script.c

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/*
 * Copyright (C) 2007 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

/**
 * @file
 *
 * iPXE scripts
 *
 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <getopt.h>
#include <ipxe/command.h>
#include <ipxe/parseopt.h>
#include <ipxe/image.h>
#include <ipxe/shell.h>
#include <usr/prompt.h>
#include <ipxe/script.h>

/** Offset within current script
 *
 * This is a global in order to allow goto_exec() to update the
 * offset.
 */
static size_t script_offset;

/**
 * Process script lines
 *
 * @v image             Script
 * @v process_line      Line processor
 * @v terminate         Termination check
 * @ret rc              Return status code
 */
static int process_script ( struct image *image,
                            int ( * process_line ) ( struct image *image,
                                                     size_t offset,
                                                     const char *label,
                                                     const char *command ),
                            int ( * terminate ) ( int rc ) ) {
        size_t len = 0;
        char *line = NULL;
        size_t line_offset;
        char *label;
        char *command;
        off_t eol;
        size_t frag_len;
        char *tmp;
        int rc;

        /* Initialise script and line offsets */
        script_offset = 0;
        line_offset = 0;

        do {

                /* Find length of next line, excluding any terminating '\n' */
                eol = memchr_user ( image->data, script_offset, '\n',
                                    ( image->len - script_offset ) );
                if ( eol < 0 )
                        eol = image->len;
                frag_len = ( eol - script_offset );

                /* Allocate buffer for line */
                tmp = realloc ( line, ( len + frag_len + 1 /* NUL */ ) );
                if ( ! tmp ) {
                        rc = -ENOMEM;
                        goto err_alloc;
                }
                line = tmp;

                /* Copy line */
                copy_from_user ( ( line + len ), image->data, script_offset,
                                 frag_len );
                len += frag_len;

                /* Move to next line in script */
                script_offset += ( frag_len + 1 );

                /* Strip trailing CR, if present */
                if ( len && ( line[ len - 1 ] == '\r' ) )
                        len--;

                /* Handle backslash continuations */
                if ( len && ( line[ len - 1 ] == '\\' ) ) {
                        len--;
                        rc = -EINVAL;
                        continue;
                }

                /* Terminate line */
                line[len] = '\0';

                /* Split line into (optional) label and command */
                command = line;
                while ( isspace ( *command ) )
                        command++;
                if ( *command == ':' ) {
                        label = ++command;
                        while ( *command && ! isspace ( *command ) )
                                command++;
                        if ( *command )
                                *(command++) = '\0';
                } else {
                        label = NULL;
                }

                /* Process line */
                rc = process_line ( image, line_offset, label, command );
                if ( terminate ( rc ) )
                        goto err_process;

                /* Free line */
                free ( line );
                line = NULL;
                len = 0;

                /* Update line offset */
                line_offset = script_offset;

        } while ( script_offset < image->len );

 err_process:
 err_alloc:
        free ( line );
        return rc;
}

/**
 * Terminate script processing on shell exit or command failure
 *
 * @v rc                Line processing status
 * @ret terminate       Terminate script processing
 */
static int terminate_on_exit_or_failure ( int rc ) {

        return ( shell_stopped ( SHELL_STOP_COMMAND_SEQUENCE ) ||
                 ( rc != 0 ) );
}

/**
 * Execute script line
 *
 * @v image             Script
 * @v offset            Offset within script
 * @v label             Label, or NULL
 * @v command           Command
 * @ret rc              Return status code
 */
static int script_exec_line ( struct image *image, size_t offset,
                              const char *label __unused,
                              const char *command ) {
        int rc;

        DBGC ( image, "[%04zx] $ %s\n", offset, command );

        /* Execute command */
        if ( ( rc = system ( command ) ) != 0 )
                return rc;

        return 0;
}

/**
 * Execute script
 *
 * @v image             Script
 * @ret rc              Return status code
 */
static int script_exec ( struct image *image ) {
        size_t saved_offset;
        int rc;

        /* Preserve state of any currently-running script */
        saved_offset = script_offset;

        /* Process script */
        rc = process_script ( image, script_exec_line,
                              terminate_on_exit_or_failure );

        /* Restore saved state */
        script_offset = saved_offset;

        return rc;
}

/**
 * Probe script image
 *
 * @v image             Script
 * @ret rc              Return status code
 */
static int script_probe ( struct image *image ) {
        static const char ipxe_magic[] = "#!ipxe";
        static const char gpxe_magic[] = "#!gpxe";
        static_assert ( sizeof ( ipxe_magic ) == sizeof ( gpxe_magic ) );
        char test[ sizeof ( ipxe_magic ) - 1 /* NUL */
                   + 1 /* terminating space */];

