呜呜呜，这件事我记得去年做的。我基本上是一个使用我自己的 telnet 克隆与互联网通信的程序。问题是 telnet 使用标准输入和标准输出工作。
看来你也有同样的情况！我解决这个问题的方法是分叉一个进程，获取标准输入和标准输出并将它们放入管道中，然后使用 telnet 调用覆盖分叉的进程映像（现在使用这些管道而不是标准输入和标准输出）。
您需要一个管道将文本发送到 bc，另一个管道从 bc 接收。如果您对所有内容都使用单个管道，那么您最终可能会读取发送到 bc 的内容并混合数据。
警告：大量代码传入。我相信您不需要了解所有内容，因为我使用线程同时写入和读取，并使用 select() 来查看管道中是否有要读取的内容。很重要！！！当通信中断时，您的进程将收到终止不干净的 SIGPIPE（如果您使用的是动态内存或类似的东西）。你必须 fflush(outpipe) 否则 bc 不会收到它。（这是因为系统只有在找到 '\n' 或类似的东西时才会刷新，如果我没记错的话）。我放了所有代码，以防您想阅读 X 的作用。但是你需要的只是评论“LOCAL FUNCTIONS END HERE”之后的小叉子
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
#include <signal.h>
#include <stdbool.h>
#include "irc.h"
#include "coloring.h"
#include "rtsp.h"
#define BUFFERSIZE 255
int main (int argc, char *argv[]) {
/* XXX: When kid dies, program doesn't exit */
char *serverName, *port, *nick, *channel;
int ptelnetin[2];
int ptelnetout[2];
FILE *fpipes[2];
bool running = true;
pid_t kid;
pthread_t pthread_input, pthread_output;
/************************************************
LOCAL FUNCTIONS START HERE
***********************************************/
void *inputprocess(void *pipes) {
bool bracket;
int i;
fd_set rfds;
struct timeval tv;
tv.tv_sec = 0.2;
tv.tv_usec = 0;
char buffer[BUFFERSIZE];
FILE *out = ((FILE **) pipes)[1];
while (running){
FD_ZERO(&rfds);
FD_SET(fileno(stdin), &rfds);
switch (select(FD_SETSIZE, &rfds, NULL, NULL, &tv)) {
case -1:
fprintf(stderr, "Error reading data at select() Line %d, File %s\n", __LINE__, __FILE__);
running = false;
break;
case 0:
/* There's no data avaiable just yet.
Do nothing and keep checking */
break;
default:
/* This check needs to be done;
select isn't completely reliable */
if(!fgets(buffer, BUFFERSIZE, stdin)) {
running = false;
break;
}
/* Check message not to contain brackets*/
for (i = 0, bracket = false; running && !bracket && buffer[i] && i < BUFFERSIZE; i++) {
if (buffer[i] == '[' || buffer[i] == ']') {
PRINT_YELLOW;
printf("Use of brackets not allowed\n");
RESET_COLOR;
fflush(stdout);
bracket = true;
break;
}
}
if (running && !bracket) ircInputWrite(out, buffer);
fflush(out);
}
}
}
void *outputprocess(void *pipes){
fd_set rfds;
struct timeval tv;
tv.tv_sec = 0.2;
tv.tv_usec = 0;
char buffer[BUFFERSIZE];
char from[100];
FILE *in = ((FILE **) pipes)[0];
FILE *out = ((FILE **) pipes)[1];
while (running){
FD_ZERO(&rfds);
FD_SET(fileno(in), &rfds);
switch (select(FD_SETSIZE, &rfds, NULL, NULL, &tv)) {
case -1:
fprintf(stderr, "Error reading data at select() Line %d, File %s\n", __LINE__, __FILE__);
running = false;
break;
case 0:
/* There's no data avaiable just yet. */
/* Select sometimes returns 0 when there IS
data to read so we'll read anyway */
default:
/* This check needs to be done;
select isn't completely reliable */
if(!fgets(buffer, BUFFERSIZE, in)) {
running = false;
break;
}
switch(ircWhatsthis(buffer)) {
case iPING:
PRINT_BLUE;
printf("PingPong!\n");
RESET_COLOR;
ircPingPong(out, buffer); fflush(out);
fflush(stdout);
break;
case iROOMMSG:
if (ircUnpackPRIVMSG(from, buffer, buffer)) {
PRINT_BRIGHT_RED;
fprintf(stdout, "Malformed private message received\n");
RESET_COLOR;
}
else {
PRINT_CYAN;
printf("<%s>: ", from);
puts(buffer);
RESET_COLOR;
}
fflush(stdout);
break;
case iPRIVMSG:
fflush(stdout);
if (ircUnpackPRIVMSG(from, buffer, buffer)) {
PRINT_BRIGHT_RED;
fprintf(stdout, "Malformed private message received\n");
RESET_COLOR;
fflush(stdout);
}
else {
if (rtspExecBrackets(out, from, buffer)) {
PRINT_BRIGHT_MAGENTA;
printf("[%s]: ", from);
puts(buffer);
RESET_COLOR;
fflush(stdout);
}
}
break;
case iERROR:
PRINT_BRIGHT_RED;
fwrite(buffer, sizeof(char), strlen(buffer)+1, stdout);
RESET_COLOR;
break;
case iOK:
PRINT_BRIGHT_CYAN;
fwrite(buffer, sizeof(char), strlen(buffer)+1, stdout);
RESET_COLOR;
break;
default:
PRINT_BRIGHT_BLACK;
fwrite(buffer, sizeof(char), strlen(buffer)+1, stdout);
RESET_COLOR;
}
fflush(stdout);
}
}
}
void terminate(int signum) {
/* XXX irc.c calls rtsp.c which uses threads.
