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Joachim Sauer da2082d012 Update timezone data to 2017a
IANA changes:

   Briefly: Southern Chile moves from -04/-03 to -03, and Mongolia
   discontinues DST.

   Changes to future time stamps

     Mongolia no longer observes DST.  (Thanks to Ganbold Tsagaankhuu.)

     Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
     Its clocks diverge from America/Santiago starting 2017-05-13 at
     23:00, hiving off a new zone America/Punta_Arenas.  Although the
     Chilean government says this change expires in May 2019, for now
     assume it's permanent.  (Thanks to Juan Correa and Deborah
     Goldsmith.)  This also affects Antarctica/Palmer.

   Changes to past time stamps

     Fix many entries for historical time stamps for Europe/Madrid
     before 1979, to agree with tables compiled by Pere Planesas of the
     National Astronomical Observatory of Spain.  As a side effect,
     this changes some time stamps for Africa/Ceuta before 1929, which
     are probably guesswork anyway.  (Thanks to Steve Allen and
     Pierpaolo Bernardi for the heads-ups, and to Michael Deckers for
     correcting the 1901 transition.)

     Ecuador observed DST from 1992-11-28 to 1993-02-05.
     (Thanks to Alois Treindl.)

     Asia/Atyrau and Asia/Oral were at +03 (not +04) before 1930-06-21.
     (Thanks to Stepan Golosunov.)

   Changes to past and future time zone abbreviations

     Switch to numeric time zone abbreviations for South America, as
     part of the ongoing project of removing invented abbreviations.
     This avoids the need to invent an abbreviation for the new Chilean
     new zone.  Similarly, switch from invented to numeric time zone
     abbreviations for Afghanistan, American Samoa, the Azores,
     Bangladesh, Bhutan, the British Indian Ocean Territory, Brunei,
     Cape Verde, Chatham Is, Christmas I, Cocos (Keeling) Is, Cook Is,
     Dubai, East Timor, Eucla, Fiji, French Polynesia, Greenland,
     Indochina, Iran, Iraq, Kiribati, Lord Howe, Macquarie, Malaysia,
     the Maldives, Marshall Is, Mauritius, Micronesia, Mongolia,
     Myanmar, Nauru, Nepal, New Caledonia, Niue, Norfolk I, Palau,
     Papua New Guinea, the Philippines, Pitcairn, Qatar, Réunion, St
     Pierre & Miquelon, Samoa, Saudi Arabia, Seychelles, Singapore,
     Solomon Is, Tokelau, Tuvalu, Wake, Vanuatu, Wallis & Futuna, and
     Xinjiang; for 20-minute daylight saving time in Ghana before 1943;
     for half-hour daylight saving time in Belize before 1944 and in
     the Dominican Republic before 1975; and for Canary Islands before
     1946, for Guinea-Bissau before 1975, for Iceland before 1969, for
     Indian Summer Time before 1942, for Indonesia before around 1964,
     for Kenya before 1960, for Liberia before 1973, for Madeira before
     1967, for Namibia before 1943, for the Netherlands in 1937-9, for
     Pakistan before 1971, for Western Sahara before 1977, and for
     Zaporozhye in 1880-1924.

     For Alaska time from 1900 through 1967, instead of "CAT" use the
     abbreviation "AST", the abbreviation commonly used at the time
     (Atlantic Standard Time had not been standardized yet).  Use "AWT"
     and "APT" instead of the invented abbreviations "CAWT" and "CAPT".

     Use "CST" and "CDT" instead of invented abbreviations for Macau
     before 1999 and Taiwan before 1938, and use "JST" instead of the
     invented abbreviation "JCST" for Japan and Korea before 1938.

Bug: 35861784
Test: CtsLibcoreTestCases / CtsBionicTestCases
Change-Id: I5e6bbdb93cb57f1b465913ba1b99572140400ef8
2017-03-07 13:49:53 +00:00
benchmarks Stop using __system_property_area__ 2017-03-01 20:43:42 +01:00
build Convert bionic benchmarks and tests to Android.bp 2016-07-14 12:30:12 -07:00
libc Update timezone data to 2017a 2017-03-07 13:49:53 +00:00
libdl Replace public library list with shared lib sonames (part 2/2) 2017-02-09 23:26:44 -08:00
libm Disable coverage sanitizer when address sanitizer is disabled on libm. 2016-12-01 02:23:13 -08:00
libstdc++ One NOTICE file to rule them all. 2016-10-20 11:48:55 -07:00
linker Remove g_default_ld_paths global variable 2017-03-06 13:02:29 -08:00
tests Stop using __system_property_area__ 2017-03-01 20:43:42 +01:00
tools versioner: fix darwin build. 2017-02-23 13:52:49 -08:00
.clang-format Fix .clang-format ContinuationIndentWidth. 2016-06-01 18:20:15 -07:00
.gitignore Merge memory checking functionality from sandbox 2010-02-16 11:43:18 -08:00
android-changes-for-ndk-developers.md Describe our dynamic linker compatibility policy. 2017-01-13 11:07:00 -08:00
Android.bp Use Android.soong.mk to handle mixed Android.mk and Android.bp dirs 2016-05-16 16:55:08 -07:00
Android.mk Rename Android.soong.mk to Android.mk 2016-07-11 16:54:20 -07:00
CleanSpec.mk Add CleanSpec for change bb16dcf28ee0f. 2015-12-12 17:13:29 +00:00
CPPLINT.cfg Add primitive CPPLINT.cfg. 2015-01-29 11:41:59 -08:00
PREUPLOAD.cfg Update our notice files as a pre-upload step. 2016-10-20 11:27:50 -07:00
README.md Document how to run CTS in the public documentation too. 2016-12-05 13:48:04 -08:00

