Full Code of vvy/wshell for AI

Repository: vvy/wshell
Branch: master
Commit: 328695314a7a
Files: 10
Total size: 21.0 KB

Directory structure:
gitextract_6f06dpcs/

├── .gitignore
├── README.md
├── builtin_command.c
├── makefile
├── parsing.c
├── read_command.c
├── test.c
├── type_prompt.c
├── wshell.c
└── wshell.h

================================================
FILE CONTENTS
================================================

================================================
FILE: .gitignore
================================================
*.[oa]
*~


================================================
FILE: README.md
================================================
# Introduction
A simple simulation of shell in Linux for learning.
A blog (in Chinese) of introduction and how to build it :http://www.cnblogs.com/wuyuegb2312/p/3399566.html

# Usage
type

　　make wshell

for wshell read input by fgets() or

　　make wshell_r
　　

for wshell with readline lib.It need to install libreadline5-dev first.


## Attention

　　Because of the lack of support for regular expressions , typing file's names such as "*.c" are not support.
　　

# File List
### wshell.c
　　main program

### type_prompt.c
　　print out the prompt of wshell including path,hostname

### read_command.c
　　read command input, and analyse the command and parameter(s).

### builtin_command.c
　　support some built-in command,such as exit,quit,about, and cd.

### test.c
　　a test program, helloworld, which can be executed in wshell.

### parsing.c
　　analyses user's input line and tell them to wshell.
　　
# Update log

## 2015
### 11.08
    -Make the README.md be a real markdown file.
    -Bug fix1:
        Redirection operator ">>" will append a file, not trunc it to 0-size.
As noted by [caiminfeng](http://www.cnblogs.com/caiminfeng/) .

    -Bug fix2:
        When inputed "cd", it would be core dump before.
As noted by [guokesong](https://github.com/guokesong) in [issues2](https://github.com/vvy/wshell/issues/2).

## 2014
### 05.14

    -Bug fix:

        In readline mode, the spaces alloced by readline() was freed only once.Now they are all freed in the end of read_command().

As noted by [xingfe123](http://home.cnblogs.com/u/614123/) 

 

### 04.14

    -Bug fix:

        Add handler of SIGCHLD. Earlier wshell would ignore the zombie process in background.

        The handler only process the background process whose pid are saved in a array.

     -Adjust some indents, although they are not errors.

 

## 2013

### 12.8

    -Bug fix:

        Output redirect function was not completed. '>' still is for make new file,but '>>' append to any file now.

 

### 11.3
    -Implemented a simple parsing function parse() to analyses the user input.
    -Support I/O redirect, background running, and pipe. 
    -Bug fix:
        Typing ctrl+d will normal exit wshell. before, segment fault when using readline lib.

        Lack of free() somewhere, which may lead to memory leak.

 

### 11.1
    -Implemented some builtin command,such as exit/quit, about, and, cd.
    -Bug fix:
        Never free the memory of command and parameters before, which may cause memory leak.
        To solve it, read_command() has been rewrited, and is more like the one in Linux.
    -Rewrite read_command():
        There is no need to malloc for command and parameters any more.
        All these just are pointers now.
    -Supply two versions:
        Using readline lib and not.the former need installing readline lib.
        Type "make wshell_r" to make the former,and "make wshell" for another.


### 10.31
    -Use execvp() instead of execve() to handle with commands like ls.
    -Detect whether the shell is executed as root by geteuid()
    -Bug fix:
        execv()'s arg[0] usually is the name of command without path.
        earlier version is not correct.
    -Plan to do:
        a built-in cd command.

##10.16
    -A shell with basic function: get input and execute the test program(hello world).


# 简介
为了学习而编写的Linux下shell的简单模拟实现。
介绍如何一步一步编写该程序的博客：http://www.cnblogs.com/wuyuegb2312/p/3399566.html

# 用法
输入

　　make wshell

构建使用fgets()接收命令的wshell

　　make wshell_r
　　

构建使用readline接收命令的wshell。需要安装libreadline5-dev或其他类似的库。


## 注意

　　由于不支持正则表达式，含有通配符如"*.c"这样的文件名是不支持的。
    不存在的命令不会提示。
　　

# 文件列表
### wshell.c
　　主程序

### type_prompt.c
　　拼接当前路径、主机名的提示符。

### read_command.c
　　读取输入的命令，并分离出其中的参数。

### builtin_command.c
　　提供对基本内建命令的支持，含exit、quit、about、cd等。

### test.c
　　用来在wshell中执行的测试程序。

### parsing.c
　　分析用户输入（是否使用了管道、重定向、后台执行等）。
　　
# 更新记录

## 2015
### 11.08
    -让README.md成为了真正的markdown文件
    -调整部分缩进
    -Bug修复1:
        重定向符">>"将正确地在文件存在时做追加，而非把它变成0大小的文件。
感谢[caiminfeng](http://www.cnblogs.com/caiminfeng/) 的指出。

