void __libc_init_common(KernelArgumentBlock& args) { // Initialize various globals. environ = args.envp; errno = 0; __progname = args.argv[0] ? args.argv[0] : "<unknown>"; __abort_message_ptr = args.abort_message_ptr; // Get the main thread from TLS and add it to the thread list. pthread_internal_t* main_thread = __get_thread(); __pthread_internal_add(main_thread); __system_properties_init(); // Requires 'environ'. }
void __libc_init_common(KernelArgumentBlock& args) { // Initialize various globals. environ = args.envp; errno = 0; __progname = args.argv[0] ? args.argv[0] : "<unknown>"; __abort_message_ptr = args.abort_message_ptr; // AT_RANDOM is a pointer to 16 bytes of randomness on the stack. __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM)); // Get the main thread from TLS and add it to the thread list. pthread_internal_t* main_thread = __get_thread(); __pthread_internal_add(main_thread); __system_properties_init(); // Requires 'environ'. }
int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, void* (*start_routine)(void*), void* arg) { ErrnoRestorer errno_restorer; // Inform the rest of the C library that at least one thread was created. __isthreaded = 1; pthread_attr_t thread_attr; if (attr == NULL) { pthread_attr_init(&thread_attr); } else { thread_attr = *attr; attr = NULL; // Prevent misuse below. } pthread_internal_t* thread = NULL; void* child_stack = NULL; int result = __allocate_thread(&thread_attr, &thread, &child_stack); if (result != 0) { return result; } // Create a lock for the thread to wait on once it starts so we can keep // it from doing anything until after we notify the debugger about it // // This also provides the memory barrier we need to ensure that all // memory accesses previously performed by this thread are visible to // the new thread. thread->startup_handshake_lock.init(false); thread->startup_handshake_lock.lock(); thread->start_routine = start_routine; thread->start_routine_arg = arg; thread->set_cached_pid(getpid()); int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID; void* tls = reinterpret_cast<void*>(thread->tls); #if defined(__i386__) // On x86 (but not x86-64), CLONE_SETTLS takes a pointer to a struct user_desc rather than // a pointer to the TLS itself. user_desc tls_descriptor; __init_user_desc(&tls_descriptor, false, tls); tls = &tls_descriptor; #endif int rc = clone(__pthread_start, child_stack, flags, thread, &(thread->tid), tls, &(thread->tid)); if (rc == -1) { int clone_errno = errno; // We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to // be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a // reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker. thread->startup_handshake_lock.unlock(); if (thread->mmap_size != 0) { munmap(thread->attr.stack_base, thread->mmap_size); } __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); return clone_errno; } int init_errno = __init_thread(thread); if (init_errno != 0) { // Mark the thread detached and replace its start_routine with a no-op. // Letting the thread run is the easiest way to clean up its resources. atomic_store(&thread->join_state, THREAD_DETACHED); __pthread_internal_add(thread); thread->start_routine = __do_nothing; thread->startup_handshake_lock.unlock(); return init_errno; } // Publish the pthread_t and unlock the mutex to let the new thread start running. *thread_out = __pthread_internal_add(thread); thread->startup_handshake_lock.unlock(); return 0; }