StrFormat.cxx

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
// $Id: StrFormat.cxx 579482 2014-01-22 09:14:16Z krasznaa $
 
#include "CxxUtils/StrFormat.h"
 
// c includes
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdexcept>
 
namespace {
  // little helper to ensure a char* is freed
  class CharLiberator
  {
    char* m_buf;
 
  public:
    explicit
    CharLiberator(char* buf) : m_buf(buf)
    {}
    CharLiberator() : m_buf (NULL) 
    {}
    ~CharLiberator()
    {
      free(m_buf);
    }
 
    CharLiberator (const CharLiberator&) = delete;
    CharLiberator& operator= (const CharLiberator&) = delete;
  };
 
}
 
namespace CxxUtils {

std::string
strformat(const char* fmt, ...)
{
  char *buf = NULL;
  int nbytes = -1;
 
  va_list ap;
  va_start(ap, fmt); /* Initialize the va_list */
 
  nbytes = vasprintf(&buf, fmt, ap);
  va_end(ap); /* Cleanup the va_list */
 
  if (nbytes < 0) {
    /*buf is undefined when allocation failed
     * see: http://linux.die.net/man/3/asprintf
     */
    // free(buf); 
    throw std::runtime_error("problem while calling vasprintf");
  }
 
  CharLiberator guard(buf);
 
  // help compiler to apply RVO
  return std::string(buf);
}
 
} //> namespace CxxUtils