source: mainline/kernel/generic/src/console/console.c

/*
 * Copyright (c) 2003 Josef Cejka
 * Copyright (c) 2005 Jakub Jermar
 * Copyright (c) 2025 Jiří Zárevúcky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup kernel_generic_console
 * @{
 */
/** @file
 */

#include <abi/kio.h>
#include <console/chardev.h>
#include <console/console.h>
#include <errno.h>
#include <ipc/event.h>
#include <log.h>
#include <panic.h>
#include <preemption.h>
#include <proc/task.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>  /* malloc */
#include <str.h>
#include <synch/mutex.h>
#include <synch/spinlock.h>
#include <syscall/copy.h>
#include <sysinfo/sysinfo.h>

#define KIO_PAGES    8
#define KIO_LENGTH   (KIO_PAGES * PAGE_SIZE)

/** Kernel log cyclic buffer */
static char kio[KIO_LENGTH];

/** Kernel log initialized */
static atomic_bool kio_inited = ATOMIC_VAR_INIT(false);

/** A mutex for preventing interleaving of output lines from different threads.
 * May not be held in some circumstances, so locking of any internal shared
 * structures is still necessary.
 */
static MUTEX_INITIALIZE(console_mutex, MUTEX_RECURSIVE);

/** Number of characters written to buffer. Periodically overflows. */
static size_t kio_written = 0;

/** Number of characters written to output devices. Periodically overflows. */
static size_t kio_processed = 0;

/** Last notification sent to uspace. */
static size_t kio_notified = 0;

/** Kernel log spinlock */
IRQ_SPINLOCK_INITIALIZE(kio_lock);

static IRQ_SPINLOCK_INITIALIZE(flush_lock);

static IRQ_SPINLOCK_INITIALIZE(early_mbstate_lock);
static mbstate_t early_mbstate;

static indev_t stdin_sink;
static outdev_t stdout_source;

static void stdin_signal(indev_t *, indev_signal_t);

static indev_operations_t stdin_ops = {
        .poll = NULL,
        .signal = stdin_signal
};

static void stdout_write(outdev_t *, const char *, size_t);
static void stdout_redraw(outdev_t *);
static void stdout_scroll_up(outdev_t *);
static void stdout_scroll_down(outdev_t *);

static outdev_operations_t stdout_ops = {
        .write = stdout_write,
        .redraw = stdout_redraw,
        .scroll_up = stdout_scroll_up,
        .scroll_down = stdout_scroll_down
};

/** Override kernel console lockout */
bool console_override = false;

/** Standard input and output character devices */
indev_t *stdin = NULL;
outdev_t *stdout = NULL;

indev_t *stdin_wire(void)
{
        if (stdin == NULL) {
                indev_initialize("stdin", &stdin_sink, &stdin_ops);
                stdin = &stdin_sink;
        }

        return stdin;
}

static void stdin_signal(indev_t *indev, indev_signal_t signal)
{
        switch (signal) {
        case INDEV_SIGNAL_SCROLL_UP:
                if (stdout != NULL)
                        stdout_scroll_up(stdout);
                break;
        case INDEV_SIGNAL_SCROLL_DOWN:
                if (stdout != NULL)
                        stdout_scroll_down(stdout);
                break;
        }
}

void stdout_wire(outdev_t *outdev)
{
        if (stdout == NULL) {
                outdev_initialize("stdout", &stdout_source, &stdout_ops);
                stdout = &stdout_source;
        }

        list_append(&outdev->link, &stdout->list);
}

static void stdout_write(outdev_t *dev, const char *s, size_t n)
{
        list_foreach(dev->list, link, outdev_t, sink) {
                if ((sink) && (sink->op->write))
                        sink->op->write(sink, s, n);
        }
}

static void stdout_redraw(outdev_t *dev)
{
        list_foreach(dev->list, link, outdev_t, sink) {
                if ((sink) && (sink->op->redraw))
                        sink->op->redraw(sink);
        }
}

static void stdout_scroll_up(outdev_t *dev)
{
        list_foreach(dev->list, link, outdev_t, sink) {
                if ((sink) && (sink->op->scroll_up))
                        sink->op->scroll_up(sink);
        }
}

static void stdout_scroll_down(outdev_t *dev)
{
        list_foreach(dev->list, link, outdev_t, sink) {
                if ((sink) && (sink->op->scroll_down))
                        sink->op->scroll_down(sink);
        }
}

