11a1589223
Files which are installed as-is (any .service and other unit files, .conf files, .policy files, etc), are left as is. My assumption is that SPDX identifiers are not yet that well known, so it's better to retain the extended header to avoid any doubt. I also kept any copyright lines. We can probably remove them, but it'd nice to obtain explicit acks from all involved authors before doing that.
73 lines
2.6 KiB
C
73 lines
2.6 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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Copyright 2016 Michael Karcher
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***/
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#include <sched.h>
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#include <sys/syscall.h>
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#include "log.h"
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#include "macro.h"
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/**
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* raw_clone() - uses clone to create a new process with clone flags
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* @flags: Flags to pass to the clone system call
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*
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* Uses the clone system call to create a new process with the cloning flags and termination signal passed in the flags
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* parameter. Opposed to glibc's clone funtion, using this function does not set up a separate stack for the child, but
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* relies on copy-on-write semantics on the one stack at a common virtual address, just as fork does.
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*
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* To obtain copy-on-write semantics, flags must not contain CLONE_VM, and thus CLONE_THREAD and CLONE_SIGHAND (which
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* require CLONE_VM) are not usable.
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*
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* Additionally, as this function does not pass the ptid, newtls and ctid parameters to the kernel, flags must not
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* contain CLONE_PARENT_SETTID, CLONE_CHILD_SETTID, CLONE_CHILD_CLEARTID or CLONE_SETTLS.
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*
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* Returns: 0 in the child process and the child process id in the parent.
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*/
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static inline pid_t raw_clone(unsigned long flags) {
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pid_t ret;
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assert((flags & (CLONE_VM|CLONE_PARENT_SETTID|CLONE_CHILD_SETTID|
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CLONE_CHILD_CLEARTID|CLONE_SETTLS)) == 0);
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#if defined(__s390x__) || defined(__s390__) || defined(__CRIS__)
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/* On s390/s390x and cris the order of the first and second arguments
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* of the raw clone() system call is reversed. */
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ret = (pid_t) syscall(__NR_clone, NULL, flags);
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#elif defined(__sparc__) && defined(__arch64__)
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{
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/**
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* sparc64 always returns the other process id in %o0, and
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* a boolean flag whether this is the child or the parent in
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* %o1. Inline assembly is needed to get the flag returned
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* in %o1.
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*/
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int in_child, child_pid;
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asm volatile("mov %2, %%g1\n\t"
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"mov %3, %%o0\n\t"
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"mov 0 , %%o1\n\t"
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"t 0x6d\n\t"
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"mov %%o1, %0\n\t"
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"mov %%o0, %1" :
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"=r"(in_child), "=r"(child_pid) :
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"i"(__NR_clone), "r"(flags) :
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"%o1", "%o0", "%g1" );
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ret = in_child ? 0 : child_pid;
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}
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#else
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ret = (pid_t) syscall(__NR_clone, flags, NULL);
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#endif
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if (ret == 0)
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reset_cached_pid();
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return ret;
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}
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