fork1 - create a new process
fork1(struct proc *p1, int flags, register_t *retval,
struct proc **rnewprocp);
fork1() creates a new process out of p1, which is assumed to be the current
process. This function is used primarily to implement the fork(2)
and vfork(2) system calls.
The flags argument controls the semantics of the fork operation, and is
made up of the bitwise-OR of the following values:
FORK_PPWAIT The parent process will sleep until the child process successfully
calls execve(2) or exits (either by a call to
_exit(2) or abnormally).
FORK_SHAREVM The child process will share the parent's virtual address
space. If this flag is not specified, the child will get a
copy-on-write snapshot of the parent's address space.
A flags value of 0 indicates a standard fork operation.
The retval argument is provided for the use of system call stubs. If
retval is not NULL, it will hold the following values after successful
completion of the fork operation:
retval This will contain the pid of the child process.
retval In the parent process, this will contain the value 0. In the
child process, this will contain 1.
User level system call stubs typically subtract 1 from retval and bitwise-AND
it with retval, thus returning the pid to the parent process
and 0 to the child.
If rnewprocp is not NULL, *rnewprocp will point to the newly created process
upon successful completion of the fork operation.
Upon successful completion of the fork operation, fork1() returns 0.
Otherwise, the following error values are returned:
[EAGAIN] The limit on the total number of system processes would be
[EAGAIN] The limit RLIMIT_NPROC on the total number of processes under
execution by this user id would be exceeded.
execve(2), fork(2), vfork(2)
BSD January 6, 1998 BSD
[ Back ]