在按下 Enter 之前线程函数不会终止

Question

以下代码（最后）表示从远程客户端接收 ls 命令并将当前工作目录发送到该客户端的线程函数。

发送成功但有一个问题：当它完全停止发送时，我希望它重新开始收听。在行：

printf("Enter 1 if you want to exit or 0 if you don't: "); 
                 fgets(exit_status,MAX_SIZE,stdin);

当我按 Enter

时卡住并终止（并启动另一个线程）

我不明白为什么？在调试时，我看到上面的打印语句在按 Enter 后执行，尽管调试器处于函数末尾（意味着它通过了此打印语句）。

我想让它在发送完数据后自动重新开始监听。

如果有人想在这里查看我的完整代码是 link:https://pastebin.com/9UmTkPge

void  *server_socket_ls(void *arg) {
    int* exit_status = (int*)malloc(sizeof(int));
    *exit_status = 0;   
    while (*exit_status == 0) {
    //socket code is here
        
    //code for ls
        
    char buffer[BUFFSIZE];
    int received = -1;
    char data[MAX];
    memset(data,0,MAX);
       // this will make server wait for another command to run until it receives exit
        data[0] = '[=11=]';
        if((received = recv(new_socket, buffer,BUFFSIZE,0))<0){
    
            perror("Failed");
        }
    
        buffer[received] = '[=11=]';
    
        strcat (data,  buffer);
        if (strcmp(data, "exit")==0) // this will force the code to exit
            exit(0);
    
        puts (data);
            char *args[100];
            setup(data,args,0);
            int pipefd[2],lenght;
    
            if(pipe(pipefd))
                perror("Failed to create pipe");
    
            pid_t pid = fork();
            char path[MAX];
    
            if(pid==0)
            {
                close(1); // close the original stdout
                dup2(pipefd[1],1); // duplicate pipfd[1] to stdout
                close(pipefd[0]); // close the readonly side of the pipe
                close(pipefd[1]); // close the original write side of the pipe
                execvp(args[0],args); // finally execute the command
            }
            else
                if(pid>0)
                {
                    close(pipefd[1]);
                    memset(path,0,MAX);
    
                    while(lenght=read(pipefd[0],path,MAX-1)){
                        printf("Data read so far %s\n", path);
                        if(send(new_socket,path,strlen(path),0) != strlen(path) ){
                            perror("Failed");
                        }
                        //fflush(NULL);
                        printf("Data sent so far %s\n", path);
                        memset(path,0,MAX);
                        
                    }
    
                    close(pipefd[0]);
                    //removed so server will not terminate
                              
                }
                else 
                {
                    printf("Error !\n");
                    exit(0);
                }
                 printf("Enter 1 if you want to exit or 0 if you don't: "); 
                 fgets(exit_status,MAX_SIZE,stdin);    
                
        }
    
    }

Answer 1

有许多个错误：

在terminal_thread中，input_command在每次循环迭代时分配——内存泄漏
去除换行符的代码已损坏
使用 .l，不指定 IP 地址会导致段错误，因为 token 是 NULL
terminal_thread中.l的端口号是5126，不匹配相应服务器代码
连接后，server_socket_file不做任何事情。
在 server_socket_ls 中，它 在 socket、bind、listen 和 accept 上循环 。循环应该在 listen 之后 开始（即只在循环中执行 accept 并且重用监听套接字）。

代码中标记的其他错误

我不得不重构代码并添加一些调试。它用错误注释。我使用 cpp 条件来表示旧代码与新代码：

#if 0 // old code #else // new code #endif #if 1 // new code #endif

这是代码。我得到了 minimal .l（远程 ls）工作：

编辑： 由于下面的更新运行超出了 SO space 限制，我删除了我在此处发布的第一个代码块。

这是 debug.txt 输出：

term term: PROMPT term term: FGETS ls ls: ENTER ls ls: SOCKET file file: ENTER ls ls: BIND prtNum=9191 file file: BIND portNum=6123 ls ls: LISTEN term term: COMMAND '.l' term term: port=9191 ls ls: ACCEPTED term term: PROMPT

This program is exiting as soon as its stops sending data at exit(0) and so doesn't ask for exit_status. Is there a way somehow to make it not stop and instead the terminal prompt reappears along with servers listening at the back? – Dragut

因为我感觉到了紧迫性，所以我犯了错误，现在部分解决方案比为时已晚的完美解决方案更好。

我可能在 ls 服务器父进程（现已修复）中引入了一个带有无关 exit 调用的错误。

但是，还有其他问题...

