Re: [Info-mtools] Error when operating on large files

[Pali Rohár]

On Thursday 23 January 2020 17:01:00 Chris Lamb wrote:
> [please retain all CCs upon replying, I am not subscribed to this list]
> 
> Hi,
> 
> I'm the maintainer of the "mtools" package in Debian. The following
> bug report was just filed there which I will quote in full, but it can
> also be viewed here:
> 
>         https://bugs.debian.org/949665
> 
> > Running e.g. mdir -i $SOMEFILE@@$LARGEOFFSET fails when the offset
> > exceeds around 2GB. The error message is:
> > 
> > | seek: Invalid argument
> > | init :: could not read boot sector
> > | Cannot initialize '::'
> >
> > Using strace one can see that mtools tries to seek the image to a
> > negative offset that results from treating the desired offset as a
> > signed 32bit number.
> […]
> > Most likely, it can be fixed by adding -D_FILE_OFFSET_BITS=64 to the
> > CFLAGS.
> 
> I then briefly asked whether this would be suitable for inclusion
> upstream, to which the reporter was in agreement. Please see https://
> bugs.debian.org/949665#15 for more on this, including the sketchings
> of a patch.

Hello!

For handling problems with large files, autoconf has m4 macro:

AC_SYS_LARGEFILE

It automatically checks if some special compiler flags are needed for
handling large files and if yes, this macro automatically modifies
compiler flags.

So I think adding AC_SYS_LARGEFILE into configure.ac should fix this
problem for all platforms (supported by autoconf).

-- 
Pali Rohár
address@hidden

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