* [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match()
@ 2024-06-18 14:36 Dmitry Antipov
2024-06-19 0:13 ` Xiubo Li
2024-06-19 12:37 ` Luis Henriques
0 siblings, 2 replies; 4+ messages in thread
From: Dmitry Antipov @ 2024-06-18 14:36 UTC (permalink / raw)
To: Xiubo Li; +Cc: ceph-devel, Dmitry Antipov
Since 'snprintf()' returns the number of characters emitted,
an extra call to 'strlen()' in 'ceph_mds_auth_match()' may
be dropped. Compile tested only.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
fs/ceph/mds_client.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index c2157f6e0c69..7224283046a7 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -5665,9 +5665,9 @@ static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
if (!_tpath)
return -ENOMEM;
/* remove the leading '/' */
- snprintf(_tpath, n, "%s/%s", spath + 1, tpath);
+ tlen = snprintf(_tpath, n, "%s/%s",
+ spath + 1, tpath);
free_tpath = true;
- tlen = strlen(_tpath);
}
/*
--
2.45.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match()
2024-06-18 14:36 [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match() Dmitry Antipov
@ 2024-06-19 0:13 ` Xiubo Li
2024-06-19 12:37 ` Luis Henriques
1 sibling, 0 replies; 4+ messages in thread
From: Xiubo Li @ 2024-06-19 0:13 UTC (permalink / raw)
To: Dmitry Antipov; +Cc: ceph-devel
On 6/18/24 22:36, Dmitry Antipov wrote:
> Since 'snprintf()' returns the number of characters emitted,
> an extra call to 'strlen()' in 'ceph_mds_auth_match()' may
> be dropped. Compile tested only.
>
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
> fs/ceph/mds_client.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index c2157f6e0c69..7224283046a7 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -5665,9 +5665,9 @@ static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
> if (!_tpath)
> return -ENOMEM;
> /* remove the leading '/' */
> - snprintf(_tpath, n, "%s/%s", spath + 1, tpath);
> + tlen = snprintf(_tpath, n, "%s/%s",
> + spath + 1, tpath);
> free_tpath = true;
> - tlen = strlen(_tpath);
> }
>
> /*
Both snprintf and strlen will return the string length without the
trailing null. So this change LGTM.
Applied to the 'testing' branch and will run the tests.
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Thanks
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match()
2024-06-18 14:36 [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match() Dmitry Antipov
2024-06-19 0:13 ` Xiubo Li
@ 2024-06-19 12:37 ` Luis Henriques
2024-06-19 13:07 ` Xiubo Li
1 sibling, 1 reply; 4+ messages in thread
From: Luis Henriques @ 2024-06-19 12:37 UTC (permalink / raw)
To: Dmitry Antipov; +Cc: Xiubo Li, ceph-devel
On Tue 18 Jun 2024 05:36:40 PM +03, Dmitry Antipov wrote;
> Since 'snprintf()' returns the number of characters emitted,
> an extra call to 'strlen()' in 'ceph_mds_auth_match()' may
> be dropped. Compile tested only.
>
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
> fs/ceph/mds_client.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index c2157f6e0c69..7224283046a7 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -5665,9 +5665,9 @@ static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
> if (!_tpath)
> return -ENOMEM;
> /* remove the leading '/' */
> - snprintf(_tpath, n, "%s/%s", spath + 1, tpath);
> + tlen = snprintf(_tpath, n, "%s/%s",
> + spath + 1, tpath);
> free_tpath = true;
> - tlen = strlen(_tpath);
> }
Unless I'm missing something, this patch is incorrect. snprintf() may not
return the actual string length *if* the output is truncated. For
example:
snprintf(str, 5, "%s", "0123456789");
snprintf() will return 10, while strlen(str) will return 4.
Cheers,
--
Luís
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match()
2024-06-19 12:37 ` Luis Henriques
@ 2024-06-19 13:07 ` Xiubo Li
0 siblings, 0 replies; 4+ messages in thread
From: Xiubo Li @ 2024-06-19 13:07 UTC (permalink / raw)
To: Luis Henriques, Dmitry Antipov; +Cc: ceph-devel
On 6/19/24 20:37, Luis Henriques wrote:
> On Tue 18 Jun 2024 05:36:40 PM +03, Dmitry Antipov wrote;
>
>> Since 'snprintf()' returns the number of characters emitted,
>> an extra call to 'strlen()' in 'ceph_mds_auth_match()' may
>> be dropped. Compile tested only.
>>
>> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
>> ---
>> fs/ceph/mds_client.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
>> index c2157f6e0c69..7224283046a7 100644
>> --- a/fs/ceph/mds_client.c
>> +++ b/fs/ceph/mds_client.c
>> @@ -5665,9 +5665,9 @@ static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
>> if (!_tpath)
>> return -ENOMEM;
>> /* remove the leading '/' */
>> - snprintf(_tpath, n, "%s/%s", spath + 1, tpath);
>> + tlen = snprintf(_tpath, n, "%s/%s",
>> + spath + 1, tpath);
>> free_tpath = true;
>> - tlen = strlen(_tpath);
>> }
> Unless I'm missing something, this patch is incorrect. snprintf() may not
> return the actual string length *if* the output is truncated. For
> example:
>
> snprintf(str, 5, "%s", "0123456789");
>
> snprintf() will return 10, while strlen(str) will return 4.
Yeah, you are correct.
Thanks Luis.
> Cheers,
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-06-19 13:07 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2024-06-18 14:36 [PATCH] ceph: avoid call to strlen() in ceph_mds_auth_match() Dmitry Antipov
2024-06-19 0:13 ` Xiubo Li
2024-06-19 12:37 ` Luis Henriques
2024-06-19 13:07 ` Xiubo Li
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