This change is intended to eliminate need to replace libc.so with libc_debug.so in order to enablememory allocation debugging.
This is also the first step towards implementing extended memoryallocation debugging using emulator's capabilities in monitoring memory access.
Some libc changes were preventing the initialization call from being made.
The basic problem appears to be that libc_init_common.c is only built once,
and it's only built for the non-debug libc.
This allows libc.so to run the C runtime initializer as soon as the
dynamic linker loads the shared library, i.e. before any other initializers
(e.g. static C++ constructors in other shared libraries the executable depends
on).
This also removes the bug where the initializers from the executable itself
were run twice: once by the dynamic linker, and another time by __libc_init
as defined by libc_init_dynamic.c
The problem was due to the fact that, in the case of dynamic executables,
the dynamic linker calls the DT_PREINIT_ARRAY, DT_INIT and DT_INIT_ARRAY
constructors when loading shared libraries and dynamic executables,
*before* calling the executable's entry point (i.e. arch-$ARCH/bionic/crtbegin_dynamic.c)
which in turns call __libc_init() in libc.so, as defined by bionic/libc_init_dynamic.c
The latter did call these constructors array again, mistakenly.
The patch also updates the documentation of many related functions.
Also adds a new section to linker/README.TXT explaining restrictions on
C library usage.
The patch has been tested on a Dream for stability issues with
proprietary blobs:
- H264 decoding works
- Camera + Video recording works
- GPS works
- Sensors work
The tests in system/extra/tests/bionic/libc/common/test_static_cpp_mutex.cpp has been
run and shows the static C++ constructor being called only once.
