Re: [Qemu-devel] [PATCH] qemu: json: Fix parsing of integers >= 0x8000000000000000

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, May 20, 2011 at 01:11:05PM -0500, Anthony Liguori wrote:
> On 05/20/2011 01:03 PM, Richard W.M. Jones wrote:
> >
> >There seem to be a few unsafe uses of strto* functions.  This patch
> >just fixes the one that affects me :-)
> 
> Sending an integer of this size is not valid JSON.
> 
> Your patch won't accept negative numbers, correct?
> 
> JSON only supports int64_t.

That's not really true. JSON supports arbitrarily large numbers
& integers.  It is merely the QEMU parser / object model which
is artifically limiting them to int64_t. The core of the problem
is with the QInt implementation in QEMU, which uses an 'int64_t'
as its canonical form, rather than just holding a string representation
of the number. The JSON parser should only validate that the
data is a valid JSON number, and then pass the number as a string
to QInt. The conversion to int_64 or other integer sizes / formats
should be done at time of use, according to the type of data the
command actually wants, whether int64t, int32t, int16t etc. eg the
QInt API should look more like:

  QInt *qint_from_string(const char *number);
  QInt *qint_from_int64(int64_t val);
  QInt *qint_from_int32(int64_t val);
  QInt *qint_from_int16(int64_t val);
  QInt *qint_from_uint64(uint64_t val);
  QInt *qint_from_uint32(uint32_t val);
  QInt *qint_from_uint16(uint16_t val);

  int qint_get_int64(QInt *qi, int64t *val);
  int qint_get_int32(QInt *qi, int32t *val);
  int qint_get_int16(QInt *qi, int16t *val);
  int qint_get_uint64(QInt *qi, uint64t *val);
  int qint_get_uint32(QInt *qi, uint32t *val);
  int qint_get_uint16(QInt *qi, uint16t *val);


Regards,
Daniel
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