Update timezone data to 2016b

  Changes affecting future time stamps

    New zones Europe/Astrakhan and Europe/Ulyanovsk for Astrakhan and
    Ulyanovsk Oblasts, Russia, both of which will switch from +03 to +04 on
    2016-03-27 at 02:00 local time.  They need distinct zones since their
    post-1970 histories disagree.  New zone Asia/Barnaul for Altai Krai and
    Altai Republic, Russia, which will switch from +06 to +07 on the same date
    and local time.  Also, Asia/Sakhalin moves from +10 to +11 on 2016-03-27
    at 02:00.  (Thanks to Alexander Krivenyshev for the heads-up, and to
    Matt Johnson and Stepan Golosunov for followup.)

    As a trial of a new system that needs less information to be made up,
    the new zones use numeric time zone abbreviations like "+04"
    instead of invented abbreviations like "ASTT".

    Haiti will not observe DST in 2016.  (Thanks to Jean Antoine via
    Steffen Thorsen.)

    Palestine's spring-forward transition on 2016-03-26 is at 01:00, not 00:00.
    (Thanks to Hannah Kreitem.) Guess future transitions will be March's last
    Saturday at 01:00, not March's last Friday at 24:00.

  Changes affecting past time stamps

    Europe/Chisinau observed DST during 1990, and switched from +04 to
    +03 at 1990-05-06 02:00, instead of switching from +03 to +02.
    (Thanks to Stepan Golosunov.)

    1991 abbreviations in Europe/Samara should be SAMT/SAMST, not
    KUYT/KUYST.  (Thanks to Stepan Golosunov.)

The update produced (apparently benign) warnings from zic as suggested here:
http://mm.icann.org/pipermail/tz-announce/2016-March/000036.html

Bug: 27656428
(cherry picked from commit 4fc72e0230732af038c5f43634b8efb84b010af2)

Change-Id: I3492fcacf2771d6cc194e4ff155a04c3817ae336
1 file changed
tree: b5b47625b7fc6b89bacb3ca3ea0920777e4a1899
  1. .clang-format
  2. .gitignore
  3. Android.mk
  4. CPPLINT.cfg
  5. CleanSpec.mk
  6. README.md
  7. benchmarks/
  8. build/
  9. libc/
  10. libdl/
  11. libm/
  12. libstdc++/
  13. linker/
  14. tests/
  15. tools/
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.