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/?

libc/
  arch-arm/
  arch-arm64/
  arch-common/
  arch-mips/
  arch-mips64/
  arch-x86/
  arch-x86_64/
    # Each architecture has its own subdirectory for stuff that isn't shared
    # because it's architecture-specific. There will be a .mk file in here that
    # drags in all the architecture-specific files.
    bionic/
      # Every architecture needs a handful of machine-specific assembler files.
      # They live here.
    include/
      machine/
        # The majority of header files are actually in libc/include/, but many
        # of them pull in a <machine/something.h> for things like limits,
        # endianness, and how floating point numbers are represented. Those
        # headers live here.
    string/
      # Most architectures have a handful of optional assembler files
      # implementing optimized versions of various routines. The 
      # functions are particular favorites.
    syscalls/
      # The syscalls directories contain script-generated assembler files.
      # See 'Adding system calls' later.

  include/
    # The public header files on everyone's include path. These are a mixture of
    # files written by us and files taken from BSD.

  kernel/
    # The kernel uapi header files. These are scrubbed copies of the originals
    # in external/kernel-headers/. These files must not be edited directly. The
    # generate_uapi_headers.sh script should be used to go from a kernel tree to
    # external/kernel-headers/ --- this takes care of the architecture-specific
    # details. The update_all.py script should be used to regenerate bionic's
    # scrubbed headers from external/kernel-headers/.

  private/
    # These are private header files meant for use within bionic itself.

  dns/
    # Contains the DNS resolver (originates from NetBSD code).

  upstream-freebsd/
  upstream-netbsd/
  upstream-openbsd/
    # These directories contain unmolested upstream source. Any time we can
    # just use a BSD implementation of something unmodified, we should.
    # The structure under these directories mimics the upstream tree,
    # but there's also...
    android/
      include/
        # This is where we keep the hacks necessary to build BSD source
        # in our world. The *-compat.h files are automatically included
        # using -include, but we also provide equivalents for missing
        # header/source files needed by the BSD implementation.

  bionic/
    # This is the biggest mess. The C++ files are files we own, typically
    # because the Linux kernel interface is sufficiently different that we
    # can't use any of the BSD implementations. The C files are usually
    # legacy mess that needs to be sorted out, either by replacing it with
    # current upstream source in one of the upstream directories or by
    # switching the file to C++ and cleaning it up.

  malloc_debug/
    # The code that implements the functionality to enable debugging of
    # native allocation problems.

  stdio/
    # These are legacy files of dubious provenance. We're working to clean
    # this mess up, and this directory should disappear.

  tools/
    # Various tools used to maintain bionic.

  tzcode/
    # A modified superset of the IANA tzcode. Most of the modifications relate
    # to Android's use of a single file (with corresponding index) to contain
    # time zone data.
  zoneinfo/
    # Android-format time zone data.
    # See 'Updating tzdata' later.

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 the function name to the correct section in libc/libc.map.txt and run ./libc/tools/genversion-scripts.py.
  6. 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 that you correctly updated the maps in step 5. (You can use strace(1) to 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 # In $ANDROID_ROOT/bionic.
$ adb root && 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

Note that we use our own custom gtest runner that offers a superset of the options documented at https://github.com/google/googletest/blob/master/googletest/docs/AdvancedGuide.md#running-test-programs-advanced-options, in particular for test isolation and parallelism (both on by default).

Device tests via CTS

Most of the unit tests are executed by CTS. By default, CTS runs as a non-root user, so the unit tests must also pass when not run as root. Some tests cannot do any useful work unless run as root. In this case, the test should check getuid() == 0 and do nothing otherwise (typically we log in this case to prevent accidents!). Obviously, if the test can be rewritten to not require root, that's an even better solution.

Currently, the list of bionic CTS tests is generated at build time by running a host version of the test executable and dumping the list of all tests. In order for this to continue to work, all architectures must have the same number of tests, and the host version of the executable must also have the same number of tests.

Running the gtests directly is orders of magnitude faster than using CTS, but in cases where you really have to run CTS:

$ make cts # In $ANDROID_ROOT.
$ adb unroot # Because real CTS doesn't run as root.
# This will sync any *test* changes, but not *code* changes:
$ cts-tradefed \
    run singleCommand cts --skip-preconditions -m CtsBionicTestCases

Host tests

The host tests require that you have lunched either an x86 or x86_64 target. Note that due to ABI limitations (specifically, the size of pthread_mutex_t), 32-bit bionic requires PIDs less than 65536. To enforce this, set /proc/sys/kernel/pid_max to 65536.

$ ./tests/run-on-host.sh 32
$ ./tests/run-on-host.sh 64   # For x86_64-bit *targets* only.

You can supply gtest flags as extra arguments to this script.

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.

$ ./tests/run-on-host.sh glibc

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.

Running the benchmarks

Device benchmarks

$ mma
$ adb remount
$ adb sync
$ adb shell /data/nativetest/bionic-benchmarks/bionic-benchmarks
$ adb shell /data/nativetest64/bionic-benchmarks/bionic-benchmarks

You can use --benchmark_filter=getpid to just run benchmarks with "getpid" in their name.

Host benchmarks

See the "Host tests" section of "Running the tests" above.

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.