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/*
 * Copyright (C) 2005 Jakub Jermar
 * 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.
 */

#include <console/kconsole.h>
#include <console/console.h>
#include <console/chardev.h>
#include <print.h>
#include <panic.h>
#include <typedefs.h>
#include <arch/types.h>
#include <list.h>
#include <arch.h>
#include <func.h>
#include <macros.h>
#include <debug.h>

#define MAX_CMDLINE 256

/** Simple kernel console.
 *
 * The console is realized by kernel thread kconsole.
 * It doesn't understand any useful command on its own,
 * but makes it possible for other kernel subsystems to
 * register their own commands.
 */
 
/** Locking.
 *
 * There is a list of cmd_info_t structures. This list
 * is protected by cmd_lock spinlock. Note that specially
 * the link elements of cmd_info_t are protected by
 * this lock.
 *
 * Each cmd_info_t also has its own lock, which protects
 * all elements thereof except the link element.
 *
 * cmd_lock must be acquired before any cmd_info lock.
 * When locking two cmd info structures, structure with
 * lower address must be locked first.
 */
 
spinlock_t cmd_lock;    /**< Lock protecting command list. */
link_t cmd_head;    /**< Command list. */

static cmd_info_t *parse_cmdline(char *cmdline, size_t len);
static bool parse_argument(char *cmdline, size_t len, index_t *start, index_t *end);

/** Data and methods for 'help' command. */
static int cmd_help(cmd_arg_t *argv);
static cmd_info_t help_info;

/** Data and methods for 'description' command. */
static int cmd_desc(cmd_arg_t *argv);
static void desc_help(void);
static cmd_info_t desc_info;
static char desc_buf[MAX_CMDLINE+1];
static cmd_arg_t desc_argv = {
    .type = ARG_TYPE_STRING,
    .buffer = desc_buf,
    .len = sizeof(desc_buf)
};

/** Data and methods for 'halt' command. */
static int cmd_halt(cmd_arg_t *argv);
static cmd_info_t halt_info;

/** Initialize kconsole data structures. */
void kconsole_init(void)
{
    spinlock_initialize(&cmd_lock, "kconsole_cmd");
    list_initialize(&cmd_head);
    
    help_info.name = "help";
    help_info.description = "List supported commands.";
    help_info.func = cmd_help;
    help_info.help = NULL;
    help_info.argc = 0;
    help_info.argv = NULL;

    spinlock_initialize(&help_info.lock, "kconsole_help");
    link_initialize(&help_info.link);

    if (!cmd_register(&help_info))
        panic("could not register command %s\n", help_info.name);


    desc_info.name = "describe";
    desc_info.description = "Describe specified command.";
    desc_info.help = desc_help;
    desc_info.func = cmd_desc;
    desc_info.argc = 1;
    desc_info.argv = &desc_argv;
    
    spinlock_initialize(&desc_info.lock, "kconsole_desc");
    link_initialize(&desc_info.link);
    
    if (!cmd_register(&desc_info))
        panic("could not register command %s\n", desc_info.name);
    
    
    halt_info.name = "halt";
    halt_info.description = "Halt the kernel.";
    halt_info.func = cmd_halt;
    halt_info.help = NULL;
    halt_info.argc = 0;
    halt_info.argv = NULL;

    spinlock_initialize(&halt_info.lock, "kconsole_halt");
    link_initialize(&halt_info.link);

    if (!cmd_register(&halt_info))
        panic("could not register command %s\n", halt_info.name);
}


/** Register kconsole command.
 *
 * @param cmd Structure describing the command.
 *
 * @return 0 on failure, 1 on success.
 */
int cmd_register(cmd_info_t *cmd)
{
    ipl_t ipl;
    link_t *cur;
    
    ipl = interrupts_disable();
    spinlock_lock(&cmd_lock);
    
    /*
     * Make sure the command is not already listed.
     */
    for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
        cmd_info_t *hlp;
        
        hlp = list_get_instance(cur, cmd_info_t, link);

        if (hlp == cmd) {
            /* The command is already there. */
            spinlock_unlock(&cmd_lock);
            interrupts_restore(ipl);
            return 0;
        }

        /* Avoid deadlock. */
        if (hlp < cmd) {
            spinlock_lock(&hlp->lock);
            spinlock_lock(&cmd->lock);
        } else {
            spinlock_lock(&cmd->lock);
            spinlock_lock(&hlp->lock);
        }
        
        if ((strncmp(hlp->name, cmd->name, strlen(cmd->name)) == 0)) {
            /* The command is already there. */
            spinlock_unlock(&hlp->lock);
            spinlock_unlock(&cmd->lock);
            spinlock_unlock(&cmd_lock);
            interrupts_restore(ipl);
            return 0;
        }
        
        spinlock_unlock(&hlp->lock);
        spinlock_unlock(&cmd->lock);
    }
    
    /*
     * Now the command can be added.
     */
    list_append(&cmd->link, &cmd_head);
    
    spinlock_unlock(&cmd_lock);
    interrupts_restore(ipl);
    return 1;
}

/** Kernel console managing thread.
 *
 * @param arg Not used.
 */
void kconsole(void *arg)
{
    char cmdline[MAX_CMDLINE+1];
    cmd_info_t *cmd_info;
    count_t len;

    if (!stdin) {
        printf("%s: no stdin\n", __FUNCTION__);
        return;
    }
    
    while (true) {
        printf("%s> ", __FUNCTION__);
        if (!(len = gets(stdin, cmdline, sizeof(cmdline))))
            continue;
        cmdline[len] = '\0';
        cmd_info = parse_cmdline(cmdline, len);
        if (!cmd_info)
            continue;
        (void) cmd_info->func(cmd_info->argv);
    }
}

