exec.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., 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 );

#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
#include <assert.h>
#include <ipxe/tables.h>
#include <ipxe/command.h>
#include <ipxe/parseopt.h>
#include <ipxe/settings.h>
#include <ipxe/shell.h>

/** @file
 *
 * Command execution
 *
 */

/** Shell stop state */
static int stop_state;

/**
 * Execute command
 *
 * @v command           Command name
 * @v argv              Argument list
 * @ret rc              Return status code
 *
 * Execute the named command.  Unlike a traditional POSIX execv(),
 * this function returns the exit status of the command.
 */
int execv ( const char *command, char * const argv[] ) {
        struct command *cmd;
        int argc;
        int rc;

        /* Count number of arguments */
        for ( argc = 0 ; argv[argc] ; argc++ ) {}

        /* An empty command is deemed to do nothing, successfully */
        if ( command == NULL ) {
                rc = 0;
                goto done;
        }

        /* Sanity checks */
        if ( argc == 0 ) {
                DBG ( "%s: empty argument list\n", command );
                rc = -EINVAL;
                goto done;
        }

        /* Reset getopt() library ready for use by the command.  This
         * is an artefact of the POSIX getopt() API within the context
         * of Etherboot; see the documentation for reset_getopt() for
         * details.
         */
        reset_getopt();

        /* Hand off to command implementation */
        for_each_table_entry ( cmd, COMMANDS ) {
                if ( strcmp ( command, cmd->name ) == 0 ) {
                        rc = cmd->exec ( argc, ( char ** ) argv );
                        goto done;
                }
        }

        printf ( "%s: command not found\n", command );
        rc = -ENOEXEC;

 done:
        /* Store error number, if an error occurred */
        if ( rc ) {
                errno = rc;
                if ( errno < 0 )
                        errno = -errno;
        }

        return rc;
}

/**
 * Split command line into tokens
 *
 * @v command           Command line
 * @v tokens            Token list to populate, or NULL
 * @ret count           Number of tokens
 *
 * Splits the command line into whitespace-delimited tokens.  If @c
 * tokens is non-NULL, any whitespace in the command line will be
 * replaced with NULs.
 */
static int split_command ( char *command, char **tokens ) {
        int count = 0;

        while ( 1 ) {
                /* Skip over any whitespace / convert to NUL */
                while ( isspace ( *command ) ) {
                        if ( tokens )
                                *command = '\0';
                        command++;
                }
                /* Check for end of line */
                if ( ! *command )
                        break;
                /* We have found the start of the next argument */
                if ( tokens )
                        tokens[count] = command;
                count++;
                /* Skip to start of next whitespace, if any */
                while ( *command && ! isspace ( *command ) ) {
                        command++;
                }
        }
        return count;
}

/**
 * Process next command only if previous command succeeded
 *
 * @v rc                Status of previous command
 * @ret process         Process next command
 */
static int process_on_success ( int rc ) {
        return ( rc == 0 );
}

/**
 * Process next command only if previous command failed
 *
 * @v rc                Status of previous command
 * @ret process         Process next command
 */
static int process_on_failure ( int rc ) {
        return ( rc != 0 );
}

/**
 * Process next command regardless of status from previous command
 *
 * @v rc                Status of previous command
 * @ret process         Process next command
 */
static int process_always ( int rc __unused ) {
        return 1;
}

/**
 * Find command terminator
 *
 * @v tokens            Token list
 * @ret process_next    "Should next command be processed?" function
 * @ret argc            Argument count
 */
static int command_terminator ( char **tokens,
                                int ( **process_next ) ( int rc ) ) {
        unsigned int i;

        /* Find first terminating token */
        for ( i = 0 ; tokens[i] ; i++ ) {
                if ( tokens[i][0] == '#' ) {
                        /* Start of a comment */
                        break;
                } else if ( strcmp ( tokens[i], "||" ) == 0 ) {
                        /* Short-circuit logical OR */
                        *process_next = process_on_failure;
                        return i;
                } else if ( strcmp ( tokens[i], "&&" ) == 0 ) {
                        /* Short-circuit logical AND */
                        *process_next = process_on_success;
                        return i;
                } else if ( strcmp ( tokens[i], ";" ) == 0 ) {
                        /* Process next command unconditionally */
                        *process_next = process_always;
                        return i;
                }
        }