主要问题是服务器（对于ls）提示用户是否继续（在stdout/stdin).这不太管用。

应该提示用户的是客户端（即terminal_thread）。或者，正如我所做的那样，客户端将在命令提示符处看到 exit，然后发送一个带有“exit”的数据包到服务器，然后终止。然后，服务器将看到此命令并终止。

我在没有完全重做所有内容的情况下尽可能多地进行了重构。

我将一些代码拆分成函数。一些 can/could 被重用来实现“文件”服务器。

但是，我会将两个函数放入单个服务器线程中。我会让服务器查看它获取的“命令”，并根据命令执行任一操作。由于在“文件”服务器中没有实际执行某些操作的代码[还]，因此很难返工。

有一件事要解决[我没有时间]:

.l 命令的格式为：.l [ip_address]。 ip_address 的默认值为 127.0.0.1。但是，这应该是 split 成两个命令（例如）：

附加 [ip_address]

ls [ls 参数]

无论如何，这是更新后的代码。我不得不移动得有点快，所以它没有我想要的那么干净。

#include <netinet/in.h> #include <pthread.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h> #include <sys/types.h> #include <unistd.h> #include <arpa/inet.h> #include <stdbool.h> #include <stdarg.h> #if 1 #include <time.h> #endif #define BACKLOG 10 #define MAX_SIZE 200 #define BACKLOG 10 #define BUFFSIZE 2048 #define MAXPENDING 5 #define MAX 2048 __thread char *tid; __thread char dbgstrbuf[1000]; FILE *xfdbg; double tsczero = 0.0; typedef struct server_arg { int portNum; } server_arg; typedef struct server_arg1 { int portNum; } server_arg1; double tscgetf(void) { struct timespec ts; double sec; clock_gettime(CLOCK_MONOTONIC,&ts); sec = ts.tv_nsec; sec /= 1e9; sec += ts.tv_sec; sec -= tsczero; return sec; } void dbgprt(const char *fmt,...) { va_list ap; char msg[1000]; char *bp = msg; bp += sprintf(bp,"[%.9f/%4s] ",tscgetf(),tid); va_start(ap,fmt); bp += vsprintf(bp,fmt,ap); va_end(ap); fputs(msg,xfdbg); } const char * dbgstr(const char *str,int len) { char *bp = dbgstrbuf; if (len < 0) len = strlen(str); bp += sprintf(bp,"'"); for (int i = 0; i < len; ++i) { int chr = str[i]; if ((chr > 0x20) && (chr <= 0x7E)) bp += sprintf(bp,"%c",chr); else bp += sprintf(bp,"{%2.2X}",chr); } bp += sprintf(bp,"'"); return dbgstrbuf; } void setup(char inputBuffer[], char *args[], int *background) { const char s[4] = " \t\n"; char *token; token = strtok(inputBuffer, s); int i = 0; while (token != NULL) { args[i] = token; i++; // printf("%s\n", token); token = strtok(NULL, s); } args[i] = NULL; } int open_remote(const char *ip,unsigned short port) { int sock; struct sockaddr_in echoserver; dbgprt("open_remote: ENTER ip=%s port=%u\n",dbgstr(ip,-1),port); if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) { perror("Failed to create socket"); exit(1); } int enable = 1; if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) < 0) { perror("error"); } memset(&echoserver, 0, sizeof(echoserver)); echoserver.sin_family = AF_INET; echoserver.sin_addr.s_addr = inet_addr(ip); // NOTE/BUG: this port number does _not_ match any server port #if 0 echoserver.sin_port = htons(5126); #else dbgprt("term: port=%u\n",port); echoserver.sin_port = htons(port); #endif if (connect(sock, (struct sockaddr *) &echoserver, sizeof(echoserver)) < 0) { perror("Failed to connect with server"); exit(1); } dbgprt("open_remote: EXIT sock=%d\n",sock); return sock; } void * terminal_thread(void *arg) { // NOTE/FIX: do this _once_ #if 1 char *input_command = malloc(MAX_SIZE); #endif tid = "term"; char buffer[BUFFSIZE]; int sock_ls = -1; while (1) { dbgprt("term: PROMPT\n"); printf(">> "); //memset(input_command,0,strlen(str)); // NOTE/BUG: this is a memory leak #if 0 char *input_command = malloc(MAX_SIZE); #endif dbgprt("term: FGETS\n"); fgets(input_command, MAX_SIZE, stdin); // NOTE/BUG: code is