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/*

 * esh - the 'extensible' shell.

 *

 * Developed by Godmar Back for CS 3214 Fall 2009

 * Virginia Tech.

 * 

 * $Id: esh.h,v 1.4 2011/03/29 15:46:28 cs3214 Exp $

 */

#include <stdbool.h>

#include <obstack.h>

#include <stdlib.h>

#include <termios.h>

#include "list.h"

/* Forward declarations. */

struct esh_command;

struct esh_pipeline;

struct esh_command_line;

/*

 * A esh_shell object allows plugins to access services and information. 

 * The shell object should support the following operations.

 */

struct esh_shell {

    /* Return the list of current jobs */

    struct list/* <esh_pipeline> */ * (* get_jobs) (void);

    /* Return job corresponding to jid */

    struct esh_pipeline * (* get_job_from_jid)(int jid);

    /* Return job corresponding to pgrp */

    struct esh_pipeline * (* get_job_from_pgrp)(pid_t pgrp);

    /* Return process corresponding to pid */

    struct esh_command * (* get_cmd_from_pid)(pid_t pid);

    /* Build a prompt.  Memory must be malloc'd */

    char * (* build_prompt) (void);

    /* Read an input line */

    char * (* readline) (const char *prompt);

    /* Parse command line */

    struct esh_command_line * (* parse_command_line) (char *);

};

/* 

 * Modules must define a esh_plugin instance named 'esh_module.'

 * Each of the following members is optional.

 * esh will call its 'init' functions upon successful load.

 *

 * For binary compatibility, do not change the order of these fields.

 */

struct esh_plugin {

    struct list_elem elem;    /* Link element */

    /* an integer number denoting the relative rank of the plugin

     * Plugins are notified of events in increasing rank. */

    int rank;

    /* Initialize plugin and pass shell object */

    bool (* init)(struct esh_shell *);

    /* The return value of the following three functions indicates

     * whether the plugin wants processing to stop.

     * true - indicates processing should stop.

     * false - indicates processing should continue.

     */

    /* The command line the user entered.

     * A plugin may change it. */

    bool (* process_raw_cmdline)(char **);

    /* A given pipeline of commands 

     * A plugin may change it. */

    bool (* process_pipeline)(struct esh_pipeline *);

    /* If the command is a built-in provided by a plugin, execute the

     * command and return true. */

    bool (* process_builtin)(struct esh_command *);

    /* Manufacture part of a prompt.  Memory must be allocated via malloc(). 

     * If no plugin implements this, the shell will provide a default prompt. */

    char * (* make_prompt)(void);

    /* The process or processes that are part of a new pipeline

     * have been forked.  

     * The jid and pgid fields of the pipeline and the pid fields

     * of all commands in the pipeline are set.

     * SIGCHLD is blocked.

     */

    void (* pipeline_forked)(struct esh_pipeline *);

    /* Notify the plugin about a child's status change.

     * 'waitstatus' is the value returned by waitpid(2) 

     *

     * May be called from SIGCHLD handler.

     * The status of the associated pipeline has not yet been

     * updated.

     * */

    bool (* command_status_change)(struct esh_command *, int waitstatus);

    /* Add additional fields here if needed. */

};

/* A command line may contain multiple pipelines. */

struct esh_command_line {

    struct list/* <esh_pipeline> */ pipes;        /* List of pipelines */

    /* Add additional fields here if needed. */

};

enum job_status  { 

    FOREGROUND,     /* job is running in foreground.  Only one job can be

                       in the foreground state. */

    BACKGROUND,     /* job is running in background */

    STOPPED,        /* job is stopped via SIGSTOP */

    NEEDSTERMINAL,  /* job is stopped because it was a background job

                       and requires exclusive terminal access */

    COMPLETED,

    TERMINATED,

};

/* A pipeline is a list of one or more commands. 

 * For the purposes of job control, a pipeline forms one job.

 */

struct esh_pipeline {

    struct list/* <esh_command> */ commands;    /* List of commands */

    char *iored_input;       /* If non-NULL, first command should read from

                                file 'iored_input' */

    char *iored_output;      /* If non-NULL, last command should write to

                                file 'iored_output' */

    bool append_to_output;   /* True if user typed >> to append */

    bool bg_job;             /* True if user entered & */

    struct list_elem elem;   /* Link element. */

    int     jid;             /* Job id. */

    pid_t   pgrp;            /* Process group. */

    enum job_status status;  /* Job status. */ 

    struct termios saved_tty_state;  /* The state of the terminal when this job was 

                                        stopped after having been in foreground */

    /* Add additional fields here if needed. */

    char cmd_string[256];   /* Command string */

};

/* A command is part of a pipeline. */

struct esh_command {

    char **argv;             /* NULL terminated array of pointers to words

                                making up this command. */

    char *iored_input;       /* If non-NULL, command should read from

                                file 'iored_input' */

    char *iored_output;      /* If non-NULL, command should write to

                                file 'iored_output' */

    bool append_to_output;   /* True if user typed >> to append */

    struct list_elem elem;   /* Link element to link commands in pipeline. */

    pid_t   pid;             /* Process id. */

    struct esh_pipeline * pipeline; 

                              /* The pipeline of which this job is a part. */

    /* Add additional fields here if needed. */

};

/** ----------------------------------------------------------- */

/* Create new command structure and initialize it */

struct esh_command * esh_command_create(char ** argv, 

                   char *iored_input, 

                   char *iored_output, 

                   bool append_to_output);

/* Create a new pipeline containing only one command */

struct esh_pipeline * esh_pipeline_create(struct esh_command *cmd);

/* Complete a pipe's setup by copying I/O redirection information

 * from first and last command */

void esh_pipeline_finish(struct esh_pipeline *pipe);

/* Create an empty command line */

struct esh_command_line * esh_command_line_create_empty(void);

/* Create a command line with a single pipeline */

struct esh_command_line * esh_command_line_create(struct esh_pipeline *pipe);

/* Deallocation functions */

void esh_command_line_free(struct esh_command_line *);

void esh_pipeline_free(struct esh_pipeline *);

void esh_command_free(struct esh_command *);

/* Print functions */

void esh_command_print(struct esh_command *cmd);

void esh_pipeline_print(struct esh_pipeline *pipe);

void esh_command_line_print(struct esh_command_line *line);

/* Parse a command line.  Implemented in esh-grammar.y */

struct esh_command_line * esh_parse_command_line(char * line);

/* Load plugins from directory dir */

void esh_plugin_load_from_directory(char *dirname);

/* Initialize loaded plugins */

void esh_plugin_initialize(struct esh_shell *shell);

/* List of loaded plugins */

extern struct list esh_plugin_list;