[Boost-bugs] [Boost C++ Libraries] #13230: _FILE_OFFSET_BITS=64 breaks compilation with Android NDK r15 and API<24

Subject: [Boost-bugs] [Boost C++ Libraries] #13230: _FILE_OFFSET_BITS=64 breaks compilation with Android NDK r15 and API<24
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-09-27 18:09:30

#13230: _FILE_OFFSET_BITS=64 breaks compilation with Android NDK r15 and API<24
------------------------------+-------------------------
 Reporter:  d.mikhirev@…      |      Owner:  Beman Dawes
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  filesystem
  Version:  Boost 1.65.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+-------------------------
 Behavior of `_FILE_OFFSET_BITS` in Android NDK is described at
 android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md

 > Android support for `_FILE_OFFSET_BITS=64` (which turns off_t into
 `off64_t` and replaces each `off_t` function with its `off64_t`
 counterpart, such as `lseek` in the source becoming `lseek64` at runtime)
 was added late. Even when it became available for the platform, it wasn‘t
 available from the NDK until !r15. Before NDK !r15, `_FILE_OFFSET_BITS=64`
 silently did nothing: all code compiled with that was actually using a
 32-bit `off_t`. With a new enough NDK, the situation becomes complicated.
 If you’re targeting an API before 21, almost all functions that take an
 `off_t` become unavailable. You‘ve asked for their 64-bit equivalents, and
 none of them (except `lseek`/`lseek64`) exist. As you increase your target
 API level, you’ll have more and more of the functions available. API 12
 adds some of the `<unistd.h>` functions, API 21 adds mmap, and by API 24
 you have everything including `<stdio.h>`.

 In `filesystem/src/operations.cpp` `_FILE_OFFSET_BITS` is unconditionally
 defined to `64` in hope that

 > at worst, these defines may have no effect

 It actually breaks compilation with Android NDK !r15 if `__ANDROID_API__`
 is less than 24.

-- 
Ticket URL: <https://svn.boost.org/trac10/boost/ticket/13230>
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