[Android] fseeko and ftello not supported on arm32 & x86 below API level 24 without disabling _FILE_OFFSET_BITS=64

[steveisok]

From 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.

An easy solution would be to bump the min API level to 24, but that is not solely a technical decision.

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[akoeplinger]

Where are these functions used? I can't seem to find any in the runtime.

[steveisok]

It starts here

runtime/src/native/corehost/hostmisc/pal.h

Line 9 in 21e92cb

#include <fstream>

I haven't looked deeply into if we'll be able to sidestep it somehow.

[akoeplinger]

you mean just including fstream causes these functions to be used somehow?

[steveisok]

Yeah, apparently. But we can't get rid of it because fstream types are used later on in the host PAL.

Here's an example of the build error you'll get:

In file included from /Users/steve/dev/customer-runtime/src/native/corehost/hostmisc/trace.cpp:4:
  In file included from /Users/steve/dev/customer-runtime/src/native/corehost/hostmisc/trace.h:7:
  In file included from /Users/steve/dev/customer-runtime/src/native/corehost/hostmisc/pal.h:9:
  /Users/steve/android-ndk-r27c/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include/c++/v1/fstream:869:9: error: no member named 'fseeko' in the global namespace; did you mean 'fseek'?
    869 |   if (::fseeko(__file_, __width > 0 ? __width * __off : 0, __whence))
        |       ~~^
  /Users/steve/android-ndk-r27c/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include/stdio.h:207:5: note: 'fseek' declared here
    207 | int fseek(FILE* _Nonnull __fp, long __offset, int __whence);
        |     ^