    -Bug修复2:
       当输入不带参数的 `cd`时，会导致崩溃。
感谢 [guokesong](https://github.com/guokesong) 在 [issues2](https://github.com/vvy/wshell/issues/2) 指出。

## 2014
### 05.14

    -Bug修复:

        在readline模式下, readline()申请的内存不会被释放。

感谢[xingfe123](http://home.cnblogs.com/u/614123/) 指出。

 

### 04.14

    -Bug修复:

        增加了SIGCHLD信号的处理器。较早版本的wshell不会处理后台的僵尸进程。

        但是该处理器只会处理事先保存了pid的子进程。

    -调整了不会导致错误的缩进。

 

## 2013

### 12.08

    -Bug修复:

        输出重定向尚未完成。 '>' 仍然会创建新文件，但是'>>'会往文件末尾追加。

 

### 11.03
    -实现了用于分析用户输入的函数parse()。
    -支持输入输出重定向、管道、后台运行。
    -Bug修复:
        输入ctrl+d会正常退出wshell了。此前，在使用readline库时会段错误。

        由于某处缺少free(), 会内存泄漏。

 

### 11.01
    -实现了一些内建命令，包括`exit` 、 `quit` 、 `about` 、 `cd`。
    -Bug修复:
        从未释放命令和参数的空间，导致内存泄漏。
        重写read_command()以解决这个问题，现在的行为更像Linux的了。
    -重写read_command():
        现在没必要为command和parameter释放内存了，它们只是指针。
    -提供了两个版本:
        使用readline库和不使用的。前者需要事先安装这个库。
        输入"make wshell_r"可以生成前者，而"make wshell"会生成后者。


### 10.31
    -用execvp()代替execve()处理 `ls` 这种命令。
    -通过geteuid()判断shell是否执行在root用户下。
    -Bug修复:
        execv()'的arg[0]一般是不含路径的命令，上一个版本处理有误。
    -下一步计划:
        支持内建命令 `cd`。

##10.16
    -一个具有基本功能的shell: 获取输入并执行测试程序(hello world).

================================================
FILE: builtin_command.c
================================================
/*
 * =====================================================================================
 *       Filename:  builtin_command.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.11.01 15h31m28s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include "wshell.h"

int builtin_command(char *command, char **parameters)
{
	extern struct passwd *pwd;
    if(strcmp(command,"exit")==0 || strcmp(command,"quit")==0)
        exit(0);
    else if(strcmp(command,"about") == 0)
    {
        printf("This is a simulation of shell (bash) in Linux.\n");
        return 1;
    }
    else if(strcmp(command,"cd")==0)
    {
        char *cd_path = NULL;

        if(parameters[1] == NULL)
        //make "cd" to "cd .." as in bash
        {
            parameters[1] = malloc(3 * sizeof(char));
            parameters[1][0]= '.';
            parameters[1][1]= '.';
            parameters[1][2]= '\0';
        }
        if(parameters[1][0] == '~')
        {
            cd_path = malloc(strlen(pwd->pw_dir)+strlen(parameters[1]));
            //'~' makes length 1 more,but instead of '\0'
            if(cd_path == NULL)
            {
                printf("cd:malloc failed.\n");
            }
            strcpy(cd_path,pwd->pw_dir);
            strncpy(cd_path+strlen(pwd->pw_dir),parameters[1]+1,strlen(parameters[1]));
			//printf("path with ~:\n%s\n",cd_path);
        }
        else
        {
            cd_path = malloc(strlen(parameters[1]+1));
            if(cd_path == NULL)
            {
                printf("cd:malloc failed.\n");
            }
            strcpy(cd_path,parameters[1]);
        }
        if(chdir(cd_path)!= 0)
            printf("-wshell: cd: %s:%s\n",cd_path,strerror(errno));
        free(cd_path);
    }
    return 0;
}


