dshell.c

linux——shell nachos 的课程设计 第一个

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>

/*命令行数据结构*/
typedef struct tagCommand
{
	char **argv;//参数
	int argc;//文件名（命令）
}COMD;

void processComd(COMD* pC, char* pBuf)
{
	char *pchr = NULL;
	char *pBegin = pBuf;
	int n=1;
	while ((pchr=strchr(pBegin, ' '))!=NULL)
	{
		pBegin=pchr+1;
		while ((*pBegin)==' ')
			pBegin++;
		n++;
	}
	pC->argv=(char**)malloc(sizeof(char*)*(n+1));
	pchr=NULL;
	pBegin=pBuf;
	int num=0;
	while ((pchr=strchr(pBegin, ' '))!=NULL)
	{
		pC->argv[num]=(char*)malloc(sizeof(char)*(pchr-pBegin+1));
		strncpy(pC->argv[num], pBegin, pchr-pBegin);
		(pC->argv[num])[pchr-pBegin]='\0';
		pBegin=pchr+1;
		while ((*pBegin)==' ')
			pBegin++;
		num++;
	}
	pC->argv[num]=(char*)malloc(sizeof(char)*strlen(pBegin));
	strcpy(pC->argv[num], pBegin);
	num++;
	pC->argv[num]=NULL;
	pC->argc=num;
}

void findExec(COMD* pC, char* pBuf)
{	
	char *pchr = NULL;
	char *paths = getenv("PATH");
	char *pBegin = paths;
	char **pDirs = NULL;
	if ((pC->argv[0])[0]=='.' || (pC->argv[0])[0]=='/')
	{
		strcpy(pBuf, pC->argv[0]);
		return;
	}
	
	int n=1;
	while ((pchr=strchr(pBegin, ':'))!=NULL)
	{
		pBegin=pchr+1;
		n++;
	}
	pDirs=(char**)malloc(sizeof(char*)*n);
	pchr=NULL;
	pBegin=paths;
	int num=0;
	while ((pchr=strchr(pBegin, ':'))!=NULL)
	{
		pDirs[num]=(char*)malloc(sizeof(char)*(pchr-pBegin+1));
		strncpy(pDirs[num], pBegin, pchr-pBegin);
		(pDirs[num])[pchr-pBegin]='\0';
		pBegin=pchr+1;
		num++;
	}
	pDirs[num]=(char*)malloc(sizeof(char)*strlen(pBegin));
	strcpy(pDirs[num], pBegin);
	num++;
	int i=0;
	for (i=0; i<num; i++)
	{
		strcpy(pBuf, pDirs[i]);
		if ((pDirs[i])[strlen(pDirs[i])-1]!='/')
			strcat(pBuf, "/");
		strcat(pBuf, pC->argv[0]);
		if (access(pBuf, F_OK)==0)
		{
			for (n=0; n<num; n++)
			{
				free(pDirs[n]);
				pDirs[n]=NULL;
			}
			free(pDirs);
			pDirs=NULL;
			return;
		}
	}
	for (n=0; n<num; n++)
	{
		free(pDirs[n]);
		pDirs[n]=NULL;
	}
	free(pDirs);
	pDirs=NULL;
	pBuf[0]='\0';
}

int isBackground(COMD* pC)
{
	if ((pC->argv[pC->argc-1])[strlen(pC->argv[pC->argc-1])-1]=='&')
	{
		if (strlen(pC->argv[pC->argc-1])-1==0)
		{
			free(pC->argv[pC->argc-1]);
			pC->argv[pC->argc-1]=NULL;
			pC->argc--;
		}
		else
			(pC->argv[pC->argc-1])[strlen(pC->argv[pC->argc-1])-1]='\0';
		return 1;
	}
	return 0;
}

void redirectInOut(COMD* pC, int* piid)
{
	int i=0;
	int j=0;
	for (i=0; i<pC->argc; i++)
	{
		if (pC->argv[i]!=NULL && (pC->argv[i])[0]=='<')
		{
			/*redirect stdin*/
			int fid;
			char rname[100];
			if ((pC->argv[i])[1]=='\0')
			{
				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';
				(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]=='>')
		{
			/*redirect stdout*/
			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];
			}
		}
	}
}

