On 4/24/2019 0128 UTC, Wuweijia wrote:
Android Q
The libc source as below:
The purpose of a test case is to reproduce the problem. What you wrote fails
badly.
It does not compile, under ANY compiler: functions are used before they are
declared.
It does not have the necessary #include statements.
It is not written in C language. 'reinterpret_cast' is C++.
It is not standard C++. __has_builtin() (from Android #include) is only in the
'clang' dialect.
It uses symbols that start with underscore ('_') without understanding what it
is doing.
They're written with a leading underscore to warn you that you should not touch
them.
You should have said:
git clone https://android.googlesource.com/platform/bionic/
git clone https://android.googlesource.com/platform/system/core
===== test-libc.cpp
#include <dlfcn.h>
#include <stdio.h>
#include <stdint.h>
#include <private/bionic_ssp.h>
#include <private/__get_tls.h>
#include <private/bionic_asm_tls.h>
#include <private/bionic_globals.h>
#include <bionic/libc_init_common.h>
static void TestInitImpl() {
printf("%s enter\n", __func__);
//-----------This is most important call, If call dlopen success, and then
malloc trace is not available now; If Not success, the malloc trace is okay;
void * handle = dlopen("liblog.so", RTLD_NOW );
printf("handle:%p\n", handle);
}
__attribute__((noinline))
static void __libc_preinit_impl() {
// Register libc.so's copy of the TLS generation variable so the linker can
// update it when it loads or unloads a shared object.
TlsModules& tls_modules = __libc_shared_globals()->tls_modules;
tls_modules.generation_libc_so = &__libc_tls_generation_copy;
__libc_tls_generation_copy = tls_modules.generation;
__libc_init_globals();
__libc_init_common();
// Hooks for various libraries to let them know that we're starting up.
TestInitImpl();
}
__attribute__((constructor(1))) static void __libc_preinit() {
// The linker has initialized its copy of the global stack_chk_guard, and
filled in the main
// thread's TLS slot with that value. Initialize the local global stack guard
with its value.
__stack_chk_guard =
reinterpret_cast<uintptr_t>(__get_tls()[TLS_SLOT_STACK_GUARD]);
__libc_preinit_impl();
}
=====
export ADIR=$PWD # after "git clone" above
# -I list: Android source is crap.
test-libc.so: test-libc.cpp
clang++ -shared -fPIC -g -nostdinc \
-I$(ADIR)/bionic/libc/include \
-I$(ADIR)/bionic/libc \
-I$(ADIR)/bionic/libc/async_safe/include \
-I$(ADIR)/core/liblog/include \
-I/usr/lib/gcc/x86_64-redhat-linux/8/include \
-I/usr/include \
$< -o $@
=====
> void * handle = dlopen("liblog.so", RTLD_NOW ); -----------This is
most important call, If call dlopen success, and then malloc trace is not available now;
If Not success, the malloc trace is okay;
So calling dlopen() while still in the initialization phase of the run-time
linker,
causes trouble for valgrind. Get the source, apply a debugger, and find out
why.
Calling dlopen() from a DT_INIT, DT_INIT_ARRAY, or DT_PREINIT_ARRAY function
is a design error: the run-time linker makes NO guarantees about what happens.
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