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From: "Nellis, Kenneth" <Kenneth.Nellis@xerox.com>
To: "cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: RE: open(O_RDWR) and lseek() fail
Date: Fri, 28 Mar 2014 12:53:31 +0000
Message-ID: <0D835E9B9CD07F40A48423F80D3B5A702CE06F27@USA7109MB022.na.xerox.net>
References: <20140328093110.GA23367@calimero.vinschen.de>
In-Reply-To: <20140328093110.GA23367@calimero.vinschen.de>
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From: Corinna Vinschen
> It doesn't matter what you use, it matters what the function expects.
> lseek expects off_t per POSIX:
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/lseek.html
> 
> and off_t is defined as 64 bit type.

After adding the missing unistd.h and return statements, gcc -Wall still
complains:

x.c: In function ‘main’:
x.c:12:2: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘off_t’ [-Wformat=]
  printf("pos = %d\n",lseek(f, 0l, SEEK_CUR));
  ^
x.c:12:2: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘off_t’ [-Wformat=]

So, then, after changing %d to %lld, gcc -Wall -pedantic complains:

x.c: In function ‘main’:
x.c:12:2: warning: ISO C90 does not support the ‘ll’ gnu_printf length modifier [-Wformat=]
  printf("pos = %lld\n",lseek(f, 0l, SEEK_CUR));
  ^
x.c:12:2: warning: ISO C90 does not support the ‘ll’ gnu_printf length modifier [-Wformat=]

Wondering how to printf an off_t value without the compiler complaining while
using -Wall -pedantic.

--Ken Nellis