================================================
FILE: makefile
================================================
wshell: wshell.h wshell.c type_prompt.c read_command.c builtin_command.c parsing.c test
	gcc wshell.c type_prompt.c read_command.c builtin_command.c parsing.c -o wshell

wshell_r: wshell.h wshell.c type_prompt.c read_command.c builtin_command.c parsing.c test
	gcc wshell.c type_prompt.c read_command.c builtin_command.c parsing.c -o wshell -D READLINE_ON -I /usr/include -lreadline -ltermcap

test: test.c
	gcc test.c -o test

clean:
	rm -f wshell test


================================================
FILE: parsing.c
================================================
/*
 * =====================================================================================
 *       Filename:  parsing.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.11.02 15h44min23s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include "wshell.h"

int parse_info_init(struct parse_info *info)
{
    info->flag = 0;
    info->in_file = NULL;
    info->out_file = NULL;
    info->command2 = NULL;
    info->parameters2 = NULL;
    return 0;
}

int parsing(char **parameters,int ParaNum,struct parse_info *info)
{
    int i;
    parse_info_init(info);
    if(strcmp(parameters[ParaNum-1],"&") ==0)
    {
        info->flag |= BACKGROUND;
        parameters[ParaNum-1] = NULL;
        ParaNum--;
    }
    for(i=0;i<ParaNum;)
    {
        if(strcmp(parameters[i],"<<")==0 || strcmp(parameters[i],"<")==0)
        {
            info->flag |= IN_REDIRECT;
            info->in_file = parameters[i+1];
            parameters[i] = NULL;
            i+=2;
        }
        else if(strcmp(parameters[i],">")==0)
        {
            info->flag |= OUT_REDIRECT;
            info->out_file = parameters[i+1];
            parameters[i] = NULL;
            i+=2;
        }
        else if(strcmp(parameters[i],">>")==0)
        {
            info->flag |= OUT_REDIRECT_APPEND;
            info->out_file = parameters[i+1];
            parameters[i] = NULL;
            i+=2;
        }
        else if(strcmp(parameters[i],"|")==0)
        {
            char* pCh;
            info->flag |= IS_PIPED;
            parameters[i] = NULL;
            info->command2 = parameters[i+1];
            info->parameters2 = &parameters[i+1];
            for(pCh = info->parameters2[0]+strlen(info->parameters2[0]);
                    pCh!=&(info->parameters2[0][0]) && *pCh!='/';pCh--)
                ;
            if(*pCh == '/')
                pCh++;
            info->parameters2[0] = pCh;
            break;
        }
        else
            i++;
    }
#ifdef DEBUG
	printf("\nbackground:%s\n",info->flag&BACKGROUND?"yes":"no");
	printf("in redirect:");
	info->flag&IN_REDIRECT?printf("yes,file:%s\n",info->in_file):printf("no\n");
	printf("out redirect:");
	info->flag&OUT_REDIRECT?printf("yes,file:%s\n",info->out_file):printf("no\n");
	printf("pipe:");
	info->flag&IS_PIPED?printf("yes,command:%s %s %s\n",info->command2,info->parameters2[0],info->parameters2[1]):printf("no\n");
#endif
    return 1;
}


================================================
FILE: read_command.c
================================================
/*
 * =====================================================================================
 *       Filename:  read_command.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.21 14h12min24s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include "wshell.h"
#ifdef READLINE_ON
#include <readline/readline.h>
#include <readline/history.h>
#endif

//return value: number of parameters
//0 represents only command without any parameters
//-1 represents wrong input
int read_command(char **command,char **parameters,char *prompt)
{
#ifdef READLINE_ON
    free(buffer);
    buffer = readline(prompt);
    if(feof(stdin)) {
        printf("\n");
        exit(0);
    }

#else
    printf("%s",prompt);
    char* Res_fgets = fgets(buffer,MAXLINE,stdin);
    if(Res_fgets == NULL)
    {
        printf("\n");
        exit(0);
    }		
#endif

    if(buffer[0] == '\0')
        return -1;
    char *pStart,*pEnd;
    int count = 0;
    int isFinished = 0;
    pStart = pEnd = buffer;
    while(isFinished == 0)
    {
        while((*pEnd == ' ' && *pStart == ' ') || (*pEnd == '\t' && *pStart == '\t'))
        {
            pStart++;
            pEnd++;
        }

        if(*pEnd == '\0' || *pEnd == '\n')
        {
            if(count == 0)
                return -1;
            break;
        }

