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review.blissroms.org / platform_bionic / dd0155f7d4853583d8d87d734908052235078311
commitdd0155f7d4853583d8d87d734908052235078311[log] [tgz]
authorNeil Fuller <nfuller@google.com>Mon Nov 07 13:24:10 2016 +0000
committerNeil Fuller <nfuller@google.com>Mon Nov 07 16:13:03 2016 +0000
treedc8ab02edb85c5905a948812470381bac35e082b
parent41e96c895b4c62ce01694968c539c0cc586432de [diff]
DO NOT MERGE : Update timezone data to 2016i.

IANA changes:

  Briefly: Cyprus split into two time zones on 2016-10-30, and Tonga
  reintroduces DST on 2016-11-06.

  Changes to future time stamps

    Pacific/Tongatapu begins DST on 2016-11-06 at 02:00, ending on
    2017-01-15 at 03:00.  Assume future observances in Tonga will be
    from the first Sunday in November through the third Sunday in
    January, like Fiji.  (Thanks to Pulu ʻAnau.)  Switch to numeric
    time zone abbreviations for this zone.

  Changes to past and future time stamps

    Northern Cyprus is now +03 year round, causing a split in Cyprus
    time zones starting 2016-10-30 at 04:00.  This creates a zone
    Asia/Famagusta.  (Thanks to Even Scharning and Matt Johnson.)

    Antarctica/Casey switched from +08 to +11 on 2016-10-22.
    (Thanks to Steffen Thorsen.)

  Changes to past time stamps

    Several corrections were made for pre-1975 time stamps in Italy.
    These affect Europe/Malta, Europe/Rome, Europe/San_Marino, and
    Europe/Vatican.

    First, the 1893-11-01 00:00 transition in Italy used the new UT
    offset (+01), not the old (+00:49:56).  (Thanks to Michael
    Deckers.)

    Second, rules for daylight saving in Italy were changed to agree
    with Italy's National Institute of Metrological Research (INRiM)
    except for 1944, as follows (thanks to Pierpaolo Bernardi, Brian
    Inglis, and Michael Deckers):

      The 1916-06-03 transition was at 24:00, not 00:00.

      The 1916-10-01, 1919-10-05, and 1920-09-19 transitions were at
      00:00, not 01:00.

      The 1917-09-30 and 1918-10-06 transitions were at 24:00, not
      01:00.

      The 1944-09-17 transition was at 03:00, not 01:00.  This
      particular change is taken from Italian law as INRiM's table,
      (which says 02:00) appears to have a typo here.  Also, keep the
      1944-04-03 transition for Europe/Rome, as Rome was controlled by
      Germany then.

      The 1967-1970 and 1972-1974 fallback transitions were at 01:00,
      not 00:00.

Bug: 32629043
Test: CtsIcuTestCases / CtsLibcoreTestCases / CtsBionicTestCases
Change-Id: Idaa395ef780c45caf9c5d15f5cb0677cec808b2b
1 file changed
tree: dc8ab02edb85c5905a948812470381bac35e082b
  1. benchmarks/
  2. build/
  3. libc/
  4. libdl/
  5. libm/
  6. libstdc++/
  7. linker/
  8. tests/
  9. tools/
  10. .clang-format
  11. .gitignore
  12. Android.mk
  13. CleanSpec.mk
  14. CPPLINT.cfg
  15. README.md
README.md

Working on bionic

What are the big pieces of bionic?

libc/ --- libc.so, libc.a

The C library. Stuff like fopen(3) and kill(2).

libm/ --- libm.so, libm.a

The math library. Traditionally Unix systems kept stuff like sin(3) and cos(3) in a separate library to save space in the days before shared libraries.

libdl/ --- libdl.so

The dynamic linker interface library. This is actually just a bunch of stubs that the dynamic linker replaces with pointers to its own implementation at runtime. This is where stuff like dlopen(3) lives.

libstdc++/ --- libstdc++.so

The C++ ABI support functions. The C++ compiler doesn't know how to implement thread-safe static initialization and the like, so it just calls functions that are supplied by the system. Stuff like __cxa_guard_acquire and __cxa_pure_virtual live here.

linker/ --- /system/bin/linker and /system/bin/linker64

The dynamic linker. When you run a dynamically-linked executable, its ELF file has a DT_INTERP entry that says "use the following program to start me". On Android, that's either linker or linker64 (depending on whether it's a 32-bit or 64-bit executable). It's responsible for loading the ELF executable into memory and resolving references to symbols (so that when your code tries to jump to fopen(3), say, it lands in the right place).

tests/ --- unit tests

The tests/ directory contains unit tests. Roughly arranged as one file per publicly-exported header file.

benchmarks/ --- benchmarks

The benchmarks/ directory contains benchmarks.