broken to strip newline #if 0 if ((strlen(input_command) > 0) && (input_command[strlen(input_command) - 1] == '\n')) input_command[strlen(input_command) - 1] = '[=12=]'; #else input_command[strcspn(input_command,"\n")] = 0; #endif dbgprt("term: COMMAND %s\n",dbgstr(input_command,-1)); char list[] = "ls"; char cp[] = "cp"; #if 0 char s[100]; printf("%s\n", getcwd(s,100)); chdir("Desktop"); printf("%s\n", getcwd(s,100)); #endif // exit program (and exit server) if (strcmp(input_command,"exit") == 0) { if (sock_ls >= 0) { dbgprt("term: SENDEXIT\n"); if (send(sock_ls,"exit",4,0) < 0) { perror("send/exit"); exit(1); } break; } } if (strcmp(input_command, list) == 0) { // ls code will run here } if ((input_command[0] == '.') && (input_command[1] == 'l')) { printf("remote ls\n"); char ip[20]; const char c[2] = " "; // strcpy(str,input_command); char *token; // get the first token token = strtok(input_command, c); // walk through other tokens int i = 0; while (token != NULL && i != -1) { token = strtok(NULL, c); i--; } #if 1 if (token == NULL) { token = "127.0.0.1"; printf("no IP address found -- using %s\n",token); } #endif if (sock_ls < 0) sock_ls = open_remote(token,9191); char s[100]; strcpy(s, "ls"); // NOTE/BUG: this blows away the "s" in "ls" because s is _set_ with strcpy #if 0 s[strlen(s) - 1] = '[=12=]'; // fgets doesn't automatically discard '\n' #endif unsigned int echolen; echolen = strlen(s); int received = 0; /* send() from client; */ if (send(sock_ls, s, echolen, 0) != echolen) { perror("Mismatch in number of sent bytes"); } fprintf(stdout, "Message from server: "); int bytes = 0; /* recv() from server; */ if ((bytes = recv(sock_ls, buffer, echolen, 0)) < 1) { perror("Failed to receive bytes from server"); } received += bytes; buffer[bytes] = '[=12=]'; /* Assure null terminated string */ fprintf(stdout, buffer); bytes = 0; // this d {...} while block will receive the buffer sent by server do { buffer[bytes] = '[=12=]'; printf("%s\n", buffer); } while ((bytes = recv(sock_ls, buffer, BUFFSIZE - 1, 0)) >= BUFFSIZE - 1); buffer[bytes] = '[=12=]'; printf("%s\n", buffer); printf("\n"); continue; } } dbgprt("term: EXIT\n"); return (void *) 0; } int ls_loop(int new_socket) { dbgprt("ls_loop: ENTER new_socket=%d\n",new_socket); //code for ls char buffer[BUFFSIZE]; int received = -1; char data[MAX]; int stop = 0; while (1) { memset(data, 0, MAX); // this will make server wait for another command to run until it // receives exit data[0] = '[=12=]'; if ((received = recv(new_socket, buffer, BUFFSIZE, 0)) < 0) { perror("Failed"); } buffer[received] = '[=12=]'; strcpy(data, buffer); dbgprt("ls_loop: COMMAND %s\n",dbgstr(data,-1)); // this will force the code to exit #if 0 if (strcmp(data, "exit") == 0) exit(0); puts(data); #else if (strncmp(data, "exit", 4) == 0) { dbgprt("ls_loop: EXIT/COMMAND\n"); stop = 1; break; } #endif char *args[100]; setup(data, args, 0); int pipefd[2], length; if (pipe(pipefd)) perror("Failed to create pipe"); pid_t pid = fork(); char path[MAX]; if (pid == 0) { // NOTE/BUG: no need to close before dup2 #if 0 close(1); // close the original stdout #endif dup2(pipefd[1], 1); // duplicate pipfd[1] to stdout close(pipefd[0]); // close the readonly side of the pipe close(pipefd[1]); // close the original write