Bug#871956: lintian: false positive: binary-file-built-without-LFS-support on x32
hi Adam, all,
On Sat, 2 Sep 2017, Adam Borowski wrote:
AC_SYS_LARGEFILE on i386 (linux) for mpgrafic-0.3.15-1 apparently does *not*
always do the right thing:
You call it but don't actually use what it returns:
mpicc -DHAVE_CONFIG_H -I. -I.. -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2
-fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat
-Werror=format-security -c -o parallel_io.o parallel_io.c
#define _XOPEN_SOURCE 500
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
You don't include "config.h" anywhere.
You're right - thanks for spotting that :).
Nope, you use pwrite() not pwrite64() -- on i386 you need the latter to get
LFS; they're aliases only on amd64, x32 and so on.
OK, so config.h + p(read|write)64 should hopefully solve the mpgrafic
bug. I initially tried hardwiring pwrite64 and pread64 (compiling on
amd64), but got "warning: implicit declaration of function ‘pwrite64’
[-Wimplicit-function-declaration]". My understanding is that
_FILE_OFFSET_BITS and __USE_FILE_OFFSET64 are *not* set for amd64 by
AC_SYS_LARGEFILE, and instead only set for some systems, such as i386.
The following should correctly work together with AC_SYS_LARGEFILE, it
seems to me.
Does this look OK?
#ifndef __USE_FILE_OFFSET64
i_stat=pwrite(fd,buffer,size,offset);
#else
i_stat=pwrite64(fd,buffer,size,offset);
#endif
#ifndef __USE_FILE_OFFSET64
i_stat = pread(fd,buffer,size,offset);
#else
i_stat = pread64(fd,buffer,size,offset);
#endif
But in any case, even if it had been indeed a false positive, it'd be a
different bug.
I think I should post a lintian bug for improving the info field for
the LFS unsafe detection - I spent quite a bit of time searching for how
to handle this, and having more detailed information could help other
debian contributors respond more easily to built-without-LFS-support
warnings.
Cheers
Boud
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