redirect.c

本软件模拟Shell 的命令解释程序

#include "dshell.h"
/***************************************************************/
/***************************************************************/
/*函数：void redirectInOut(Cmd* pC, int* piid）
  函数功能：设置输入输出文件重定向
  函数参数：pC为命令数据结构，piid为文件描述符
  函数返回值：无*/
  
void redirectInOut(Cmd* pC, int* piid)//文件重定向 
{
	int i=0;
	int j=0;
	for (i=0; i<pC->argc; i++)
	{
		if (pC->argv[i]!=NULL && (pC->argv[i])[0]=='<')
		{
	   	/*输入重定向*/
			int fid;
			char rname[100];
			if ((pC->argv[i])[1]=='\0')
			{
				strcpy(rname, pC->argv[i+1]);
				fid = open(rname, O_RDONLY);//打开文件
				if (fid==-1)//打开失败
				{
					printf("Error opening input file!\n");
					exit(2);
				}
				close(0);
				dup(fid);
				close(fid);
				(pC->argv[i])[0]='\0';
				(pC->argv[i+1])[0]='\0';
				free(pC->argv[i]);
				pC->argv[i]=NULL;
				free(pC->argv[i+1]);
				pC->argv[i+1]=NULL;
			}
			else
				if ((pC->argv[i])[1]=='/' && (pC->argv[i])[2]=='\0')
				{
					close(0);
					dup(piid[0]);
					close(piid[1]);
					(pC->argv[i])[0]='\0';
					free(pC->argv[i]);
					pC->argv[i]=NULL;
				}
				else
				{
					strcpy(rname, (pC->argv[i])+1);
					fid = open(rname, O_RDONLY);
					if (fid==-1)
					{
						printf("Error opening input file!\n");
						exit(2);
					}
					close(0);
					dup(fid);
					close(fid);
					(pC->argv[i])[0]='\0';
					free(pC->argv[i]);
					pC->argv[i]=NULL;
				}
		}
		if (pC->argv[i]!=NULL && (pC->argv[i])[0]=='>')
		{
		/*输出重定向*/
			int fid;
			char rname[100];
			if ((pC->argv[i])[1]=='\0')
			{
				strcpy(rname, pC->argv[i+1]);
				fid = open(rname, O_WRONLY | O_CREAT);
				if (fid==-1)
				{
					printf("Error accessing output file!\n");
					exit(2);
				}
				close(1);
				dup(fid);
				close(fid);
				(pC->argv[i])[0]='\0';
				(pC->argv[i+1])[0]='\0';
				free(pC->argv[i]);
				pC->argv[i]=NULL;
				free(pC->argv[i+1]);
				pC->argv[i+1]=NULL;
			}
			else
				if ((pC->argv[i])[1]=='/' && (pC->argv[i])[2]=='\0')
				{
					close(1);
					dup(piid[1]);
					close(piid[0]);
					(pC->argv[i])[0]='\0';
					free(pC->argv[i]);
					pC->argv[i]=NULL;
				}
				else
				{
					strcpy(rname, (pC->argv[i])+1);
					fid = open(rname, O_WRONLY | O_CREAT);
					if (fid==-1)
					{
						printf("Error accessing output file!\n");
						exit(2);
					}
					close(1);
					dup(fid);
					close(fid);
					(pC->argv[i])[0]='\0';
					free(pC->argv[i]);
					pC->argv[i]=NULL;
				}
		}
	}
	for (i=0; i<pC->argc; i++)
	{
		int move=0;
		for (j=0; j<pC->argc; j++)
		{
			if ((pC->argv[j])==NULL)
			{
				pC->argv[j]=pC->argv[j+1];
				move=1;
			}
			if (move)
			{
				pC->argv[j]=pC->argv[j+1];
			}
		}
	}
}