side of the pipe execvp(args[0], args); // finally execute the command exit(1); } if (pid < 0) { perror("fork"); exit(1); } dbgprt("ls_loop: PARENT\n"); close(pipefd[1]); while (length = read(pipefd[0], path, MAX - 1)) { dbgprt("ls_loop: DATAREAD %s\n",dbgstr(path,length)); if (send(new_socket, path, length, 0) != length) { perror("Failed"); } memset(path, 0, MAX); } close(pipefd[0]); } dbgprt("ls_loop: EXIT stop=%d\n",stop); } void * server_socket_ls(void *arg) { tid = "ls"; dbgprt("lsmain: ENTER\n"); do { server_arg *s = (server_arg *) arg; int server_fd, new_socket; struct sockaddr_in address; int addrlen = sizeof(address); dbgprt("lsmain: SOCKET\n"); // Creating socket file descriptor if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) { perror("socket failed"); exit(EXIT_FAILURE); } int enable = 1; if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) < 0) { perror("error"); } address.sin_family = AF_INET; address.sin_addr.s_addr = INADDR_ANY; address.sin_port = htons(s->portNum); dbgprt("lsmain: BIND prtNum=%u\n",s->portNum); if (bind(server_fd, (struct sockaddr *) &address, sizeof(address)) < 0) { perror("bind failed"); } dbgprt("lsmain: LISTEN\n"); if (listen(server_fd, 3) < 0) { perror("listen"); } while (1) { if ((new_socket = accept(server_fd, (struct sockaddr *) &address, (socklen_t *) & addrlen)) < 0) { perror("accept"); } dbgprt("lsmain: ACCEPTED\n"); int stop = ls_loop(new_socket); close(new_socket); if (stop) { dbgprt("lsmain: STOP\n"); break; } } } while (0); dbgprt("lsmain: EXIT\n"); return (void *) 0; } void * server_socket_file(void *arg) { tid = "file"; dbgprt("file: ENTER\n"); server_arg1 *s1 = (server_arg1 *) arg; int server_fd, new_socket; struct sockaddr_in address; int addrlen = sizeof(address); // Creating socket file descriptor if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) { perror("socket failed"); exit(EXIT_FAILURE); } int enable = 1; if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) < 0) { perror("error"); } address.sin_family = AF_INET; address.sin_addr.s_addr = INADDR_ANY; address.sin_port = htons(s1->portNum); dbgprt("file: BIND portNum=%u\n",s1->portNum); if (bind(server_fd, (struct sockaddr *) &address, sizeof(address)) < 0) { perror("bind failed"); } if (listen(server_fd, 3) < 0) { perror("listen"); } if ((new_socket = accept(server_fd, (struct sockaddr *) &address, (socklen_t *) & addrlen)) < 0) { perror("accept"); } printf("Server Connected\n"); } int main(int argc, char const *argv[]) { tid = "main"; tsczero = tscgetf(); server_arg *s = (server_arg *) malloc(sizeof(server_arg)); server_arg1 *s1 = (server_arg1 *) malloc(sizeof(server_arg1)); pthread_t id_1; pthread_t id_2; pthread_t id_3; xfdbg = fopen("debug.txt","w"); setlinebuf(xfdbg); if (pthread_create(&id_3, NULL, terminal_thread, NULL) != 0) { perror("pthread_create"); } // NOTE/BUG: this port (or the one below) doesn't match the client code // port of 5126 s->portNum = 9191; pthread_create(&id_1, NULL, server_socket_ls, s); s1->portNum = 6123; if (0) pthread_create(&id_2, NULL, server_socket_file, s1); pthread_join(id_1, NULL); if (0) pthread_join(id_2, NULL); pthread_join(id_3, NULL); // NOTE/BUG: pthread_exit in main thread is wrong #if 0 pthread_exit(0); #else fclose(xfdbg); return 0; #endif }