        while(*pEnd != ' ' && *pEnd != '\0' && *pEnd != '\n')
            pEnd++;


        if(count == 0)
        {
            char *p = pEnd;
            *command = pStart;
            while(p!=pStart && *p !='/')
                p--;
            if(*p == '/')
                p++;
            //else //p==pStart
            parameters[0] = p;
            count += 2;
#ifdef DEBUG
            printf("\ncommand:%s\n",*command);
#endif
        }
        else if(count <= MAXARG)
        {
            parameters[count-1] = pStart;
            count++;
        }
        else
        {
            break;
        }

        if(*pEnd == '\0' || *pEnd == '\n')
        {
            *pEnd = '\0';
            isFinished = 1;
        }
        else
        {
            *pEnd = '\0';
            pEnd++;
			pStart = pEnd;
        }
    }

    parameters[count-1] = NULL;

#ifdef DEBUG
    /*input analysis*/
    printf("input analysis:\n");
    printf("pathname:[%s]\ncommand:[%s]\nparameters:\n",*command,parameters[0]);
    int i;
    for(i=0;i<count-1;i++)
        printf("[%s]\n",parameters[i]);
#endif

    return count;
}


================================================
FILE: test.c
================================================
/*
 * =====================================================================================
 *       Filename:  test.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.16 20h40m39s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include <stdio.h>
int main()
{
    printf("Hello world!\n");
    return 0;
}


================================================
FILE: type_prompt.c
================================================
/*
 * =====================================================================================
 *       Filename:  type_prompt.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.16 20h18min28s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
//#include <sys/utsname.h>
#include "wshell.h"
const int max_name_len = 256;
const int max_path_len = 1024;

void type_prompt(char *prompt)
{
    extern struct passwd *pwd;
    char hostname[max_name_len];
    char pathname[max_path_len];
    int length;
    pwd = getpwuid(getuid());
    getcwd(pathname,max_path_len);
    if(gethostname(hostname,max_name_len)==0)
        sprintf(prompt,"[Wshell]%s@%s:",pwd->pw_name,hostname);
    else
        sprintf(prompt,"[Wshell]%s@unknown:",pwd->pw_name);
    //printf("pathname: %s,length:%d\npw_dir:%s,length:%d\n",
    //pathname,strlen(pathname),pwd->pw_dir,strlen(pwd->pw_dir));
    length = strlen(prompt);
    if(strlen(pathname) < strlen(pwd->pw_dir) || 
            strncmp(pathname,pwd->pw_dir,strlen(pwd->pw_dir))!=0)
        sprintf(prompt+length,"%s",pathname);
    else
        sprintf(prompt+length,"~%s",pathname+strlen(pwd->pw_dir));
    length = strlen(prompt);
    if(geteuid()==0)
        sprintf(prompt+length,"#");
    else
        sprintf(prompt+length,"$");
    return;
}

//int main()
//{
//    type_prompt();
//    return 0;
//}


================================================
FILE: wshell.c
================================================
/*
 * =====================================================================================
 *       Filename:  wshell.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.16 17h12min19s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include "wshell.h"
#define TRUE 1
#define MAXPIDTABLE 1024

pid_t BPTable[MAXPIDTABLE];

void sig_handler(int sig)
{
    pid_t pid;
    int i;
    for(i=0;i<MAXPIDTABLE;i++)
        if(BPTable[i] != 0) //only handler the background processes
        {
            pid = waitpid(BPTable[i],NULL,WNOHANG);
            if(pid > 0)
            {
                printf("process %d exited.\n",pid);
                BPTable[i] = 0; //clear
            }
            else if(pid < 0)
            {
	if(errno != ECHILD)
                    perror("waitpid error");
            }
            //else:do nothing.
            //Not background processses has their waitpid() in wshell.
         }
    return;
}

void proc(void)
{
    int status,i;
    char *command = NULL;
    char **parameters;
    int ParaNum;
    char prompt[MAX_PROMPT];
    struct parse_info info;
    pid_t ChdPid,ChdPid2;
    parameters = malloc(sizeof(char *)*(MAXARG+2));
    buffer = malloc(sizeof(char) * MAXLINE);
    if(parameters == NULL || buffer == NULL)
    {
        printf("Wshell error:malloc failed.\n");
        return;
    }
	//arg[0] is command
	//arg[MAXARG+1] is NULL

