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/*
* Copyright (C) 2010 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#define __GNU_SOURCE 1
#include <sched.h>
#include <stdlib.h>
#include <stdarg.h>
#include "pthread_internal.h"
extern "C" pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
extern "C" __noreturn void __exit(int status);
// Called from the __bionic_clone assembler to call the thread function then exit.
extern "C" __LIBC_HIDDEN__ void __start_thread(int (*fn)(void*), void* arg) {
int status = (*fn)(arg);
__exit(status);
}
int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {
int* parent_tid = NULL;
void* new_tls = NULL;
int* child_tid = NULL;
// Extract any optional parameters required by the flags.
va_list args;
va_start(args, arg);
if ((flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
parent_tid = va_arg(args, int*);
}
if ((flags & (CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
new_tls = va_arg(args, void*);
}
if ((flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
child_tid = va_arg(args, int*);
}
va_end(args);
// Align 'child_stack' to 16 bytes.
uintptr_t child_stack_addr = reinterpret_cast<uintptr_t>(child_stack);
child_stack_addr &= ~0xf;
child_stack = reinterpret_cast<void*>(child_stack_addr);
// Remember the parent pid and invalidate the cached value while we clone.
pthread_internal_t* self = __get_thread();
pid_t parent_pid = self->invalidate_cached_pid();
// Actually do the clone.
int clone_result = __bionic_clone(flags, child_stack, parent_tid, new_tls, child_tid, fn, arg);
// We're the parent, so put our known pid back in place.
// We leave the child without a cached pid, but:
// 1. pthread_create gives its children their own pthread_internal_t with the correct pid.
// 2. fork makes a clone system call directly.
// If any other cases become important, we could use a double trampoline like __pthread_start.
self->set_cached_pid(parent_pid);
return clone_result;
}
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