更新：

Feedback 2: the program does make terminal thread to reappear, but it doesn't listen anymore. When I tried to send ls command again from remote pc, it just blocks (and debugging shows it is because it gets stuck at blocking receive function). – Dragut

我试图避免过多的重构，但现在，我添加了更多更改。这个版本几乎是一个完整的重构：

pthread_create 在测试时没问题，但如果服务器在 不同的 系统上，则不够通用。

通常，客户端和服务器是独立的程序（例如，我们在不同的window或从systemd启动服务器）。

服务器通常会创建一个subprocess/subthread来传输请求（下面，我做了一个fork但是服务器可以做pthread_create).

此子进程处理 accept 之后的所有内容，因此服务器主进程可以自由循环 accept 并同时拥有多个客户端。

因为我们正在使用 stream 套接字（例如 TCP），每一方都需要知道何时停止读取。通常是创建一个 struct ，它是要遵循的数据的描述符（例如下面的 xmsg_t ），它具有“类型”和“有效负载长度”。

sent/received 的有效载荷数据的每一位都以这样的描述符为前缀。

换句话说，我们需要一个简单的“协议”

现在，我们需要两个 windows（它们可以在不同的系统上）：

启动服务器：./myprogram -s

启动客户端：./myprogram

这是重构后的代码。注释为：

#include <netinet/in.h> #include <pthread.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h> #include <sys/types.h> #include <unistd.h> #include <arpa/inet.h> #include <stdbool.h> #include <stdarg.h> #if 1 #include <errno.h> #include <time.h> #include <sys/file.h> #include <sys/wait.h> #endif #define MAXBUFF 2048 // max buffer size #define MAXPENDING 5 // max number of connections (listen) #define MAXARG 100 // max number of args #define PORTNO 9191 // default port number #if 0 #define STOP_SIGNO SIGTERM // stop signal to use #else #define STOP_SIGNO SIGHUP // stop signal to use #endif #define CLOSEME(_fd) \ do { \ dbgprt("CLOSEME fd=%d (" #_fd ")\n",_fd); \ if (_fd >= 0) \ close(_fd); \ _fd = -1; \ } while (0) int opt_h; // 1=send HELO message int opt_s; // 1=doserver, 0=doclient int opt_n; // 1=run server command in foreground char ipaddr[100] = { "127.0.0.1" }; unsigned short portno = PORTNO; pid_t server_pid; // pid of server main process volatile int server_signo; // signal received by server main __thread char *tid; __thread char dbgstrbuf[MAXBUFF + 1]; int dbgfd = -1; double tsczero = 0.0; typedef struct { int xmsg_type; int xmsg_paylen; } xmsg_t; enum { XMSG_NOP, XMSG_CMD, XMSG_DATA, XMSG_EOF, }; double tscgetf(void) { struct timespec ts; double sec; clock_gettime(CLOCK_MONOTONIC,&ts); sec = ts.tv_nsec; sec /= 1e9; sec += ts.tv_sec; sec -= tsczero; return sec; } #if _USE_ZPRT_ #ifndef DEBUG #define DEBUG 1 #endif #endif #if DEBUG #define dbgprt(_fmt...) \ xdbgprt(__FUNCTION__,_fmt) #else #define dbgprt(_fmt...) \ do { } while (0) #endif void xdbgprt(const char *fnc,const char *fmt,...) { va_list ap; char msg[MAXBUFF * 4]; char *bp = msg; int sverr = errno; bp += sprintf(bp,"[%.9f/%4s] %s: ",tscgetf(),tid,fnc); va_start(ap,fmt); bp += vsprintf(bp,fmt,ap); va_end(ap); // when doing forks, we have to lock the stream to guarantee atomic, // non-interspersed messages that are sequential flock(dbgfd,LOCK_EX); lseek(dbgfd,0,2); ssize_t remlen = bp - msg; ssize_t curlen; for (bp = msg; remlen > 0; remlen -= curlen, bp += curlen) { curlen = write(dbgfd,bp,remlen); if (curlen < 0) { perror("xdbgprt"); break; } } flock(dbgfd,LOCK_UN); errno = sverr; } const char * dbgstr(const char *str,int len) { char *bp = dbgstrbuf; if (len < 0) len = strlen(str); bp += sprintf(bp,"'"); for (int i = 0; i < len; ++i) { int chr = str[i]; if ((chr > 0x20) && (chr <= 0x7E)) bp += sprintf(bp,"%c",chr); else bp += sprintf(bp,"{%2.2X}",chr); } bp += sprintf(bp,"'"); return dbgstrbuf; } // tokenize -- convert buffer to tokens int tokenize(char **argv,const char *cmdbuf) { static char tokbuf[MAXBUFF]; char **av = argv; strcpy(tokbuf,cmdbuf); char *token = strtok(tokbuf," "); while (token != NULL) { *av++ = token; token = strtok(NULL," "); } *av = NULL; return (av - argv); } // xsend -- send buffer (guaranteed delivery) ssize_t xsend(int sock,const void *vp,size_t buflen,int flags) { const char *buf = vp; ssize_t curlen; ssize_t totlen = 0; dbgprt("ENTER buflen=%zu flags=%8.8X\n",buflen,flags); for (; totlen < buflen; totlen += curlen) { dbgprt("LOOP totlen=%zd\n",totlen); curlen = send(sock,&buf[totlen],buflen - totlen,flags); if (curlen <= 0) break; } dbgprt("EXIT totlen=%zd\n",totlen); return totlen; } // xrecv -- receive buffer (guaranteed delivery) ssize_t xrecv(int sock,void *vp,size_t buflen,int flags) { char *buf = vp; ssize_t curlen; ssize_t totlen = 0; dbgprt("ENTER buflen=%zu flags=%8.8X\n",buflen,flags); for (; totlen < buflen; totlen += curlen) { dbgprt("LOOP totlen=%zu\n",totlen); curlen = recv(sock,&buf[totlen],buflen - totlen,flags); if (curlen <= 0) break; } dbgprt("EXIT totlen=%zd\n",totlen); return totlen; } // open_remote -- client open connection to server int open_remote(const char *ip,unsigned short port) { int sock; struct sockaddr_in echoserver; dbgprt("ENTER ip=%s port=%u\n",dbgstr(ip,-1),port); if ((sock = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP)) < 0) { perror("Failed to create socket"); exit(1); } // NOTE/BUG: only server (who does bind) needs to do this #if 0 int enable = 1; if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&enable,sizeof(enable)) < 0) { perror("error"); } #endif memset(&echoserver,0,sizeof(echoserver)); echoserver.sin_family = AF_INET; echoserver.sin_addr.s_addr = inet_addr(ip); echoserver.sin_port = htons(port); if (connect(sock,(struct sockaddr *) &echoserver,sizeof(echoserver)) < 0) { perror("Failed to connect with server"); exit(1); } dbgprt("EXIT sock=%d\n",sock); return sock; } // send_cmd -- client send command to server and process reply void send_cmd(int type,const char *cmd,int paylen) { int sock; xmsg_t xmsg; char buffer[MAXBUFF]; dbgprt("ENTER type=%d\n",type); // open socket to remote server sock = open_remote(ipaddr,portno); // send command descriptor xmsg.xmsg_type = type; if (paylen < 0) paylen = strlen(cmd); xmsg.xmsg_paylen = paylen; xsend(sock,&xmsg,sizeof(xmsg),0); // send command payload xsend(sock,cmd,xmsg.xmsg_paylen,0); fprintf(stdout,"Message from server:\n"); int received = 0; int bytes; // get all data that the server sends back while (1) { dbgprt("LOOP\n"); // get descriptor for next chunk xrecv(sock,&xmsg,sizeof(xmsg),0); // handle EOF from server if (xmsg.xmsg_paylen <= 0) break; // get payload bytes = recv(sock,buffer,xmsg.xmsg_paylen,0); dbgprt("RCVD bytes=%d\n",bytes); #if 0 if (bytes == 0) break; #endif /* recv() from server; */ if (bytes < 0) { perror("Failed to receive bytes from server"); break; } received += bytes; dbgprt("PAYLOAD %s\n",dbgstr(buffer,bytes)); // send payload to terminal fwrite(buffer,1,bytes,stdout); } close(sock); dbgprt("EXIT\n"); } void doclient(void) { char