/** Initialize kernel logging facility
 */
void kio_init(void)
{
        event_set_unmask_callback(EVENT_KIO, kio_update);
        atomic_store(&kio_inited, true);
}

void grab_console(void)
{
        sysinfo_set_item_val("kconsole", NULL, true);
        event_notify_1(EVENT_KCONSOLE, false, true);
        bool prev = console_override;

        console_override = true;
        if ((stdout) && (stdout->op->redraw))
                stdout->op->redraw(stdout);

        if ((stdin) && (!prev)) {
                /*
                 * Force the console to print the prompt.
                 */
                indev_push_character(stdin, '\n');
        }
}

void release_console(void)
{
        sysinfo_set_item_val("kconsole", NULL, false);
        console_override = false;
        event_notify_1(EVENT_KCONSOLE, false, false);
}

/** Activate kernel console override */
sysarg_t sys_debug_console(void)
{
#ifdef CONFIG_KCONSOLE
        grab_console();
        return true;
#else
        return false;
#endif
}

void kio_update(void *event)
{
        if (!atomic_load(&kio_inited))
                return;

        irq_spinlock_lock(&kio_lock, true);

        if (kio_notified != kio_written) {
                if (event_notify_1(EVENT_KIO, true, kio_written) == EOK)
                        kio_notified = kio_written;
        }

        irq_spinlock_unlock(&kio_lock, true);
}

/** Flush characters that are stored in the output buffer
 *
 */
void kio_flush(void)
{
        bool ordy = ((stdout) && (stdout->op->write));

        if (!ordy)
                return;

        irq_spinlock_lock(&kio_lock, true);

        if (!irq_spinlock_trylock(&flush_lock)) {
                /* Someone is currently flushing. */
                irq_spinlock_unlock(&kio_lock, true);
                return;
        }

        /* A small-ish local buffer so that we can write to output in chunks. */
        char buffer[256];

        /* Print characters that weren't printed earlier */
        while (kio_written != kio_processed) {
                size_t offset = kio_processed % KIO_LENGTH;
                size_t len = min(kio_written - kio_processed, KIO_LENGTH - offset);
                len = min(len, sizeof(buffer));

                /* Take out a chunk of the big buffer. */
                memcpy(buffer, &kio[offset], len);
                kio_processed += len;

                /*
                 * We need to give up the spinlock for the physical operation of writing
                 * out the buffer.
                 */
                irq_spinlock_unlock(&kio_lock, true);
                stdout->op->write(stdout, buffer, len);
                irq_spinlock_lock(&kio_lock, true);
        }

        irq_spinlock_unlock(&flush_lock, false);
        irq_spinlock_unlock(&kio_lock, true);
}

void kio_push_bytes(const char *s, size_t n)
{
        /* Skip the section we know we can't keep. */
        if (n > KIO_LENGTH) {
                size_t lost = n - KIO_LENGTH;
                kio_written += lost;
                s += lost;
                n -= lost;
        }

        size_t offset = kio_written % KIO_LENGTH;
        if (offset + n > KIO_LENGTH) {
                size_t first = KIO_LENGTH - offset;
                size_t last = n - first;
                memcpy(kio + offset, s, first);
                memcpy(kio, s + first, last);
        } else {
                memcpy(kio + offset, s, n);
        }

        kio_written += n;
}

static void early_putstr(const char *s, size_t n)
{
        irq_spinlock_lock(&early_mbstate_lock, true);

        size_t offset = 0;
        char32_t c;

        while ((c = str_decode_r(s, &offset, n, U_SPECIAL, &early_mbstate)))
                early_putuchar(c);

        irq_spinlock_unlock(&early_mbstate_lock, true);
}

void putstr(const char *s, size_t n)
{
        bool ordy = ((stdout) && (stdout->op->write));

        irq_spinlock_lock(&kio_lock, true);
        kio_push_bytes(s, n);
        irq_spinlock_unlock(&kio_lock, true);

