Dear Maintainer,

v4l-utils fails to build from source on armhf and armel with the
following error:

In file included from /usr/include/features.h:393,
                 from /usr/include/arm-linux-gnueabi/bits/libc-header-start.h:33,
                 from /usr/include/stdlib.h:26,
                 from ../lib/libv4l2/v4l2convert.c:27:
/usr/include/features-time64.h:26:5: error: #error "_TIME_BITS=64 is allowed only with _FILE_OFFSET_BITS=64"
   26 | #   error "_TIME_BITS=64 is allowed only with _FILE_OFFSET_BITS=64"
      |     ^~~~~

The build logs show that the time64 flags -D_FILE_OFFSET_BITS=64
-D_TIME_BITS=64 are used as expected throughout the build process, with
the exception of v4l2convert.c.o which uses -D_FILE_OFFSET_BITS=32:

[94/286] cc -Ilib/libv4l2/v4l2convert.so.p -Ilib/libv4l2 -I../lib/libv4l2 -I../lib/include -I../include -fdiagnostics-color=always -Wall -Winvalid-pch -std=gnu99 -Wpointer-arith -D_GNU_SOURCE -DPROMOTED_MODE_T=int -DENABLE_NLS -include /<<PKGBUILDDIR>>/obj-arm-linux-gnueabihf/config.h -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -U_FILE_OFFSET_BITS -D_FILE_OFFSET_BITS=32 -D_LARGEFILE64_SOURCE -MD -MQ lib/libv4l2/v4l2convert.so.p/v4l2convert.c.o -MF lib/libv4l2/v4l2convert.so.p/v4l2convert.c.o.d -o lib/libv4l2/v4l2convert.so.p/v4l2convert.c.o -c ../lib/libv4l2/v4l2convert.c

This seems intentional, see meson.build:

  v4l2_wrapper_args = [
      # As the library needs to provide both 32-bit and 64-bit versions
      # of file operations, disable transparent large file support (fixes
      # 'Error: symbol `open64/mmap64' is already defined' compile failure
      # otherwise)
      '-U_FILE_OFFSET_BITS',
      '-D_FILE_OFFSET_BITS=32',
      '-D_LARGEFILE64_SOURCE',
  ]

https://sources.debian.org/src/v4l-utils/1.26.1-3.1/meson.build/#L51

Hello,

Bug #1065153 in libv4l reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/debian/libv4l/-/commit/c656a24b12c6256a7066117f572fabf0bdee5e73

(this message was generated automatically)
-- 
Greetings

https://bugs.debian.org/1065153

We believe that the bug you reported is fixed in the latest version of
v4l-utils, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1065153@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Gregor Jasny <gjasny@googlemail.com> (supplier of updated v4l-utils package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Fri, 01 Mar 2024 17:52:19 +0100
Source: v4l-utils
Architecture: source
Version: 1.26.1-4
Distribution: unstable
Urgency: medium
Maintainer: Gregor Jasny <gjasny@googlemail.com>
Changed-By: Gregor Jasny <gjasny@googlemail.com>
Closes: 1065153
Changes:
 v4l-utils (1.26.1-4) unstable; urgency=medium
 .
   * Avoid invalid file and time bits combination (Closes: #1065153)
Checksums-Sha1:
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 ab5f0c05d9fb195a71c2706812ef82b468baee83 23220 v4l-utils_1.26.1-4.debian.tar.xz
 dc37c15e01469fb27286d0194433992fa16a4075 18197 v4l-utils_1.26.1-4_arm64.buildinfo
Checksums-Sha256:
 6a32865ed3b91e087984e038027bceab8ba824ec31f3d29ac52e5c36cf8f3954 3242 v4l-utils_1.26.1-4.dsc
 4d0f834042eb9ad0ae0ba7d4ec409d3e96b2cf5fb3957e673ab5b2ba571d5d35 23220 v4l-utils_1.26.1-4.debian.tar.xz
 d63360d53f276140d69fceb360fb03040d10aa25fea50d53cfe2ca992c9a74d0 18197 v4l-utils_1.26.1-4_arm64.buildinfo
Files:
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 989524f95dbed9666073ed56590b437a 23220 video optional v4l-utils_1.26.1-4.debian.tar.xz
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Hello,

You're right disabling LFS was intentional. Those "wrappers" are meent
to be preloaded with LD_PRELOAD and should intercept all V4L related
calls like open, close, mmap, etc.

I believe the conflict arose because the Debian CFLAGS now define a 64
bit time_t value on 32bit architectures. I believe none of the code
within those wrappers is sensitive to time_t. Therefore I also undefined
the _TIME_BITS. That should resolve the issue for the Debian package.

For upstream the problem is a little bit trickier because the "tracer"
also uses those flags. But the tracer consists of lots of files. Maybe
those have to be split up.

Thanks,
Gregor