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From: Alejandro Colomar <colomar.6.4.3@gmail.com>
To: kbukin@gmail.com
Cc: linux-man@vger.kernel.org, mtk.manpages@gmail.com,
	"Dmitry V. Levin" <ldv@altlinux.org>
Subject: Re: [PATCH] stat.2: fixed inode printing in example program
Date: Sun, 13 Sep 2020 20:43:50 +0200	[thread overview]
Message-ID: <68e2c613-3ccf-a62d-f2ae-3e33e9450a3a@gmail.com> (raw)
In-Reply-To: <20200913182949.29815-1-kbukin@gmail.com>

> Such erroneous reporting happens for inode values greater than maximum
> value which can be stored in signed long. Casting does not seem to be
> necessary here. Printing inode as unsigned long long fixes the issue.

The cast is necessary.

Relevant standard: C18 §6.5.2.2 6

Details: 'ino_t' may (and will likely) be defined as 'unsigned long'.
If you try to print an 'unsigned long' with "%llu" you will:
- have Undefined Behavior (and a warning) if 'sizeof(long) < sizeof(long
long)'.
- have a warning if 'sizeof(long) == sizeof(long long)'.

So if you want to use 'unsigned long long', you'll need to cast.

Cheers,

Alex

  reply	other threads:[~2020-09-13 18:44 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-13 18:29 [PATCH] stat.2: fixed inode printing in example program Konstantin Bukin
2020-09-13 18:43 ` Alejandro Colomar [this message]
2020-09-13 19:32   ` Konstantin Bukin
  -- strict thread matches above, loose matches on Subject: below --
2020-09-13 15:04 Konstantin Bukin
2020-09-13 15:16 ` Dmitry V. Levin
2020-09-13 17:24   ` Konstantin Bukin
2020-09-13 17:38     ` Dmitry V. Levin
2020-09-13 18:04       ` Alejandro Colomar
2020-09-13 18:16         ` Konstantin Bukin
2020-09-13 18:30           ` Alejandro Colomar
2020-09-13 18:42             ` Konstantin Bukin
2020-09-13 18:46               ` Alejandro Colomar
2020-09-13 19:12                 ` Konstantin Bukin
2020-09-13 19:39                   ` Konstantin Bukin
2020-09-13 19:40                     ` Konstantin Bukin
2020-09-14  9:30                       ` Michael Kerrisk (man-pages)
2020-09-13 18:04       ` Konstantin Bukin

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