Lennart Poettering
3bda3f17fa
Let's start with the conversion of PID 1 to pidfds. Let's add a simple structure with just two fields that can be used to maintain a reference to arbitrary processes via both pid_t and pidfd. This is an embeddable struct, to keep it in line with where we previously used a pid_t directly to track a process. Of course, since this might contain an fd on systems where we have pidfd this structure has a proper lifecycle. (Note that this is quite different from sd_event_add_child() event source objects as that one is only for child processes and collects process results, while this infra is much simpler and more generic and can be used to reference any process, anywhere in the tree.)
146 lines
3.1 KiB
C
146 lines
3.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "errno-util.h"
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#include "fd-util.h"
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#include "missing_syscall.h"
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#include "parse-util.h"
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#include "pidref.h"
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#include "process-util.h"
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int pidref_set_pid(PidRef *pidref, pid_t pid) {
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int fd;
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assert(pidref);
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if (pid < 0)
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return -ESRCH;
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if (pid == 0)
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pid = getpid_cached();
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fd = pidfd_open(pid, 0);
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if (fd < 0) {
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/* Graceful fallback in case the kernel doesn't support pidfds or is out of fds */
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if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno) && !ERRNO_IS_RESOURCE(errno))
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return -errno;
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fd = -EBADF;
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}
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*pidref = (PidRef) {
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.fd = fd,
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.pid = pid,
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};
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return 0;
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}
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int pidref_set_pidstr(PidRef *pidref, const char *pid) {
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pid_t nr;
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int r;
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assert(pidref);
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r = parse_pid(pid, &nr);
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if (r < 0)
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return r;
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return pidref_set_pid(pidref, nr);
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}
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int pidref_set_pidfd(PidRef *pidref, int fd) {
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int r;
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assert(pidref);
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if (fd < 0)
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return -EBADF;
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int fd_copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
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if (fd_copy < 0) {
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pid_t pid;
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if (!ERRNO_IS_RESOURCE(errno))
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return -errno;
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/* Graceful fallback if we are out of fds */
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r = pidfd_get_pid(fd, &pid);
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if (r < 0)
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return r;
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*pidref = (PidRef) {
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.fd = -EBADF,
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.pid = pid,
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};
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return 0;
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}
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return pidref_set_pidfd_consume(pidref, fd_copy);
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}
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int pidref_set_pidfd_take(PidRef *pidref, int fd) {
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pid_t pid;
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int r;
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assert(pidref);
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if (fd < 0)
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return -EBADF;
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r = pidfd_get_pid(fd, &pid);
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if (r < 0)
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return r;
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*pidref = (PidRef) {
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.fd = fd,
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.pid = pid,
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};
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return 0;
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}
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int pidref_set_pidfd_consume(PidRef *pidref, int fd) {
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int r;
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r = pidref_set_pidfd_take(pidref, fd);
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if (r < 0)
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safe_close(fd);
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return r;
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}
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void pidref_done(PidRef *pidref) {
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assert(pidref);
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*pidref = (PidRef) {
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.fd = safe_close(pidref->fd),
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};
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}
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int pidref_kill(PidRef *pidref, int sig) {
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if (!pidref)
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return -ESRCH;
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if (pidref->fd >= 0)
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return RET_NERRNO(pidfd_send_signal(pidref->fd, sig, NULL, 0));
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if (pidref->pid > 0)
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return RET_NERRNO(kill(pidref->pid, sig));
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return -ESRCH;
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}
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int pidref_kill_and_sigcont(PidRef *pidref, int sig) {
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int r;
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r = pidref_kill(pidref, sig);
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if (r < 0)
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return r;
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if (!IN_SET(sig, SIGCONT, SIGKILL))
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(void) pidref_kill(pidref, SIGCONT);
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return 0;
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}
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