    if(signal(SIGCHLD,sig_handler) == SIG_ERR)
        perror("signal() error");

    while(TRUE)
    {
        int pipe_fd[2],in_fd,out_fd;
        type_prompt(prompt);
        ParaNum = read_command(&command,parameters,prompt);
        if(-1 == ParaNum)
            continue;
        ParaNum--;//count of units in buffer
        parsing(parameters,ParaNum,&info);
        if(builtin_command(command,parameters))
            continue;
        if(info.flag & IS_PIPED) //command2 is not null
        {                
            if(pipe(pipe_fd)<0)
            {
                printf("Wshell error:pipe failed.\n");
                exit(0);
            }
        }  
        if((ChdPid = fork())!=0) //wshell
        {
            if(info.flag & IS_PIPED)
            {
                if((ChdPid2=fork()) == 0) //command2
                {
                    close(pipe_fd[1]);
                    close(fileno(stdin)); 
                    dup2(pipe_fd[0], fileno(stdin));
                    close(pipe_fd[0]); 
                    execvp(info.command2,info.parameters2);
                }
                else
                {
                    close(pipe_fd[0]);
                    close(pipe_fd[1]);
                    waitpid(ChdPid2,&status,0); //wait command2
                }
            }

            if(info.flag & BACKGROUND)
            {
                printf("Child pid:%u\n",ChdPid);
                int i;
                for(i=0;i<MAXPIDTABLE;i++)
                    if(BPTable[i]==0)
                        BPTable[i] = ChdPid; //register a background process
                if(i==MAXPIDTABLE)
                    perror("Too much background processes\nThere will be zombine process");                    
            }
            else
            {          
                waitpid(ChdPid,&status,0);//wait command1
            } 
        }
        else //command1
        {
			
            if(info.flag & IS_PIPED) //command2 is not null
            {                
                if(!(info.flag & OUT_REDIRECT) && !(info.flag & OUT_REDIRECT_APPEND)) // ONLY PIPED
	           {
                    close(pipe_fd[0]);
                    close(fileno(stdout)); 
                    dup2(pipe_fd[1], fileno(stdout));
                    close(pipe_fd[1]);
                }
                else //OUT_REDIRECT and PIPED
	           {
                    close(pipe_fd[0]);
                    close(pipe_fd[1]);//send a EOF to command2
                    if(info.flag & OUT_REDIRECT)
    	               out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_TRUNC, 0666);
                    else
    	               out_fd = open(info.out_file, O_WRONLY|O_APPEND|O_TRUNC, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);	        
                }
            }
            else
            {
                if(info.flag & OUT_REDIRECT) // OUT_REDIRECT WITHOUT PIPE
	           {
                    out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_TRUNC, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);
                }
                if(info.flag & OUT_REDIRECT_APPEND) // OUT_REDIRECT_APPEND WITHOUT PIPE
	           {
                    out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_APPEND, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);
                }
            }
            
            if(info.flag & IN_REDIRECT)
            {
                in_fd = open(info.in_file, O_CREAT |O_RDONLY, 0666);
                close(fileno(stdin)); 
                dup2(in_fd, fileno(stdin));
                close(in_fd); 
            }
            execvp(command,parameters);
        }
    }
    free(parameters);
	free(buffer);
}

int main() {
    int i;
    //init the BPTable
    for(i=0;i<MAXPIDTABLE;i++)
        BPTable[i] = 0;
    proc();
    return 0;
}


================================================
FILE: wshell.h
================================================
/*
 * =====================================================================================
 *       Filename:  wshell.h
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.16 20h15min26s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h> 
#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h> 
#define MAX_PROMPT 1024
#define MAXLINE 4096 //the length of all args is ARG_MAX
#define MAXARG 20

struct parse_info;
struct passwd *pwd;
char *buffer;

void type_prompt(char*);
int read_command(char **,char **,char*);
int builtin_command(char *,char **);
int parsing(char **,int,struct parse_info *);
void proc(void);
void sig_handler(int sig);



#ifndef STRUCT_PARSE_INFO
#define STRUCT_PARSE_INFO
#define BACKGROUND 			1
#define IN_REDIRECT 		2
#define OUT_REDIRECT 		4
#define OUT_REDIRECT_APPEND	8
#define IS_PIPED 			16
struct parse_info 
{
    int flag;
    char* in_file;
    char* out_file;
    char* command2;
	char** parameters2;
};
#endif