[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] qcow2: Use a GString in report_unsupported_feature()
From: |
Alex Bennée |
Subject: |
Re: [PATCH] qcow2: Use a GString in report_unsupported_feature() |
Date: |
Tue, 14 Jan 2020 18:08:04 +0000 |
User-agent: |
mu4e 1.3.6; emacs 28.0.50 |
Alberto Garcia <address@hidden> 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 <address@hidden>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
> 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 <address@hidden>
> 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