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+#pragma once
+
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+ Copyright 2016 Michael Karcher
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sched.h>
+#include <sys/syscall.h>
+
+#include "log.h"
+#include "macro.h"
+
+/**
+ * raw_clone() - uses clone to create a new process with clone flags
+ * @flags: Flags to pass to the clone system call
+ *
+ * Uses the clone system call to create a new process with the cloning
+ * flags and termination signal passed in the flags parameter. Opposed
+ * to glibc's clone funtion, using this function does not set up a
+ * separate stack for the child, but relies on copy-on-write semantics
+ * on the one stack at a common virtual address, just as fork does.
+ *
+ * To obtain copy-on-write semantics, flags must not contain CLONE_VM,
+ * and thus CLONE_THREAD and CLONE_SIGHAND (which require CLONE_VM) are
+ * not usabale.
+ * Additionally, as this function does not pass the ptid, newtls and ctid
+ * parameters to the kernel, flags must not contain CLONE_PARENT_SETTID,
+ * CLONE_CHILD_SETTID, CLONE_CHILD_CLEARTID or CLONE_SETTLS.
+ *
+ * Returns: 0 in the child process and the child process id in the parent.
+ */
+static inline int raw_clone(unsigned long flags) {
+ assert((flags & (CLONE_VM|CLONE_PARENT_SETTID|CLONE_CHILD_SETTID|
+ CLONE_CHILD_CLEARTID|CLONE_SETTLS)) == 0);
+#if defined(__s390__) || defined(__CRIS__)
+ /* On s390 and cris the order of the first and second arguments
+ * of the raw clone() system call is reversed. */
+ return (int) syscall(__NR_clone, NULL, flags);
+#elif defined(__sparc__) && defined(__arch64__)
+ {
+ /**
+ * sparc64 always returns the other process id in %o0, and
+ * a boolean flag whether this is the child or the parent in
+ * %o1. Inline assembly is needed to get the flag returned
+ * in %o1.
+ */
+ int in_child;
+ int child_pid;
+ asm volatile("mov %2, %%g1\n\t"
+ "mov %3, %%o0\n\t"
+ "mov 0 , %%o1\n\t"
+ "t 0x6d\n\t"
+ "mov %%o1, %0\n\t"
+ "mov %%o0, %1" :
+ "=r"(in_child), "=r"(child_pid) :
+ "i"(__NR_clone), "r"(flags) :
+ "%o1", "%o0", "%g1" );
+ if (in_child)
+ return 0;
+ else
+ return child_pid;
+ }
+#else
+ return (int) syscall(__NR_clone, flags, NULL);
+#endif
+}