        /* Sanity check */
        if ( image->len < sizeof ( test ) ) {
                DBGC ( image, "Too short to be a script\n" );
                return -ENOEXEC;
        }

        /* Check for magic signature */
        copy_from_user ( test, image->data, 0, sizeof ( test ) );
        if ( ! ( ( ( memcmp ( test, ipxe_magic, sizeof ( test ) - 1 ) == 0 ) ||
                   ( memcmp ( test, gpxe_magic, sizeof ( test ) - 1 ) == 0 )) &&
                 isspace ( test[ sizeof ( test ) - 1 ] ) ) ) {
                DBGC ( image, "Invalid magic signature\n" );
                return -ENOEXEC;
        }

        return 0;
}

/** Script image type */
struct image_type script_image_type __image_type ( PROBE_NORMAL ) = {
        .name = "script",
        .probe = script_probe,
        .exec = script_exec,
};

/** "goto" options */
struct goto_options {};

/** "goto" option list */
static struct option_descriptor goto_opts[] = {};

/** "goto" command descriptor */
static struct command_descriptor goto_cmd =
        COMMAND_DESC ( struct goto_options, goto_opts, 1, 1, "<label>" );

/**
 * Current "goto" label
 *
 * Valid only during goto_exec().  Consider this part of a closure.
 */
static const char *goto_label;

/**
 * Check for presence of label
 *
 * @v image             Script
 * @v offset            Offset within script
 * @v label             Label
 * @v command           Command
 * @ret rc              Return status code
 */
static int goto_find_label ( struct image *image, size_t offset,
                             const char *label, const char *command __unused ) {

        /* Check label exists */
        if ( ! label )
                return -ENOENT;

        /* Check label matches */
        if ( strcmp ( goto_label, label ) != 0 )
                return -ENOENT;

        /* Update script offset */
        script_offset = offset;
        DBGC ( image, "[%04zx] Gone to :%s\n", offset, label );

        return 0;
}

/**
 * Terminate script processing when label is found
 *
 * @v rc                Line processing status
 * @ret terminate       Terminate script processing
 */
static int terminate_on_label_found ( int rc ) {
        return ( rc == 0 );
}

/**
 * "goto" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int goto_exec ( int argc, char **argv ) {
        struct image *image = current_image.image;
        struct goto_options opts;
        size_t saved_offset;
        int rc;

        /* Parse options */
        if ( ( rc = parse_options ( argc, argv, &goto_cmd, &opts ) ) != 0 )
                return rc;

        /* Sanity check */
        if ( ! image ) {
                rc = -ENOTTY;
                printf ( "Not in a script: %s\n", strerror ( rc ) );
                return rc;
        }

        /* Parse label */
        goto_label = argv[optind];

        /* Find label */
        saved_offset = script_offset;
        if ( ( rc = process_script ( image, goto_find_label,
                                     terminate_on_label_found ) ) != 0 ) {
                script_offset = saved_offset;
                DBGC ( image, "[%04zx] No such label :%s\n",
                       script_offset, goto_label );
                return rc;
        }

        /* Terminate processing of current command */
        shell_stop ( SHELL_STOP_COMMAND );

        return 0;
}

/** "goto" command */
struct command goto_command __command = {
        .name = "goto",
        .exec = goto_exec,
};

/** "prompt" options */
struct prompt_options {
        /** Key to wait for */
        unsigned int key;
        /** Timeout */
        unsigned long timeout;
};

/** "prompt" option list */
static struct option_descriptor prompt_opts[] = {
        OPTION_DESC ( "key", 'k', required_argument,
                      struct prompt_options, key, parse_key ),
        OPTION_DESC ( "timeout", 't', required_argument,
                      struct prompt_options, timeout, parse_timeout ),
};

/** "prompt" command descriptor */
static struct command_descriptor prompt_cmd =
        COMMAND_DESC ( struct prompt_options, prompt_opts, 0, MAX_ARGUMENTS,
                       "[<text>]" );

/**
 * "prompt" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int prompt_exec ( int argc, char **argv ) {
        struct prompt_options opts;
        char *text;
        int rc;

        /* Parse options */
        if ( ( rc = parse_options ( argc, argv, &prompt_cmd, &opts ) ) != 0 )
                goto err_parse;

        /* Parse prompt text */
        text = concat_args ( &argv[optind] );
        if ( ! text ) {
                rc = -ENOMEM;
                goto err_concat;
        }

        /* Display prompt and wait for key */
        if ( ( rc = prompt ( text, opts.timeout, opts.key ) ) != 0 )
                goto err_prompt;

        /* Free prompt text */
        free ( text );

        return 0;

 err_prompt:
        free ( text );
 err_concat:
 err_parse:
        return rc;
}

/** "prompt" command */
struct command prompt_command __command = {
        .name = "prompt",
        .exec = prompt_exec,
};