L_ECHO(tty))
process_output('\a', tty);
return;
}
/*
* XXX are EOL_CHAR and EOL2_CHAR echoed?!?
*/
if (L_ECHO(tty)) {
/* Record the column of first canon char. */
if (tty->canon_head == tty->read_head)
echo_set_canon_col(tty);
echo_char(c, tty);
process_echoes(tty);
}
/*
* XXX does PARMRK doubling happen for
* EOL_CHAR and EOL2_CHAR?
*/
if (parmrk)
put_tty_queue(c, tty);
handle_newline:
spin_lock_irqsave(&tty->read_lock, flags);
set_bit(tty->read_head, tty->read_flags);
put_tty_queue_nolock(c, tty);
tty->canon_head = tty->read_head;
tty->canon_data++;
spin_unlock_irqrestore(&tty->read_lock, flags);
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
wake_up_interruptible(&tty->read_wait);
return;
}
}
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
/* beep if no space */
if (L_ECHO(tty))
process_output('\a', tty);
return;
}
if (L_ECHO(tty)) {
finish_erasing(tty);
if (c == '\n')
echo_char_raw('\n', tty);
else {
/* Record the column of first canon char. */
if (tty->canon_head == tty->read_head)
echo_set_canon_col(tty);
echo_char(c, tty);
}
process_echoes(tty);
}
if (parmrk)
put_tty_queue(c, tty);
put_tty_queue(c, tty);
}
/**
* n_tty_write_wakeup - asynchronous I/O notifier
* @tty: tty device
*
* Required for the ptys, serial driver etc. since processes
* that attach themselves to the master and rely on ASYNC
* IO must be woken up
*/
static void n_tty_write_wakeup(struct tty_struct *tty)
{
if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
}
/**
* n_tty_receive_buf - data receive
* @tty: terminal device
* @cp: buffer
* @fp: flag buffer
* @count: characters
*
* Called by the terminal driver when a block of characters has
* been received. This function must be called from soft contexts
* not from interrupt context. The driver is responsible for making
* calls one at a time and in order (or using flush_to_ldisc)
*/
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
const unsigned char *p;
char *f, flags = TTY_NORMAL;
int i;
char buf[64];
unsigned long cpuflags;
if (!tty->read_buf)
return;
if (tty->real_raw) {
spin_lock_irqsave(&tty->read_lock, cpuflags);
i = min(N_TTY_BUF_SIZE - tty->read_cnt,
N_TTY_BUF_SIZE - tty->read_head);
i = min(count, i);
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
cp += i;
count -= i;
i = min(N_TTY_BUF_SIZE - tty->read_cnt,
N_TTY_BUF_SIZE - tty->read_head);
i = min(count, i);
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
spin_unlock_irqrestore(&tty->read_lock, cpuflags);
} else {
for (i = count, p = cp, f = fp; i; i--, p++) {
if (f)
flags = *f++;
switch (flags) {
case TTY_NORMAL:
n_tty_receive_char(tty, *p);
break;
case TTY_BREAK:
n_tty_receive_break(tty);
break;
case TTY_PARITY:
case TTY_FRAME:
n_tty_receive_parity_error(tty, *p);
break;
case TTY_OVERRUN:
n_tty_receive_overrun(tty);
break;
default:
printk(KERN_ERR "%s: unknown flag %d\n",
tty_name(tty, buf), flags);
break;
}
}
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}
n_tty_set_room(tty);
if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
wake_up_interruptible(&tty->read_wait);
}
/*
* Check the remaining room for the input canonicalization
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
tty_throttle(tty);
}
int is_ignored(int sig)
{
return (sigismember(&current->blocked, sig) ||
current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
}
/**
* n_tty_set_termios - termios data changed
* @tty: terminal
* @old: previous data
*
* Called by the tty layer when the user changes termios flags so
* that the line discipline can plan ahead. This function cannot sleep
* and is protected from re-entry by the tty layer. The user is
* guaranteed that this function will not be re-entered or in progress
* when the ldisc is closed.
