readline.c

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/*
 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <console.h>
#include <gpxe/keys.h>
#include <gpxe/editstring.h>
#include <readline/readline.h>

/** @file
 *
 * Minimal readline
 *
 */

#define READLINE_MAX 256

static void sync_console ( struct edit_string *string ) __nonnull;

/**
 * Synchronise console with edited string
 *
 * @v string            Editable string
 */
static void sync_console ( struct edit_string *string ) {
        unsigned int mod_start = string->mod_start;
        unsigned int mod_end = string->mod_end;
        unsigned int cursor = string->last_cursor;
        size_t len = strlen ( string->buf );

        /* Expand region back to old cursor position if applicable */
        if ( mod_start > string->last_cursor )
                mod_start = string->last_cursor;

        /* Expand region forward to new cursor position if applicable */
        if ( mod_end < string->cursor )
                mod_end = string->cursor;

        /* Backspace to start of region */
        while ( cursor > mod_start ) {
                putchar ( '\b' );
                cursor--;
        }

        /* Print modified region */
        while ( cursor < mod_end ) {
                putchar ( ( cursor >= len ) ? ' ' : string->buf[cursor] );
                cursor++;
        }

        /* Backspace to new cursor position */
        while ( cursor > string->cursor ) {
                putchar ( '\b' );
                cursor--;
        }
}

/**
 * Read line from console
 *
 * @v prompt            Prompt string
 * @ret line            Line read from console (excluding terminating newline)
 *
 * The returned line is allocated with malloc(); the caller must
 * eventually call free() to release the storage.
 */
char * readline ( const char *prompt ) {
        char buf[READLINE_MAX];
        struct edit_string string;
        int key;
        char *line;

        if ( prompt )
                printf ( "%s", prompt );

        memset ( &string, 0, sizeof ( string ) );
        string.buf = buf;
        string.len = sizeof ( buf );
        buf[0] = '\0';

        while ( 1 ) {
                key = edit_string ( &string, getkey() );
                sync_console ( &string );
                switch ( key ) {
                case CR:
                case LF:
                        putchar ( '\n' );
                        line = strdup ( buf );
                        if ( ! line )
                                printf ( "Out of memory\n" );
                        return line;
                case CTRL_C:
                        putchar ( '\n' );
                        return NULL;
                default:
                        /* Do nothing */
                        break;
                }
        }
}