RlinkPortFifo.cpp

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// $Id: RlinkPortFifo.cpp 1186 2019-07-12 17:49:59Z mueller $
// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright 2011-2018 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>
// 
// Revision History: 
// Date         Rev Version  Comment
// 2017-04-15   875   1.2.1  Open(): set default scheme
// 2015-04-12   666   1.2    add xon,noinit attributes
// 2013-02-23   492   1.1    use RparseUrl
// 2011-03-27   374   1.0    Initial version
// 2011-01-15   356   0.1    First draft
// ---------------------------------------------------------------------------
 
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
 
#include "RlinkPortFifo.hpp"
 
using namespace std;
 
// all method definitions in namespace Retro
namespace Retro {
 
//------------------------------------------+-----------------------------------
 
RlinkPortFifo::RlinkPortFifo()
  : RlinkPort()
{}
 
//------------------------------------------+-----------------------------------
 
RlinkPortFifo::~RlinkPortFifo()
{
  // no need to call Close() here, no RlinkPortFifo::Close()
  // cleanup will be done by ~RlinkPort()
}
 
//------------------------------------------+-----------------------------------
 
bool RlinkPortFifo::Open(const std::string& url, RerrMsg& emsg)
{
  if (IsOpen()) Close();
 
  if (!fUrl.Set(url, "|keep|xon|noinit|", "fifo", emsg)) return false;
 
  // Note: _rx fifo must be opened before the _tx fifo, otherwise the test
  //       bench might close with EOF on read prematurely (is a race condition).
 
  fFdWrite = OpenFifo(fUrl.Path() + "_rx", true, emsg);
  if (fFdWrite < 0) return false;
  
  fFdRead = OpenFifo(fUrl.Path() + "_tx", false, emsg);
  if (fFdRead < 0) {
    ::close(fFdWrite);
    fFdWrite = -1;
    return false;
  }
 
  fXon = fUrl.FindOpt("xon");
  fIsOpen = true;
 
  return true;
}
 
//------------------------------------------+-----------------------------------
 
int RlinkPortFifo::OpenFifo(const std::string& name, bool snd, RerrMsg& emsg)
{
  struct stat stat_fifo;
  int irc = ::stat(name.c_str(), &stat_fifo);
  if (irc == 0) {
    if ((stat_fifo.st_mode & S_IFIFO) == 0) {
      emsg.Init("RlinkPortFifo::OpenFiFo()",
                string("'") + name + "' exists but is not a pipe");
      return -1;
    }
  } else {
    mode_t mode = S_IRUSR | S_IWUSR;        // user read and write allowed
    irc = ::mkfifo(name.c_str(), mode);
    if (irc != 0) {
      emsg.InitErrno("RlinkPortFifo::OpenFifo()", 
                     string("mkfifo() for '") + name + "' failed: ",
                     errno);
      return -1;
    }    
  }
  
  /* coverity[toctou] */
  irc = ::open(name.c_str(), snd ? O_WRONLY : O_RDONLY);
  if (irc < 0) {
    emsg.InitErrno("RlinkPortFifo::OpenFifo()", 
                   string("open() for '") + name + "' failed: ",
                   errno);
    return -1;
  }
 
  return irc;
}
 
} // end namespace Retro