mrw-cxx/mrw/unistd.hpp

#ifndef __MRW_UNISTD_HPP__
#define __MRW_UNISTD_HPP__

#include <unistd.h> // pipe, close
#include <errno.h> // errno

namespace mrw {
  /** @addtogroup AutoTools */
  //@{
  
  /** @brief class that implements an unnamed UNIX pipe
      @pre #include <mrw/unistd.hpp>

      Implements a UNIX pipe that is automatically closed in
      destructor and offers some facilities. */
  class pipe {
  private:
    /// the filedescriptor, [0] to read and [1] to write
    int _fd[2];
    int _lastError;
  public:
    /// creates a unix pipe
    pipe(): _lastError(-1) {
      _fd[0] = -1;
      _fd[1] = -1;
      if (::pipe(_fd)==-1)
        {
          _lastError=errno;
        }
    }
    /// destructor closes pipe if still open
    ~pipe() {
      close();
    }
    /// closes pipe if open
    void close() {
      close_in();
      close_out();
    }
    /// closes input pipe if open
    void close_in() {
      if (_fd[0]!=-1) while (::close(_fd[0])==-1) if (errno!=EINTR) {
        _lastError = errno;
        break;
      }
      _fd[0] = -1;
    }
    /// closes output pipe if open
    void close_out() {
      if (_fd[1]!=-1) while (::close(_fd[1])==-1) if (errno!=EINTR) {
        _lastError = errno;
        break;
      }
      _fd[1] = -1;
    }
    /// @return true if no error occured
    operator bool() {
      return _lastError == -1;
    }
    /// @return last error code, -1 if no error
    int error() {
      return _lastError;
    }
    /// connect output stream to @c stdout
    void connect_cout() {
      while (::dup2(_fd[1], 1)==-1) if (errno!=EINTR) {
        _lastError = errno;
        return;
      }
    }
    /// connect output stream to @c stderr
    void connect_cerr() {
      while (::dup2(_fd[1], 2)==-1) if (errno!=EINTR) {
        _lastError = errno;
        return;
      }
    }
    /// get an input stream
    /** @return stream to read from
        @note invalid after destruction or @c close or @c close_in */
    int istream() {
      return _fd[0];
    }
    /// get an output stream
    /** @return stream to write to
        @note invalid after destruction or @c close or @c close_out */
    int ostream() {
      return _fd[1];
    }
  };

  //@}
  
}
#endif