* [PATCH] qcow2: Use a GString in report_unsupported_feature()
@ 2020-01-14 14:54 Alberto Garcia
2020-01-14 18:08 ` Alex Bennée
0 siblings, 1 reply; 6+ messages in thread
From: Alberto Garcia @ 2020-01-14 14:54 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Philippe Mathieu-Daudé,
Alberto Garcia, qemu-block, Max Reitz
This is a bit more efficient than having to allocate and free memory
for each item.
The default size (60) is enough for all the existing incompatible
features.
Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
---
block/qcow2.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index cef9d72b3a..ecf6827420 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -453,16 +453,15 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
uint64_t mask)
{
- char *features = g_strdup("");
- char *old;
+ GString *features = g_string_sized_new(60);
while (table && table->name[0] != '\0') {
if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
if (mask & (1ULL << table->bit)) {
- old = features;
- features = g_strdup_printf("%s%s%.46s", old, *old ? ", " : "",
- table->name);
- g_free(old);
+ if (features->len > 0) {
+ g_string_append(features, ", ");
+ }
+ g_string_append_printf(features, "%.46s", table->name);
mask &= ~(1ULL << table->bit);
}
}
@@ -470,14 +469,15 @@ static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
}
if (mask) {
- old = features;
- features = g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64,
- old, *old ? ", " : "", mask);
- g_free(old);
+ if (features->len > 0) {
+ g_string_append(features, ", ");
+ }
+ g_string_append_printf(features,
+ "Unknown incompatible feature: %" PRIx64, mask);
}
- error_setg(errp, "Unsupported qcow2 feature(s): %s", features);
- g_free(features);
+ error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
+ g_string_free(features, TRUE);
}
/*
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
2020-01-14 14:54 [PATCH] qcow2: Use a GString in report_unsupported_feature() Alberto Garcia
@ 2020-01-14 18:08 ` Alex Bennée
2020-01-14 18:43 ` Philippe Mathieu-Daudé
2020-01-15 13:49 ` Alberto Garcia
0 siblings, 2 replies; 6+ messages in thread
From: Alex Bennée @ 2020-01-14 18:08 UTC (permalink / raw)
To: Alberto Garcia
Cc: Kevin Wolf, Philippe Mathieu-Daudé,
qemu-devel, qemu-block, Max Reitz
Alberto Garcia <berto@igalia.com> writes:
> This is a bit more efficient than having to allocate and free memory
> for each item.
>
> The default size (60) is enough for all the existing incompatible
> features.
>
> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
> block/qcow2.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index cef9d72b3a..ecf6827420 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -453,16 +453,15 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
> static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
> uint64_t mask)
> {
> - char *features = g_strdup("");
> - char *old;
> + GString *features = g_string_sized_new(60);
g_autoptr(GString) features = g_string_sized_new(60);
will save you the clean-up later.
>
> while (table && table->name[0] != '\0') {
> if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
> if (mask & (1ULL << table->bit)) {
> - old = features;
> - features = g_strdup_printf("%s%s%.46s", old, *old ? ", " : "",
> - table->name);
> - g_free(old);
> + if (features->len > 0) {
> + g_string_append(features, ", ");
> + }
> + g_string_append_printf(features, "%.46s",
> table->name);
We have a number of cases of this sort of idiom in the code base. I
wonder if it calls for a utility function:
qemu_append_with_sep(features, ", ", "%.46s", table->name)
Anyway not mandatory for this patch so with the autoptr fix:
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> mask &= ~(1ULL << table->bit);
> }
> }
> @@ -470,14 +469,15 @@ static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
> }
>
> if (mask) {
> - old = features;
> - features = g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64,
> - old, *old ? ", " : "", mask);
> - g_free(old);
> + if (features->len > 0) {
> + g_string_append(features, ", ");
> + }
> + g_string_append_printf(features,
> + "Unknown incompatible feature: %" PRIx64, mask);
> }
>
> - error_setg(errp, "Unsupported qcow2 feature(s): %s", features);
> - g_free(features);
> + error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
> + g_string_free(features, TRUE);
> }
>
> /*
--
Alex Bennée
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
2020-01-14 18:08 ` Alex Bennée
@ 2020-01-14 18:43 ` Philippe Mathieu-Daudé
2020-01-14 21:35 ` Alex Bennée
2020-01-15 13:49 ` Alberto Garcia
1 sibling, 1 reply; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-01-14 18:43 UTC (permalink / raw)
To: Alex Bennée, Alberto Garcia
Cc: Kevin Wolf, qemu-devel, qemu-block, Max Reitz
On 1/14/20 7:08 PM, Alex Bennée wrote:
> Alberto Garcia <berto@igalia.com> writes:
>
>> This is a bit more efficient than having to allocate and free memory
>> for each item.
>>
>> The default size (60) is enough for all the existing incompatible
>> features.
