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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 bein the foreground state. */BACKGROUND, /* job is running in background */STOPPED, /* job is stopped via SIGSTOP */NEEDSTERMINAL, /* job is stopped because it was a background joband 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 fromfile 'iored_input' */char *iored_output; /* If non-NULL, last command should write tofile '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 wasstopped 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 wordsmaking up this command. */char *iored_input; /* If non-NULL, command should read fromfile 'iored_input' */char *iored_output; /* If non-NULL, command should write tofile '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;