When the child process terminates, a signal may be sent to the Parent_tid parent_tid See CLONE_PARENT_SETTID Of clone() and the fields in the clone_args argument supplied toįlags & ~0xff flags For most flags detailsĬhild_tid child_tid See CLONE_CHILD_SETTID The following table shows the equivalence between the arguments Structure allows for a superset of the information passed via the Packaged into the clone_args structure shown above. Individually, in the newer clone3() interface the arguments are Unlike the older clone() interface, where arguments are passed The remaining fields in the cl_args argument are discussed below.Įquivalence between clone() and clone3() arguments Otherwise, these two fields can be specified as NULL and 0, whichĬauses the child to use the same stack area as the parent (in the Specified, a stack must be explicitly allocated and specified. In the case where the CLONE_VM flag (see below) is Which points to the lowest byte of the stack area, andĬl_args.stack_size, which specifies the size of the stack inīytes. The stack for the child process is specified via cl_args.stack, Size argument permits future extensions to the clone_args Initialized to the size of this structure. The size argument that is supplied to clone3() should be U64 cgroup /* File descriptor for target cgroup U64 set_tid_size /* Number of elements in set_tid U64 stack /* Pointer to lowest byte of stack */ U64 exit_signal /* Signal to deliver to parent on U64 parent_tid /* Where to store child TID, U64 child_tid /* Where to store child TID, ![]() U64 pidfd /* Where to store PID file descriptor The cl_args argument of clone3() is a structure of the following It returns 0 in the child process and returns the PID of Specify the size of the child's stack area.Īs with fork(2), clone3() returns in both the parent and theĬhild. Separation in the use of various arguments and the ability to Improvements, including: space for additional flags bits cleaner The clone3() system call provides a superset of the functionality The remaining arguments to clone() are discussed below. Whereby the caller can inform the kernel of the size of the stack Note that clone() does not provide a means Usually points to the topmost address of the memory space set upįor the child stack. Processors that run Linux (except the HP PA processors), so stack Therefore set up memory space for the child stack and pass a Memory, it is not possible for the child process to execute in Since the child and calling process may share The stack argument specifies the location of the stack used by The child process may also terminate explicitly byĬalling exit(2) or after receiving a fatal signal. The integer returned by fn is the exit status for the child When the fn( arg) function returns, the child process terminates. (This differs from fork(2), whereĮxecution continues in the child from the point of the fork(2)Ĭall.) The arg argument is passed as the argument of the When the child process is created with the clone() wrapperįunction, it commences execution by calling the function pointed Is used when noting details that apply to all of these In the remainder of this page, the terminology "the clone call" Wrapper function the differences for the raw system call are * The glibc clone() wrapper function and the underlying systemĬall on which it is based. ![]() This page describes the following interfaces: Note that in this manual page, "calling process" normallyĬorresponds to "parent process". These systemĬalls also allow the new child process to be placed in separate Processes share the virtual address space, the table of fileĭescriptors, and the table of signal handlers. These system calls, the caller can control whether or not the two The calling process and the child process. These system calls create a new ("child") process, in a mannerīy contrast with fork(2), these system calls provide more preciseĬontrol over what pieces of execution context are shared between #include long syscall(SYS_clone3, struct clone_args * cl_args, size_t size ) Note: glibc provides no wrapper for clone3(), necessitating the #include /* Definition of SYS_* constants */ #include /* Definition of CLONE_* constants */ #include /* Definition of struct clone_args */ * For the prototype of the raw clone() system call, see NOTES */ ![]() * pid_t * parent_tid, void * tls, pid_t * child_tid */ ) #define _GNU_SOURCE #include int clone(int (* fn )(void *), void * stack, int flags, void * arg. * Prototype for the glibc wrapper function */ CLONE(2) Linux Programmer's Manual CLONE(2) NAME topĬlone, _clone2, clone3 - create a child process
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