mirror of
https://github.com/morgan9e/systemd
synced 2026-04-14 00:14:32 +09:00
370 lines
9.7 KiB
C
370 lines
9.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
|
|
|
|
#include "errno-util.h"
|
|
#include "fd-util.h"
|
|
#include "missing_syscall.h"
|
|
#include "missing_wait.h"
|
|
#include "parse-util.h"
|
|
#include "pidref.h"
|
|
#include "process-util.h"
|
|
#include "signal-util.h"
|
|
|
|
int pidref_set_pid(PidRef *pidref, pid_t pid) {
|
|
int fd;
|
|
|
|
assert(pidref);
|
|
|
|
if (pid < 0)
|
|
return -ESRCH;
|
|
if (pid == 0)
|
|
pid = getpid_cached();
|
|
|
|
fd = pidfd_open(pid, 0);
|
|
if (fd < 0) {
|
|
/* Graceful fallback in case the kernel doesn't support pidfds or is out of fds */
|
|
if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno) && !ERRNO_IS_RESOURCE(errno))
|
|
return -errno;
|
|
|
|
fd = -EBADF;
|
|
}
|
|
|
|
*pidref = (PidRef) {
|
|
.fd = fd,
|
|
.pid = pid,
|
|
};
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pidref_set_pidstr(PidRef *pidref, const char *pid) {
|
|
pid_t nr;
|
|
int r;
|
|
|
|
assert(pidref);
|
|
|
|
r = parse_pid(pid, &nr);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
return pidref_set_pid(pidref, nr);
|
|
}
|
|
|
|
int pidref_set_pidfd(PidRef *pidref, int fd) {
|
|
int r;
|
|
|
|
assert(pidref);
|
|
|
|
if (fd < 0)
|
|
return -EBADF;
|
|
|
|
int fd_copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
|
|
if (fd_copy < 0) {
|
|
pid_t pid;
|
|
|
|
if (!ERRNO_IS_RESOURCE(errno))
|
|
return -errno;
|
|
|
|
/* Graceful fallback if we are out of fds */
|
|
r = pidfd_get_pid(fd, &pid);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
*pidref = PIDREF_MAKE_FROM_PID(pid);
|
|
return 0;
|
|
}
|
|
|
|
return pidref_set_pidfd_consume(pidref, fd_copy);
|
|
}
|
|
|
|
int pidref_set_pidfd_take(PidRef *pidref, int fd) {
|
|
pid_t pid;
|
|
int r;
|
|
|
|
assert(pidref);
|
|
|
|
if (fd < 0)
|
|
return -EBADF;
|
|
|
|
r = pidfd_get_pid(fd, &pid);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
*pidref = (PidRef) {
|
|
.fd = fd,
|
|
.pid = pid,
|
|
};
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pidref_set_pidfd_consume(PidRef *pidref, int fd) {
|
|
int r;
|
|
|
|
r = pidref_set_pidfd_take(pidref, fd);
|
|
if (r < 0)
|
|
safe_close(fd);
|
|
|
|
return r;
|
|
}
|
|
|
|
int pidref_set_parent(PidRef *ret) {
|
|
_cleanup_(pidref_done) PidRef parent = PIDREF_NULL;
|
|
pid_t ppid;
|
|
int r;
|
|
|
|
assert(ret);
|
|
|
|
/* Acquires a pidref to our parent process. Deals with the fact that parent processes might exit, and
|
|
* we get reparented to other processes, with our old parent's PID already being recycled. */
|
|
|
|
ppid = getppid();
|
|
for (;;) {
|
|
r = pidref_set_pid(&parent, ppid);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (parent.fd < 0) /* If pidfds are not available, then we are done */
|
|
break;
|
|
|
|
pid_t now_ppid = getppid();
|
|
if (now_ppid == ppid) /* If our ppid is still the same, then we are done */
|
|
break;
|
|
|
|
/* Otherwise let's try again with the new ppid */
|
|
ppid = now_ppid;
|
|
pidref_done(&parent);
|
|
}
|
|
|
|
*ret = TAKE_PIDREF(parent);
|
|
return 0;
|
|
}
|
|
|
|
void pidref_done(PidRef *pidref) {
|
|
assert(pidref);
|
|
|
|
*pidref = (PidRef) {
|
|
.fd = safe_close(pidref->fd),
|
|
};
|
|
}
|
|
|
|
PidRef *pidref_free(PidRef *pidref) {
|
|
/* Regularly, this is an embedded structure. But sometimes we want it on the heap too */
|
|
if (!pidref)
|
|
return NULL;
|
|
|
|
pidref_done(pidref);
|
|
return mfree(pidref);
|
|
}
|
|
|
|
int pidref_copy(const PidRef *pidref, PidRef *dest) {
|
|
_cleanup_close_ int dup_fd = -EBADF;
|
|
pid_t dup_pid = 0;
|
|
|
|
assert(dest);
|
|
|
|
/* Allocates a new PidRef on the heap, making it a copy of the specified pidref. This does not try to
|
|
* acquire a pidfd if we don't have one yet!