int* pipeInOut(COMD* pC)
{
	int i=0;
	int* pipeid = NULL;
	for (i=0; i<pC->argc; i++)
	{
		if (((pC->argv[i])[0]=='<' || (pC->argv[i])[0]=='>') && (pC->argv[i])[1]=='/')
		{
			/*create pipe*/
			pipeid = (int*)malloc(2*sizeof(int));
			if (pipe(pipeid) == -1)
			{
				printf("Pipe creation error!\n");
				exit(3);
			}
		}
	}
	return pipeid;
}

char* procPipe(char* pBuf)
{
	char *pSecProc = NULL;
	char *pchr = NULL;
	if ((pchr=strchr(pBuf, '|'))!=NULL)
	{
		pchr--;
		while ((*pchr)==' ')
			pchr--;
		pchr++;
		(*pchr)='\0';
		pchr++;
		while ((*pchr)==' ')
			pchr++;
		if ((*pchr)=='|')
			pchr++;
		while ((*pchr)==' ')
			pchr++;
		pSecProc=(char*)malloc(sizeof(char)*1024);
		strcpy(pSecProc, pchr);
	}
	return pSecProc;
}

int main(int argc, char *argv[], char *env[])
{
	printf ("Shell by llr, type \"exit\" return to bash.\n");
	COMD execmd;
	COMD* pSecCom = NULL;
	execmd.argv=NULL;
	execmd.argc=0;
	char buf[1024],tmp;
	char *pSecP = NULL;
	do
	{
		if (execmd.argv!=NULL)
		{
			for (; execmd.argc>0; execmd.argc--)
			{
				free(execmd.argv[execmd.argc-1]);
				execmd.argv[execmd.argc-1]=NULL;
			}
			free(execmd.argv);
			execmd.argv=NULL;
		}
		printf("DShell>");
		int i=0;
		while((tmp=getchar())!='\n')
		{
			buf[i]=tmp;
			i++;
		}
		buf[i]='\0';
		pSecP = procPipe(buf);
		if (pSecP!=NULL)
		{
			char *ad=" >/";
			strcat(buf, ad);
			char *ad2=" </";
			strcat(pSecP, ad2);
		}
		processComd(&execmd, buf);
		if (i==0)
			continue;
		findExec(&execmd, buf);
		int bg=isBackground(&execmd);
		if (pSecP!=NULL)
		{
			pSecCom = (COMD*)malloc(sizeof(COMD));
			pSecCom->argv=NULL;
			pSecCom->argc=0;
			processComd(pSecCom, pSecP);
			findExec(pSecCom, pSecP);
			bg=isBackground(pSecCom);
		}
		
		int* pipeID = NULL;
		if (strcmp(execmd.argv[0], "exit")!=0)
		{
			if (strcmp(buf, "")==0)
			{
				printf("Bad command or file name.\n");
				continue;
			}
			/*ready to execute*/
			int npid;
			pipeID = pipeInOut(&execmd);
			if ((npid=fork())==0)
			{
				errno=0;
				redirectInOut(&execmd, pipeID);
				int status = execve(buf, execmd.argv, env);
				printf("Error executing specified file. (#%d)\n", errno);
				return 1;
			}
			else
			{
				if (pSecP==NULL)
				{
					if (!bg)
					{
						int status;
						wait(&status);
					}
					else
					{
						printf("Program ID#%d executed successful at background.\n", npid);
					}
				}
			}
			if (pSecP!=NULL)
			{
				if ((npid=fork())==0)
				{
					errno=0;
					/*redirect to pipe*/
					redirectInOut(pSecCom, pipeID);
					int status = execve(pSecP, pSecCom->argv, env);
					printf("Error executing specified file. (#%d)\n", errno);
					return 1;
				}
				else
				{
					close(pipeID[0]);
					close(pipeID[1]);
					if (!bg)
					{
						int status;
						wait(&status);
					}
					else
					{
						printf("Program ID#%d executed successful at background.\n", npid);
					}
				}
			}
		}
		if (pSecP!=NULL)
		{
			sleep(1);
			free(pipeID);
			pipeID=NULL;
			free(pSecP);
			pSecP=NULL;
			free(pSecCom);
			pSecCom=NULL;
		}
	}while(strcmp(execmd.argv[0], "exit")!=0);
	
	if (execmd.argv!=NULL)
	{
		for (; execmd.argc>0; execmd.argc--)
		{
			free(execmd.argv[execmd.argc-1]);
			execmd.argv[execmd.argc-1]=NULL;
		}
		free(execmd.argv);
		execmd.argv=NULL;
	}
	printf("Bye!\n");
	return 0;
}