/*
 * proc_tty.c -- handles /proc/tty
 *
 * Copyright 1997, Theodore Ts'o
 */

#include <asm/uaccess.h>

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/seq_file.h>
#include <linux/bitops.h>

static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
                                int count, int *eof, void *data);

/*
 * The /proc/tty directory inodes...
 */
static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;

/*
 * This is the handler for /proc/tty/drivers
 */
static void show_tty_range(struct seq_file *m, struct tty_driver *p,
        dev_t from, int num)
{
        seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
        seq_printf(m, "/dev/%-8s ", p->name);
        if (p->num > 1) {
                seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from),
                        MINOR(from) + num - 1);
        } else {
                seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
        }
        switch (p->type) {
        case TTY_DRIVER_TYPE_SYSTEM:
                seq_printf(m, "system");
                if (p->subtype == SYSTEM_TYPE_TTY)
                        seq_printf(m, ":/dev/tty");
                else if (p->subtype == SYSTEM_TYPE_SYSCONS)
                        seq_printf(m, ":console");
                else if (p->subtype == SYSTEM_TYPE_CONSOLE)
                        seq_printf(m, ":vtmaster");
                break;
        case TTY_DRIVER_TYPE_CONSOLE:
                seq_printf(m, "console");
                break;
        case TTY_DRIVER_TYPE_SERIAL:
                seq_printf(m, "serial");
                break;
        case TTY_DRIVER_TYPE_PTY:
                if (p->subtype == PTY_TYPE_MASTER)
                        seq_printf(m, "pty:master");
                else if (p->subtype == PTY_TYPE_SLAVE)
                        seq_printf(m, "pty:slave");
                else
                        seq_printf(m, "pty");
                break;
        default:
                seq_printf(m, "type:%d.%d", p->type, p->subtype);
        }
        seq_putc(m, '\n');
}

static int show_tty_driver(struct seq_file *m, void *v)
{
        struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers);
        dev_t from = MKDEV(p->major, p->minor_start);
        dev_t to = from + p->num;

        if (&p->tty_drivers == tty_drivers.next) {
                /* pseudo-drivers first */
                seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
                seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
                seq_printf(m, "system:/dev/tty\n");
                seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
                seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
                seq_printf(m, "system:console\n");
#ifdef CONFIG_UNIX98_PTYS
                seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
                seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
                seq_printf(m, "system\n");
#endif
#ifdef CONFIG_VT
                seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
                seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
                seq_printf(m, "system:vtmaster\n");
#endif
        }

        while (MAJOR(from) < MAJOR(to)) {
                dev_t next = MKDEV(MAJOR(from)+1, 0);
                show_tty_range(m, p, from, next - from);
                from = next;
        }
        if (from != to)
                show_tty_range(m, p, from, to - from);
        return 0;
}

/* iterator */
static void *t_start(struct seq_file *m, loff_t *pos)
{
        mutex_lock(&tty_mutex);
        return seq_list_start(&tty_drivers, *pos);
}

static void *t_next(struct seq_file *m, void *v, loff_t *pos)
{
        return seq_list_next(v, &tty_drivers, pos);
}

static void t_stop(struct seq_file *m, void *v)
{
        mutex_unlock(&tty_mutex);
}

static struct seq_operations tty_drivers_op = {
        .start  = t_start,
        .next   = t_next,
        .stop   = t_stop,
        .show   = show_tty_driver
};

static int tty_drivers_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &tty_drivers_op);
}

static const struct file_operations proc_tty_drivers_operations = {
        .open           = tty_drivers_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

/*
 * This is the handler for /proc/tty/ldiscs
 */
static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
                                int count, int *eof, void *data)
{
        int     i;
        int     len = 0;
        off_t   begin = 0;
        struct tty_ldisc *ld;
        
        for (i=0; i < NR_LDISCS; i++) {
                ld = tty_ldisc_get(i);
                if (ld == NULL)
                        continue;
                len += sprintf(page+len, "%-10s %2d\n",
                               ld->name ? ld->name : "???", i);
                tty_ldisc_put(i);
                if (len+begin > off+count)
                        break;
                if (len+begin < off) {
                        begin += len;
                        len = 0;
                }
        }
        if (i >= NR_LDISCS)
                *eof = 1;
        if (off >= len+begin)
                return 0;
        *start = page + (off-begin);
        return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * This function is called by tty_register_driver() to handle
 * registering the driver's /proc handler into /proc/tty/driver/<foo>
 */
void proc_tty_register_driver(struct tty_driver *driver)
{
        struct proc_dir_entry *ent;
                
        if ((!driver->read_proc && !driver->write_proc) ||
            !driver->driver_name ||
            driver->proc_entry)
                return;

        ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
        if (!ent)
                return;
        ent->read_proc = driver->read_proc;
        ent->write_proc = driver->write_proc;
        ent->owner = driver->owner;
        ent->data = driver;

        driver->proc_entry = ent;
}

/*
 * This function is called by tty_unregister_driver()
 */
void proc_tty_unregister_driver(struct tty_driver *driver)
{
        struct proc_dir_entry *ent;

        ent = driver->proc_entry;
        if (!ent)
                return;
                
        remove_proc_entry(driver->driver_name, proc_tty_driver);
        
        driver->proc_entry = NULL;
}

/*
 * Called by proc_root_init() to initialize the /proc/tty subtree
 */
void __init proc_tty_init(void)
{
        struct proc_dir_entry *entry;
        if (!proc_mkdir("tty", NULL))
                return;
        proc_tty_ldisc = proc_mkdir("tty/ldisc", NULL);
        /*
         * /proc/tty/driver/serial reveals the exact character counts for
         * serial links which is just too easy to abuse for inferring
         * password lengths and inter-keystroke timings during password
         * entry.
         */
        proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, NULL);

        create_proc_read_entry("tty/ldiscs", 0, NULL, tty_ldiscs_read_proc, NULL);
        entry = create_proc_entry("tty/drivers", 0, NULL);
        if (entry)
                entry->proc_fops = &proc_tty_drivers_operations;
}