|
|
*
|
|
* If NULL is passed we'll generate a PidRef that refers to no process. This makes it easy to copy
|
|
* pidref fields that might or might not reference a process yet. */
|
|
|
|
if (pidref) {
|
|
if (pidref->fd >= 0) {
|
|
dup_fd = fcntl(pidref->fd, F_DUPFD_CLOEXEC, 3);
|
|
if (dup_fd < 0) {
|
|
if (!ERRNO_IS_RESOURCE(errno))
|
|
return -errno;
|
|
|
|
dup_fd = -EBADF;
|
|
}
|
|
}
|
|
|
|
if (pidref->pid > 0)
|
|
dup_pid = pidref->pid;
|
|
}
|
|
|
|
*dest = (PidRef) {
|
|
.fd = TAKE_FD(dup_fd),
|
|
.pid = dup_pid,
|
|
};
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pidref_dup(const PidRef *pidref, PidRef **ret) {
|
|
_cleanup_(pidref_freep) PidRef *dup_pidref = NULL;
|
|
int r;
|
|
|
|
assert(ret);
|
|
|
|
dup_pidref = newdup(PidRef, &PIDREF_NULL, 1);
|
|
if (!dup_pidref)
|
|
return -ENOMEM;
|
|
|
|
r = pidref_copy(pidref, dup_pidref);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
*ret = TAKE_PTR(dup_pidref);
|
|
return 0;
|
|
}
|
|
|
|
int pidref_new_from_pid(pid_t pid, PidRef **ret) {
|
|
_cleanup_(pidref_freep) PidRef *n = 0;
|
|
int r;
|
|
|
|
assert(ret);
|
|
|
|
if (pid < 0)
|
|
return -ESRCH;
|
|
|
|
n = new(PidRef, 1);
|
|
if (!n)
|
|
return -ENOMEM;
|
|
|
|
*n = PIDREF_NULL;
|
|
|
|
r = pidref_set_pid(n, pid);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
*ret = TAKE_PTR(n);
|
|
return 0;
|
|
}
|
|
|
|
int pidref_kill(const PidRef *pidref, int sig) {
|
|
|
|
if (!pidref)
|
|
return -ESRCH;
|
|
|
|
if (pidref->fd >= 0)
|
|
return RET_NERRNO(pidfd_send_signal(pidref->fd, sig, NULL, 0));
|
|
|
|
if (pidref->pid > 0)
|
|
return RET_NERRNO(kill(pidref->pid, sig));
|
|
|
|
return -ESRCH;
|
|
}
|
|
|
|
int pidref_kill_and_sigcont(const PidRef *pidref, int sig) {
|
|
int r;
|
|
|
|
r = pidref_kill(pidref, sig);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (!IN_SET(sig, SIGCONT, SIGKILL))
|
|
(void) pidref_kill(pidref, SIGCONT);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pidref_sigqueue(const PidRef *pidref, int sig, int value) {
|
|
|
|
if (!pidref)
|
|
return -ESRCH;
|
|
|
|
if (pidref->fd >= 0) {
|
|
siginfo_t si;
|
|
|
|
/* We can't use structured initialization here, since the structure contains various unions
|
|
* and these fields lie in overlapping (carefully aligned) unions that LLVM is allergic to
|
|
* allow assignments to */
|
|
zero(si);
|
|
si.si_signo = sig;
|
|
si.si_code = SI_QUEUE;
|
|
si.si_pid = getpid_cached();
|
|
si.si_uid = getuid();
|
|
si.si_value.sival_int = value;
|
|
|
|
return RET_NERRNO(pidfd_send_signal(pidref->fd, sig, &si, 0));
