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line.c

/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include "linux/irqreturn.h"
#include "linux/kd.h"
#include "chan_kern.h"
#include "irq_kern.h"
#include "irq_user.h"
#include "kern_util.h"
#include "os.h"

#define LINE_BUFSIZE 4096

static irqreturn_t line_interrupt(int irq, void *data)
{
      struct chan *chan = data;
      struct line *line = chan->line;
      struct tty_struct *tty = line->tty;

      if (line)
            chan_interrupt(&line->chan_list, &line->task, tty, irq);
      return IRQ_HANDLED;
}

static void line_timer_cb(struct work_struct *work)
{
      struct line *line = container_of(work, struct line, task.work);

      if (!line->throttled)
            chan_interrupt(&line->chan_list, &line->task, line->tty,
                         line->driver->read_irq);
}

/*
 * Returns the free space inside the ring buffer of this line.
 *
 * Should be called while holding line->lock (this does not modify data).
 */
static int write_room(struct line *line)
{
      int n;

      if (line->buffer == NULL)
            return LINE_BUFSIZE - 1;

      /* This is for the case where the buffer is wrapped! */
      n = line->head - line->tail;

      if (n <= 0)
            n += LINE_BUFSIZE; /* The other case */
      return n - 1;
}

int line_write_room(struct tty_struct *tty)
{
      struct line *line = tty->driver_data;
      unsigned long flags;
      int room;

      spin_lock_irqsave(&line->lock, flags);
      room = write_room(line);
      spin_unlock_irqrestore(&line->lock, flags);

      return room;
}

int line_chars_in_buffer(struct tty_struct *tty)
{
      struct line *line = tty->driver_data;
      unsigned long flags;
      int ret;

      spin_lock_irqsave(&line->lock, flags);
      /* write_room subtracts 1 for the needed NULL, so we readd it.*/
      ret = LINE_BUFSIZE - (write_room(line) + 1);
      spin_unlock_irqrestore(&line->lock, flags);

      return ret;
}

/*
 * This copies the content of buf into the circular buffer associated with
 * this line.
 * The return value is the number of characters actually copied, i.e. the ones
 * for which there was space: this function is not supposed to ever flush out
 * the circular buffer.
 *
 * Must be called while holding line->lock!
 */
static int buffer_data(struct line *line, const char *buf, int len)
{
      int end, room;

      if (line->buffer == NULL) {
            line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
            if (line->buffer == NULL) {
                  printk(KERN_ERR "buffer_data - atomic allocation "
                         "failed\n");
                  return 0;
            }
            line->head = line->buffer;
            line->tail = line->buffer;
      }

      room = write_room(line);
      len = (len > room) ? room : len;

      end = line->buffer + LINE_BUFSIZE - line->tail;

      if (len < end) {
            memcpy(line->tail, buf, len);
            line->tail += len;
      }
      else {
            /* The circular buffer is wrapping */
            memcpy(line->tail, buf, end);
            buf += end;
            memcpy(line->buffer, buf, len - end);
            line->tail = line->buffer + len - end;
      }

      return len;
}

/*
 * Flushes the ring buffer to the output channels. That is, write_chan is
 * called, passing it line->head as buffer, and an appropriate count.
 *
 * On exit, returns 1 when the buffer is empty,
 * 0 when the buffer is not empty on exit,
 * and -errno when an error occurred.
 *
 * Must be called while holding line->lock!*/
static int flush_buffer(struct line *line)
{
      int n, count;

      if ((line->buffer == NULL) || (line->head == line->tail))
            return 1;

      if (line->tail < line->head) {
            /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
            count = line->buffer + LINE_BUFSIZE - line->head;

            n = write_chan(&line->chan_list, line->head, count,
                         line->driver->write_irq);
            if (n < 0)
                  return n;
            if (n == count) {
                  /*
                   * We have flushed from ->head to buffer end, now we
                   * must flush only from the beginning to ->tail.
                   */
                  line->head = line->buffer;
            } else {
                  line->head += n;
                  return 0;
            }
      }

      count = line->tail - line->head;
      n = write_chan(&line->chan_list, line->head, count,
                   line->driver->write_irq);

      if (n < 0)
            return n;

      line->head += n;
      return line->head == line->tail;
}

void line_flush_buffer(struct tty_struct *tty)
{
      struct line *line = tty->driver_data;
      unsigned long flags;
      int err;

      spin_lock_irqsave(&line->lock, flags);
      err = flush_buffer(line);
      spin_unlock_irqrestore(&line->lock, flags);
}