        /* Output stored characters */
        kio_flush();

        if (!ordy) {
                /*
                 * No standard output routine defined yet.
                 * The character is still stored in the kernel log
                 * for possible future output.
                 *
                 * The early_putuchar() function is used to output
                 * the character for low-level debugging purposes.
                 * Note that the early_putuchar() function might be
                 * a no-op on certain hardware configurations.
                 */
                early_putstr(s, n);
        }

        /* Force notification when containing a newline */
        if (memchr(s, '\n', n) != NULL)
                kio_update(NULL);
}

/** Reads up to `size` characters from kio buffer starting at character `at`.
 *
 * @param size  Maximum number of characters that can be stored in buffer.
 *              Values greater than KIO_LENGTH are silently treated as KIO_LENGTH
 *              for the purposes of calculating the return value.
 * @return Number of characters read. Can be more than `size`.
 *         In that case, `size` characters are written to user buffer
 *         and the extra amount is the number of characters missed.
 */
sysarg_t sys_kio_read(uspace_addr_t buf, size_t size, size_t at)
{
        errno_t rc;
        size_t missed = 0;

        irq_spinlock_lock(&kio_lock, true);

        if (at == kio_written) {
                irq_spinlock_unlock(&kio_lock, true);
                return 0;
        }

        size_t readable_chars = kio_written - at;
        if (readable_chars > KIO_LENGTH) {
                missed = readable_chars - KIO_LENGTH;
                readable_chars = KIO_LENGTH;
        }

        size_t actual_read = min(readable_chars, size);
        size_t offset = (kio_written - readable_chars) % KIO_LENGTH;

        if (offset + actual_read > KIO_LENGTH) {
                size_t first = KIO_LENGTH - offset;
                size_t last = actual_read - first;

                rc = copy_to_uspace(buf, &kio[offset], first);
                if (rc == EOK)
                        rc = copy_to_uspace(buf + first, &kio[0], last);
        } else {
                rc = copy_to_uspace(buf, &kio[offset], actual_read);
        }

        irq_spinlock_unlock(&kio_lock, true);

        if (rc != EOK) {
                log(LF_OTHER, LVL_WARN,
                    "[%s(%" PRIu64 ")] Terminating due to invalid memory buffer"
                    " in SYS_KIO_READ.\n", TASK->name, TASK->taskid);
                task_kill_self(true);
        }

        return actual_read + missed;
}

/** Print using kernel facility
 *
 * Print to kernel log.
 *
 */
sys_errno_t sys_kio(int cmd, uspace_addr_t buf, size_t size)
{
        char *data;
        errno_t rc;

        switch (cmd) {
        case KIO_UPDATE:
                kio_update(NULL);
                return EOK;
        case KIO_WRITE:
        case KIO_COMMAND:
                break;
        default:
                return ENOTSUP;
        }

        if (size > PAGE_SIZE)
                return (sys_errno_t) ELIMIT;

        if (size > 0) {
                data = (char *) malloc(size + 1);
                if (!data)
                        return (sys_errno_t) ENOMEM;

                rc = copy_from_uspace(data, buf, size);
                if (rc) {
                        free(data);
                        return (sys_errno_t) rc;
                }
                data[size] = 0;

                uint8_t substitute = '\x1a';
                str_sanitize(data, size, substitute);

                switch (cmd) {
                case KIO_WRITE:
                        printf("[%s(%lu)] %s\n", TASK->name,
                            (unsigned long) TASK->taskid, data);
                        break;
                case KIO_COMMAND:
                        if (!stdin)
                                break;
                        for (unsigned int i = 0; i < size; i++)
                                indev_push_character(stdin, data[i]);
                        indev_push_character(stdin, '\n');
                        break;
                }

                free(data);
        }

        return EOK;
}

/** Lock console output, ensuring that lines from different threads don't
 * interleave. Does nothing when preemption is disabled, so that debugging
 * and error printouts in sensitive areas still work.
 */
void console_lock(void)
{
        if (!PREEMPTION_DISABLED)
                mutex_lock(&console_mutex);
}

/** Unlocks console output. See console_lock()
 */
void console_unlock(void)
{
        if (!PREEMPTION_DISABLED)
                mutex_unlock(&console_mutex);
}

/** @}
 */