analysis.c

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。

  case 6:
#line 28 "sh.y"
    {cmd_flag=PIPE_CMD;resettoppipe();}
    break;

  case 7:
#line 30 "sh.y"
    {}
    break;

  case 8:
#line 32 "sh.y"
    {storepipe();reset();}
    break;

  case 10:
#line 35 "sh.y"
    {storepipe();reset();}
    break;

  case 11:
#line 37 "sh.y"
    {storepipe();reset();}
    break;

  case 12:
#line 39 "sh.y"
    {}
    break;

  case 14:
#line 42 "sh.y"
    {pushio();storefile();cmd_flag=REDIRECT_CMD;io_flag=FD_READ;}
    break;

  case 16:
#line 45 "sh.y"
    {pushio();storefile();cmd_flag=REDIRECT_CMD;io_flag=FD_WRITE;}
    break;

  case 17:
#line 47 "sh.y"
    {pushcmd();}
    break;

  case 19:
#line 50 "sh.y"
    {pushpara();}
    break;


/* Line 1267 of yacc.c.  */
#line 1395 "analysis.c"
      default: break;
    }
  YY_SYMBOL_PRINT ("-> $$ =", yyr1[yyn], &yyval, &yyloc);

  YYPOPSTACK (yylen);
  yylen = 0;
  YY_STACK_PRINT (yyss, yyssp);

  *++yyvsp = yyval;


  /* Now `shift' the result of the reduction.  Determine what state
     that goes to, based on the state we popped back to and the rule
     number reduced by.  */

  yyn = yyr1[yyn];

  yystate = yypgoto[yyn - YYNTOKENS] + *yyssp;
  if (0 <= yystate && yystate <= YYLAST && yycheck[yystate] == *yyssp)
    yystate = yytable[yystate];
  else
    yystate = yydefgoto[yyn - YYNTOKENS];

  goto yynewstate;


/*------------------------------------.
| yyerrlab -- here on detecting error |
`------------------------------------*/
yyerrlab:
  /* If not already recovering from an error, report this error.  */
  if (!yyerrstatus)
    {
      ++yynerrs;
#if ! YYERROR_VERBOSE
      yyerror (YY_("syntax error"));
#else
      {
	YYSIZE_T yysize = yysyntax_error (0, yystate, yychar);
	if (yymsg_alloc < yysize && yymsg_alloc < YYSTACK_ALLOC_MAXIMUM)
	  {
	    YYSIZE_T yyalloc = 2 * yysize;
	    if (! (yysize <= yyalloc && yyalloc <= YYSTACK_ALLOC_MAXIMUM))
	      yyalloc = YYSTACK_ALLOC_MAXIMUM;
	    if (yymsg != yymsgbuf)
	      YYSTACK_FREE (yymsg);
	    yymsg = (char *) YYSTACK_ALLOC (yyalloc);
	    if (yymsg)
	      yymsg_alloc = yyalloc;
	    else
	      {
		yymsg = yymsgbuf;
		yymsg_alloc = sizeof yymsgbuf;
	      }
	  }

	if (0 < yysize && yysize <= yymsg_alloc)
	  {
	    (void) yysyntax_error (yymsg, yystate, yychar);
	    yyerror (yymsg);
	  }
	else
	  {
	    yyerror (YY_("syntax error"));
	    if (yysize != 0)
	      goto yyexhaustedlab;
	  }
      }
#endif
    }



  if (yyerrstatus == 3)
    {
      /* If just tried and failed to reuse look-ahead token after an
	 error, discard it.  */

      if (yychar <= YYEOF)
	{
	  /* Return failure if at end of input.  */
	  if (yychar == YYEOF)
	    YYABORT;
	}
      else
	{
	  yydestruct ("Error: discarding",
		      yytoken, &yylval);
	  yychar = YYEMPTY;
	}
    }

  /* Else will try to reuse look-ahead token after shifting the error
     token.  */
  goto yyerrlab1;


/*---------------------------------------------------.
| yyerrorlab -- error raised explicitly by YYERROR.  |
`---------------------------------------------------*/
yyerrorlab:

  /* Pacify compilers like GCC when the user code never invokes
     YYERROR and the label yyerrorlab therefore never appears in user
     code.  */
  if (/*CONSTCOND*/ 0)
     goto yyerrorlab;

  /* Do not reclaim the symbols of the rule which action triggered
     this YYERROR.  */
  YYPOPSTACK (yylen);
  yylen = 0;
  YY_STACK_PRINT (yyss, yyssp);
  yystate = *yyssp;
  goto yyerrlab1;


/*-------------------------------------------------------------.
| yyerrlab1 -- common code for both syntax error and YYERROR.  |
`-------------------------------------------------------------*/
yyerrlab1:
  yyerrstatus = 3;	/* Each real token shifted decrements this.  */

  for (;;)
    {
      yyn = yypact[yystate];
      if (yyn != YYPACT_NINF)
	{
	  yyn += YYTERROR;
	  if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == YYTERROR)
	    {
	      yyn = yytable[yyn];
	      if (0 < yyn)
		break;
	    }
	}

      /* Pop the current state because it cannot handle the error token.  */
      if (yyssp == yyss)
	YYABORT;


      yydestruct ("Error: popping",
		  yystos[yystate], yyvsp);
      YYPOPSTACK (1);
      yystate = *yyssp;
      YY_STACK_PRINT (yyss, yyssp);
    }

  if (yyn == YYFINAL)
    YYACCEPT;

  *++yyvsp = yylval;


  /* Shift the error token.  */
  YY_SYMBOL_PRINT ("Shifting", yystos[yyn], yyvsp, yylsp);

  yystate = yyn;
  goto yynewstate;


/*-------------------------------------.
| yyacceptlab -- YYACCEPT comes here.  |
`-------------------------------------*/
yyacceptlab:
  yyresult = 0;
  goto yyreturn;

/*-----------------------------------.
| yyabortlab -- YYABORT comes here.  |
`-----------------------------------*/
yyabortlab:
  yyresult = 1;
  goto yyreturn;

#ifndef yyoverflow
/*-------------------------------------------------.
| yyexhaustedlab -- memory exhaustion comes here.  |
`-------------------------------------------------*/
yyexhaustedlab:
  yyerror (YY_("memory exhausted"));
  yyresult = 2;
  /* Fall through.  */
#endif

yyreturn:
  if (yychar != YYEOF && yychar != YYEMPTY)
     yydestruct ("Cleanup: discarding lookahead",
		 yytoken, &yylval);
  /* Do not reclaim the symbols of the rule which action triggered
     this YYABORT or YYACCEPT.  */
  YYPOPSTACK (yylen);
  YY_STACK_PRINT (yyss, yyssp);
  while (yyssp != yyss)
    {
      yydestruct ("Cleanup: popping",
		  yystos[*yyssp], yyvsp);
      YYPOPSTACK (1);
    }
#ifndef yyoverflow
  if (yyss != yyssa)
    YYSTACK_FREE (yyss);
#endif
#if YYERROR_VERBOSE
  if (yymsg != yymsgbuf)
    YYSTACK_FREE (yymsg);
#endif
  /* Make sure YYID is used.  */
  return YYID (yyresult);
}


#line 53 "sh.y"


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;
}