Linux 进程间通信管道系列: 匿名和定名管道,自定义shell当中下令行管道的 - ToB企服应用市场:ToB评测及商务社交产业平台

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>
#include <fcntl.h>
#include <vector>
#include <iostream>
#define NoneRedir 0
#define OutputRedir 1
#define InputRedir 2
#define AppendRedir 3
using namespace std;
int lastcode=0;//上一次进程退出时的退出码
int redir=NoneRedir;
char* filename=NULL;
char cwd[1024]={'\0'};
char env[1024][1024]={'\0'};
int my_index=0;
//将字符串s按照空格作为分割符拆分后添加到vs当中(不过: 空格可能会连续出现)
void CommandLineSplit(char* command,char* commandV[])
{
char* s=strtok(command," ");
commandV[0]=s;
int i=1;
while(commandV[i++]=strtok(NULL," ")){}
}
#define SkipSpace(pos) do{while(isspace(*pos)){pos++;}}while(0)
void CheckRedir(char* command)
{
int len=strlen(command);
char* pos;
for(int i=len-1;i>=0;)
{
if(command[i]=='>')
{
if(i>0 && command[i-1]=='>')//追加
{
redir=AppendRedir;
command[i-1]='\0';
}
else//输出
{
redir=OutputRedir;
command[i]='\0';
}
pos=command+i+1;
SkipSpace(pos);
filename=pos;
break;
}
else if(command[i]=='<')//输入
{
redir=InputRedir;
command[i]='\0';
pos=command+i+1;
SkipSpace(pos);
filename=pos;
break;
}
else
{
i--;
}
}
}
void Exec(char* commandV[])
{
pid_t id=fork();
if(id==0)
{
if(redir==InputRedir)
{
int fd=open(filename,O_RDONLY);
dup2(fd,0);
}
else if(redir==OutputRedir)
{
int fd=open(filename,O_WRONLY | O_CREAT | O_TRUNC,0666);
dup2(fd,1);
}
else if(redir==AppendRedir)
{
int fd=open(filename,O_WRONLY | O_CREAT | O_APPEND,0666);
dup2(fd,1);
}
execvp(commandV[0],commandV);
}
wait(NULL);
}
void cd(char* path)
{
chdir(path);
char tmp[1024]={'\0'};
getcwd(tmp,sizeof(tmp));
sprintf(cwd,"PWD=%s",tmp);
putenv(cwd);
}
void Export(char* s)
{
strcpy(env[my_index],s);
putenv(env[my_index++]);
}
int echo(char* commandV[])
{
//1.echo后面什么都没有,相当于'\n'
if(commandV[1]==NULL)
{
printf("\n");
lastcode=0;
return 1;
}
//2.echo $? echo $PWD echo $
char* cmd=commandV[1];
int len=strlen(cmd);
if(cmd[0]=='$' && len>1)
{
//echo $?
if(cmd[1]=='?')
{
printf("%d\n",lastcode);
lastcode=0;
}
//echo $PWD
else
{
char* tmp=cmd+1;
const char* env=getenv(tmp);
//找不到该环境变量,打印'\n',退出码依旧为0
if(env==NULL)
{
printf("\n");
}
else
{
printf("%s\n",env);
}
lastcode=0;
}
}
else
{
if(cmd[0]=='"' && cmd[len-1]=='"')
{
cmd[len-1]='\0';
printf("%s\n",cmd+1);
}
else
printf("%s\n",cmd);
}
return 1;
}
int doBulidIn(char* commandV[])
{
int ret=0;
if(strcmp(commandV[0],"cd")==0)
{
cd(commandV[1]);
ret=1;
}
else if(strcmp(commandV[0],"export")==0)
{
Export(commandV[1]);
ret=1;
}
else if(strcmp(commandV[0],"echo")==0)
{
echo(commandV);
ret=1;
}
return ret;
}
//打印提示符和修正redir,filename的函数
void step1()
{
redir=NoneRedir;
filename=NULL;
//1.打印提示符wzs@VM-16-10-ubuntu:~/ubuntucode/shell$
printf("%s@VM-16-10-ubuntu:%s$ ",getenv("USER"),getenv("PWD"));
}
//具体执行指令的函数
void step3(char* command)
{
//3.检查重定向
CheckRedir(command);
//4.解析字符串
char* commandV[1024]={NULL};
CommandLineSplit(command,commandV);
//5.分析内建命令
int ret=doBulidIn(commandV);
if(ret==0)
{
//6.进程程序替换
Exec(commandV);
}
}
int main()
{
while(1)
{
step1();
char command[1024]={'\0'};
fgets(command,sizeof(command),stdin);
int len=strlen(command);
command[len-1]='\0';
step3(command);
}
return 0;
}

