consoles.c

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/*
 * Copyright (c) 2010 Werner Fink, Jiri Slaby
 *
 * Licensed under GPLv2
 */

#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/tty_driver.h>

/*
 * This is handler for /proc/consoles
 */
static int show_console_dev(struct seq_file *m, void *v)
{
    static const struct {
        short flag;
        char name;
    } con_flags[] = {
        { CON_ENABLED,      'E' },
        { CON_CONSDEV,      'C' },
        { CON_BOOT,     'B' },
        { CON_PRINTBUFFER,  'p' },
        { CON_BRL,      'b' },
        { CON_ANYTIME,      'a' },
    };
    char flags[ARRAY_SIZE(con_flags) + 1];
    struct console *con = v;
    unsigned int a;
    int len;
    dev_t dev = 0;

    if (con->device) {
        const struct tty_driver *driver;
        int index;
        driver = con->device(con, &index);
        if (driver) {
            dev = MKDEV(driver->major, driver->minor_start);
            dev += index;
        }
    }

    for (a = 0; a < ARRAY_SIZE(con_flags); a++)
        flags[a] = (con->flags & con_flags[a].flag) ?
            con_flags[a].name : ' ';
    flags[a] = 0;

    seq_printf(m, "%s%d%n", con->name, con->index, &len);
    len = 21 - len;
    if (len < 1)
        len = 1;
    seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
            con->write ? 'W' : '-', con->unblank ? 'U' : '-',
            flags);
    if (dev)
        seq_printf(m, " %4d:%d", MAJOR(dev), MINOR(dev));

    seq_printf(m, "\n");

    return 0;
}

static void *c_start(struct seq_file *m, loff_t *pos)
{
    struct console *con;
    loff_t off = 0;

    console_lock();
    for_each_console(con)
        if (off++ == *pos)
            break;

    return con;
}

static void *c_next(struct seq_file *m, void *v, loff_t *pos)
{
    struct console *con = v;
    ++*pos;
    return con->next;
}

static void c_stop(struct seq_file *m, void *v)
{
    console_unlock();
}

static const struct seq_operations consoles_op = {
    .start  = c_start,
    .next   = c_next,
    .stop   = c_stop,
    .show   = show_console_dev
};

static int consoles_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &consoles_op);
}

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

static int __init proc_consoles_init(void)
{
    proc_create("consoles", 0, NULL, &proc_consoles_operations);
    return 0;
}
module_init(proc_consoles_init);