cmdbuf[MAXBUFF]; char *argv[MAXARG]; tid = "clnt"; while (1) { dbgprt("PROMPT\n"); printf(">> "); fflush(stdout); dbgprt("FGETS\n"); fgets(cmdbuf,sizeof(cmdbuf),stdin); cmdbuf[strcspn(cmdbuf,"\n")] = 0; dbgprt("COMMAND %s\n",dbgstr(cmdbuf,-1)); // tokenize the line int argc = tokenize(argv,cmdbuf); if (argc <= 0) continue; // set/display remote server IP address if (strcmp(argv[0],"remote") == 0) { if (argc >= 2) strcpy(ipaddr,argv[1]); if (ipaddr[0] != 0) printf("REMOTE: %s\n",ipaddr); continue; } // stop server if (strcmp(argv[0],"stop") == 0) { if (ipaddr[0] != 0) { dbgprt("STOP/SERVER\n"); send_cmd(XMSG_CMD,cmdbuf,-1); } ipaddr[0] = 0; continue; } // exit client program if (strcmp(argv[0],"exit") == 0) { dbgprt("STOP/CLIENT\n"); break; } // send command and echo response to terminal send_cmd(XMSG_CMD,cmdbuf,-1); } dbgprt("EXIT\n"); } // server_cmd -- process command on server void server_cmd(int new_socket) { xmsg_t xmsg; char cmdbuf[MAXBUFF]; char *argv[MAXARG]; dbgprt("ENTER new_socket=%d\n",new_socket); do { // get command descriptor xrecv(new_socket,&xmsg,sizeof(xmsg),0); // get command text xrecv(new_socket,cmdbuf,xmsg.xmsg_paylen,0); cmdbuf[xmsg.xmsg_paylen] = 0; dbgprt("COMMAND %s\n",dbgstr(cmdbuf,-1)); // tokenize the command int argc = tokenize(argv,cmdbuf); if (argc <= 0) break; // stop the server if (strcmp(argv[0],"stop") == 0) { dbgprt("KILL server_pid=%d\n",server_pid); // FIXME -- we could send a "stopping server" message here // send EOF to client xmsg.xmsg_type = XMSG_EOF; xmsg.xmsg_paylen = 0; xsend(new_socket,&xmsg,sizeof(xmsg),0); // signal the server main process to stop (cleanly) if (opt_s) server_signo = STOP_SIGNO; else kill(server_pid,STOP_SIGNO); break; } int pipefd[2]; int length; if (pipe(pipefd)) perror("Failed to create pipe"); pid_t pid = fork(); dbgprt("FORK pid=%d\n",pid); // invoke the target program (under a pipe) if (pid == 0) { tid = "exec"; dbgprt("DUP2\n"); fflush(stdout); int err = dup2(pipefd[1],1); // duplicate pipefd[1] to stdout if (err < 0) perror("dup2"); CLOSEME(pipefd[0]); // close the readonly side of the pipe CLOSEME(pipefd[1]); // close the write side of the pipe dbgprt("EXECVP\n"); CLOSEME(dbgfd); if (opt_h) { int len = sprintf(cmdbuf,"HELO\n"); write(1,cmdbuf,len); } execvp(argv[0],argv); // finally execute the command perror("execvp"); exit(1); } // fork error if (pid < 0) { perror("fork"); exit(1); } dbgprt("PARENT\n"); CLOSEME(pipefd[1]); // grab all output from the target program and send in packets to // client while (1) { dbgprt("READBEG\n"); length = read(pipefd[0],cmdbuf,sizeof(cmdbuf)); dbgprt("READEND length=%d\n",length); if (length < 0) { perror("readpipe"); break; } if (length == 0) break; dbgprt("READBUF %s\n",dbgstr(cmdbuf,length)); // send descriptor for this chunk xmsg.xmsg_type = XMSG_DATA; xmsg.xmsg_paylen = length; xsend(new_socket,&xmsg,sizeof(xmsg),0); // send the payload if (xsend(new_socket,cmdbuf,length,0) != length) { perror("Failed"); } } CLOSEME(pipefd[0]); // tell client we have no more data xmsg.xmsg_paylen = 0; xmsg.xmsg_type = XMSG_EOF; xsend(new_socket,&xmsg,sizeof(xmsg),0); } while (0); CLOSEME(new_socket); dbgprt("EXIT\n"); } void sighdr(int signo) { server_signo = signo; } void doserver(void) { int