sh.y.svn-base

大学操作系统课程实验：Linux下实现的一个shell解释器。能够比较完整完好地执行Linux下的普通命令、重定向命令、管道命令等多种命令。

%{
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "global.h"

#define LEN 20
%}
%union{
char *sym;
}
%token String
%right '&'
%type <sym> String ExecFile
%type <sym> '&'

%%

CommandLine : //NULL
           |FgCommandLine                  {reset();}
	   |FgCommandLine '&'             {reset();is_back=1;}               
	         ;

FgCommandLine :   SimpleCommand            {storesimple();}
                   |FirstCommand MidCommand LastCommand   {cmd_flag=PIPE_CMD;resettoppipe();}
                         	;
SimpleCommand:    ProgInvocation  InputRedirect OutputRedirect   {}
;
FirstCommand :    ProgInvocation  InputRedirect  {storepipe();reset();}
;
MidCommand:     //NULL
                |MidCommand '|' ProgInvocation   {storepipe();reset();}
                   ;
LastCommand:    '|'ProgInvocation  OutputRedirect   {storepipe();reset();}
;
ProgInvocation :  ExecFile Args   {}
;
InputRedirect:  //NULL
                    |'<'String  {pushio();storefile();cmd_flag=REDIRECT_CMD;io_flag=FD_READ;}
;
OutputRedirect: //NULL
                     |'>'String {pushio();storefile();cmd_flag=REDIRECT_CMD;io_flag=FD_WRITE;}
;
ExecFile:	String                   {pushcmd();}
	  ;
Args:    //NULL
	|  Args String                   {pushpara();}
	;

%%

char *backjobs="&";
char *pipejobs="|";
char *injobs="<";
char *outjobs=">";
char *stackpara[LEN];
char *stackcmd[LEN];
char *stackfile[LEN];
char buf[100];
char *p = buf;
int lineno = 0;
int topcmd = 0;
int toppara=0;
int topfile=0;
int toppipe=0;
    
/**********************************************************************************************************/ 

yylex()
{
	int c;
	p = buf;
	while((c = getchar()) == ' ' || c == '\t');
	if(c == '\n'){
	return 0; 
               }
	if(c != '\n') {
		do {
			*p++ = c;
			c = getchar();
		}while(c != ' ' && c != '\t' && c != '\n');
		ungetc(c,stdin);
		*p = '\0';
		yylval.sym = buf;
		if(!strcmp(buf,backjobs))
			return '&';
                else if(!strcmp(buf,injobs))
                        return '<';
                else if(!strcmp(buf,outjobs))
                        return '>';
                else if(!strcmp(buf,pipejobs))
                        return '|'; 
		else
			return String;
	} else {
		lineno ++;
	}
	return c;
}    
/**********************************************************************************************************/ 

yyerror(char *s){
	warning(s, (char *)0);
}
    
/**********************************************************************************************************/ 
warning(char *s,char *t)
{
	
}


    
/**********************************************************************************************************/ 

reset()
{
	int i;
	for(i = 0; i < topcmd; i++) {
		free(stackcmd[i]);
		stackcmd[i] = NULL;
	}
	topcmd = 0;
	for(i = 0; i < toppara; i++) {
		free(stackpara[i]);
		stackpara[i] = NULL;
	}
	toppara=0;
	for(i=0;i<topfile;i++){
	    free(stackfile[i]);
	    stackfile[i]=NULL;
	    }
	topfile=0;
}
    
/**********************************************************************************************************/ 
pushcmd()
{
	char *temp = NULL;
	if(topcmd == 0)
		temp = (char *)malloc(sizeof(char) * 10);
	else
		temp = (char *)malloc(strlen(buf) + 1);
	strcpy(temp,buf);
	stackcmd[topcmd] = temp;
	topcmd++;
}
    
/**********************************************************************************************************/ 
pushpara()
{
	char *temp = NULL;
	if(toppara == 0)
		temp = (char *)malloc(sizeof(char) * 30);
	else
		temp = (char *)malloc(strlen(buf) + 1);
	strcpy(temp,buf);
	stackpara[toppara] = temp;
        toppara++;
}
    
/**********************************************************************************************************/ 
pushio()
{
	char *temp = NULL;
	if(topfile == 0)
		temp = (char *)malloc(sizeof(char) * 30);
	else
		temp = (char *)malloc(strlen(buf) + 1);
	strcpy(temp,buf);
	stackfile[topfile] = temp;
        
	topfile++;
}
    
/**********************************************************************************************************/ 
storesimple(){
	int i=0;
        if(topcmd)
        {
	   cmdStr.cmd=(char *)malloc(sizeof(char) * 10);
	   strcpy(cmdStr.cmd,stackcmd[0]);	
	}
        for(i=0;i<toppara;i++){
	cmdStr.para[i]=(char *)malloc(sizeof(char) * 10);
	strcpy(cmdStr.para[i],stackpara[i]);
        cmdStr.para[i+1]=NULL;	}
}


/**********************************************************************************************************/
storefile(){
    cmdStr.filename=(char*)malloc(sizeof(char)*50);
    strcpy(cmdStr.filename,stackfile[0]);
    }
    
    
/**********************************************************************************************************/    
    
storepipe(){
    int i=0;
    if(topcmd)
    {
  
       pipeStr[toppipe].cmd=(char *)malloc(sizeof(char) * 10);
       strcpy(pipeStr[toppipe].cmd,stackcmd[0]);
  
    }
    
    for(i=0;i<toppara;i++){
        pipeStr[toppipe].para[i]=(char *)malloc(sizeof(char) * 10);
        strcpy(pipeStr[toppipe].para[i],stackpara[i]);
    }
  
   if(stackfile[0]!=NULL){
        pipeStr[toppipe].filename=(char *)malloc(sizeof(char) * 50);
        strcpy(pipeStr[toppipe].filename,stackfile[0]);
    }
    pipeStr[toppipe].io_flag = io_flag;
    io_flag = NO_IO;
    toppipe++;
    pipe_len=toppipe;
}
/****************************************************************************************************************/
resettoppipe(){
toppipe=0;
}