        /* End of token list */
        *process_next = NULL;
        return i;
}

/**
 * Set shell stop state
 *
 * @v stop              Shell stop state
 */
void shell_stop ( int stop ) {
        stop_state = stop;
}

/**
 * Test and consume shell stop state
 *
 * @v stop              Shell stop state to consume
 * @v stopped           Shell had been stopped
 */
int shell_stopped ( int stop ) {
        int stopped;

        /* Test to see if we need to stop */
        stopped = ( stop_state >= stop );

        /* Consume stop state */
        if ( stop_state <= stop )
                stop_state = 0;

        return stopped;
}

/**
 * Expand settings within a token list
 *
 * @v argc              Argument count
 * @v tokens            Token list
 * @v argv              Argument list to fill in
 * @ret rc              Return status code
 */
static int expand_tokens ( int argc, char **tokens, char **argv ) {
        int i;

        /* Expand each token in turn */
        for ( i = 0 ; i < argc ; i++ ) {
                argv[i] = expand_settings ( tokens[i] );
                if ( ! argv[i] )
                        goto err_expand_settings;
        }

        return 0;

 err_expand_settings:
        assert ( argv[i] == NULL );
        for ( ; i >= 0 ; i-- )
                free ( argv[i] );
        return -ENOMEM;
}

/**
 * Free an expanded token list
 *
 * @v argv              Argument list
 */
static void free_tokens ( char **argv ) {

        /* Free each expanded argument */
        while ( *argv )
                free ( *(argv++) );
}

/**
 * Execute command line
 *
 * @v command           Command line
 * @ret rc              Return status code
 *
 * Execute the named command and arguments.
 */
int system ( const char *command ) {
        int count = split_command ( ( char * ) command, NULL );
        char *all_tokens[ count + 1 ];
        int ( * process_next ) ( int rc );
        char *command_copy;
        char **tokens;
        int argc;
        int process;
        int rc = 0;

        /* Create modifiable copy of command */
        command_copy = strdup ( command );
        if ( ! command_copy )
                return -ENOMEM;

        /* Split command into tokens */
        split_command ( command_copy, all_tokens );
        all_tokens[count] = NULL;

        /* Process individual commands */
        process = 1;
        for ( tokens = all_tokens ; ; tokens += ( argc + 1 ) ) {

                /* Find command terminator */
                argc = command_terminator ( tokens, &process_next );

                /* Expand tokens and execute command */
                if ( process ) {
                        char *argv[ argc + 1 ];

                        /* Expand tokens */
                        if ( ( rc = expand_tokens ( argc, tokens, argv ) ) != 0)
                                break;
                        argv[argc] = NULL;

                        /* Execute command */
                        rc = execv ( argv[0], argv );

                        /* Free tokens */
                        free_tokens ( argv );
                }

                /* Stop processing, if applicable */
                if ( shell_stopped ( SHELL_STOP_COMMAND ) )
                        break;

                /* Stop processing if we have reached the end of the
                 * command.
                 */
                if ( ! process_next )
                        break;

                /* Determine whether or not to process next command */
                process = process_next ( rc );
        }

        /* Free modified copy of command */
        free ( command_copy );

        return rc;
}

/**
 * Concatenate arguments
 *
 * @v args              Argument list (NULL-terminated)
 * @ret string          Concatenated arguments
 *
 * The returned string is allocated with malloc().  The caller is
 * responsible for eventually free()ing this string.
 */
char * concat_args ( char **args ) {
        char **arg;
        size_t len;
        char *string;
        char *ptr;

        /* Calculate total string length */
        len = 1 /* NUL */;
        for ( arg = args ; *arg ; arg++ )
                len += ( 1 /* possible space */ + strlen ( *arg ) );

        /* Allocate string */
        string = zalloc ( len );
        if ( ! string )
                return NULL;

        /* Populate string */
        ptr = string;
        for ( arg = args ; *arg ; arg++ ) {
                ptr += sprintf ( ptr, "%s%s",
                                 ( ( arg == args ) ? "" : " " ), *arg );
        }
        assert ( ptr < ( string + len ) );

        return string;
}

/** "echo" options */
struct echo_options {
        /** Do not print trailing newline */
        int no_newline;
};

