Why does read of /proc/cpuinfo seem to not advance file position?

Question

I have the following code which ends up forever reading '/proc/cpuinfo' as it keeps getting the same result every read. Why doesn't the file pointer get advanced and reach eof ever? Seems this special file has different semantics.

  const int bufSize = 4096;
  char buf[bufSize + 1];
  const string cpuInfo = "/proc/cpuinfo";
  int cpuFD = ::open(cpuInfo.c_str(), O_RDONLY);

  if (cpuFD == -1) {
    logOutputStream << "Failed attempt to open '" << cpuInfo << "': "
                    << strerror(errno) << endl;
  } else {
    assert(bufSize <= SSIZE_MAX);

    logOutputStream << "Contents of: '" << cpuInfo << "'.\n";

    for (int nRead = ::read(cpuFD, buf, bufSize); nRead != 0;) {
      if (nRead == -1) {
        logOutputStream << "Failed attempt to read '" << cpuInfo << "': "
                        << strerror(errno) << endl;
        break;
      } else {
        buf[nRead] = '\0';
        logOutputStream << buf;
      }
    }
    if (::close(cpuFD) == -1) {
      logOutputStream << "Failed attempt to close '" << cpuInfo << "': "
                      << strerror(errno) << endl;
    }
  }

Answer 1

What happens if you try dumping the content into an actual text file with something like

cat /proc/cpuinfo > cpuinfo.txt

and then reading that file ?

Answer 2

for (int nRead = ::read(cpuFD, buf, bufSize); nRead != 0;) {

is wrong. You're using read as an initializer, so read is only being called once, not once per loop. After that, you're just looping forever printing it out (because nothing is changing nRead).