/*
 * We map both ->flush_chars and ->put_char (which go in pair) onto
 * ->flush_buffer and ->write. Hope it's not that bad.
 */
void line_flush_chars(struct tty_struct *tty)
{
      line_flush_buffer(tty);
}

int line_put_char(struct tty_struct *tty, unsigned char ch)
{
      return line_write(tty, &ch, sizeof(ch));
}

int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
{
      struct line *line = tty->driver_data;
      unsigned long flags;
      int n, ret = 0;

      spin_lock_irqsave(&line->lock, flags);
      if (line->head != line->tail)
            ret = buffer_data(line, buf, len);
      else {
            n = write_chan(&line->chan_list, buf, len,
                         line->driver->write_irq);
            if (n < 0) {
                  ret = n;
                  goto out_up;
            }

            len -= n;
            ret += n;
            if (len > 0)
                  ret += buffer_data(line, buf + n, len);
      }
out_up:
      spin_unlock_irqrestore(&line->lock, flags);
      return ret;
}

void line_set_termios(struct tty_struct *tty, struct ktermios * old)
{
      /* nothing */
}

static const struct {
      int  cmd;
      char *level;
      char *name;
} tty_ioctls[] = {
      /* don't print these, they flood the log ... */
      { TCGETS,      NULL,       "TCGETS"      },
      { TCSETS,      NULL,       "TCSETS"      },
      { TCSETSW,     NULL,       "TCSETSW"     },
      { TCFLSH,      NULL,       "TCFLSH"      },
      { TCSBRK,      NULL,       "TCSBRK"      },

      /* general tty stuff */
      { TCSETSF,     KERN_DEBUG, "TCSETSF"     },
      { TCGETA,      KERN_DEBUG, "TCGETA"      },
      { TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
      { TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
      { TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },

      /* linux-specific ones */
      { TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
      { KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
      { KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
      { KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
};

int line_ioctl(struct tty_struct *tty, struct file * file,
             unsigned int cmd, unsigned long arg)
{
      int ret;
      int i;

      ret = 0;
      switch(cmd) {
#ifdef TIOCGETP
      case TIOCGETP:
      case TIOCSETP:
      case TIOCSETN:
#endif
#ifdef TIOCGETC
      case TIOCGETC:
      case TIOCSETC:
#endif
#ifdef TIOCGLTC
      case TIOCGLTC:
      case TIOCSLTC:
#endif
      case TCGETS:
      case TCSETSF:
      case TCSETSW:
      case TCSETS:
      case TCGETA:
      case TCSETAF:
      case TCSETAW:
      case TCSETA:
      case TCXONC:
      case TCFLSH:
      case TIOCOUTQ:
      case TIOCINQ:
      case TIOCGLCKTRMIOS:
      case TIOCSLCKTRMIOS:
      case TIOCPKT:
      case TIOCGSOFTCAR:
      case TIOCSSOFTCAR:
            return -ENOIOCTLCMD;
#if 0
      case TCwhatever:
            /* do something */
            break;
#endif
      default:
            for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
                  if (cmd == tty_ioctls[i].cmd)
                        break;
            if (i == ARRAY_SIZE(tty_ioctls)) {
                  printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
                         __func__, tty->name, cmd);
            }
            ret = -ENOIOCTLCMD;
            break;
      }
      return ret;
}

void line_throttle(struct tty_struct *tty)
{
      struct line *line = tty->driver_data;

      deactivate_chan(&line->chan_list, line->driver->read_irq);
      line->throttled = 1;
}

void line_unthrottle(struct tty_struct *tty)
{
      struct line *line = tty->driver_data;

      line->throttled = 0;
      chan_interrupt(&line->chan_list, &line->task, tty,
                   line->driver->read_irq);

      /*
       * Maybe there is enough stuff pending that calling the interrupt
       * throttles us again.  In this case, line->throttled will be 1
       * again and we shouldn't turn the interrupt back on.
       */
      if (!line->throttled)
            reactivate_chan(&line->chan_list, line->driver->read_irq);
}

static irqreturn_t line_write_interrupt(int irq, void *data)
{
      struct chan *chan = data;
      struct line *line = chan->line;
      struct tty_struct *tty = line->tty;
      int err;

