monitor/src/BidirectionalPipe.cpp

   1 #include <unistd.h>
   2 #include <cstring>
   3 #include <sys/types.h>
   4 #include <sys/ptrace.h>
   5 #include <errno.h>
   6 #include <fcntl.h>
   7 #include <iostream>
   8 #include "BidirectionalPipe.h"
   9 #include "misc/Exception.h"
  10
  11 namespace Aesalon {
  12 namespace Platform {
  13
  14 BidirectionalPipeException::BidirectionalPipeException(std::string message,
  15     bool strerr) : Misc::Exception(Misc::StreamAsString() << message << (strerr?strerror(errno):"")) {
  16 }
  17
  18 BidirectionalPipe::BidirectionalPipe(Misc::ArgumentList argument_list, bool block) : block(block) {
  19
  20     pipe(pc_pipe_fd);
  21     pipe(cp_pipe_fd);
  22
  23     pid = fork();
  24
  25     if(pid == -1) throw BidirectionalPipeException("Could not fork to execute child process: ", true);
  26     else if(pid == 0) {
  27         close(pc_pipe_fd[1]); /* Close the write end of the pc pipe */
  28         close(cp_pipe_fd[0]); /* Close the read end of the cp pipe */
  29
  30         fcntl(pc_pipe_fd[0], F_SETFL, fcntl(pc_pipe_fd[0], F_GETFL) & ~O_NONBLOCK);
  31         fcntl(cp_pipe_fd[1], F_SETFL, fcntl(cp_pipe_fd[1], F_GETFL) & ~O_NONBLOCK);
  32
  33         dup2(pc_pipe_fd[0], STDIN_FILENO);
  34         dup2(cp_pipe_fd[1], STDOUT_FILENO);
  35
  36         execv(argument_list.get_argument(0).c_str(), argument_list.get_as_argv());
  37
  38         throw BidirectionalPipeException("Failed to execute file: ", true);
  39     }
  40     close(pc_pipe_fd[0]);  /* Close the read end of the pc pipe */
  41     close(cp_pipe_fd[1]);  /* Close the write end of the cp pipe */
  42
  43     fcntl(pc_pipe_fd[1], F_SETFL, fcntl(cp_pipe_fd[1], F_GETFL) & ~O_NONBLOCK);
  44     set_blocking(block);
  45
  46     /* Pipe opened and ready to go. */
  47     is_connected = true;
  48 }
  49
  50 BidirectionalPipe::~BidirectionalPipe() {
  51     if(is_connected) close(pc_pipe_fd[1]), close(cp_pipe_fd[0]);
  52     is_connected = false;
  53 }
  54
  55 std::string BidirectionalPipe::get_string() {
  56     std::string data;
  57     char recv;
  58     int ret_value;
  59
  60     if(!is_open()) return "";
  61
  62     while((ret_value = read(cp_pipe_fd[0], &recv, sizeof(recv))) > 0) {
  63         if(recv == '\n') {
  64             return data;
  65         }
  66         data += recv;
  67     }
  68     /* EAGAIN on a pipe read with O_NONBLOCK set means no data waiting. */
  69     if(!block && ret_value == -1 && errno == EAGAIN) {
  70         return "";
  71     }
  72     is_connected = false;
  73     return data;
  74 }
  75
  76 void BidirectionalPipe::send_string(std::string data) {
  77     if(is_open()) write(pc_pipe_fd[1], data.c_str(), data.length());
  78 }
  79
  80 void BidirectionalPipe::set_blocking(bool new_blocking) {
  81     block = new_blocking;
  82     if(!block) fcntl(cp_pipe_fd[0], F_SETFL, fcntl(cp_pipe_fd[0], F_GETFL) | O_NONBLOCK);
  83     else fcntl(cp_pipe_fd[0], F_SETFL, fcntl(cp_pipe_fd[0], F_GETFL) & ~O_NONBLOCK);
  84 }
  85
  86 } // namespace Platform
  87 } // namespace Aesalon