复制代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>
#include <fcntl.h>
#include <vector>
#include <iostream>
#define NoneRedir 0
#define OutputRedir 1
#define InputRedir 2
#define AppendRedir 3
using namespace std;
int lastcode=0;//上一次进程退出时的退出码
int redir=NoneRedir;
char* filename=NULL;
char cwd[1024]={'\0'};
char env[1024][1024]={'\0'};
int my_index=0;
//将字符串s按照空格作为分割符拆分后添加到vs当中(不过: 空格可能会连续出现)
void CommandLineSplit(char* command,char* commandV[])
{
char* s=strtok(command," ");
commandV[0]=s;
int i=1;
while(commandV[i++]=strtok(NULL," ")){}
}
#define SkipSpace(pos) do{while(isspace(*pos)){pos++;}}while(0)
void CheckRedir(char* command)
{
int len=strlen(command);
char* pos;
for(int i=len-1;i>=0;)
{
if(command[i]=='>')
{
if(i>0 && command[i-1]=='>')//追加
{
redir=AppendRedir;
command[i-1]='\0';
}
else//输出
{
redir=OutputRedir;
command[i]='\0';
}
pos=command+i+1;
SkipSpace(pos);
filename=pos;
break;
}
else if(command[i]=='<')//输入
{
redir=InputRedir;
command[i]='\0';
pos=command+i+1;
SkipSpace(pos);
filename=pos;
break;
}
else
{
i--;
}
}
}
void Exec(char* commandV[])
{
pid_t id=fork();
if(id==0)
{
if(redir==InputRedir)
{
int fd=open(filename,O_RDONLY);
dup2(fd,0);
}
else if(redir==OutputRedir)
{
int fd=open(filename,O_WRONLY | O_CREAT | O_TRUNC,0666);
dup2(fd,1);
}
else if(redir==AppendRedir)
{
int fd=open(filename,O_WRONLY | O_CREAT | O_APPEND,0666);
dup2(fd,1);
}
execvp(commandV[0],commandV);
}
wait(NULL);
}
void cd(char* path)
{
chdir(path);
char tmp[1024]={'\0'};
getcwd(tmp,sizeof(tmp));
sprintf(cwd,"PWD=%s",tmp);
putenv(cwd);
}
void Export(char* s)
{
strcpy(env[my_index],s);
putenv(env[my_index++]);
}
int echo(char* commandV[])
{
//1.echo后面什么都没有,相当于'\n'
if(commandV[1]==NULL)
{
printf("\n");
lastcode=0;
return 1;
}
//2.echo $? echo $PWD echo $
char* cmd=commandV[1];
int len=strlen(cmd);
if(cmd[0]=='$' && len>1)
{
//echo $?
if(cmd[1]=='?')
{
printf("%d\n",lastcode);
lastcode=0;
}
//echo $PWD
else
{
char* tmp=cmd+1;
const char* env=getenv(tmp);
//找不到该环境变量,打印'\n',退出码依旧为0
if(env==NULL)
{
printf("\n");
}
else
{
printf("%s\n",env);
}
lastcode=0;
}
}
else
{
if(cmd[0]=='"' && cmd[len-1]=='"')
{
cmd[len-1]='\0';
printf("%s\n",cmd+1);
}
else
printf("%s\n",cmd);
}
return 1;
}
int doBulidIn(char* commandV[])
{
int ret=0;
if(strcmp(commandV[0],"cd")==0)
{
cd(commandV[1]);
ret=1;
}
else if(strcmp(commandV[0],"export")==0)
{
Export(commandV[1]);
ret=1;
}
else if(strcmp(commandV[0],"echo")==0)
{
echo(commandV);
ret=1;
}
return ret;
}
void step1()
{
redir=NoneRedir;
filename=NULL;
//1.打印提示符wzs@VM-16-10-ubuntu:~/ubuntucode/shell$
printf("%s@VM-16-10-ubuntu:%s$ ",getenv("USER"),getenv("PWD"));
}
void step3(char* command)
{
//3.检查重定向
CheckRedir(command);
//4.解析字符串
char* commandV[1024]={NULL};
CommandLineSplit(command,commandV);
//5.分析内建命令
int ret=doBulidIn(commandV);
if(ret==0)
{
//6.进程程序替换
Exec(commandV);
}
}
int CheckPipe(char* command,vector<int>& v)//返回管道个数,并且把|的位置填到数组当中
{
int len=strlen(command);
for(int i=0;i<len;i++)
{
if(command[i]=='|')
{
v.push_back(i);
command[i]='\0';//直接截断
}
}
return v.size();
}
void Execpipe(char* command)
{
vector<int> pos(1,-1);//为了后续分割方便
int sz=CheckPipe(command,pos);
if(sz==1)
{
step3(command);
return;
}
vector<int> child_id;
vector<pair<int,int>> v;//v[i].first:i号管道的读 second:写
for(int i=0;i<sz-1;i++)//创建sz个进程,sz-1个管道
{
int pipefd[2];
int n=pipe(pipefd);
pid_t id=fork();
if(id==0)
{
close(pipefd[0]);//关闭当前管道的读
int prev_fd_sz=v.size();
for(int j=0;j<prev_fd_sz;j++)
{
if(j<prev_fd_sz-1)
{
//把前面打开的读都关上(除了最近的那一个管道)
close(v[j].first);
}
//把前面打开的管道的写都关上
close(v[j].second);
}
dup2(pipefd[1],1);//当前管道的写重定向到我的1
if(!v.empty()) dup2(v.back().first,0);//上一个管道的读重定向到我的0
step3(command+pos[i]+1);
exit(0);
}
else
{
v.push_back({pipefd[0],pipefd[1]});
child_id.push_back(id);
}
}
//最后一个进程:
pid_t id=fork();
if(id==0)
{
int prev_fd_sz=v.size();
for(int j=0;j<prev_fd_sz;j++)
{
if(j<prev_fd_sz-1)
{
//把前面打开的读都关上(除了最近的那一个管道)
close(v[j].first);
}
//把前面打开的管道的写都关上
close(v[j].second);
}
dup2(v.back().first,0);
step3(command+pos[sz-1]+1);
exit(0);
}
child_id.push_back(id);
for(auto& e:v)
{
//最后的时候父亲关闭所有的读写端
close(e.first);close(e.second);
}
for(auto& e:child_id)
{
pid_t rid=waitpid(e,nullptr,0);
if(rid>0) cout<<"wait success, pid: "<<rid<<endl;
}
}
int main()
{
while(1)
{
step1();
char command[1024]={'\0'};
fgets(command,sizeof(command),stdin);
int len=strlen(command);
command[len-1]='\0';
Execpipe(command);
}
return 0;
}

复制代码