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Message-ID: <431F2D6D.8000200@lapo.it>
Date: Wed, 07 Sep 2005 20:11:57 +0200
From: Lapo Luchini <lapo@lapo.it>
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To: "[ML] CygWin " <cygwin@cygwin.com>
Subject: Re: happily messing up with raw devices (aka: lseek problems)
References: <431F266D.3050604@lapo.it> <20050907174848.GR5555@calimero.vinschen.de>
In-Reply-To: <20050907174848.GR5555@calimero.vinschen.de>
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Corinna Vinschen wrote:
> I really thought you know better.

But you know that using a "user" mailing list you can't resist to do
silly question ;-)
Except jokes, what I really forgot to tell is that the program is still
that small (119 lines) that would be a good testcase in itself (and for
now it is O_RDONLY so there is no probability it will do strange things
to the hard drive).

Seek error in file [/dev/sdb] (-1/22528): Invalid argument

That would be an error 22 aka EINVAL at line 93 of gagulator.c
(which should be downloadable from here: http://tinyurl.com/77jne )

> - What about a simple testcase(tm) to demonstrate the problem?

At the bare minumum it all boils down to:

% cat short.c
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#define GAG_OFFSET 0x59BD
main() {
  char sect[512];
  int dev, i;
  dev = open("/dev/sdb", O_RDONLY | O_BINARY, 0);
  if (dev < 0) perror("open");
  i = lseek(dev, GAG_OFFSET & (~0x1FF), SEEK_SET);
  if (i < 0) perror("seek");
}
% gcc -O -ggdb -o short short.c
% ./short
seek: Invalid argument

- --
L a p o   L u c h i n i
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