What's in libc/?

Adding system calls

Adding a system call usually involves:

  1. Add entries to SYSCALLS.TXT. See SYSCALLS.TXT itself for documentation on the format.
  2. Run the gensyscalls.py script.
  3. Add constants (and perhaps types) to the appropriate header file. Note that you should check to see whether the constants are already in kernel uapi header files, in which case you just need to make sure that the appropriate POSIX header file in libc/include/ includes the relevant file or files.
  4. Add function declarations to the appropriate header file.
  5. Add at least basic tests. Even a test that deliberately supplies an invalid argument helps check that we're generating the right symbol and have the right declaration in the header file. (And strace(1) can confirm that the correct system call is being made.)

Updating kernel header files

As mentioned above, this is currently a two-step process:

  1. Use generate_uapi_headers.sh to go from a Linux source tree to appropriate contents for external/kernel-headers/.
  2. Run update_all.py to scrub those headers and import them into bionic.

Updating tzdata

This is fully automated (and these days handled by the libcore team, because they own icu, and that needs to be updated in sync with bionic):

  1. Run update-tzdata.py in external/icu/tools/.

Verifying changes

If you make a change that is likely to have a wide effect on the tree (such as a libc header change), you should run make checkbuild. A regular make will not build the entire tree; just the minimum number of projects that are required for the device. Tests, additional developer tools, and various other modules will not be built. Note that make checkbuild will not be complete either, as make tests covers a few additional modules, but generally speaking make checkbuild is enough.

Running the tests

The tests are all built from the tests/ directory.

Device tests

$ mma
$ adb remount
$ adb sync
$ adb shell /data/nativetest/bionic-unit-tests/bionic-unit-tests32
$ adb shell \
    /data/nativetest/bionic-unit-tests-static/bionic-unit-tests-static32
# Only for 64-bit targets
$ adb shell /data/nativetest64/bionic-unit-tests/bionic-unit-tests64
$ adb shell \
    /data/nativetest64/bionic-unit-tests-static/bionic-unit-tests-static64

Host tests

The host tests require that you have lunched either an x86 or x86_64 target.

$ mma
$ mm bionic-unit-tests-run-on-host32
$ mm bionic-unit-tests-run-on-host64  # For 64-bit *targets* only.

Against glibc

As a way to check that our tests do in fact test the correct behavior (and not just the behavior we think is correct), it is possible to run the tests against the host's glibc. The executables are already in your path.

$ mma
$ bionic-unit-tests-glibc32
$ bionic-unit-tests-glibc64

Gathering test coverage

For either host or target coverage, you must first:

  • $ export NATIVE_COVERAGE=true
    • Note that the build system is ignorant to this flag being toggled, i.e. if you change this flag, you will have to manually rebuild bionic.
  • Set bionic_coverage=true in libc/Android.mk and libm/Android.mk.

Coverage from device tests

$ mma
$ adb sync
$ adb shell \
    GCOV_PREFIX=/data/local/tmp/gcov \
    GCOV_PREFIX_STRIP=`echo $ANDROID_BUILD_TOP | grep -o / | wc -l` \
    /data/nativetest/bionic-unit-tests/bionic-unit-tests32
$ acov

acov will pull all coverage information from the device, push it to the right directories, run lcov, and open the coverage report in your browser.

Coverage from host tests

First, build and run the host tests as usual (see above).

$ croot
$ lcov -c -d $ANDROID_PRODUCT_OUT -o coverage.info
$ genhtml -o covreport coverage.info # or lcov --list coverage.info

The coverage report is now available at covreport/index.html.

Attaching GDB to the tests

Bionic's test runner will run each test in its own process by default to prevent tests failures from impacting other tests. This also has the added benefit of running them in parallel, so they are much faster.

However, this also makes it difficult to run the tests under GDB. To prevent each test from being forked, run the tests with the flag --no-isolate.

32-bit ABI bugs

This probably belongs in the NDK documentation rather than here, but these are the known ABI bugs in the 32-bit ABI:

  • time_t is 32-bit. http://b/5819737. In the 64-bit ABI, time_t is 64-bit.

  • off_t is 32-bit. There is off64_t, and in newer releases there is almost-complete support for _FILE_OFFSET_BITS. Unfortunately our stdio implementation uses 32-bit offsets and -- worse -- function pointers to functions that use 32-bit offsets, so there's no good way to implement the last few pieces http://b/24807045. In the 64-bit ABI, off_t is off64_t.

  • sigset_t is too small on ARM and x86 (but correct on MIPS), so support for real-time signals is broken. http://b/5828899 In the 64-bit ABI, sigset_t is the correct size for every architecture.