|
|
}
|
|
|
|
if (pidref->pid > 0)
|
|
return RET_NERRNO(sigqueue(pidref->pid, sig, (const union sigval) { .sival_int = value }));
|
|
|
|
return -ESRCH;
|
|
}
|
|
|
|
int pidref_verify(const PidRef *pidref) {
|
|
int r;
|
|
|
|
/* This is a helper that is supposed to be called after reading information from procfs via a
|
|
* PidRef. It ensures that the PID we track still matches the PIDFD we pin. If this value differs
|
|
* after a procfs read, we might have read the data from a recycled PID. */
|
|
|
|
if (!pidref_is_set(pidref))
|
|
return -ESRCH;
|
|
|
|
if (pidref->pid == 1)
|
|
return 1; /* PID 1 can never go away, hence never be recycled to a different process → return 1 */
|
|
|
|
if (pidref->fd < 0)
|
|
return 0; /* If we don't have a pidfd we cannot validate it, hence we assume it's all OK → return 0 */
|
|
|
|
r = pidfd_verify_pid(pidref->fd, pidref->pid);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
return 1; /* We have a pidfd and it still points to the PID we have, hence all is *really* OK → return 1 */
|
|
}
|
|
|
|
bool pidref_is_self(const PidRef *pidref) {
|
|
if (!pidref)
|
|
return false;
|
|
|
|
return pidref->pid == getpid_cached();
|
|
}
|
|
|
|
int pidref_wait(const PidRef *pidref, siginfo_t *ret, int options) {
|
|
int r;
|
|
|
|
if (!pidref_is_set(pidref))
|
|
return -ESRCH;
|
|
|
|
if (pidref->pid == 1 || pidref->pid == getpid_cached())
|
|
return -ECHILD;
|
|
|
|
siginfo_t si = {};
|
|
|
|
if (pidref->fd >= 0) {
|
|
r = RET_NERRNO(waitid(P_PIDFD, pidref->fd, &si, options));
|
|
if (r >= 0) {
|
|
if (ret)
|
|
*ret = si;
|
|
return r;
|
|
}
|
|
if (r != -EINVAL) /* P_PIDFD was added in kernel 5.4 only */
|
|
return r;
|
|
}
|
|
|
|
r = RET_NERRNO(waitid(P_PID, pidref->pid, &si, options));
|
|
if (r >= 0 && ret)
|
|
*ret = si;
|
|
return r;
|
|
}
|
|
|
|
int pidref_wait_for_terminate(const PidRef *pidref, siginfo_t *ret) {
|
|
int r;
|
|
|
|
for (;;) {
|
|
r = pidref_wait(pidref, ret, WEXITED);
|
|
if (r != -EINTR)
|
|
return r;
|
|
}
|
|
}
|
|
|
|
static void pidref_hash_func(const PidRef *pidref, struct siphash *state) {
|
|
siphash24_compress_typesafe(pidref->pid, state);
|
|
}
|
|
|
|
static int pidref_compare_func(const PidRef *a, const PidRef *b) {
|
|
return CMP(a->pid, b->pid);
|
|
}
|
|
|
|
DEFINE_HASH_OPS(pidref_hash_ops, PidRef, pidref_hash_func, pidref_compare_func);
|
|
|
|
DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(pidref_hash_ops_free,
|
|
PidRef, pidref_hash_func, pidref_compare_func,
|
|
pidref_free);
|