fork-journal: add helpers for spawning off journalctl from 'systemctl start' or 'systemd-run'
This is modelled after the polkit or askpw agents, but simply invokes journalctl for the specified unit name, to show logs.
This commit is contained in:
Lennart Poettering
@@ -0,0 +1,202 @@
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <sys/types.h>
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#include <unistd.h>
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#include "build-path.h"
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#include "escape.h"
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#include "event-util.h"
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#include "exit-status.h"
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#include "fd-util.h"
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#include "fork-journal.h"
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#include "log.h"
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#include "notify-recv.h"
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#include "parse-util.h"
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#include "process-util.h"
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#include "signal-util.h"
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#include "socket-util.h"
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#include "strv.h"
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static int on_child_exit(sd_event_source *s, const siginfo_t *si, void *userdata) {
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PidRef *child = ASSERT_PTR(userdata);
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assert(si);
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assert(si->si_pid == child->pid);
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/* Let's first do some debug logging about the exit status of the child */
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if (si->si_code == CLD_EXITED) {
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if (si->si_status == EXIT_SUCCESS)
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log_debug("journalctl " PID_FMT " exited successfully.", si->si_pid);
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else
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log_debug("journalctl " PID_FMT " died with a failure exit status %i, ignoring.", si->si_pid, si->si_status);
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} else if (si->si_code == CLD_KILLED)
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log_debug("journalctl " PID_FMT " was killed by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status));
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else if (si->si_code == CLD_DUMPED)
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log_debug("journalctl " PID_FMT " dumped core by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status));
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else
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log_debug("Got unexpected exit code %i via SIGCHLD, ignoring.", si->si_code);
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/* And let's then fail the whole thing, because regardless what the exit status of the child is
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* (i.e. even if successful), if it exits before sending READY=1 something is wrong. */
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return log_debug_errno(SYNTHETIC_ERRNO(EPROTO), "Child " PID_FMT " died before sending notification message.", child->pid);
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}
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static int on_child_notify(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
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PidRef *child = ASSERT_PTR(userdata);
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int r;
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assert(s);
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assert(fd >= 0);
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_cleanup_strv_free_ char **msg = NULL;
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_cleanup_(pidref_done) PidRef sender = PIDREF_NULL;
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r = notify_recv_strv(fd, &msg, /* ret_ucred= */ NULL, &sender);
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if (r == -EAGAIN)
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return 0;
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if (r < 0)
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return r;
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if (!pidref_equal(child, &sender)) {
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log_warning("Received notification message from unexpected process " PID_FMT " (expected " PID_FMT "), ignoring.",
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sender.pid, child->pid);
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return 0;
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}
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if (strv_contains(msg, "READY=1"))
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return sd_event_exit(sd_event_source_get_event(s), EXIT_SUCCESS);
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const char *e = strv_find_startswith(msg, "ERRNO=");
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if (e) {
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int error;
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r = safe_atoi(e, &error);
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if (r < 0) {
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log_debug_errno(r, "Received invalid ERRNO= notification message, ignoring: %s", e);
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return 0;
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}
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if (error <= 0) {
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log_debug("Received non-positive ERRNO= notification message, ignoring: %m");
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return 0;
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}
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return -error;
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}
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return 0;
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}
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int journal_fork(RuntimeScope scope, const char * const *units, PidRef *ret_pidref) {
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int r;
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assert(scope >= 0);
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assert(scope < _RUNTIME_SCOPE_MAX);
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assert(ret_pidref);
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if (!is_main_thread())
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return -EPERM;
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if (strv_isempty((char**) units))
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return 0;
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_cleanup_(sd_event_unrefp) sd_event *event = NULL;
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r = sd_event_new(&event);
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if (r < 0)
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return r;
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_cleanup_(sd_event_source_disable_unrefp) sd_event_source *notify_event_source = NULL;
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_cleanup_(pidref_done_sigkill_wait) PidRef child = PIDREF_NULL;
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_cleanup_free_ char *addr_string = NULL;
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r = notify_socket_prepare(
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event,
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SD_EVENT_PRIORITY_NORMAL-10, /* We want the notification message from the child before the SIGCHLD */
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on_child_notify,
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&child,
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&addr_string,
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¬ify_event_source);
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if (r < 0)
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return r;
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r = sd_event_source_set_exit_on_failure(notify_event_source, true);
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if (r < 0)
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return r;
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_cleanup_strv_free_ char **argv = strv_new(
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"journalctl",
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"-q",
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"--follow",
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"--no-pager",
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"--lines=1");
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if (!argv)
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return log_oom_debug();
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STRV_FOREACH(u, units)
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if (strv_extendf(&argv,
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scope == RUNTIME_SCOPE_SYSTEM ? "--unit=%s" : "--user-unit=%s",
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*u) < 0)
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return log_oom_debug();
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if (DEBUG_LOGGING) {
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_cleanup_free_ char *l = quote_command_line(argv, SHELL_ESCAPE_EMPTY);
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log_debug("Invoking '%s' as child.", strnull(l));
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}
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BLOCK_SIGNALS(SIGCHLD);
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r = pidref_safe_fork_full(
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"(journalctl)",
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(const int[3]) { -EBADF, STDOUT_FILENO, STDERR_FILENO },
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/* except_fds= */ NULL,
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/* n_except_fds= */ 0,
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FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_CLOSE_ALL_FDS|FORK_REARRANGE_STDIO,
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&child);
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if (r < 0)
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return r;
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if (r == 0) {
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/* In the child: */
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if (setenv("NOTIFY_SOCKET", addr_string, /* overwrite= */ true) < 0) {
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log_debug_errno(errno, "Failed to set $NOTIFY_SOCKET: %m");
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_exit(EXIT_MEMORY);
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}
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r = invoke_callout_binary(argv[0], (char**) argv);
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log_debug_errno(r, "Failed to invoke journalctl: %m");
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_exit(EXIT_EXEC);
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}
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_cleanup_(sd_event_source_disable_unrefp) sd_event_source *child_event_source = NULL;
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r = event_add_child_pidref(event, &child_event_source, &child, WEXITED, on_child_exit, &child);
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if (r < 0)
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return r;
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r = sd_event_source_set_exit_on_failure(child_event_source, true);
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if (r < 0)
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return r;
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(void) sd_event_source_set_description(child_event_source, "fork-journal-child");
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r = sd_event_loop(event);
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if (r < 0)
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return r;
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assert(r == 0);
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*ret_pidref = TAKE_PIDREF(child);
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return 0;
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}
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void journal_terminate(PidRef *pidref) {
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int r;
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if (!pidref_is_set(pidref))
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return;
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r = pidref_kill(pidref, SIGTERM);
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if (r < 0)
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log_debug_errno(r, "Failed to send SIGTERM to journalctl child " PID_FMT ", ignoring: %m", pidref->pid);
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(void) pidref_wait_for_terminate_and_check("journalctl", pidref, /* flags= */ 0);
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pidref_done(pidref);
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}
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@@ -0,0 +1,11 @@
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include "macro.h"
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#include "pidref.h"
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#include "runtime-scope.h"
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#include "set.h"
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int journal_fork(RuntimeScope scope, const char * const *units, PidRef *ret_pidref);
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void journal_terminate(PidRef *pidref);
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@@ -77,6 +77,7 @@ shared_sources = files(
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'find-esp.c',
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'firewall-util-nft.c',
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'firewall-util.c',
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'fork-journal.c',
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'format-table.c',
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'fstab-util.c',
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'generator.c',
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