*
* Locking: Caller holds tty->termios_mutex
*/
static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
{
int canon_change = 1;
BUG_ON(!tty);
if (old)
canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
if (canon_change) {
memset(&tty->read_flags, 0, sizeof tty->read_flags);
tty->canon_head = tty->read_tail;
tty->canon_data = 0;
tty->erasing = 0;
}
if (canon_change && !L_ICANON(tty) && tty->read_cnt)
wake_up_interruptible(&tty->read_wait);
tty->icanon = (L_ICANON(tty) != 0);
if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
tty->raw = 1;
tty->real_raw = 1;
n_tty_set_room(tty);
return;
}
if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
I_PARMRK(tty)) {
memset(tty->process_char_map, 0, 256/8);
if (I_IGNCR(tty) || I_ICRNL(tty))
set_bit('\r', tty->process_char_map);
if (I_INLCR(tty))
set_bit('\n', tty->process_char_map);
if (L_ICANON(tty)) {
set_bit(ERASE_CHAR(tty), tty->process_char_map);
set_bit(KILL_CHAR(tty), tty->process_char_map);
set_bit(EOF_CHAR(tty), tty->process_char_map);
set_bit('\n', tty->process_char_map);
set_bit(EOL_CHAR(tty), tty->process_char_map);
if (L_IEXTEN(tty)) {
set_bit(WERASE_CHAR(tty),
tty->process_char_map);
set_bit(LNEXT_CHAR(tty),
tty->process_char_map);
set_bit(EOL2_CHAR(tty),
tty->process_char_map);
if (L_ECHO(tty))
set_bit(REPRINT_CHAR(tty),
tty->process_char_map);
}
}
if (I_IXON(tty)) {
set_bit(START_CHAR(tty), tty->process_char_map);
set_bit(STOP_CHAR(tty), tty->process_char_map);
}
if (L_ISIG(tty)) {
set_bit(INTR_CHAR(tty), tty->process_char_map);
set_bit(QUIT_CHAR(tty), tty->process_char_map);
set_bit(SUSP_CHAR(tty), tty->process_char_map);
}
clear_bit(__DISABLED_CHAR, tty->process_char_map);
tty->raw = 0;
tty->real_raw = 0;
} else {
tty->raw = 1;
if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
(I_IGNPAR(tty) || !I_INPCK(tty)) &&
(tty->driver->flags & TTY_DRIVER_REAL_RAW))
tty->real_raw = 1;
else
tty->real_raw = 0;
}
n_tty_set_room(tty);
/* The termios change make the tty ready for I/O */
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
}
/**
* n_tty_close - close the ldisc for this tty
* @tty: device
*
* Called from the terminal layer when this line discipline is
* being shut down, either because of a close or becsuse of a
* discipline change. The function will not be called while other
* ldisc methods are in progress.
*/
static void n_tty_close(struct tty_struct *tty)
{
n_tty_flush_buffer(tty);
if (tty->read_buf) {
kfree(tty->read_buf);
tty->read_buf = NULL;
}
if (tty->echo_buf) {
kfree(tty->echo_buf);
tty->echo_buf = NULL;
}
}
/**
* n_tty_open - open an ldisc
* @tty: terminal to open
*
* Called when this line discipline is being attached to the
* terminal device. Can sleep. Called serialized so that no
* other events will occur in parallel. No further open will occur
* until a close.
*/
static int n_tty_open(struct tty_struct *tty)
{
if (!tty)
return -EINVAL;
/* These are ugly. Currently a malloc failure here can panic */
if (!tty->read_buf) {
tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
if (!tty->read_buf)
return -ENOMEM;
}
if (!tty->echo_buf) {
tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
if (!tty->echo_buf)
return -ENOMEM;
}
reset_buffer_flags(tty);
tty_unthrottle(tty);
tty->column = 0;
n_tty_set_termios(tty, NULL);
tty->minimum_to_wake = 1;
tty->closing = 0;
return 0;
}
static inline int input_available_p(struct tty_struct *tty, int amt)
{
tty_flush_to_ldisc(tty);
if (tty->icanon && !L_EXTPROC(tty)) {
if (tty->canon_data)
return 1;
} else if (tty->read_cnt >= (amt ? amt : 1))
return 1;
return 0;
}
/**
* copy_from_read_buf - copy read data directly
* @tty: terminal device
* @b: user data
* @nr: size of data
*
* Helper function to speed up n_tty_read. It is only called when
* ICANON is off; it copies characters straight from the tty queue to
* user space directly. It can be profitably called twice; once to
* drain the space from the tail pointer to the (physical) end of the
* buffer, and once to drain the space from the (physical) beginning of
* the buffer to head pointer.
