c – Linux 3.0：使用管道stdin / stdout执行子进程

close(wpipefd[1]);

并且随后写入关闭的描述符.这只是转置,但是它显示这个代码从未被使用过.以下是我测试过的一个版本.不幸的是,我改变了代码风格,所以这不被接受为编辑eerpini的代码.

唯一的结构性变化是我只重定向孩子中的I / O(请注意,dup2调用仅在子路径中)这是非常重要的,因为否则父进程的I / O会被弄乱.感谢eerpini的初步答案,我用来开发这个答案.

#define PIPE_READ 0
#define PIPE_WRITE 1

int createChild(const char* szCommand,char* const aArguments[],char* const aEnvironment[],const char* szMessage) {
  int aStdinPipe[2];
  int aStdoutPipe[2];
  int nChild;
  char nChar;
  int nResult;

  if (pipe(aStdinPipe) < 0) {
    perror("allocating pipe for child input redirect");
    return -1;
  }
  if (pipe(aStdoutPipe) < 0) {
    close(aStdinPipe[PIPE_READ]);
    close(aStdinPipe[PIPE_WRITE]);
    perror("allocating pipe for child output redirect");
    return -1;
  }

  nChild = fork();
  if (0 == nChild) {
    // child continues here

    // redirect stdin
    if (dup2(aStdinPipe[PIPE_READ],STDIN_FILENO) == -1) {
      perror("redirecting stdin");
      return -1;
    }

    // redirect stdout
    if (dup2(aStdoutPipe[PIPE_WRITE],STDOUT_FILENO) == -1) {
      perror("redirecting stdout");
      return -1;
    }

    // redirect stderr
    if (dup2(aStdoutPipe[PIPE_WRITE],STDERR_FILENO) == -1) {
      perror("redirecting stderr");
      return -1;
    }

    // all these are for use by parent only
    close(aStdinPipe[PIPE_READ]);
    close(aStdinPipe[PIPE_WRITE]);
    close(aStdoutPipe[PIPE_READ]);
    close(aStdoutPipe[PIPE_WRITE]); 

    // run child process image
    // replace this with any exec* function find easier to use ("man exec")
    nResult = execve(szCommand,aArguments,aEnvironment);

    // if we get here at all,an error occurred,but we are in the child
    // process,so just exit
    perror("exec of the child process");
    exit(nResult);
  } else if (nChild > 0) {
    // parent continues here

    // close unused file descriptors,these are for child only
    close(aStdinPipe[PIPE_READ]);
    close(aStdoutPipe[PIPE_WRITE]); 

    // Include error check here
    if (NULL != szMessage) {
      write(aStdinPipe[PIPE_WRITE],szMessage,strlen(szMessage));
    }

    // Just a char by char read here,you can change it accordingly
    while (read(aStdoutPipe[PIPE_READ],&nChar,1) == 1) {
      write(STDOUT_FILENO,1);
    }

    // done with these in this example program,you would normally keep these
    // open of course as long as you want to talk to the child
    close(aStdinPipe[PIPE_WRITE]);
    close(aStdoutPipe[PIPE_READ]);
  } else {
    // failed to create child
    close(aStdinPipe[PIPE_READ]);
    close(aStdinPipe[PIPE_WRITE]);
    close(aStdoutPipe[PIPE_READ]);
    close(aStdoutPipe[PIPE_WRITE]);
  }
  return nChild;
}