These threads never clean up if exiting via ^C
*/
RESET_COLOR;
running = false;
/*Close IO*/
fclose(fpipes[0]);
fclose(fpipes[1]);
/* Call child */
kill(kid, SIGINT);
wait(NULL);
exit(0);
}
/************************************************
LOCAL FUNCTIONS END HERE
***********************************************/
signal(SIGPIPE, terminate);
signal(SIGINT, terminate);
/* Get parameters */
if (argc != 5) {
fprintf(stderr, "Usage:\n %s <server> <port> <nick> <channel>\n", argv[0]);
return -1;
}
serverName = argv[1];
port = argv[2];
nick = argv[3];
channel = argv[4];
/* Startup pipes */
pipe(ptelnetin);
pipe(ptelnetout);
/* Launch telnete */
switch (kid = fork()) {
case -1:
perror("OMG ABORTION at main");
exit(-2);
case 0: /* CHILD */
/*Overwrite stdin with pipein and discard pipe*/
dup2(ptelnetin[0], 0);
close(ptelnetin[0]);
close(ptelnetin[1]);
/*Overwrite stdout with pipeout and discard pipe*/
dup2(ptelnetout[1], 1);
close(ptelnetout[0]);
close(ptelnetout[1]);
/*Overwrite process image with telnete*/
execlp("./telnete", "./telnete", argv[1], argv[2], (char *) NULL);
perror("Call to exec failed at main");
exit(-3);
default: /* PARENT */
/* Close reading end of pipein */
close(ptelnetin[0]);
/* Close writing end on pipeout */
close(ptelnetout[1]);
}
/* Turn (fileno) into (FILE *) */
fpipes[1] = fdopen(ptelnetin[1],"w");
if(!fpipes[1]) {
perror("Error at fdopen(in) at main");
kill(kid, SIGINT);
abort();
}
fpipes[0] = fdopen(ptelnetout[0],"r");
if(!fpipes[0]) {
perror("Error at fdopen(out) at main");
kill(kid, SIGINT);
abort();
}
/* Sleep for a few seconds so server doesn't ignore it */
PRINT_YELLOW;
printf("Logging in IRC...\n");
RESET_COLOR;
fflush(stdout);
if (ircRegister(argv[3], fpipes[1], fpipes[0])) {
fprintf(stderr, "Error registering in IRC.\n");
terminate(-1);
}
PRINT_YELLOW;
printf("Joining room %s\n", argv[4]);
RESET_COLOR;
ircJOIN(fpipes[1], argv[4]);
fflush(fpipes[1]);
/* Launch threads */
if (pthread_create(&pthread_input, NULL, inputprocess, fpipes)){
fprintf(stderr,"Couldn't launch input thread");
kill(kid, SIGINT);
abort();
}
if (pthread_create(&pthread_output, NULL, outputprocess, fpipes)){
fprintf(stderr,"Couldn't launch output thread");
kill(kid, SIGINT);
abort();
}
/* Wait for threads */
if (pthread_join(pthread_input,NULL)){
fprintf(stderr, "Error joining thread.\n");
}
if (pthread_join(pthread_output,NULL)){
fprintf(stderr,"Error joining thread.\n");
}
terminate(0);
}
我将把关键片段放在这里，这样更清楚：
/* Startup pipes */
pipe(ptelnetin);
pipe(ptelnetout);
/* Launch telnete */
switch (kid = fork()) {
case -1:
perror("OMG ABORTION at main");
exit(-2);
case 0: /* CHILD */
/*Overwrite stdin with pipein and discard pipe*/
dup2(ptelnetin[0], 0);
close(ptelnetin[0]);
close(ptelnetin[1]);
/*Overwrite stdout with pipeout and discard pipe*/
dup2(ptelnetout[1], 1);
close(ptelnetout[0]);
close(ptelnetout[1]);
/*Overwrite process image with telnete*/
execlp("./telnete", "./telnete", argv[1], argv[2], (char *) NULL);
perror("Call to exec failed at main");
exit(-3);
default: /* PARENT */
/* Close reading end of pipein */
close(ptelnetin[0]);
/* Close writing end on pipeout */
close(ptelnetout[1]);
}
/* Turn (fileno) into (FILE *) */
fpipes[1] = fdopen(ptelnetin[1],"w");
if(!fpipes[1]) {
perror("Error at fdopen(in) at main");
kill(kid, SIGINT);
abort();
}
fpipes[0] = fdopen(ptelnetout[0],"r");
if(!fpipes[0]) {
perror("Error at fdopen(out) at main");
kill(kid, SIGINT);
abort();
}
完成此操作后，您可以从 (FILE *) fpipes[0] 读取 bc 的结果并将其写入 fpipes[1]。记住每次写入后都要 fflush(fpipes[1]) 。像对待任何文件一样对待这两个。