diff options
Diffstat (limited to 'drivers/char/n_tty.c')
| -rw-r--r-- | drivers/char/n_tty.c | 2121 |
1 files changed, 0 insertions, 2121 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c deleted file mode 100644 index 428f4fe..0000000 --- a/drivers/char/n_tty.c +++ /dev/null @@ -1,2121 +0,0 @@ -/* - * 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); |
