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From:   Junio C Hamano <gitster@pobox.com>
To:     SZEDER =?utf-8?Q?G=C3=A1bor?= <szeder.dev@gmail.com>
Cc:     Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
        git@vger.kernel.org, jrnieder@gmail.com, jonathantanmy@google.com,
        sluongng@gmail.com, congdanhqx@gmail.com,
        Derrick Stolee <derrickstolee@github.com>,
        Derrick Stolee <dstolee@microsoft.com>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Todd Zullinger <tmz@pobox.com>
Subject: Re: [PATCH 5/7] maintenance: add start/stop subcommands
References: <pull.724.git.1599234126.gitgitgadget@gmail.com>
        <e02641881d998d1e6a31e941b61eb6f89d0519f7.1599234127.git.gitgitgadget@gmail.com>
        <20200908062914.GC6209@szeder.dev>
Date:   Tue, 08 Sep 2020 12:31:39 -0700
In-Reply-To: <20200908062914.GC6209@szeder.dev> ("SZEDER =?utf-8?Q?G=C3=A1?=
 =?utf-8?Q?bor=22's?= message of
        "Tue, 8 Sep 2020 08:29:14 +0200")
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SZEDER G=C3=A1bor <szeder.dev@gmail.com> writes:

>> +int cmd__crontab(int argc, const char **argv)
>> +{
>> +	char a;
>
> So 'a' is a char...
>
>> +	FILE *from, *to;
>> +
>> +	if (argc =3D=3D 3 && !strcmp(argv[2], "-l")) {
>> +		from =3D fopen(argv[1], "r");
>> +		if (!from)
>> +			return 0;
>> +		to =3D stdout;
>> +	} else if (argc =3D=3D 2) {
>> +		from =3D stdin;
>> +		to =3D fopen(argv[1], "w");
>> +	} else
>> +		return error("unknown arguments");
>> +
>> +	while ((a =3D fgetc(from)) !=3D EOF)
>
> fgetc() returns an int, which is assigned to a char, which is then
> compared to whatever EOF might be on the platform.  Apparently this
> casting and comparison doesn't work as expected on s390x (I haven't
> even tried to think it through...), and instead of detecting EOF and
> exiting we end up in an endless loop writing 0xff bytes to 'cron.txt',
> while 'git maintenance start' in vain waits for 'test-crontab' to
> exit.

Ah, is this fun with unsigned char never comparing equal to -1?