/data/refman/pasoursint/CMSSW_5_3_1/src/Utilities/StorageFactory/src/IOInput.cc

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#include "Utilities/StorageFactory/interface/IOInput.h"
#include "FWCore/Utilities/interface/EDMException.h"
#include <cassert>

IOInput::~IOInput (void)
{}


int
IOInput::read (void)
{
  unsigned char byte;
  IOSize n = read (&byte, 1);
  return n == 0 ? -1 : byte;
}

IOSize
IOInput::read (IOBuffer into)
{ return read (into.data (), into.size ()); }

IOSize
IOInput::readv (IOBuffer *into, IOSize buffers)
{
  assert (! buffers || into);

  // Keep reading as long as possible; ignore errors if we have read
  // something, otherwise pass it on.
  IOSize status;
  IOSize done = 0;
  try
  {
    for (IOSize i = 0; i < buffers; done += status, ++i)
      if ((status = read (into [i])) == 0)
        break;
  }
  catch (cms::Exception &)
  {
    if (! done)
      throw;
  }

  return done;
}


IOSize
IOInput::xread (IOBuffer into)
{ return xread (into.data (), into.size ()); }

IOSize
IOInput::xread (void *into, IOSize n)
{
  assert (into);

  // Keep reading as long as possible.  Let system errors fly over
  // us, they are a hard error.
  IOSize x;
  IOSize done = 0;
  while (done < n && (x = read ((char *) into + done, n - done)))
    done += x;

  return done;
}

IOSize
IOInput::xreadv (IOBuffer *into, IOSize buffers)
{
  // FIXME: Use read(into, buffers) and then sort out in case of
  // failure, the readv probably succeed directly with much less
  // overhead.

  assert (! buffers || into);

  // Keep reading as long as possible.  Let system errors fly
  // over us, they are a hard error.
  IOSize x;
  IOSize done = 0;
  for (IOSize i = 0; i < buffers; ++i)
  {
    done += (x = xread (into [i]));
    if (x < into [i].size ())
      break;
  }
  return done;
}