server_fd,new_socket; struct sockaddr_in address; pid_t pid; tid = "serv"; dbgprt("ENTER\n"); server_pid = getpid(); #if 0 signal(STOP_SIGNO,(void *) sighdr); #else struct sigaction act; sigaction(STOP_SIGNO,NULL,&act); act.sa_sigaction = (void *) sighdr; sigaction(STOP_SIGNO,&act,NULL); sigset_t set; sigemptyset(&set); sigaddset(&set,STOP_SIGNO); sigprocmask(SIG_UNBLOCK,&set,NULL); #endif #if 0 int addrlen = sizeof(address); #else socklen_t addrlen = sizeof(address); #endif dbgprt("SOCKET\n"); // Creating socket file descriptor if ((server_fd = socket(AF_INET,SOCK_STREAM,0)) == 0) { perror("socket failed"); exit(EXIT_FAILURE); } int enable = 1; if (setsockopt(server_fd,SOL_SOCKET,SO_REUSEADDR,&enable,sizeof(int)) < 0) { perror("error"); } address.sin_family = AF_INET; address.sin_addr.s_addr = INADDR_ANY; address.sin_port = htons(portno); dbgprt("BIND portno=%u\n",portno); if (bind(server_fd,(struct sockaddr *) &address,sizeof(address)) < 0) { perror("bind failed"); } dbgprt("LISTEN\n"); if (listen(server_fd,MAXPENDING) < 0) { perror("listen"); } int pending = 0; int status; while (1) { dbgprt("LOOP\n"); // reap all finished children while (1) { pid = waitpid(-1,&status,WNOHANG); if (pid <= 0) break; dbgprt("REAP pid=%d pending=%d\n",pid,pending); --pending; } // one of the children was given a stop command and it signaled us if (server_signo) { dbgprt("SIGNO server_signo=%d\n",server_signo); break; } // wait for new connection from a client // FIXME -- sending us a signal to stop cleanly is _broken_ because // we do _not_ get an early return here (e.g. EINTR) -- we may need // select with timeout dbgprt("WAITACCEPT\n"); new_socket = accept(server_fd,(struct sockaddr *) &address, (socklen_t *) &addrlen); // stop cleanly if (server_signo) { dbgprt("SIGNO server_signo=%d\n",server_signo); break; } if (new_socket < 0) { if (errno == EINTR) break; perror("accept"); } dbgprt("ACCEPTED\n"); // do command execution in main process (i.e. debug) if (opt_n) { server_cmd(new_socket); continue; } pid = fork(); if (pid < 0) { CLOSEME(new_socket); continue; } // process the command in the child if (pid == 0) { server_cmd(new_socket); exit(0); } ++pending; dbgprt("CHILD pid=%d\n",pid); // server main doesn't need this after fork #if 1 CLOSEME(new_socket); #endif } // reap all children while (pending > 0) { pid = waitpid(-1,&status,0); if (pid <= 0) break; dbgprt("REAP pid=%d pending=%d\n",pid,pending); --pending; } dbgprt("EXIT\n"); } int main(int argc,char **argv) { --argc; ++argv; for (; argc > 0; --argc, ++argv) { char *cp = *argv; if (*cp != '-') break; cp += 2; switch (cp[-1]) { case 'h': opt_h = ! opt_h; break; case 'n': // do _not_ fork server opt_n = ! opt_n; break; case 'p': portno = (*cp != 0) ? atoi(cp) : PORTNO; break; case 's': // invoke server opt_s = ! opt_s; break; } } tsczero = tscgetf(); #if DEBUG int flags = O_WRONLY | O_APPEND; if (opt_s) flags |= O_TRUNC | O_CREAT; dbgfd = open("debug.txt",flags,0644); if (dbgfd < 0) { perror("debug.txt"); exit(1); } #endif if (opt_s) doserver(); else doclient(); #if DEBUG if (dbgfd >= 0) close(dbgfd); #endif return 0; }

在按下 Enter 之前线程函数不会终止

thread function doesn't terminate until Enter is pressed

c

sockets

pthreads