*
* Called under the tty->atomic_read_lock sem
*
*/
static int copy_from_read_buf(struct tty_struct *tty,
unsigned char __user **b,
size_t *nr)
{
int retval;
size_t n;
unsigned long flags;
retval = 0;
spin_lock_irqsave(&tty->read_lock, flags);
n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
n = min(*nr, n);
spin_unlock_irqrestore(&tty->read_lock, flags);
if (n) {
retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
n -= retval;
tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
tty->read_cnt -= n;
/* Turn single EOF into zero-length read */
if (L_EXTPROC(tty) && tty->icanon && n == 1) {
if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
n--;
}
spin_unlock_irqrestore(&tty->read_lock, flags);
*b += n;
*nr -= n;
}
return retval;
}
extern ssize_t redirected_tty_write(struct file *, const char __user *,
size_t, loff_t *);
/**
* job_control - check job control
* @tty: tty
* @file: file handle
*
* Perform job control management checks on this file/tty descriptor
* and if appropriate send any needed signals and return a negative
* error code if action should be taken.
*
* FIXME:
* Locking: None - redirected write test is safe, testing
* current->signal should possibly lock current->sighand
* pgrp locking ?
*/
static int job_control(struct tty_struct *tty, struct file *file)
{
/* Job control check -- must be done at start and after
every sleep (POSIX.1 7.1.1.4). */
/* NOTE: not yet done after every sleep pending a thorough
check of the logic of this change. -- jlc */
/* don't stop on /dev/console */
if (file->f_op->write != redirected_tty_write &&
current->signal->tty == tty) {
if (!tty->pgrp)
printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
else if (task_pgrp(current) != tty->pgrp) {
if (is_ignored(SIGTTIN) ||
is_current_pgrp_orphaned())
return -EIO;
kill_pgrp(task_pgrp(current), SIGTTIN, 1);
set_thread_flag(TIF_SIGPENDING);
return -ERESTARTSYS;
}
}
return 0;
}
/**
* n_tty_read - read function for tty
* @tty: tty device
* @file: file object
* @buf: userspace buffer pointer
* @nr: size of I/O
*
* Perform reads for the line discipline. We are guaranteed that the
* line discipline will not be closed under us but we may get multiple
* parallel readers and must handle this ourselves. We may also get
* a hangup. Always called in user context, may sleep.
*
* This code must be sure never to sleep through a hangup.
*/
static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
unsigned char __user *buf, size_t nr)
{
unsigned char __user *b = buf;
DECLARE_WAITQUEUE(wait, current);
int c;
int minimum, time;
ssize_t retval = 0;
ssize_t size;
long timeout;
unsigned long flags;
int packet;
do_it_again:
BUG_ON(!tty->read_buf);
c = job_control(tty, file);
if (c < 0)
return c;
minimum = time = 0;
timeout = MAX_SCHEDULE_TIMEOUT;
if (!tty->icanon) {
time = (HZ / 10) * TIME_CHAR(tty);
minimum = MIN_CHAR(tty);
if (minimum) {
if (time)
tty->minimum_to_wake = 1;
else if (!waitqueue_active(&tty->read_wait) ||
(tty->minimum_to_wake > minimum))
tty->minimum_to_wake = minimum;
} else {
timeout = 0;
if (time) {
timeout = time;
time = 0;
}
tty->minimum_to_wake = minimum = 1;
}
}
/*
* Internal serialization of reads.
