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Re: [Qemu-devel] [PATCH v2 1/7] qapi: correctly parse uint64_t values fr
From: |
David Hildenbrand |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/7] qapi: correctly parse uint64_t values from strings |
Date: |
Tue, 23 Oct 2018 14:10:33 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 17/10/2018 14:42, Markus Armbruster wrote:
> Quick peek only for now.
>
> David Hildenbrand <address@hidden> writes:
>
>> Right now, we parse uint64_t values just like int64_t values, resulting
>> in negative values getting accepted and certain valid large numbers only
>> being representable as negative numbers. Also, reported errors indicate
>> that an int64_t is expected.
>>
>> Parse uin64_t separately. Implementation inspired by original
>> parse_str() implementation.
>>
>> E.g. we can now specify
>> -device nvdimm,memdev=mem1,id=nv1,addr=0xFFFFFFFFC0000000
>> Instead of going via negative values
>> -device nvdimm,memdev=mem1,id=nv1,addr=-0x40000000
>>
>> Resulting in the same values
>>
>> (qemu) info memory-devices
>> Memory device [nvdimm]: "nv1"
>> addr: 0xffffffffc0000000
>> slot: 0
>> node: 0
>>
>> Signed-off-by: David Hildenbrand <address@hidden>
>
> Related work on the QObject input visitor:
>
> commit 5923f85fb82df7c8c60a89458a5ae856045e5ab1
> Author: Marc-André Lureau <address@hidden>
> Date: Wed Jun 7 20:36:03 2017 +0400
>
> qapi: update the qobject visitor to use QNUM_U64
>
> Switch to use QNum/uint where appropriate to remove i64 limitation.
>
> The input visitor will cast i64 input to u64 for compatibility
> reasons (existing json QMP client already use negative i64 for large
> u64, and expect an implicit cast in qemu).
>
> Note: before the patch, uint64_t values above INT64_MAX are sent over
> json QMP as negative values, e.g. UINT64_MAX is sent as -1. After the
> patch, they are sent unmodified. Clearly a bug fix, but we have to
> consider compatibility issues anyway. libvirt should cope fine,
> because its parsing of unsigned integers accepts negative values
> modulo 2^64. There's hope that other clients will, too.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> Reviewed-by: Markus Armbruster <address@hidden>
> Message-Id: <address@hidden>
> [check_native_list() tweaked for consistency with signed case]
> Signed-off-by: Markus Armbruster <address@hidden>
>
> Note who it considers backward compatibility. Have you done that for
> the string input visitor? The commit message should tell.
There should be no compat issues, negative values are still accepted. At
least I can't think of any :) We simply allow accepting bigger values.
>
>> ---
>> qapi/string-input-visitor.c | 117 ++++++++++++++++++++++++++++++++----
>> 1 file changed, 106 insertions(+), 11 deletions(-)
>>
>> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
>> index b3fdd0827d..af0a841152 100644
>> --- a/qapi/string-input-visitor.c
>> +++ b/qapi/string-input-visitor.c
>> @@ -19,6 +19,7 @@
>> #include "qapi/qmp/qnull.h"
>> #include "qemu/option.h"
>> #include "qemu/queue.h"
>> +#include "qemu/cutils.h"
>> #include "qemu/range.h"
>>
>>
>> @@ -44,7 +45,8 @@ static void free_range(void *range, void *dummy)
>> g_free(range);
>> }
>>
>> -static int parse_str(StringInputVisitor *siv, const char *name, Error
>> **errp)
>> +static int parse_str_int64(StringInputVisitor *siv, const char *name,
>> + Error **errp)
>> {
>> char *str = (char *) siv->string;
>> long long start, end;
>> @@ -118,6 +120,75 @@ error:
>> return -1;
>> }
>>
>> +static int parse_str_uint64(StringInputVisitor *siv, const char *name,
>> + Error **errp)
>> +{
>> + const char *str = (char *) siv->string;
>> + uint64_t start, end;
>> + const char *endptr;
>> + Range *cur;
>> +
>> + if (siv->ranges) {
>> + return 0;
>> + }
>> +
>> + if (!*str) {
>> + return 0;
>> + }
>> +
>> + do {
>> + if (!qemu_strtou64(str, &endptr, 0, &start)) {
>> + if (*endptr == '\0') {
>> + cur = g_malloc0(sizeof(*cur));
>> + range_set_bounds(cur, start, start);
>> + siv->ranges = range_list_insert(siv->ranges, cur);
>> + cur = NULL;
>> + str = NULL;
>> + } else if (*endptr == '-') {
>> + str = endptr + 1;
>> + if (!qemu_strtou64(str, &endptr, 0, &end) && start <= end) {
>> + if (*endptr == '\0') {
>> + cur = g_malloc0(sizeof(*cur));
>> + range_set_bounds(cur, start, end);
>> + siv->ranges = range_list_insert(siv->ranges, cur);
>> + cur = NULL;
>> + str = NULL;
>> + } else if (*endptr == ',') {
>> + str = endptr + 1;
>> + cur = g_malloc0(sizeof(*cur));
>> + range_set_bounds(cur, start, end);
>> + siv->ranges = range_list_insert(siv->ranges, cur);
>> + cur = NULL;
>> + } else {
>> + goto error;
>> + }
>> + } else {
>> + goto error;
>> + }
>> + } else if (*endptr == ',') {
>> + str = endptr + 1;
>> + cur = g_malloc0(sizeof(*cur));
>> + range_set_bounds(cur, start, start);
>> + siv->ranges = range_list_insert(siv->ranges, cur);
>> + cur = NULL;
>> + } else {
>> + goto error;
>> + }
>> + } else {
>> + goto error;
>> + }
>> + } while (str);
>> +
>> + return 0;
>> +error:
>> + g_list_foreach(siv->ranges, free_range, NULL);
>> + g_list_free(siv->ranges);
>> + siv->ranges = NULL;
>> + error_setg(errp, QERR_INVALID_PARAMETER_VALUE, name ? name : "null",
>> + "an uint64 value or range");
>> + return -1;
>> +}
>> +
>
> Do we actually need unsigned ranges? I'm asking because I hate this
> code, and duplicating can only make it worse.
>
> [...]
I don't think we need unsigned ranges BUT I am concerned about backwards
compatibility. I'll have to check all users to make sure no property
flagged as uint64_t will actually expect ranges. Then we can drop it.
(and simplify this code)
--
Thanks,
David / dhildenb
- [Qemu-devel] [PATCH v2 0/7] qapi/range/memory-device: fixes and cleanups, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 2/7] qapi: use qemu_strtoi64() in parse_str_int64, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 3/7] range: pass const pointer where possible, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 4/7] range: add some more functions, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 5/7] memory-device: use QEMU_IS_ALIGNED, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 6/7] memory-device: avoid overflows on very huge devices, David Hildenbrand, 2018/10/12
- [Qemu-devel] [PATCH v2 7/7] memory-device: rewrite address assignment using ranges, David Hildenbrand, 2018/10/12