      /*
       * Interrupts are disabled here because we registered the interrupt with
       * IRQF_DISABLED (see line_setup_irq).
       */

      spin_lock(&line->lock);
      err = flush_buffer(line);
      if (err == 0) {
            return IRQ_NONE;
      } else if (err < 0) {
            line->head = line->buffer;
            line->tail = line->buffer;
      }
      spin_unlock(&line->lock);

      if (tty == NULL)
            return IRQ_NONE;

      tty_wakeup(tty);
      return IRQ_HANDLED;
}

int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
{
      const struct line_driver *driver = line->driver;
      int err = 0, flags = IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM;

      if (input)
            err = um_request_irq(driver->read_irq, fd, IRQ_READ,
                               line_interrupt, flags,
                               driver->read_irq_name, data);
      if (err)
            return err;
      if (output)
            err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
                              line_write_interrupt, flags,
                              driver->write_irq_name, data);
      line->have_irq = 1;
      return err;
}

/*
 * Normally, a driver like this can rely mostly on the tty layer
 * locking, particularly when it comes to the driver structure.
 * However, in this case, mconsole requests can come in "from the
 * side", and race with opens and closes.
 *
 * mconsole config requests will want to be sure the device isn't in
 * use, and get_config, open, and close will want a stable
 * configuration.  The checking and modification of the configuration
 * is done under a spinlock.  Checking whether the device is in use is
 * line->tty->count > 1, also under the spinlock.
 *
 * tty->count serves to decide whether the device should be enabled or
 * disabled on the host.  If it's equal to 1, then we are doing the
 * first open or last close.  Otherwise, open and close just return.
 */

int line_open(struct line *lines, struct tty_struct *tty)
{
      struct line *line = &lines[tty->index];
      int err = -ENODEV;

      spin_lock(&line->count_lock);
      if (!line->valid)
            goto out_unlock;

      err = 0;
      if (tty->count > 1)
            goto out_unlock;

      spin_unlock(&line->count_lock);

      tty->driver_data = line;
      line->tty = tty;

      err = enable_chan(line);
      if (err)
            return err;

      INIT_DELAYED_WORK(&line->task, line_timer_cb);

      if (!line->sigio) {
            chan_enable_winch(&line->chan_list, tty);
            line->sigio = 1;
      }

      chan_window_size(&line->chan_list, &tty->winsize.ws_row,
                   &tty->winsize.ws_col);

      return err;

out_unlock:
      spin_unlock(&line->count_lock);
      return err;
}

static void unregister_winch(struct tty_struct *tty);

void line_close(struct tty_struct *tty, struct file * filp)
{
      struct line *line = tty->driver_data;

      /*
       * If line_open fails (and tty->driver_data is never set),
       * tty_open will call line_close.  So just return in this case.
       */
      if (line == NULL)
            return;

      /* We ignore the error anyway! */
      flush_buffer(line);

      spin_lock(&line->count_lock);
      if (!line->valid)
            goto out_unlock;

      if (tty->count > 1)
            goto out_unlock;

      spin_unlock(&line->count_lock);

      line->tty = NULL;
      tty->driver_data = NULL;

      if (line->sigio) {
            unregister_winch(tty);
            line->sigio = 0;
      }

      return;

out_unlock:
      spin_unlock(&line->count_lock);
}

void close_lines(struct line *lines, int nlines)
{
      int i;

      for(i = 0; i < nlines; i++)
            close_chan(&lines[i].chan_list, 0);
}

static int setup_one_line(struct line *lines, int n, char *init, int init_prio,
                    char **error_out)
{
      struct line *line = &lines[n];
      int err = -EINVAL;

      spin_lock(&line->count_lock);

      if (line->tty != NULL) {
            *error_out = "Device is already open";
            goto out;
      }

      if (line->init_pri <= init_prio) {
            line->init_pri = init_prio;
            if (!strcmp(init, "none"))
                  line->valid = 0;
            else {
                  line->init_str = init;
                  line->valid = 1;
            }
      }
      err = 0;
out:
      spin_unlock(&line->count_lock);
      return err;
}