*/
if (file->f_flags & O_NONBLOCK) {
if (!mutex_trylock(&tty->atomic_read_lock))
return -EAGAIN;
} else {
if (mutex_lock_interruptible(&tty->atomic_read_lock))
return -ERESTARTSYS;
}
packet = tty->packet;
add_wait_queue(&tty->read_wait, &wait);
while (nr) {
/* First test for status change. */
if (packet && tty->link->ctrl_status) {
unsigned char cs;
if (b != buf)
break;
spin_lock_irqsave(&tty->link->ctrl_lock, flags);
cs = tty->link->ctrl_status;
tty->link->ctrl_status = 0;
spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
if (tty_put_user(tty, cs, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
break;
}
/* This statement must be first before checking for input
so that any interrupt will set the state back to
TASK_RUNNING. */
set_current_state(TASK_INTERRUPTIBLE);
if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
((minimum - (b - buf)) >= 1))
tty->minimum_to_wake = (minimum - (b - buf));
if (!input_available_p(tty, 0)) {
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
retval = -EIO;
break;
}
if (tty_hung_up_p(file))
break;
if (!timeout)
break;
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
/* FIXME: does n_tty_set_room need locking ? */
n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
BUG_ON(!tty->read_buf);
continue;
}
__set_current_state(TASK_RUNNING);
/* Deal with packet mode. */
if (packet && b == buf) {
if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (tty->icanon && !L_EXTPROC(tty)) {
/* N.B. avoid overrun if nr == 0 */
while (nr && tty->read_cnt) {
int eol;
eol = test_and_clear_bit(tty->read_tail,
tty->read_flags);
c = tty->read_buf[tty->read_tail];
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = ((tty->read_tail+1) &
(N_TTY_BUF_SIZE-1));
tty->read_cnt--;
if (eol) {
/* this test should be redundant:
* we shouldn't be reading data if
* canon_data is 0
*/
if (--tty->canon_data < 0)
tty->canon_data = 0;
}
spin_unlock_irqrestore(&tty->read_lock, flags);
if (!eol || (c != __DISABLED_CHAR)) {
if (tty_put_user(tty, c, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (eol) {
tty_audit_push(tty);
break;
}
}
if (retval)
break;
} else {
int uncopied;
/* The copy function takes the read lock and handles
locking internally for this case */
uncopied = copy_from_read_buf(tty, &b, &nr);
uncopied += copy_from_read_buf(tty, &b, &nr);
if (uncopied) {
retval = -EFAULT;
break;
}
}
/* If there is enough space in the read buffer now, let the
* low-level driver know. We use n_tty_chars_in_buffer() to
* check the buffer, as it now knows about canonical mode.
* Otherwise, if the driver is throttled and the line is
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
* we won't get any more characters.
*/
if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
n_tty_set_room(tty);
check_unthrottle(tty);
}
if (b - buf >= minimum)
break;
if (time)
timeout = time;
}
mutex_unlock(&tty->atomic_read_lock);
remove_wait_queue(&tty->read_wait, &wait);
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = minimum;
__set_current_state(TASK_RUNNING);
size = b - buf;
if (size) {
retval = size;
if (nr)
clear_bit(TTY_PUSH, &tty->flags);
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
goto do_it_again;
n_tty_set_room(tty);
return retval;
}
/**
* n_tty_write - write function for tty
* @tty: tty device
* @file: file object
* @buf: userspace buffer pointer
* @nr: size of I/O
*
* Write function of the terminal device. This is serialized with
* respect to other write callers but not to termios changes, reads
* and other such events. Since the receive code will echo characters,
* thus calling driver write methods, the output_lock is used in
* the output processing functions called here as well as in the
* echo processing function to protect the column state and space
* left in the buffer.
*
* This code must be sure never to sleep through a hangup.
