Re: [PATCH] http: fix some printf format warnings on 32-bit builds

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Nov 11, 2015, 20:31 UTC
Message-ID: <CAPig+cS54yTsZ8NWjyh6kj6nXy966EkYPHh_sjMbMcDGemnFuA@mail.gmail.com>
In-Reply-To: <56437F3F.7050305@ramsayjones.plus.com>

On Wed, Nov 11, 2015 at 12:47 PM, Ramsay Jones <ramsay@ramsayjones.plus.com> wrote:

Show 10 quoted lines

> On 11/11/15 01:22, Eric Sunshine wrote:
>> On Tue, Nov 10, 2015 at 7:23 PM, Ramsay Jones
>> <ramsay@ramsayjones.plus.com> wrote:
>> My machine is 64-bit, though, so perhaps it's misleading to
>> characterize this as a fix for 32-bit builds. In particular, off_t is
>> 'long long' on this machine, so it complains about the "long" format
>> specifier.
>
> ... but this seems to imply that sizeof(long) is 4 on your machine, right?
> (on x86_64 linux it's 8, which is why I hadn't noticed before).

This code on my Mac:

    printf("sizeof(long)=%zu\n", sizeof(long));
    printf("sizeof(long long)=%zu\n", sizeof(long long));
    printf("sizeof(off_t)=%zu\n", sizeof(off_t));

produces:

    sizeof(long)=8
    sizeof(long long)=8
    sizeof(off_t)=8

The fact that 'long' and 'long long' happen to be the same size (in this case) is immaterial. What is important is that the code is just wrong to be using the "%l" specifier for 'long' when the actual datatype is 'long long' (which is what 'off_t' is under-the-hood in this case).