Expose -DBUILD_WITHOUT_64BIT_OFFSET

[m-kuhn]

to allow building for 32bit Android

[rouault]

to allow building for 32bit Android

As far as I can see from https://github.com/OSGeo/gdal/runs/6955472239?check_suite_focus=true which is the autoconf Android build of https://github.com/OSGeo/gdal/blob/master/.github/workflows/android/start.sh , 64-bit I/O is correctly supported and this is a 32 bit build

checking for 64bit file io... yes
checking for stat64... yes
checking for fopen64... yes
checking for ftruncate64... yes
checking size of int... 4
checking size of unsigned long... 4
checking size of void*... 4

So I assume that there's something missing in the CMake detection logic (our CMake Android build https://github.com/OSGeo/gdal/blob/master/.github/workflows/android_cmake/start.sh is a 64-bit one)

[m-kuhn]

That's what I got here (x86-android)

[73/939] /usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ --target=i686-none-linux-android21 --gcc-toolchain=/usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64 --sysroot=/usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/sysroot -DDONT_DEPRECATE_SPRINTF -DENABLE_UFFD -DGDAL_CMAKE_BUILD -DGDAL_COMPILATION -DHAVE_LIBZ -DHAVE_ZLIB -DHAVE_ZLIB_H -DINST_DATA=\"/home/runner/work/QField/QField/vcpkg/base/packages/gdal_x86-android/share/gdal\" -DSYSCONFDIR=\"/home/runner/work/QField/QField/vcpkg/base/packages/gdal_x86-android/etc\" -DZIP_SUPPORT -I/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port -I/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/x86-android-rel/port -I/home/runner/builddir/vcpkg_installed/x86-android/include/json-c -I/home/runner/builddir/vcpkg_installed/x86-android/include -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -frtti -fexceptions  -fPIC -fstack-protector-strong  -fvisibility=hidden -O2 -DNDEBUG    -Wall -Wextra -Winit-self -Wunused-parameter -Wmissing-declarations -Wshorten-64-to-32 -Wshadow -Wshadow-field -Wmissing-include-dirs -Wformat -Werror=format-security -Wno-format-nonliteral -Werror=vla -Wdate-time -Wnull-dereference -Wextra-semi -Wcomma -Wfloat-conversion -Wdocumentation -Wno-documentation-deprecated-sync -Wunused-private-field -Wnon-virtual-dtor -Woverloaded-virtual -Wsuggest-override -fno-operator-names -Wzero-as-null-pointer-constant -Wold-style-cast -Weffc++ -pthread -std=gnu++11 -MD -MT port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o -MF port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o.d -o port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o -c /home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp
FAILED: port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o 
/usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ --target=i686-none-linux-android21 --gcc-toolchain=/usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64 --sysroot=/usr/local/lib/android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/sysroot -DDONT_DEPRECATE_SPRINTF -DENABLE_UFFD -DGDAL_CMAKE_BUILD -DGDAL_COMPILATION -DHAVE_LIBZ -DHAVE_ZLIB -DHAVE_ZLIB_H -DINST_DATA=\"/home/runner/work/QField/QField/vcpkg/base/packages/gdal_x86-android/share/gdal\" -DSYSCONFDIR=\"/home/runner/work/QField/QField/vcpkg/base/packages/gdal_x86-android/etc\" -DZIP_SUPPORT -I/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port -I/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/x86-android-rel/port -I/home/runner/builddir/vcpkg_installed/x86-android/include/json-c -I/home/runner/builddir/vcpkg_installed/x86-android/include -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -frtti -fexceptions  -fPIC -fstack-protector-strong  -fvisibility=hidden -O2 -DNDEBUG    -Wall -Wextra -Winit-self -Wunused-parameter -Wmissing-declarations -Wshorten-64-to-32 -Wshadow -Wshadow-field -Wmissing-include-dirs -Wformat -Werror=format-security -Wno-format-nonliteral -Werror=vla -Wdate-time -Wnull-dereference -Wextra-semi -Wcomma -Wfloat-conversion -Wdocumentation -Wno-documentation-deprecated-sync -Wunused-private-field -Wnon-virtual-dtor -Woverloaded-virtual -Wsuggest-override -fno-operator-names -Wzero-as-null-pointer-constant -Wold-style-cast -Weffc++ -pthread -std=gnu++11 -MD -MT port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o -MF port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o.d -o port/CMakeFiles/cpl.dir/cpl_vsil_unix_stdio_64.cpp.o -c /home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp
/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp:139:1: error: static_assert failed due to requirement 'sizeof (ftello(nullptr)) == sizeof(unsigned long long)' "File API does not seem to support 64-bit offset. If you still want to build GDAL without > 4GB file support, add the -DBUILD_WITHOUT_64BIT_OFFSET define"
static_assert( sizeof(VSI_FTELL64(nullptr)) == sizeof(vsi_l_offset),
^              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp:315:42: warning: implicit conversion loses integer precision: 'vsi_l_offset' (aka 'unsigned long long') to 'off_t' (aka 'long') [-Wshorten-64-to-32]
    const int nResult = VSI_FSEEK64( fp, nOffsetIn, nWhence );
                        ~~~~~~~~~~~      ^~~~~~~~~
/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp:422:30: warning: implicit conversion loses integer precision: 'vsi_l_offset' (aka 'unsigned long long') to 'off_t' (aka 'long') [-Wshorten-64-to-32]
        if( VSI_FSEEK64( fp, m_nOffset, SEEK_SET ) != 0 )
            ~~~~~~~~~~~      ^~~~~~~~~
/home/runner/work/QField/QField/vcpkg/base/buildtrees/gdal/src/v3.5.0RC2-9048b93868.clean/port/cpl_vsil_unix_stdio_64.cpp:484:30: warning: implicit conversion loses integer precision: 'vsi_l_offset' (aka 'unsigned long long') to 'off_t' (aka 'long') [-Wshorten-64-to-32]
        if( VSI_FSEEK64( fp, m_nOffset, SEEK_SET ) != 0 )
            ~~~~~~~~~~~      ^~~~~~~~~
3 warnings and 1 error generated.

[m-kuhn]

For reference with the same environment this also had to be disabled with autoconf.

[rouault]

Perhaps related to https://android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md : "Android does not require the _LARGEFILE_SOURCE macro to be used to make fseeko and ftello available. Instead they're always available from API level 24 where they were introduced, and never available before then." . Can you bump API level to 24 ?

[m-kuhn]

Thanks for the insights.
For the moment we try to keep old hardware running (Down to Android 5).
Especially 32 bit hardware very often runs an API level <24 (< Android 7). Given that, limitation on file size sounds preferable to me.
We'll build for newer hardware (64bit) with this flag disabled.

[rouault]

For the moment we try to keep old hardware running (Down to Android 5).

ok, makes sense.