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Re: [Qemu-devel] [PATCH 06/10] json-parser: fix handling of large whole
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH 06/10] json-parser: fix handling of large whole number values |
Date: |
Fri, 10 May 2013 13:55:55 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 |
On 05/10/13 04:20, Michael Roth wrote:
> Currently our JSON parser assumes that numbers lacking a mantissa are
> integers and attempts to store them as QInt/int64 values. This breaks in
> the case where the number overflows/underflows int64 values (which is
> still valid JSON)
>
> Fix this by detecting such cases and using a QFloat to store the value
> instead.
>
> Signed-off-by: Michael Roth <address@hidden>
> ---
> qobject/json-parser.c | 26 +++++++++++++++++++++++---
> 1 file changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/qobject/json-parser.c b/qobject/json-parser.c
> index 05279c1..4d14e71 100644
> --- a/qobject/json-parser.c
> +++ b/qobject/json-parser.c
> @@ -640,9 +640,29 @@ static QObject *parse_literal(JSONParserContext *ctxt)
> case JSON_STRING:
> obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
> break;
> - case JSON_INTEGER:
> - obj = QOBJECT(qint_from_int(strtoll(token_get_value(token), NULL,
> 10)));
> - break;
> + case JSON_INTEGER: {
> + /* A possibility exists that this is a whole-valued float where the
> + * mantissa was left out due to being 0 (.0). It's not a big deal to
> + * treat these as ints in the parser, so long as users of the
> + * resulting QObject know to expect a QInt in place of a QFloat in
> + * cases like these.
> + *
> + * However, in some cases these values will overflow/underflow a
> + * QInt/int64 container, thus we should assume these are to be
> handled
> + * as QFloats/doubles rather than silently changing their values.
> + *
> + * strtoll() indicates these instances by setting errno to ERANGE
> + */
> + int64_t value;
> +
> + errno = 0; /* strtoll doesn't set errno on success */
> + value = strtoll(token_get_value(token), NULL, 10);
> + if (errno != ERANGE) {
> + obj = QOBJECT(qint_from_int(value));
> + break;
> + }
> + /* fall through to JSON_FLOAT */
> + }
> case JSON_FLOAT:
> /* FIXME dependent on locale */
> obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token),
> NULL)));
>
I wanted to correct you here and propose s/mantissa/fractional part/
everywhere in this patch (including commit message and patch body).
However <http://en.wiktionary.org/wiki/mantissa> tells me one meaning of
"mantissa" *is* "fractional part".
In that sense I won't try to "correct" you, but can you consider doing
the replacement still, in order not to confuse non-native speakers who
associate "mantissa" only with the third meaning Wiktionary gives, ie.
the significand in FP representation?
Otherwise the v2 series looks good to me (not R-b-ing it since you'll
post v3 to address Amos's note).
Thanks,
Laszlo
- Re: [Qemu-devel] [PATCH 01/10] qapi: qapi-types.py, native list support, (continued)
- [Qemu-devel] [PATCH 02/10] qapi: qapi-visit.py, fix list handling for union types, Michael Roth, 2013/05/09
- [Qemu-devel] [PATCH 03/10] qapi: qapi-visit.py, native list support, Michael Roth, 2013/05/09
- [Qemu-devel] [PATCH 04/10] qapi: enable generation of native list code, Michael Roth, 2013/05/09
- [Qemu-devel] [PATCH 05/10] qapi: fix leak in unit tests, Michael Roth, 2013/05/09
- [Qemu-devel] [PATCH 06/10] json-parser: fix handling of large whole number values, Michael Roth, 2013/05/09
- Re: [Qemu-devel] [PATCH 06/10] json-parser: fix handling of large whole number values, Luiz Capitulino, 2013/05/10
[Qemu-devel] [PATCH 07/10] qapi: fix visitor serialization tests for numbers/doubles, Michael Roth, 2013/05/09
[Qemu-devel] [PATCH 08/10] qapi: add native list coverage for visitor serialization tests, Michael Roth, 2013/05/09
[Qemu-devel] [PATCH 09/10] qapi: add native list coverage for QMP output visitor tests, Michael Roth, 2013/05/09