/** Parse command line.
 *
 * @param cmdline Command line as read from input device.
 * @param len Command line length.
 *
 * @return Structure describing the command.
 */
cmd_info_t *parse_cmdline(char *cmdline, size_t len)
{
    index_t start = 0, end = 0;
    cmd_info_t *cmd = NULL;
    link_t *cur;
    ipl_t ipl;
    int i;
    
    if (!parse_argument(cmdline, len, &start, &end)) {
        /* Command line did not contain alphanumeric word. */
        return NULL;
    }

    ipl = interrupts_disable();
    spinlock_lock(&cmd_lock);
    
    for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
        cmd_info_t *hlp;
        
        hlp = list_get_instance(cur, cmd_info_t, link);
        spinlock_lock(&hlp->lock);
        
        if (strncmp(hlp->name, &cmdline[start], (end - start) + 1) == 0) {
            cmd = hlp;
            break;
        }
        
        spinlock_unlock(&hlp->lock);
    }
    
    spinlock_unlock(&cmd_lock); 
    
    if (!cmd) {
        /* Unknown command. */
        printf("Unknown command.\n");
        interrupts_restore(ipl);
        return NULL;
    }

    /* cmd == hlp is locked */
    
    /*
     * The command line must be further analyzed and
     * the parameters therefrom must be matched and
     * converted to those specified in the cmd info
     * structure.
     */

    for (i = 0; i < cmd->argc; i++) {
        char *buf;
        start = end + 1;
        if (!parse_argument(cmdline, len, &start, &end)) {
            printf("Too few arguments.\n");
            spinlock_unlock(&cmd->lock);
            interrupts_restore(ipl);
            return NULL;
        }
        
        switch (cmd->argv[i].type) {
            case ARG_TYPE_STRING:
                buf = cmd->argv[i].buffer;
                strncpy(buf, (const char *) &cmdline[start], min((end - start) + 1, cmd->argv[i].len - 1));
            buf[min((end - start) + 1, cmd->argv[i].len - 1)] = '\0';
            break;
            case ARG_TYPE_INT:
            case ARG_TYPE_INVALID:
            default:
            panic("invalid argument type\n");
            break;
        }
    }
    
    start = end + 1;
    if (parse_argument(cmdline, len, &start, &end)) {
        printf("Too many arguments.\n");
        spinlock_unlock(&cmd->lock);
        interrupts_restore(ipl);
        return NULL;
    }
    
    spinlock_unlock(&cmd->lock);
    interrupts_restore(ipl);
    return cmd;
}

/** Parse argument.
 *
 * Find start and end positions of command line argument.
 *
 * @param cmdline Command line as read from the input device.
 * @param len Number of characters in cmdline.
 * @param start On entry, 'start' contains pointer to the index 
 *        of first unprocessed character of cmdline.
 *        On successful exit, it marks beginning of the next argument.
 * @param end Undefined on entry. On exit, 'end' points to the last character
 *        of the next argument.
 *
 * @return false on failure, true on success.
 */
bool parse_argument(char *cmdline, size_t len, index_t *start, index_t *end)
{
    int i;
    bool found_start = false;
    
    ASSERT(start != NULL);
    ASSERT(end != NULL);
    
    for (i = *start; i < len; i++) {
        if (!found_start) {
            if (is_white(cmdline[i]))
                (*start)++;
            else
                found_start = true;
        } else {
            if (is_white(cmdline[i]))
                break;
        }
    }
    *end = i - 1;

    return found_start;
}


/** List supported commands.
 *
 * @param argv Argument vector.
 *
 * @return 0 on failure, 1 on success.
 */
int cmd_help(cmd_arg_t *argv)
{
    link_t *cur;
    ipl_t ipl;

    ipl = interrupts_disable();
    spinlock_lock(&cmd_lock);
    
    for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
        cmd_info_t *hlp;
        
        hlp = list_get_instance(cur, cmd_info_t, link);
        spinlock_lock(&hlp->lock);
        
        printf("%s - %s\n", hlp->name, hlp->description);

        spinlock_unlock(&hlp->lock);
    }
    
    spinlock_unlock(&cmd_lock); 
    interrupts_restore(ipl);

    return 1;
}

/** Describe specified command.
 *
 * @param argv Argument vector.
 *
 * @return 0 on failure, 1 on success.
 */
int cmd_desc(cmd_arg_t *argv)
{
    link_t *cur;
    ipl_t ipl;

    ipl = interrupts_disable();
    spinlock_lock(&cmd_lock);
    
    for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
        cmd_info_t *hlp;
        
        hlp = list_get_instance(cur, cmd_info_t, link);
        spinlock_lock(&hlp->lock);

        if (strncmp(hlp->name, (const char *) argv->buffer, strlen(hlp->name)) == 0) {
            printf("%s - %s\n", hlp->name, hlp->description);
            if (hlp->help)
                hlp->help();
            spinlock_unlock(&hlp->lock);
            break;
        }

        spinlock_unlock(&hlp->lock);
    }
    
    spinlock_unlock(&cmd_lock); 
    interrupts_restore(ipl);

    return 1;
}

/** Print detailed description of 'describe' command. */
void desc_help(void)
{
    printf("Syntax: describe command_name\n");
}

/** Halt the kernel.
 *
 * @param argv Argument vector (ignored).
 *
 * @return 0 on failure, 1 on success (never returns).
 */
int cmd_halt(cmd_arg_t *argv)
{
    halt();
    return 1;
}