// SPDX-License-Identifier: GPL-2.0
/*
 *  Unified handling of special chars.
 *
 *    Copyright IBM Corp. 2001
 *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
 *
 */

#include <linux/stddef.h>
#include <asm/errno.h>
#include <linux/sysrq.h>
#include <linux/ctype.h>

#include "ctrlchar.h"

#ifdef CONFIG_MAGIC_SYSRQ
static struct sysrq_work ctrlchar_sysrq;

static void
ctrlchar_handle_sysrq(struct work_struct *work)
{
        struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);

        handle_sysrq(sysrq->key);
}

void schedule_sysrq_work(struct sysrq_work *sw)
{
        INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
        schedule_work(&sw->work);
}
#endif


/**
 * ctrlchar_handle - check for special chars at start of input
 *
 * @buf: console input buffer
 * @len: length of valid data in buffer
 * @tty: the tty struct for this console
 *
 * Return: CTRLCHAR_NONE, if nothing matched,
 *         CTRLCHAR_SYSRQ, if sysrq was encountered
 *         otherwise char to be inserted logically or'ed
 *         with CTRLCHAR_CTRL
 */
unsigned int
ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
{
        if ((len < 2) || (len > 3))
                return CTRLCHAR_NONE;

        /* hat is 0xb1 in codepage 037 (US etc.) and thus */
        /* converted to 0x5e in ascii ('^') */
        if ((buf[0] != '^') && (buf[0] != '\252'))
                return CTRLCHAR_NONE;

#ifdef CONFIG_MAGIC_SYSRQ
        /* racy */
        if (len == 3 && buf[1] == '-') {
                ctrlchar_sysrq.key = buf[2];
                schedule_sysrq_work(&ctrlchar_sysrq);
                return CTRLCHAR_SYSRQ;
        }
#endif

        if (len != 2)
                return CTRLCHAR_NONE;

        switch (tolower(buf[1])) {
        case 'c':
                return INTR_CHAR(tty) | CTRLCHAR_CTRL;
        case 'd':
                return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
        case 'z':
                return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
        }
        return CTRLCHAR_NONE;
}