From: Junio C Hamano <gitster@pobox.com>
To: Danh Doan <congdanhqx@gmail.com>
Cc: Elia Pinto <gitter.spiros@gmail.com>, git@vger.kernel.org
Subject: Re: [PATCH 31/32] commit-graph.c: fix code that could convert the result of an integer multiplication to a larger type
Date: Thu, 07 Nov 2019 12:37:00 +0900 [thread overview]
Message-ID: <xmqqtv7gs6g3.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20191107022347.GE6351@danh.dev> (Danh Doan's message of "Thu, 7 Nov 2019 09:23:47 +0700")
Danh Doan <congdanhqx@gmail.com> writes:
> On 2019-11-06 11:23:00 +0900, Junio C Hamano wrote:
>> > @@ -1454,7 +1454,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
>> > num_chunks);
>> > ctx->progress = start_delayed_progress(
>> > progress_title.buf,
>> > - num_chunks * ctx->commits.nr);
>> > + (uint64_t)num_chunks * ctx->commits.nr);
>>
>> Hmph, do we need this? I understand that the second parameter to
>> the callee is u64, so the caller needs to come up with u64 without
>> overflow, but doesn't that automatically get promoted?
>
> Neither num_chunks nor ctx->commits.nr is promoted because both of
> them are int. The result of `num_chunks * ctx->commits.nr' will be int
> and will be promoted to u64 to pass to caller.
Ah, yes. Thanks.
The commit title is about "integer multiplication", but can the same
issue arise with addition and subtraction as well, by the way?
next prev parent reply other threads:[~2019-11-07 3:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 9:59 [PATCH 30/32] ident.c: fix LGTM warning on the possible abuse of the '=' operator Elia Pinto
2019-11-04 9:59 ` [PATCH 31/32] commit-graph.c: fix code that could convert the result of an integer multiplication to a larger type Elia Pinto
2019-11-06 2:23 ` Junio C Hamano
2019-11-07 2:23 ` Danh Doan
2019-11-07 3:37 ` Junio C Hamano [this message]
2019-11-07 4:06 ` Danh Doan
2019-11-07 12:49 ` Johannes Schindelin
2019-11-07 12:45 ` Johannes Schindelin
2019-11-04 9:59 ` [PATCH 32/32] date.c: fix code that may overflow 'int' before it is converted to 'time_t' Elia Pinto
2019-11-04 10:26 ` [PATCH 30/32] ident.c: fix LGTM warning on the possible abuse of the '=' operator SZEDER Gábor
2019-11-04 13:55 ` Elia Pinto
2019-11-04 15:11 ` Phillip Wood
2019-11-04 19:55 ` Elia Pinto
2019-11-06 2:16 ` Junio C Hamano
2019-11-06 11:32 ` Johannes Schindelin
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