/*
 * Common setup code for both startup command line and mconsole initialization.
 * @lines contains the array (of size @num) to modify;
 * @init is the setup string;
 * @error_out is an error string in the case of failure;
 */

int line_setup(struct line *lines, unsigned int num, char *init,
             char **error_out)
{
      int i, n, err;
      char *end;

      if (*init == '=') {
            /*
             * We said con=/ssl= instead of con#=, so we are configuring all
             * consoles at once.
             */
            n = -1;
      }
      else {
            n = simple_strtoul(init, &end, 0);
            if (*end != '=') {
                  *error_out = "Couldn't parse device number";
                  return -EINVAL;
            }
            init = end;
      }
      init++;

      if (n >= (signed int) num) {
            *error_out = "Device number out of range";
            return -EINVAL;
      }
      else if (n >= 0) {
            err = setup_one_line(lines, n, init, INIT_ONE, error_out);
            if (err)
                  return err;
      }
      else {
            for(i = 0; i < num; i++) {
                  err = setup_one_line(lines, i, init, INIT_ALL,
                                   error_out);
                  if (err)
                        return err;
            }
      }
      return n == -1 ? num : n;
}

int line_config(struct line *lines, unsigned int num, char *str,
            const struct chan_opts *opts, char **error_out)
{
      struct line *line;
      char *new;
      int n;

      if (*str == '=') {
            *error_out = "Can't configure all devices from mconsole";
            return -EINVAL;
      }

      new = kstrdup(str, GFP_KERNEL);
      if (new == NULL) {
            *error_out = "Failed to allocate memory";
            return -ENOMEM;
      }
      n = line_setup(lines, num, new, error_out);
      if (n < 0)
            return n;

      line = &lines[n];
      return parse_chan_pair(line->init_str, line, n, opts, error_out);
}

int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
                int size, char **error_out)
{
      struct line *line;
      char *end;
      int dev, n = 0;

      dev = simple_strtoul(name, &end, 0);
      if ((*end != '\0') || (end == name)) {
            *error_out = "line_get_config failed to parse device number";
            return 0;
      }

      if ((dev < 0) || (dev >= num)) {
            *error_out = "device number out of range";
            return 0;
      }

      line = &lines[dev];

      spin_lock(&line->count_lock);
      if (!line->valid)
            CONFIG_CHUNK(str, size, n, "none", 1);
      else if (line->tty == NULL)
            CONFIG_CHUNK(str, size, n, line->init_str, 1);
      else n = chan_config_string(&line->chan_list, str, size, error_out);
      spin_unlock(&line->count_lock);

      return n;
}

int line_id(char **str, int *start_out, int *end_out)
{
      char *end;
      int n;

      n = simple_strtoul(*str, &end, 0);
      if ((*end != '\0') || (end == *str))
            return -1;

      *str = end;
      *start_out = n;
      *end_out = n;
      return n;
}

int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
{
      int err;
      char config[sizeof("conxxxx=none\0")];

      sprintf(config, "%d=none", n);
      err = line_setup(lines, num, config, error_out);
      if (err >= 0)
            err = 0;
      return err;
}

struct tty_driver *register_lines(struct line_driver *line_driver,
                          const struct tty_operations *ops,
                          struct line *lines, int nlines)
{
      int i;
      struct tty_driver *driver = alloc_tty_driver(nlines);

      if (!driver)
            return NULL;

      driver->driver_name = line_driver->name;
      driver->name = line_driver->device_name;
      driver->major = line_driver->major;
      driver->minor_start = line_driver->minor_start;
      driver->type = line_driver->type;
      driver->subtype = line_driver->subtype;
      driver->flags = TTY_DRIVER_REAL_RAW;
      driver->init_termios = tty_std_termios;
      tty_set_operations(driver, ops);

      if (tty_register_driver(driver)) {
            printk(KERN_ERR "register_lines : can't register %s driver\n",
                   line_driver->name);
            put_tty_driver(driver);
            return NULL;
      }

      for(i = 0; i < nlines; i++) {
            if (!lines[i].valid)
                  tty_unregister_device(driver, i);
      }

      mconsole_register_dev(&line_driver->mc);
      return driver;
}

static DEFINE_SPINLOCK(winch_handler_lock);
static LIST_HEAD(winch_handlers);

void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
{
      struct line *line;
      char *error;
      int i;

      for(i = 0; i < nlines; i++) {
            line = &lines[i];
            INIT_LIST_HEAD(&line->chan_list);