/** "echo" option list */
static struct option_descriptor echo_opts[] = {
        OPTION_DESC ( "n", 'n', no_argument,
                      struct echo_options, no_newline, parse_flag ),
};

/** "echo" command descriptor */
static struct command_descriptor echo_cmd =
        COMMAND_DESC ( struct echo_options, echo_opts, 0, MAX_ARGUMENTS,
                       "[...]" );

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

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

        /* Parse text */
        text = concat_args ( &argv[optind] );
        if ( ! text )
                return -ENOMEM;

        /* Print text */
        printf ( "%s%s", text, ( opts.no_newline ? "" : "\n" ) );

        free ( text );
        return 0;
}

/** "echo" command */
struct command echo_command __command = {
        .name = "echo",
        .exec = echo_exec,
};

/** "exit" options */
struct exit_options {};

/** "exit" option list */
static struct option_descriptor exit_opts[] = {};

/** "exit" command descriptor */
static struct command_descriptor exit_cmd =
        COMMAND_DESC ( struct exit_options, exit_opts, 0, 1, "[<status>]" );

/**
 * "exit" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int exit_exec ( int argc, char **argv ) {
        struct exit_options opts;
        unsigned int exit_code = 0;
        int rc;

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

        /* Parse exit status, if present */
        if ( optind != argc ) {
                if ( ( rc = parse_integer ( argv[optind], &exit_code ) ) != 0 )
                        return rc;
        }

        /* Stop shell processing */
        shell_stop ( SHELL_STOP_COMMAND_SEQUENCE );

        return exit_code;
}

/** "exit" command */
struct command exit_command __command = {
        .name = "exit",
        .exec = exit_exec,
};

/** "isset" options */
struct isset_options {};

/** "isset" option list */
static struct option_descriptor isset_opts[] = {};

/** "isset" command descriptor */
static struct command_descriptor isset_cmd =
        COMMAND_DESC ( struct isset_options, isset_opts, 1, 1, "<value>" );

/**
 * "isset" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int isset_exec ( int argc, char **argv ) {
        struct isset_options opts;
        int rc;

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

        /* Return success iff argument is non-empty */
        return ( argv[optind][0] ? 0 : -ENOENT );
}

/** "isset" command */
struct command isset_command __command = {
        .name = "isset",
        .exec = isset_exec,
};

/** "iseq" options */
struct iseq_options {};

/** "iseq" option list */
static struct option_descriptor iseq_opts[] = {};

/** "iseq" command descriptor */
static struct command_descriptor iseq_cmd =
        COMMAND_DESC ( struct iseq_options, iseq_opts, 2, 2,
                       "<value1> <value2>" );

/**
 * "iseq" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int iseq_exec ( int argc, char **argv ) {
        struct iseq_options opts;
        int rc;

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

        /* Return success iff arguments are equal */
        return ( ( strcmp ( argv[optind], argv[ optind + 1 ] ) == 0 ) ?
                 0 : -ERANGE );
}

/** "iseq" command */
struct command iseq_command __command = {
        .name = "iseq",
        .exec = iseq_exec,
};

/** "sleep" options */
struct sleep_options {};

/** "sleep" option list */
static struct option_descriptor sleep_opts[] = {};

/** "sleep" command descriptor */
static struct command_descriptor sleep_cmd =
        COMMAND_DESC ( struct sleep_options, sleep_opts, 1, 1, "<seconds>" );

/**
 * "sleep" command
 *
 * @v argc              Argument count
 * @v argv              Argument list
 * @ret rc              Return status code
 */
static int sleep_exec ( int argc, char **argv ) {
        struct sleep_options opts;
        unsigned int seconds;
        int rc;

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

        /* Parse number of seconds */
        if ( ( rc = parse_integer ( argv[optind], &seconds ) ) != 0 )
                return rc;

        /* Delay for specified number of seconds */
        if ( sleep ( seconds ) != 0 )
                return -ECANCELED;

        return 0;
}

/** "sleep" command */
struct command sleep_command __command = {
        .name = "sleep",
        .exec = sleep_exec,
};