>>
>> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>> ---
>> block/qcow2.c | 24 ++++++++++++------------
>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index cef9d72b3a..ecf6827420 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -453,16 +453,15 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
>> static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>> uint64_t mask)
>> {
>> - char *features = g_strdup("");
>> - char *old;
>> + GString *features = g_string_sized_new(60);
>
> g_autoptr(GString) features = g_string_sized_new(60);
>
> will save you the clean-up later.
Does this work with g_string_free() too?
>>
>> while (table && table->name[0] != '\0') {
>> if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
>> if (mask & (1ULL << table->bit)) {
>> - old = features;
>> - features = g_strdup_printf("%s%s%.46s", old, *old ? ", " : "",
>> - table->name);
>> - g_free(old);
>> + if (features->len > 0) {
>> + g_string_append(features, ", ");
>> + }
>> + g_string_append_printf(features, "%.46s",
>> table->name);
>
> We have a number of cases of this sort of idiom in the code base. I
> wonder if it calls for a utility function:
>
> qemu_append_with_sep(features, ", ", "%.46s", table->name)
Good idea for https://wiki.qemu.org/Contribute/BiteSizedTasks
> Anyway not mandatory for this patch so with the autoptr fix:
>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>
>> mask &= ~(1ULL << table->bit);
>> }
>> }
>> @@ -470,14 +469,15 @@ static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>> }
>>
>> if (mask) {
>> - old = features;
>> - features = g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64,
>> - old, *old ? ", " : "", mask);
>> - g_free(old);
>> + if (features->len > 0) {
>> + g_string_append(features, ", ");
>> + }
>> + g_string_append_printf(features,
>> + "Unknown incompatible feature: %" PRIx64, mask);
>> }
>>
>> - error_setg(errp, "Unsupported qcow2 feature(s): %s", features);
>> - g_free(features);
>> + error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
>> + g_string_free(features, TRUE);
>> }
>>
>> /*
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
2020-01-14 18:43 ` Philippe Mathieu-Daudé
@ 2020-01-14 21:35 ` Alex Bennée
2020-01-15 14:23 ` Philippe Mathieu-Daudé
0 siblings, 1 reply; 6+ messages in thread
From: Alex Bennée @ 2020-01-14 21:35 UTC (permalink / raw)
To: Philippe Mathieu-Daudé
Cc: Kevin Wolf, Alberto Garcia, qemu-devel, qemu-block, Max Reitz
Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> On 1/14/20 7:08 PM, Alex Bennée wrote:
>> Alberto Garcia <berto@igalia.com> writes:
>>
>>> This is a bit more efficient than having to allocate and free memory
>>> for each item.
>>>
>>> The default size (60) is enough for all the existing incompatible
>>> features.
>>>
>>> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>>> ---
>>> block/qcow2.c | 24 ++++++++++++------------
>>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/block/qcow2.c b/block/qcow2.c
>>> index cef9d72b3a..ecf6827420 100644
>>> --- a/block/qcow2.c
>>> +++ b/block/qcow2.c
>>> @@ -453,16 +453,15 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
>>> static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>>> uint64_t mask)
>>> {
>>> - char *features = g_strdup("");
>>> - char *old;
>>> + GString *features = g_string_sized_new(60);
>> g_autoptr(GString) features = g_string_sized_new(60);
>> will save you the clean-up later.
>
> Does this work with g_string_free() too?
It does:
static inline void g_autoptr_cleanup_gstring_free (GString *string)
{
if (string)
g_string_free (string, TRUE);
}
If you want to keep the allocated string but drop the GString you are
still best doing that yourself.
>
>>> while (table && table->name[0] != '\0') {
>>> if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
>>> if (mask & (1ULL << table->bit)) {
>>> - old = features;
>>> - features = g_strdup_printf("%s%s%.46s", old, *old ? ", " : "",
>>> - table->name);
>>> - g_free(old);
>>> + if (features->len > 0) {
>>> + g_string_append(features, ", ");
>>> + }
>>> + g_string_append_printf(features, "%.46s",
>>> table->name);
>> We have a number of cases of this sort of idiom in the code base. I
>> wonder if it calls for a utility function:
>> qemu_append_with_sep(features, ", ", "%.46s", table->name)
>
> Good idea for https://wiki.qemu.org/Contribute/BiteSizedTasks
>
>> Anyway not mandatory for this patch so with the autoptr fix:
>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>>
>>> mask &= ~(1ULL << table->bit);
>>> }
>>> }
>>> @@ -470,14 +469,15 @@ static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>>> }
>>> if (mask) {
>>> - old = features;
>>> - features = g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64,
>>> - old, *old ? ", " : "", mask);
>>> - g_free(old);
>>> + if (features->len > 0) {
>>> + g_string_append(features, ", ");
>>> + }
>>> + g_string_append_printf(features,
>>> + "Unknown incompatible feature: %" PRIx64, mask);
>>> }
>>> - error_setg(errp, "Unsupported qcow2 feature(s): %s",
>>> features);
>>> - g_free(features);
>>> + error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
>>> + g_string_free(features, TRUE);
>>> }
>>> /*
>>
--
Alex Bennée
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
2020-01-14 21:35 ` Alex Bennée
@ 2020-01-15 14:23 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-01-15 14:23 UTC (permalink / raw)
To: Alex Bennée
Cc: Kevin Wolf, Alberto Garcia, qemu-devel, qemu-block, Max Reitz
On 1/14/20 10:35 PM, Alex Bennée wrote:
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>
>> On 1/14/20 7:08 PM, Alex Bennée wrote:
>>> Alberto Garcia <berto@igalia.com> writes:
>>>
>>>> This is a bit more efficient than having to allocate and free memory
>>>> for each item.