            if (line->init_str == NULL)
                  continue;

            line->init_str = kstrdup(line->init_str, GFP_KERNEL);
            if (line->init_str == NULL)
                  printk(KERN_ERR "lines_init - kstrdup returned NULL\n");

            if (parse_chan_pair(line->init_str, line, i, opts, &error)) {
                  printk(KERN_ERR "parse_chan_pair failed for "
                         "device %d : %s\n", i, error);
                  line->valid = 0;
            }
      }
}

struct winch {
      struct list_head list;
      int fd;
      int tty_fd;
      int pid;
      struct tty_struct *tty;
      unsigned long stack;
};

static void free_winch(struct winch *winch, int free_irq_ok)
{
      list_del(&winch->list);

      if (winch->pid != -1)
            os_kill_process(winch->pid, 1);
      if (winch->fd != -1)
            os_close_file(winch->fd);
      if (winch->stack != 0)
            free_stack(winch->stack, 0);
      if (free_irq_ok)
            free_irq(WINCH_IRQ, winch);
      kfree(winch);
}

static irqreturn_t winch_interrupt(int irq, void *data)
{
      struct winch *winch = data;
      struct tty_struct *tty;
      struct line *line;
      int err;
      char c;

      if (winch->fd != -1) {
            err = generic_read(winch->fd, &c, NULL);
            if (err < 0) {
                  if (err != -EAGAIN) {
                        printk(KERN_ERR "winch_interrupt : "
                               "read failed, errno = %d\n", -err);
                        printk(KERN_ERR "fd %d is losing SIGWINCH "
                               "support\n", winch->tty_fd);
                        free_winch(winch, 0);
                        return IRQ_HANDLED;
                  }
                  goto out;
            }
      }
      tty = winch->tty;
      if (tty != NULL) {
            line = tty->driver_data;
            if (line != NULL) {
                  chan_window_size(&line->chan_list, &tty->winsize.ws_row,
                               &tty->winsize.ws_col);
                  kill_pgrp(tty->pgrp, SIGWINCH, 1);
            }
      }
 out:
      if (winch->fd != -1)
            reactivate_fd(winch->fd, WINCH_IRQ);
      return IRQ_HANDLED;
}

void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
                  unsigned long stack)
{
      struct winch *winch;

      winch = kmalloc(sizeof(*winch), GFP_KERNEL);
      if (winch == NULL) {
            printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
            goto cleanup;
      }

      *winch = ((struct winch) { .list    = LIST_HEAD_INIT(winch->list),
                           .fd      = fd,
                           .tty_fd  = tty_fd,
                           .pid     = pid,
                           .tty     = tty,
                           .stack   = stack });

      if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
                     IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
                     "winch", winch) < 0) {
            printk(KERN_ERR "register_winch_irq - failed to register "
                   "IRQ\n");
            goto out_free;
      }

      spin_lock(&winch_handler_lock);
      list_add(&winch->list, &winch_handlers);
      spin_unlock(&winch_handler_lock);

      return;

 out_free:
      kfree(winch);
 cleanup:
      os_kill_process(pid, 1);
      os_close_file(fd);
      if (stack != 0)
            free_stack(stack, 0);
}

static void unregister_winch(struct tty_struct *tty)
{
      struct list_head *ele;
      struct winch *winch;

      spin_lock(&winch_handler_lock);

      list_for_each(ele, &winch_handlers) {
            winch = list_entry(ele, struct winch, list);
            if (winch->tty == tty) {
                  free_winch(winch, 1);
                  break;
            }
      }
      spin_unlock(&winch_handler_lock);
}

static void winch_cleanup(void)
{
      struct list_head *ele, *next;
      struct winch *winch;

      spin_lock(&winch_handler_lock);

      list_for_each_safe(ele, next, &winch_handlers) {
            winch = list_entry(ele, struct winch, list);
            free_winch(winch, 1);
      }

      spin_unlock(&winch_handler_lock);
}
__uml_exitcall(winch_cleanup);

char *add_xterm_umid(char *base)
{
      char *umid, *title;
      int len;

      umid = get_umid();
      if (*umid == '\0')
            return base;

      len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
      title = kmalloc(len, GFP_KERNEL);
      if (title == NULL) {
            printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
            return base;
      }

      snprintf(title, len, "%s (%s)", base, umid);
      return title;
}

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