*
* Locking: output_lock to protect column state and space left
* (note that the process_output*() functions take this
* lock themselves)
*/
static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
const unsigned char *buf, size_t nr)
{
const unsigned char *b = buf;
DECLARE_WAITQUEUE(wait, current);
int c;
ssize_t retval = 0;
/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
retval = tty_check_change(tty);
if (retval)
return retval;
}
/* Write out any echoed characters that are still pending */
process_echoes(tty);
add_wait_queue(&tty->write_wait, &wait);
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
retval = -EIO;
break;
}
if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
while (nr > 0) {
ssize_t num = process_output_block(tty, b, nr);
if (num < 0) {
if (num == -EAGAIN)
break;
retval = num;
goto break_out;
}
b += num;
nr -= num;
if (nr == 0)
break;
c = *b;
if (process_output(c, tty) < 0)
break;
b++; nr--;
}
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
} else {
while (nr > 0) {
c = tty->ops->write(tty, b, nr);
if (c < 0) {
retval = c;
goto break_out;
}
if (!c)
break;
b += c;
nr -= c;
}
}
if (!nr)
break;
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
schedule();
}
break_out:
__set_current_state(TASK_RUNNING);
remove_wait_queue(&tty->write_wait, &wait);
if (b - buf != nr && tty->fasync)
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
return (b - buf) ? b - buf : retval;
}
/**
* n_tty_poll - poll method for N_TTY
* @tty: terminal device
* @file: file accessing it
* @wait: poll table
*
* Called when the line discipline is asked to poll() for data or
* for special events. This code is not serialized with respect to
* other events save open/close.
*
* This code must be sure never to sleep through a hangup.
* Called without the kernel lock held - fine
*/
static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
poll_table *wait)
{
unsigned int mask = 0;
poll_wait(file, &tty->read_wait, wait);
poll_wait(file, &tty->write_wait, wait);
if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
mask |= POLLIN | POLLRDNORM;
if (tty->packet && tty->link->ctrl_status)
mask |= POLLPRI | POLLIN | POLLRDNORM;
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
mask |= POLLHUP;
if (tty_hung_up_p(file))
mask |= POLLHUP;
if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
if (MIN_CHAR(tty) && !TIME_CHAR(tty))
tty->minimum_to_wake = MIN_CHAR(tty);
else
tty->minimum_to_wake = 1;
}
if (tty->ops->write && !tty_is_writelocked(tty) &&
tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
tty_write_room(tty) > 0)
mask |= POLLOUT | POLLWRNORM;
return mask;
}
static unsigned long inq_canon(struct tty_struct *tty)
{
int nr, head, tail;
if (!tty->canon_data)
return 0;
head = tty->canon_head;
tail = tty->read_tail;
nr = (head - tail) & (N_TTY_BUF_SIZE-1);
/* Skip EOF-chars.. */
while (head != tail) {
if (test_bit(tail, tty->read_flags) &&
tty->read_buf[tail] == __DISABLED_CHAR)
nr--;
tail = (tail+1) & (N_TTY_BUF_SIZE-1);
}
return nr;
}
static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
int retval;
switch (cmd) {
case TIOCOUTQ:
return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
case TIOCINQ:
/* FIXME: Locking */
retval = tty->read_cnt;
if (L_ICANON(tty))
retval = inq_canon(tty);
return put_user(retval, (unsigned int __user *) arg);
default:
return n_tty_ioctl_helper(tty, file, cmd, arg);
}
}
struct tty_ldisc_ops tty_ldisc_N_TTY = {
.magic = TTY_LDISC_MAGIC,
.name = "n_tty",
.open = n_tty_open,
.close = n_tty_close,
.flush_buffer = n_tty_flush_buffer,
.chars_in_buffer = n_tty_chars_in_buffer,
.read = n_tty_read,
.write = n_tty_write,
.ioctl = n_tty_ioctl,
.set_termios = n_tty_set_termios,
.poll = n_tty_poll,
.receive_buf = n_tty_receive_buf,
.write_wakeup = n_tty_write_wakeup
};
/**
* n_tty_inherit_ops - inherit N_TTY methods
* @ops: struct tty_ldisc_ops where to save N_TTY methods
*
* Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
* methods.
*/
void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
{
*ops = tty_ldisc_N_TTY;
ops->owner = NULL;
ops->refcount = ops->flags = 0;
}
EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
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