>>>>
>>>> The default size (60) is enough for all the existing incompatible
>>>> features.
>>>>
>>>> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>>>> ---
>>>> block/qcow2.c | 24 ++++++++++++------------
>>>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/block/qcow2.c b/block/qcow2.c
>>>> index cef9d72b3a..ecf6827420 100644
>>>> --- a/block/qcow2.c
>>>> +++ b/block/qcow2.c
>>>> @@ -453,16 +453,15 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
>>>> static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>>>> uint64_t mask)
>>>> {
>>>> - char *features = g_strdup("");
>>>> - char *old;
>>>> + GString *features = g_string_sized_new(60);
>>> g_autoptr(GString) features = g_string_sized_new(60);
>>> will save you the clean-up later.
>>
>> Does this work with g_string_free() too?
>
> It does:
>
> static inline void g_autoptr_cleanup_gstring_free (GString *string)
> {
> if (string)
> g_string_free (string, TRUE);
> }
The implicit use of free_segment=TRUE was not obvious to me.
Thanks for checking it in glib source.
> If you want to keep the allocated string but drop the GString you are
> still best doing that yourself.
I agree. I asked because I had the other patch from Alberto in mind:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg669862.html
In this case we can not use the g_autoptr feature.
>>>> while (table && table->name[0] != '\0') {
>>>> if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
>>>> if (mask & (1ULL << table->bit)) {
>>>> - old = features;
>>>> - features = g_strdup_printf("%s%s%.46s", old, *old ? ", " : "",
>>>> - table->name);
>>>> - g_free(old);
>>>> + if (features->len > 0) {
>>>> + g_string_append(features, ", ");
>>>> + }
>>>> + g_string_append_printf(features, "%.46s",
>>>> table->name);
>>> We have a number of cases of this sort of idiom in the code base. I
>>> wonder if it calls for a utility function:
>>> qemu_append_with_sep(features, ", ", "%.46s", table->name)
>>
>> Good idea for https://wiki.qemu.org/Contribute/BiteSizedTasks
>>
>>> Anyway not mandatory for this patch so with the autoptr fix:
>>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>>>
>>>> mask &= ~(1ULL << table->bit);
>>>> }
>>>> }
>>>> @@ -470,14 +469,15 @@ static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
>>>> }
>>>> if (mask) {
>>>> - old = features;
>>>> - features = g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64,
>>>> - old, *old ? ", " : "", mask);
>>>> - g_free(old);
>>>> + if (features->len > 0) {
>>>> + g_string_append(features, ", ");
>>>> + }
>>>> + g_string_append_printf(features,
>>>> + "Unknown incompatible feature: %" PRIx64, mask);
>>>> }
>>>> - error_setg(errp, "Unsupported qcow2 feature(s): %s",
>>>> features);
>>>> - g_free(features);
>>>> + error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
>>>> + g_string_free(features, TRUE);
>>>> }
>>>> /*
>>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
2020-01-14 18:08 ` Alex Bennée
2020-01-14 18:43 ` Philippe Mathieu-Daudé
@ 2020-01-15 13:49 ` Alberto Garcia
1 sibling, 0 replies; 6+ messages in thread
From: Alberto Garcia @ 2020-01-15 13:49 UTC (permalink / raw)
To: Alex Bennée
Cc: Kevin Wolf, Philippe Mathieu-Daudé,
qemu-devel, qemu-block, Max Reitz
On Tue 14 Jan 2020 07:08:04 PM CET, Alex Bennée wrote:
> g_autoptr(GString) features = g_string_sized_new(60);
>
> will save you the clean-up later.
Ok, will send v2 now.
>> + if (features->len > 0) {
>> + g_string_append(features, ", ");
>> + }
>> + g_string_append_printf(features, "%.46s",
>> table->name);
>
> We have a number of cases of this sort of idiom in the code base. I
> wonder if it calls for a utility function:
>
> qemu_append_with_sep(features, ", ", "%.46s", table->name)
Maybe it's worth checking. I can have a look once this is applied (there
was another similar one in the queue already).
Berto
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-01-14 14:54 [PATCH] qcow2: Use a GString in report_unsupported_feature() Alberto Garcia
2020-01-14 18:08 ` Alex Bennée
2020-01-14 18:43 ` Philippe Mathieu-Daudé
2020-01-14 21:35 ` Alex Bennée
2020-01-15 14:23 ` Philippe Mathieu-Daudé
2020-01-15 13:49 ` Alberto Garcia
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