/*
* Clone the current process.
*
* The new thread is given a copy of the caller's file handles if RET
* is not null. (If RET is null, what we're creating is a kernel-only
* thread and it doesn't need an address space or file handles.)
* However, the new thread always inherits its current working
* directory from the caller. The new thread is given no address space
* (the caller decides that).
*/
int
proc_fork(struct proc **ret)
{
struct proc *proc;
struct filetable *tbl;
int result;
proc = proc_create(curproc->p_name);
if (proc == NULL) {
return ENOMEM;
}
/* VM fields */
/* do not clone address space -- let caller decide on that */
/* VFS fields */
tbl = curproc->p_filetable;
if (tbl != NULL) {
result = filetable_copy(tbl, &proc->p_filetable);
if (result) {
as_destroy(proc->p_addrspace);
proc->p_addrspace = NULL;
proc_destroy(proc);
return result;
}
}
spinlock_acquire(&curproc->p_lock);
/* we don't need to lock proc->p_lock as we have the only reference */
if (curproc->p_cwd != NULL) {
VOP_INCREF(curproc->p_cwd);
proc->p_cwd = curproc->p_cwd;
}
spinlock_release(&curproc->p_lock);
*ret = proc;
return 0;
}
int sys_fork(struct trapframe *tf, pid_t *retval) {
int result;
char* name;
(void) result;
(void) tf;
(void) retval;
struct trapframe *temp_tf = kmalloc(sizeof(*temp_tf));
*temp_tf = *tf;
struct proc *newproc = proc_create("forked_process");
// TODO: concurrency issue?
as_copy(curproc->p_addrspace, &newproc->p_addrspace);
newproc->p_filetable = kmalloc(sizeof(struct filetable));
newproc->p_filetable->filetable_lock = lock_create("filetable_lock");
filetable_copy(newproc->p_filetable);
// copied from proc.c init p_cwd
spinlock_acquire(&curproc->p_lock);
if (curproc->p_cwd != NULL) {
VOP_INCREF(curproc->p_cwd);
newproc->p_cwd = curproc->p_cwd;
}
spinlock_release(&curproc->p_lock);
newproc->parent_pid = curproc->pid;
name = kstrdup(curproc->p_name);
*retval = newproc->pid;
thread_fork(name, newproc ,run_forked_proc, (void *)temp_tf, 0);
return 0;
}
int
sys_fork(struct trapframe* tf, pid_t* retval)
{
DEBUG(DB_EXEC,"sys_fork(): entering\n");
KASSERT(curproc != NULL);
KASSERT(sizeof(struct trapframe)==(37*4));
char* child_name = kmalloc(sizeof(char)* NAME_MAX);
strcpy(child_name, curproc->p_name);
strcat(child_name, "_c");
// create PCB for child
struct proc* child_proc = NULL;
proc_fork(&child_proc);
if (child_proc == NULL)
{
return ENOMEM;
}
strcpy(child_proc->p_name, child_name);
KASSERT(child_proc->p_pid > 0);
// copy address space and registers from this process to child
struct addrspace* child_as = kmalloc(sizeof(struct addrspace));
if (child_as == NULL)
{
kfree(child_name);
proc_destroy(child_proc);
return ENOMEM;
}
struct trapframe* child_tf = kmalloc(sizeof(struct trapframe));
if (child_tf == NULL)
{
kfree(child_name);
as_destroy(child_as);
proc_destroy(child_proc);
return ENOMEM;
}
DEBUG(DB_EXEC,"sys_fork(): copying address space...\n");
// copy the address space just created into the child process's
// PCB structure
int result = as_copy(curproc->p_addrspace, &child_as);
if (result)
{
kfree(child_name);
as_destroy(child_as);
proc_destroy(child_proc);
return result;
}
child_proc->p_addrspace = child_as;
DEBUG(DB_EXEC,"sys_fork(): copying trapframe space...\n");
// copy this process's trapframe to the child process
memcpy(child_tf, tf, sizeof(struct trapframe));
DEBUG(DB_EXEC, "sys_fork(): copying filetable...\n");
filetable_copy(curproc->p_filetable,&child_proc->p_filetable);
DEBUG(DB_EXEC,"sys_fork(): assigning child process's parent as this process...\n");
// assign child processes parent as this process
child_proc->p_parent = curproc;
DEBUG(DB_EXEC,"sys_fork(): adding child to children procarray...\n");
result = procarray_add(&curproc->p_children, child_proc, NULL);
if (result)
{
DEBUG(DB_EXEC, "sys_fork(): failed to add child process to proc_table...\n");
}
DEBUG(DB_EXEC,"sys_fork(): allocating data...\n");
void **data = kmalloc(2*sizeof(void*));
data[0] = (void*)child_tf;
data[1] = (void*)child_as;
result = thread_fork(child_name, child_proc, &enter_forked_process, data, 0);
if (result)
{
kfree(child_name);
kfree(child_tf);
as_destroy(child_as);
proc_destroy(child_proc);
return ENOMEM;
}
*retval = child_proc->p_pid;
DEBUG(DB_EXEC, "sys_fork(): thread_fork returned: curproc=%u, child_proc=%u\n",curproc->p_pid,child_proc->p_pid);
return 0;
}
