From: Andrey Okoshkin <a.okoshkin@samsung.com>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: "Jeff King" <peff@peff.net>, "Junio C Hamano" <gitster@pobox.com>,
"Martin Ågren" <martin.agren@gmail.com>,
"Stefan Beller" <sbeller@google.com>,
"git@vger.kernel.org" <git@vger.kernel.org>,
vmiklos@frugalware.org
Subject: Re: [PATCH v2] merge-recursive: check GIT_MERGE_VERBOSITY only once
Date: Wed, 25 Oct 2017 15:27:44 +0300 [thread overview]
Message-ID: <84d89e54-4e72-9938-4d71-e24a0617fe82@samsung.com> (raw)
In-Reply-To: <CAPig+cRq1AEOgDoXeH-hDMvhEMnfiNK5CuSBbbio-mbHros=QQ@mail.gmail.com>
Thanks, Eric, indeed it's better to change the commit message.
25.10.2017 14:53, Eric Sunshine wrote:
> On Wed, Oct 25, 2017 at 7:39 AM, Andrey Okoshkin <a.okoshkin@samsung.com> wrote:
>> Check 'GIT_MERGE_VERBOSITY' environment variable only once in
>> init_merge_options().
>> Consequential call of getenv() may return NULL pointer.
>
> It would be particularly nice to have a more detailed explanation in
> the commit message of the potential problem this patch is trying to
> solve. Given the amount of discussion, thus far, surrounding such a
> simple patch, this cryptic warning about getenv() returning NULL upon
> second invocation is insufficient to explain why this patch is
> desirable; it merely leads to a lot of head-scratching.
>
>> However the stored pointer to the obtained getenv() result may be invalidated
>> by some other getenv() call as getenv() is not thread-safe.
>
> This is even more cryptic, as it appears to be arguing for or against
> _something_ (it's not clear what) and it seems to be talking about a
> facet of the existing code, rather than explaining why the updated
> code consumes its 'merge_verbosity' value as early as possible after
> being assigned. Perhaps this part could be reworded something like
> this:
>
> Instead, call getenv() only once, storing its value and
> consulting it as many times as needed. This update takes care
> to consume the value returned by getenv() without any
> intervening calls to getenv(), setenv(), unsetenv(), or
> putenv(), any of which might invalidate the pointer returned
> by the initial call.
>
>> Signed-off-by: Andrey Okoshkin <a.okoshkin@samsung.com>
>> Reviewed-by: Stefan Beller <sbeller@google.com>
>
> As this patch is semantically quite different from the original to
> which Stefan gave his Reviewed-by: (and which other people argued
> against), it might be better omit this footer and let him re-give it
> if he so desires.
>
>> ---
>> Changes since the previous patch:
>> * no actions are taken between the merge_verbosity assignment and check.
>> merge-recursive.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/merge-recursive.c b/merge-recursive.c
>> index 1494ffdb8..60084e3a0 100644
>> --- a/merge-recursive.c
>> +++ b/merge-recursive.c
>> @@ -2163,6 +2163,7 @@ static void merge_recursive_config(struct merge_options *o)
>>
>> void init_merge_options(struct merge_options *o)
>> {
>> + const char *merge_verbosity;
>> memset(o, 0, sizeof(struct merge_options));
>> o->verbosity = 2;
>> o->buffer_output = 1;
>> @@ -2171,9 +2172,9 @@ void init_merge_options(struct merge_options *o)
>> o->renormalize = 0;
>> o->detect_rename = 1;
>> merge_recursive_config(o);
>> - if (getenv("GIT_MERGE_VERBOSITY"))
>> - o->verbosity =
>> - strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
>> + merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
>> + if (merge_verbosity)
>> + o->verbosity = strtol(merge_verbosity, NULL, 10);
>> if (o->verbosity >= 5)
>> o->buffer_output = 0;
>> strbuf_init(&o->obuf, 0);
>> --
>> 2.14.3
>
>
>
--
Best regards,
Andrey Okoshkin
next prev parent reply other threads:[~2017-10-25 12:27 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20171024152727epcas2p4fb7dcf147e44aadf7733098151d469a5@epcas2p4.samsung.com>
2017-10-24 15:27 ` [PATCH] merge-recursive: check GIT_MERGE_VERBOSITY only once Andrey Okoshkin
2017-10-24 16:28 ` Stefan Beller
2017-10-24 16:45 ` Eric Sunshine
2017-10-24 17:11 ` Martin Ågren
2017-10-24 19:52 ` Jeff King
2017-10-25 1:48 ` Junio C Hamano
2017-10-25 4:07 ` Eric Sunshine
2017-10-25 7:27 ` Jeff King
2017-10-25 11:39 ` [PATCH v2] " Andrey Okoshkin
2017-10-25 11:53 ` Eric Sunshine
2017-10-25 12:27 ` Andrey Okoshkin [this message]
2017-10-25 13:03 ` [PATCH v3] " Andrey Okoshkin
2017-10-27 17:29 ` Stefan Beller
2017-10-30 7:42 ` [PATCH v4] " Andrey Okoshkin
2017-10-31 1:42 ` Junio C Hamano
2017-10-31 2:26 ` Junio C Hamano
2017-10-31 7:13 ` Andrey Okoshkin
2017-10-31 7:20 ` Junio C Hamano
2017-10-31 9:09 ` [PATCH v5] " Andrey Okoshkin
2017-10-25 11:13 ` [PATCH] " Andrey Okoshkin
2017-10-25 10:49 ` Andrey Okoshkin
2017-10-25 10:49 ` Andrey Okoshkin
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