Large file support on 32-bit systems

[Ralph Böhme]

On Thu, Jul 02, 2015 at 03:01:20PM +0300, Uri Simchoni wrote:
> Hi,
> 
> I detected the following large-file support bug in lib/util/util.c:
> - I have a 32-bit system
> - The configuration process added _FILE_OFFSET_BITS=64 into config.h
> (that is, it detected that the system does not support large files
> without adding something, and found the correct thing to add - so far
> so good).
> - However, in lib/util/util.c, <talloc.h> is included before
> "replace.h", and this causes off_t to be 32 bits (because what matters
> is whether _FILE_OFFSET_BITS set to 64 on the FIRST time glibc's
> features.h is included)
> - This causes  fcntl_lock() to fail on 32-bit x86 (i686), and all the
> daemons fail to run because they fail to generate a lock file.
> 
> A workaround is to add _FILE_OFFSET_BITS=64 to the external CPPFLAGS,
> but if this is the recommended method, then configure should simply
> fail if it cannot get large files, and not add stuff to config.h.
> 
> Another possible fix is to switch the order of talloc.h and replace.h
> - this is fragile and there may be other places that need fixing.
> Still this may be the right fix because if we cannot trust config.h
> then who knows what else we get wrong. In that case the question is
> how to detect files in which config.h is not first.

Maybe this would work:

$ make clean

Add something like this to the top of bin/default/include/config.h

#ifdef _YIKES
#error YIKES!
#endif

# cp /usr/include/features.h /usr/include/features.h.bak

Then add something like

#define _YIKES

$ make

Explodes right away at:
...
[ 488/2643] Compiling lib/util/util.c
In file included from ../lib/replace/replace.h:32:0,
                 from ../lib/util/util.c:26:
default/include/config.h:6:2: error: #error YIKES!
 #error YIKES!
  ^

Afaict the right thing to do is to make sure "replace.h" is included
first.

-Ralph

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