diff options
Diffstat (limited to 'drivers/tty/n_tty.c')
| -rw-r--r-- | drivers/tty/n_tty.c | 2121 |
1 files changed, 2121 insertions, 0 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c new file mode 100644 index 0000000..428f4fe --- /dev/null +++ b/drivers/tty/n_tty.c @@ -0,0 +1,2121 @@ +/* + * 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> + +#include <asm/system.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; + + /* + * 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; + tty->receive_room = left; +} + +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); + check_unthrottle(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(¤t->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->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); + 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); |
